Boat Fault Finding - General Technical Problems

The first thing to say is that unless you have a landline connected you can not get corrosion associated with mains power, so if you do not use a land line the corrosion must be due to something else. If you do use a landline then it would be best to have a galvanic isolator fitted into the earth system, or even better, to use an isolation transformer. There is an explanation in the Electrical Course Notes on www.reading-college.ac.uk/marine.

How new is the boat? Unless it was a very expensive hull it was likely to be covered in mill scale when the boat was built. Traditionally, in engineering, the bare steel hull would have been allowed to rust for several months, that would have loosened the mill scale so it could be disked off before painting. Mill scale falling off would be my number 1 suspect because this would also bring the blacking off with it. This is bourn out by the underlying steel being bright when exposed.

There is also an issue with the new blacking being insufficiently "worked" into the rust pits. From correspondence it would appear that if care is not taken with the first coat, the pits can be left bare, this allows rusting and would loosen any mill scale that might be present.

Blakes (the marine paint people) say that you should never wire brush as part of the preparation before blacking because this polishes the steel and prevents the blacking adhering - so it falls off. They say that you should disk the hull if you are doing any mechanical preparation.

There must also be a question over how thin each coat was and how well each coat was allowed to dry before over-coating. The coats should be fairly thin to allow complete drying and adequate time left between coats.

For a 12/24v DC earth fault to cause such problems the electricity would have to be going out of and back into the hull, via the water. As long as you only have one point where the 12/24v DC is connected to the metal-work (often on the engine block/starter motor) this is not likely to be the cause. Just make sure that your horn, tunnel light, and any other electrical items at the front of the boat have not been "earthed" to the hull. Please note that any radio aerial may well be earthing to the hull, but so is it on many boats, so is unlikely to be the cause. When we changed from positive to negative earth very many years ago the corrosion problem was very much reduced.

It might be worth while ensuring all positive wires and joints are well above bilge water level and out of the damp, although a slight leakage here is more likely to cause internal hull corrosion - do not worry, its rare.

Whilst some form of shot or grit blasting of the hull would remove the mill scale and also give the blacking a good substrate to bond to, you will almost certainly get flash rusting before coating and unless the whole process is carefully monitored you may not get optimum adhesions. One can not argue that an epoxide coating is far "better" in many respects than a conventional blacking product, cost is not one of them. They are far more resistant to abrasion than blacking, but touching up a two pack product becomes much more difficult. I have also noticed that some epoxide coatings develop a gray tinge over time. It is really up to you to work out the cost implications, but some of the prices I have seen indicate that I can have my boat blacked every three years for about 15 years for similar costs - AND I can touch up as I damage it.

Which river? Was this the boat, discussed at length on Uk.rec.waterways, on the Wey? If so I can only re-iterate that the water on the upper Wey is unlikely, in my view, to cause corrosion. The further down river one goes and the more industry the river passes through, the more likely it is to cause corrosion. Rivers like the Weaver might cause problems with salt content.

I hope this clarifies the issues, but unless I had 4mm sides and a 6mm bottom I would try a bash of DIY blacking, taking care with the aspects I have commented upon.

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The "old gasometer" waterways myth may or may not be correct and I have no way of knowing. I also have no way of knowing what grade of steel was used. As Springers were a budget maker I would take nothing for granted - especially something said by a vendor to support a sale. In any case steel bought from one batch is likely to be different from the next batch.

2. What is it blacked with? Commastic may do 4 years or more, an ordinary blacking normally is thought to do 2 to 4 years. Shot blasting and an epoxide coating may do 10 years, but cost an arm and a leg.

If you look at the magazines over a period of time you will see a number of Harborough Marine boats and Springers that are advertised as being re-bottomed, re-plated, or re-footed, so I suspect that you may have problems. One of which is that you have no idea about exactly how thick the steel is, where it is thinning and thus where to look for problems to occur.

I am very sorry, but no-one who does not have a thickness instrument can give you any meaningful info about your boat. It really was unfortunate that you did not get some sort of survey. If you were able to get a sample of the steel from your hull, you may be able to get it analysed so you know the exact grade (but I rather doubt it), but I expect that you would not be able to afford the cost.

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I had only visited the shop to by some sort of trim for the hole that I had cut in the ceiling as it looked a bit messy! Now I'm worried that I have a very expensive job on my hands and no heating until it's sorted!

I am reluctant to answer this question. I am a diesel mechanic of sorts - not a solid fuel combustion expert, and having been told that our Parkray at home that we have used for about 35 years was unsafe (by a heating "expert"), despite CO checks in both the bedroom with the chimney and the living room and absolutely no hint of problems, I am very cynical.

I think he is worried that the temperature of the flue might fall, so the gasses in the flu contract, become denser, and fall back down, out of the stove and into the room. Insulating the chimney would help minimise - not remove - this danger.

My best advice would be to talk to say Uxbridge Boat Services or another chandler specialising in stoves. If it were mine, I would cut the polystyrene away, but if you check its self extinguishing (try lighting a scrap with a match, if it goes out, it is) any overheating is likely to first show by liquid running out of the roof. Having made sure there was a good air gap around the pipe (as you have) I would cut a copper disk to fit around the chimney and cover the hole. Please make sure that all flue joints are as gas tight as you an easily make them.

May I suggest that you post this question on the internet news group uk.rec.waterways, where you will get much good, practical advice.

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If the pump is within warrantee get it changed.

If it is out of warrantee, I fear you may have problems. I know I was unable to stop a Flojet leaking that I opened up to clean the valves (also running every now and again). My neighbour in the marina is also struggling to stop one leaking - I think its the cheap plastic bodies.

If you find a new pump too costly there are a couple of things you could try.

First adjust the pressure switch down to about 10 - 15 psi. The screw is usually under a stick on label. Otherwise fit a separate pressure switch to do the same job. The lower pressure might be enough to stop the leak.

If you do this and you have an accumulator you must reset the accumulator pressure to about half pump cutout pressure for maximum benefit.

If you do not have an accumulator, fitting one (Whatever the pump manufacturer might say about the need for one) would dramatically increase the period between pump operation. This would not cure the problem because its the leak that is causing the pressure loss, but it would help to make it less intrusive in the evenings etc. If you do take this course of action I would advise that you turn the pump off at night.

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The first problem is with the water pump. When I switch it on it pumps once which I assume is normal (sorry, lots of assumptions going on here!). However it continues to do this sporadically, about every 30 seconds or so even though all the taps are switched off. I've checked that the inlet and outlet pipes are securely fastened and no air is escaping there.

The second problem I'm having is with the hot water tank. This is situated at the stern, in the engine room (the water tank is at the bow). It looks like your standard hot water tank that I have at home. There is a hose pipe fed from the bottom, the end of which goes to a bucket. This bucket has started to overflow quite badly (i.e. three or four litres were emptied from the hull this morning after only a couple of days.)

Your "hot water tank" is a calorifier that heats your hot water by using waste engine heat. On the top there should be a valve with a plastic knob on top. I think your hose is attached to this valve. The valve is a pressure relief valve that allows expanding (because of getting hotel) water to escape rather "blow up" the cylinder. It is fairly clear that this valve is leaking, thereby causing water to flow into the bucket all the time the pump is turned on.

With the pump on, give the knob on the valve some turns - it will click and water will spurt out of the hose - with a bit of luck this will flush some grit or scale off the seating and that may well cure your problem. If not, just check that water is coming from the hose all the time the pump is turned on, if so change the valve.

It is normal to have water spurting out of the hose each time the water in the tank is heated up. If the hose is not leaking all the time, you must either have a water leak else where or the non-return valves in the pump are leaking. The pump valves can be cured by fitting a plumbers non-return valve between the water tank and pump.

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What I have tried:
I have replaced the pressure relief valve. I have reduced the intervals at which the pump activates by turning the screw located on the side. I have reduced the running temp of my Alde boiler (although now I realise that the tank does the same whether the tank is hot or cold or whether the tap tuned on is hot or cold).

The system setup:
Pump - Flow King 10 1.4 bar
Accumulator - 8ltr 1.5 bar capacity
Calorifier tank - not sure of the make as very difficult to see the label. What I can see is that it has a 50lt hot water capacity & a test pressure of 3.65 bar
Pressure relief valve - 2 bar

I wondered if the pressure of the relief valve could be increased to solve the problem, or if you had any other ideas.

I suspect that the water flowing through the open tap builds up inertia, so that when the tap is closed the water continues to "rush" down the pipe and causes a pressure pulse sufficient to force the relief valve off its seat.

First I would give the plastic knob on the relief valve a few turns with the pump turn on. This will list the valve so the resultant water flow may flush any scale etc off the seating. However I do not think this will cure your problem.

Next, take a car tyre pressure gauge and measure the pressure in the accumulator with the pump off - I suspect this may be virtually zero. You need to set it to about half the pump cut out pressure. In your case it will be about 11 psi.

If that does not work I would clamp the pressure gauge to the accumulator with the pump ON. This should then read pump cut out pressure. Expect about 22psi. It could be higher if the pump pressure switch is maladjusted or faulty. Most of these pumps have an adjusting screw under the label.

In any case I would set the system to run at no more than 15psi. If the pump switch is faulty, you may find it cheaper to have an external switch fitted.

If none of this works you may have to have the accumulator moved to just before the calorifier or fit another accumulator there, however I suspect that lowering the pressure will solve it - as may not turning the taps on so far.

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If this is a boat for use under one of the UK inland navigation authorities I doubt that a plastic tank will satisfy the Boat Safety Scheme. Contact them at Watford (British Waterways should be able to give you the number). Even if it will be allowed under the revised rules, I would still fit a steel tank because that will be the type least likely to fall foul of any future revision. You also need to ensure that the filling and venting arrangements also meet the BSS.

Apart from the need to ensure such a tank is suitably fire and heat resistance I can see no reason not to use it if the boat is not subject to the BSS - however I would still go for steel.

As far as I know, most stove manufacturers will also supply a low power electric fuel pump to supply the stove.

Exactly what the advantage a separate heating oil tank will be IF the derogation in not re-negotiated must be open to question. If you use suitable central heating oil at home and are happy to decant and carry it, a separate tank will be a cost saving measure. However if you intend to replenish at marinas etc. you have to ask if it will cost effective for them to put in another diesel pump. Current thinking is that unless they have a significant throughput of diesel for boats that will still be allowed to use red diesel, most will not think it worthwhile.

You will have to decide on:
a. The likelihood of the derogation being renewed.
b. How easy it will then be to get red diesel for heating.
c. The long term trend for diesel prices.

Basically your guess will be as good as mine, however I have decided that a combination of gas for a quick warm up and solid fuel for long term use is the way I will go. If the derogation does go, I think that the need for diesel for road fuel will ensure it becomes increasingly expensive. I do know about the "mess" solid fuel stoves are supposed to create because we have used a Parkray at home for years.

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The steering on a narrow boat is so agricultural that there is very little that can go wrong with it. If the blade had been swung into something and been bent it would still (more or less) go straight ahead, but with the tiller arm off centre, so I do not think this is the problem.

All single screw boats will tend to swing one way if you let go of the tiller. This is to do with prop rotation. With a clockwise (from the back ) prop the stern will tend to swing to the right and so require slight left rudder, whilst an anti-clockwise screw would pull to the left, requiring right rudder. This tendency does not require considerable force to hold, just steady, gently pressure.

I rather suspect this occurs when you get interaction between the channel side and the hull. Often the prop draws water from between the hull and channel side without there being room for more water to flow back into the space. This causes low pressure on that side (usually the right) that "sucks" the stern to the right and causes the prow to swing to the left. When this happens considerable force is required and not always to any great effect. Sometimes throttling back may help.

I think that you are probably not very experienced narrow boaters and have yet to get to grips with the finer points of boat control on canals. Often this type of handling occurs because the boat is attempting to go too fast for the depth of water available. I know a number of places where 2mph produces handling problems.

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With a bit of luck the boat will trim down slightly by the stern - if it does not I would introduce a bit of scrap iron etc at the back to help it. It only needs to be by a very slight amount.

Now try to find a place just in front of the rear bulkhead where you can "doctor" the floor without too much cosmetic damage. This could be in the bottom of a cupboard or below steps etc.

Remove an area of floor covering and look for fixings or tap the floor to try to locate the bearers. These could be running fore & aft or crossways - a wall stud locator may also do. mark the bearers so you stay away from them.

Using either a jigsaw with a short blade (you do not know what clearance you have between floor and ballast) or a circular saw set to just about half a mm less than the thickness of the floorboards (or a router come to that) cut a rectangle out of the floor - say about 12" x 10".

If you have cut through a water pipe you will now have access to repair it. The electrical cables and gas pipes should all be much higher than bilge level.

Cut some strips of scrap wood about 2" wide to glue and screw around the hole on the underside of the hole with about 1" stand out from the edge - this will support the bit you cut out.

Now mop/sponge/pump the water out of the bilge. Expect to continue this for at least a week as the water gradually drains from other parts of the boat.

Now you must try to find out where the water came from.
Possibilities are:
Condensation running down inside of the hull (quiet likely if you are living aboard).
Leak from domestic water system - could be this if the water pump runs two or three times over night without any water use (assuming an accumulator)
Leak from shower.
Leaks from window or door joints running down inside of hull.
Leaks from instruments (depending upon boat design)
I would advise that you dry the bilge (leaving the trap up for ventilation if possible) and see if you can tie water appearing to incidents of rain (window leaks), the start of winter (condensation) or showering.

It may take several days for the water to find its way to the back of the boat.

You might also consider applying "Captain Tolly's Creeping Crack Cure" to the window frames and door surrounds (instructions on bottle - I know its not exactly best practice, but if it is a window leak and you try to remove them, you may well snap screws and have the lining fall down) - available from chandlers and it worked well for me.

Be assured that it is not likely to be a hull leak - my guess would be condensation or window leak.

Good practice would be to try the bilge ventilated by a through draught, but that is often difficult to do on a canal boat. Often the best you can do is to leave the trap open when you leave the boat.

Hi Tony,

After reading your reply I called our marina and arranged for a plumber to inspect the boat. After meeting the plumber I know the following:

The plumber removed a section of floor from the wardrobe in the aft of the boat. Ballast was not needed as the boat naturally lists to the aft. He discovered the top of a steal hollow tank with no way of getting round the sides. The boat is an ex hire boat and has 2 pump-outs each side, 3 of which are now redundant. He thought it could be a disused holding tank (he's not a boat plumber! I have no idea but it can't be a very deep holding tank, the gap between deck and bottom is about a foot). The location is not suitable to pump out the water.

We have had several domestic water leeks over the past year. The first happened after returning the boat to the canal after being in a dry dock for a week for blackening. I am told the pipes were stretched, the joints cracked and we heard the pump for 2-3 seconds every 3 hours or so. The problem was not fixed for 1 week. The wooden floor was damaged. There has been no leeks until about 1 week ago when we noticed the pump working for 3-4 seconds, longer than before. This leak prompted me looking into the bilge.

The plumber suspected the water tank. He removed the plastic bladder that had been installed in the original tank and noticed a large volume of water surrounding the bladder. He surmised that this could be a factor in the problem and pumped out the water, ascertained that the bladder was not leaking and that , in fact, the water was entering through the un-bolted down , inspection hatch that had let in rain water. He also suggested that water was "bleeding through the steal" (is that possible? It didn't look too badly corroded"

He also found a cross threaded water connection and fixed it. The bladder has not yet been replaced so we do not know if this is the cause of the new domestic water leak problem.

Finally we get the windows. We have been suffering from visible water leaks throughout the year only during heavy downpours. The boat has many large windows, 6 per side. I have inspected all of them in search of leaks many times, but cannot visible see a problem. After examining the woodwork inside the boat it can be seen that water has damaged the wood directly beneath nearly each window. I don't understand how water flows over metal and leeks through an aluminium/steel join but is it possible that each window has been letting water in even in light rain and that we only see visible drips during heavy rain?

So the question I and the "plumber" has is can 3 inches of water in a 50ft bilge accumulate through windows leaking and the 1 domestic water leak?

Answer to question - yes, very easily, especially if there is no ventilation to help dry it. I have seen boats with water over the back floor.

Have you heard of capillary action - where water is drawn into very small cracks. The slightest crack in whatever sealer that's been used between the window frame and cabin side will actually try to draw water through the crack. This is common and why I suggested Cpt. Tollys.

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I am no expert in this subject. The real experts are the anode manufacturers.

Normal corrosion requires steel (iron), water and oxygen, so remove the oxygen by coating and the corrosion is prevented - until water seeps under the coating. If something that is more reactive than steel is in contact with the water and electrically bonded (welded) to the steel, then that will tend to corrode, rather than the steel, so we use sacrificial anodes to do the job.

There is also the problem of corrosion caused by electrical flow.

For fresh water use magnesium anodes, but if you are in an area with very salt water and the magnesium is being eaten away very rapidly, you could use zinc, but it may not be so protective in clean, fresh water.

I doubt that 2 anodes at the front and two at the back would fully protect a hull that is much over 35 to 40 feet long, however a centre anode would be knocked off unless recessed into the hull. If you do that you have to consider the introduction of more welds to fail and more dissimilar metals (weld + steel plate) that may cause even more corrosion. Most narrowboats put up with incomplete protection.

Unless you have a very thin hull (6mm or less bottom plate) it is not normally thought that the bottom requires protecting, so its is only the hull sides that are blacked. In any case I understand that a 10mm bottom plate is 2mm thicker than a destroyers hull, so you need not be too concerned.

If you have a brand new hull that is still coated with mill scale it should either be left to rust for a time or ideally the hull should be shot blasted to remover the scale, otherwise the scale may cause the blacking to fall off. Not may boats are treated like this, so as long as the blacking is done regularly to re-black any parts where the scale has fallen off, it should be OK.

The "normal" periods between blacking, depending upon type of material, is probably between every two to four years. Twin pack products may last far longer, but I would be concerned over mechanical damage to the coating.

You choose your blacking, but make sure its compatible with what went on before. I think I would use something like Comastic, but it all depends upon the depth of your pocket. I think that the expensive systems still have some time to run before their true cost-benefit can be decided.

Only earth the negative side of the electrics to ONE point - usually the engine block. Doing anything other might cause electrical corrosion. Run all cables as high as possible and avoid things like "choc block" conectors in damp areas.

If you must put mains on the boat via a shore line ideally use an isolation transformer. If this is beyond your means use a Galvanic Isolator (Zinc Saver). Otherwise only use extension leads and portable appliances from shore power.

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I believe that at least some Springers simply passed their rudder stock (shaft) up through a tube, and as long as this was in regular use I do not see how it could have gone stiff - but if it was left, it is very likely to have jammed the stock & tube with rust.

There may be a top ball bearing, again if left unused and ungreased that could have rusted up, but they more usually fall apart.

With either of these systems someone may have inserted some material between stock & tube to prevent water spraying up when revving the engine and turning.

The only advice I can give is to be there when it is removed and get an explanation of what is required and why. If a new top bearing is suggested, I would advise trying to insist on a nylon one (as opposed to ball bearings).

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After visiting the boat recently I noticed that the header tank for the central heating was empty. I tried the Eberspacher and it duly failed to start - I think there is a safety cut-out on the unit for instances when there's not enough liquid (water/anti-freeze) in the circuit. Rather alarmed at this (because I know the header can store 8 litres) I immediately started looking everywhere for puddles around all accessible joints on the circuit and around the rads. I couldn't find any puddles or any signs of staining by water on the wooden floor. I filled the header with water/anti-freeze solution to halfway between max and min. I stayed on the boat for an hour and in that time the level had certainly dropped - nothing great but lets say an inch in an hour (that probably equates to at least a litre).

As I wasn't able to find any sign of leaking in the boat I assumed there must have been a problem with the unit itself. This is located in the engine room and although there was signs of dampness in the vicinity of the unit there is always lots of damp in bilges and engine rooms this time of year. The Eberspacher engineer has visited the boat and has confirmed there is no problem with the unit but agrees that we are losing water in the system somewhere. He topped up the header and I think he looked for a good 30 minutes but was unable to locate the fault or any leaking. It was suggested by someone that it may be leaking into the bilges but I'm confident all the pipe work for the circuit is above the floor rather than underneath.

I'm getting a little frustrated now because I know I'm losing water somewhere - just not sure where from? I can't fix the problem if I cannot find the fault. Have you got any tips on how I could troubleshoot this issue?

You do not say what type of calorifier you have - vertical or horizontal. If its horizontal I would suspect an internal leak. Vertical ones will also sometimes leak, but they are not as prone as horizontal ones.

I assume you have had your domestic water system turned off, so there may well be a slight leak between central heating and the domestic water system inside the calorifier.

I would find the pipes/hoses coupling the heating circuit to the calorifier and clamp or plug them. If the water still drops (having allowed for any air gradually finding its way out of the system) the the fault is not in the calorifier.

If the water does still drop, I think you need to find a way of pressurising the domestic water system, to make any leak bad enough to locate.

Another approach is to turn the domestic water pump on and see if the level in the heating header tank rises - indicating an internal calorifier leak.

You may have a single or a twin coil calorifier. If it is a single one the engine and heating water will be the same (I do not suppose you have drained your engine?). This is not usual, and would require an engine filler at heating header tank height, but if your system is like this, it could be an engine leak.

I assume that you have checked you accommodation bilge for water/antifreeze mixture.

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You tell me very little, so I must make a lot of assumptions. I assume its grp and that its driven by an outboard.

1. It is not very likely that the cabin floor is the actual hull of the boat, although it may well be if it is angled upwards at the edges.

2. The space between the floor and the bottom of the boat is called the bilges and these can & do fill up with water from rain in the cockpit, leaky windows, poorly bedded handrails and other deck fittings, leaking fresh water pipes/tank and so on.

3. You may have a sealed bulkhead between cabin and cockpit, or you may not, or it may have been once, but now leaks. You need to establish exactly what you have at this point. If it does have a sealed bulkhead somewhere close to the back of the cabin there should be a plate you can lift up to inspect and pump out the bilges - it is possible that this is what your "plug" is, but if its in the galley I would suspect its the remains of a fresh water foot pump for the sink outlet. The plate might be under a stem or at the base of a built in unit or something. If you can find this it should be easy to simply pump/sponge the bilge dry.

I would advise against you trying to cut one because you do not know how much clearance there is between the floor and hull, and a mis-placed drill or jigsaw would ensure rather rapid immersion;-)

If it is a single bilge boat with one bilge running the fill length of the boat, I would expect the way in to be in the cockpit area

A suitable simple hand bilge pump should cost no more than £20.

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From memory some Gardners did not use thermostats and in this case using the water to heat anything else could lead to over cooling and all that brings - as could running the engine at the low canal power and speeds!

I think one of the Gardner specialist does a thermostat conversion so as long as the engine either has a thermostat as standard or is fitted with a conversion, I see no reason not to use the engine to heat the domestic water.

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The Buckingham is a GRP boat, but I have never inspected one in great detail so I can not be 100% sure about its design.

Whilst steel, rear cockpit, narrow beam boats usually have two independent bilges, GRP ones often do not. The area between the hole" and the bottom of the is the bilge. It is normal for bilges to collect water, although the bilges under accommodation should only collect spillages, leaks from pipe & showers, leaks from windows and condensation. Without leaks this is normally minimal. he undercockpit bilge usually does fill up with water from rain etc. and requires regular checking and pumping out (all through the inter I visit my boat every two to three weeks to check the bilges, un up the engine, and charge the batteries) otherwise the water is likely to overflow into the engine drip tray and spread oil all over the lace.

Make sure the are under the cockpit is pumped & then sponged out. Look forward (& aft if it is a centre cockpit boat), along the hull. If the bulkhead(s) separating this space from the rest of the boat join the hull, without holes, and with a "glassed over" joint, then you have two separate bilges,. If there are holes, or the bulkhead(s) finish at floor level then you have an all in one bilge.

All in one bilges will normally be drained from the cockpit area. so just pump this out and the water under the floor should go.

If you have separate bilges, both need pumping out and a careful watch kept on the cabin bilge to see how fast the water comes back, if it fills up over a few weeks, after three weekly pumping outs, you have a leakage problem that needs looking at. I rather suspect that after a couple of pump outs the water will only need pumping out every 6 months or so.

This will make the boat ride higher, and as its GRP and light, it will be more subject to the wind. You may find, once you remove the carpets, that you have floor boards that can be removed - if so you could use the underfloor space for concrete or steel ballast.

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I was wondering is this the case and if so what should I buy, how much should I use and when is the best time to add it?

If there was evidence of brownish slime (rather than brownish water) then the mechanic was correct.

If you can keep water out of your tank you will not get this problem, however that is nearly impossible.

I do not see how the slime would block the pump inlet valve, this is a mechanical valve with a spring - I do see how flakes of rust would do it though. I trust he also changed your fuel filter and any "pre-filters" (stretching the word filter a bit) you have. If he did not and it is the bug expect more trouble.

There are two methods of combating the bug. One is a biocide, but I fear microbes could mutate to be tolerant of anything used long term. Other products remove the water, and some do both.

I personally use Fuelset because its in an easy dose container, but there are others. Fuelset removes the water.

If the diagnosis was correct I would give the tank a strong dose of the biocide type (read the label) and then use a water removing one regularly.

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How much of a concern is this? Is it worth bringing it out again and redoing it or is it okay to leave it until next year. A surveyor I spoke to said that untreated steel loses 0.17mm a year through corrosion, is it likely to be more than that?

It is not altogether clear that it is being caused by excess thickness.

If the "new" plates were covered with mill scale, or if the welds did not have the scale and flux properly removed that could equally be the cause. Were the new plates shot blasted or disked off before blacking - if not expect more of it.

If you have a shore power connection without some form of "earth" isolation (this does not mean disconnect the mains earth wire), that again can cause what you describe, as can overlarge anodes, but suspect the latter will be rare on a narrowboat.

I think the surveyor was being less than competent in giving you a corrosion figure - it all depends upon the water you are floating in (pollution, salt content, temperature, etc.) and even what you are tied up to and other boats around you.

I would hope your replating was done in 6mm, so using your surveyors figures, you have over 30 years before it will perforate - give or take a few years. If it was not 6mm you could work out how long it will take to fail.

If you have diy facilities and can afford the docking fee, I would look at it again next year - simply to remove a nagging worry. Otherwise I can not see leaving a year or two will make any significant difference.

By the way - never simply rotary wire brush the scale/rust of a hull you are going to black. This can/will polish the metal so the blacking does not adhere properly - it tends to fall off. By all means wire brush to remove the worst of the rust, but then disc to key the metal.

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I am busy installing two 25 gal plastic truck diesel tanks in the engine section of the cruiser style boat. They are brand new Iveco tanks jettisoned 'cos they are too small and drivers love big polished ally ones. Is this OK or is plastic a no-no?

If not going on inland waters and as long as there is no fire - Yes. If using inland waters the Boat Safety Scheme says a very big NO -its the fire thing.

May I suggest that you contact the Boat Safety Scheme Office and British Waterways, Watford and ask if they can let you have a paper copy of the scheme. I am fairly certain they have a downloadable version as well, but BW are messing about with a new site and url, so you might have problems finding it. (Try www.waterscape.com)

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 I continue to be amazed at the plumbing on boats. I suspect that if you trace the pipe from the pump you will find it goes to the galley first, and the the heads (bathroom for the NB readers). I also suspect that if you look at the pipework, you will find it is some odd plastic system. I think you are simply suffering from too small a pipe diameter. Add the propensity of yard staff/owners to add quantities of "sealer" to joints and you have restricted water flow.

My advice would be to check the pipework by physically removing it and checking for size of bore, crushing on bends, blocking in connectors. In fact, I would (if it worried me, and by boats the same & its too much trouble) repipe the system, using large diameter pipes and proper connectors to go around corners. the equivalent of 15mm copper pipe bore should be the minimum, and it might make sense to pipe the run to the calorifier and then to the first hot tap in 22mm equivalent.

The pump "not running smoothly" when feeding the heads (without hearing it) is probably just the pressure switch turning on and off as the pump builds up pressure against the pipe restriction.

I have no answer to why the pump did not force water through the calorifier, because unless there was a physical restriction (not air), it should. I suspect you have a non-return valve mounted at the cold water inlet to the calorifier, and that this stuck closed. Banging the pipes may have freed it. I have had to remove the hose/pipe and poke the valve with a small screwdriver under similar circumstances in the past.

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Our problem now is that on checking that the pump was working correctly, the water ran through to the taps but the supply only lasted for a matter of a minute before drying up. Once the tap had been turned off for a couple of minutes and then back on the water again only ran for about a minute. This happened with both hot and cold taps. We have filled up the water and the batteries seem to be charging as the lights are 'powered up'.

We have 2 pumps (one hot & one cold). Someone told us that it would take a couple of minutes for the water to flow through to the accumulator tank but this did not make any difference.

I think both problems might be related, but can not be sure without more information.
1. Is the engine running or stationary when you tried the water pump?
2. Exactly what did the pumps do when the water stopped flowing?

I, personally have never heard of a system with separate pumps for hot and cold water, but it does not mean they do not exist, especially on large boats with lots of taps. A number of hire fleets do fit two pumps in parallel with a switch wired so that one or the other works at any one time. This saves a callout when one pump fails.

Batteries that need lots of water usually indicate overcharging or failing batteries.

Put a volt meter across the battery (+ to -) and run the engine at about 2000rpm (assuming a modern diesel) otherwise run as fast as is reasonable. At any time the maximum voltage should not be more than about 14.4 to 14.5 volts, and without an advanced alternator regulator it should be no more than about 14.3 volts. Expect this reading after a long period of running with well charged batteries when the alternator is producing 10 amps or less.

Assuming the voltage is below the above limits I think we can assume one or more batteries are starting to fail. Having topped them up and charged them for a few hours (as you have done) get a float type battery hydrometer - not ball or disc type (a few pounds from Halfords type outlet) and measure and record the specific gravity (relative density) from each cell.

All cells should produce clear acid - not cloudy/brownish - and all readings should be within 0.05 of each other, a greater variation indicates faulty cells. The table for hydrometer readings to state of cell charge can be found in Course Notes, on
www.reading-college.ac.uk/marine.

Take care because if there is overcharging (which may well have ruined the batteries) or faulty cells there will be lots of explosive hydrogen in and around the batteries. If you have any doubt about the batteries, take them to a battery specialist for testing. Make sure absolutely all domestic loads, including radio code, bilge pump and alarm supplies are turned off before disconnecting. Take off the negative terminal first.

I suspect that the water pump problem is that, although the batteries can supply the amp or so the lights need, they are not holding sufficient charge to supply the 8 to 10 amps (in your case 16 to 20 amps) required by the water pump(s) as they run up to pressure, so the pumps start and the "run out of electricity" and stop. Turn the pumps off and the batteries either charge up a bit from the engine or de-polarise (the bubbles of gas leaves the plates) so they can supply a little more electricity. Also the water pressure is likely to have fallen, so the pumps can start again at low load.

To prove this, disconnect the domestic batteries and, using a couple of car jump leads, connect the engine battery to the
disconnected domestic battery leads (make sure they are away from the domestic batteries). If the pumps now work, you know there is a problem with the domestic batteries.

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Most direct cooled engine provide a means of allowing some, or all the water pump output to bypass the engine thermostat when the stat is closed, this is then mixed with any water flowing past the thermostat before injecting it into a wet exhaust system. It may be that you have a dry exhaust and simply direct the waste water over the side.

Often the thermostat housing has two pipes fitted to it. One coming from the water pump, and the other running from the housing to the exhaust/over the side. The mixing of the water is done inside the housing. Other engines do the mixing by means of a T in the pipework.

If you can isolate the water that is passing through the thermostat (may need the housing modified), this could be fed through the calorifier, and then mixed in a T for passing to the exhaust.

Try to keep the pipe runs to & from the calorifer short and of a larger diameter than the existing pipework (to reduce friction/ back pressure) otherwise the water might bypass the engine to some degree, causing overheating. You might have to fit some type of valve just before the mixing T in the "bypass" water pipe to restrict the flow to compensate for the increase of back pressure on the "inside the engine/thermosatat" circuit. My Bukh did not need this, although I fitted such a valve (the Bukh had already been converted to indirect cooling)

This is very much a "suck it and see" solution and I take no responsibility for any mishaps, accidents or damage. If it looks like a suitable modification, I would advise doing the mod, but feeding the calorifier water through a good length of garden hose before buying the calorifier - that way you can test for overheating before parting with too much cash.

One last thing. On no account increase the thermostat temperature. If you run your engine much over 70 C it will start to "fur up" inside.

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The short answer is - you can't. I consider myself an experienced engineer, yet I was more than happy to pay for the boat to be drydocked and a survey done. The cost of the survey and docking should be less that £500, and you could easily recoup this by using the report to negotiate a lower price. In any case £500 is a lot less that having a new bottom welded in at a later date.

The surveyor should test the hull with ultrasound to establish its thickness and at the same time advise you on the state of your anodes, sterngear etc.

I would advise that you ask your local boaters for teh name of a reliable surveyor who appears know his job - mine did not know the difference between a thermostat and pressure switch, or between a sedimentor, agglomerator, and fuel filter.

As far as routine maintenance is concerned, the normal advice is to dock or slip the boat every two to four years and get the hull pressure washed and re-blacked. At the same time the sterngear and anodes are checked and replaced if required. This will again cost about £400 to £500 depending on length of boat and location. You can do it yourself if you hire a drydock for a few days.

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Granted we are green but surely the way this is done is to turn off the water stop cock and run the pump until the taps dry up? I would be grateful if you could clear this up for me before I make a complete fool of myself. Thanks, Ian.

They are correct, especially if you have any copper pipes - plastic ones are more resistant to freezing. The following does not apply to live aboards.

Any central heating should be filled with a 50% antifreeze mixture and left, this will not need draining down, but good practice suggests it should be changed about every 3 to 5 years.

The following is the procedure I use on JennyB.

Open all taps and run the domestic water pump until no more water runs.

Remove the domestic water "board" and store at home in warm (A removable board with pump, pressure relief valve, pressure switch, accumulator, non-return valve, filter).

Remove shower mixer (or just take the front off to drain any water inside if it was not jammed on).

If there is an instant water heater drain down or loosen the screws surrounding the diaphragm.

Drain down the calorifier (remove bottom domestic water connector & loosen the top one - when drained fit a T with a domestic drain valve in one side to make it easy next year!.)

Do something to stop water freezing in the shower pump - remove it and take it home - loosen the end cap, or, as I do, pour neat antifreeze into the shower and pump it out (you should catch it as it leave the boat because it is not very nice stuff, but there is now available some "green" antifreeze, but do not mix this with ordinary stuff.

The engine should be filled with a 50% antifreeze mixture and any raw water circuit (which you probably do not have) should be either drained or dealt with in a similar way to the shower pump, except much more antifreeze will be needed, the sea inlet should be turned off.

Even if you do all the above, there is still a chance that water laying in a low point in the system might still freeze, so take care when filling in the spring.

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As hot liquid rises, and horizontal tank with the main cooling surface at the bottom must raise questions about the science underpinning horizontal cooling tanks.

I would NEVER allow a builder to make such a thing for me unless there was no other way (& I do not think saving a bit of cash by using the engine bed, hull, & swim as part of the tank constitutes no other way).

The tank should be vertical with baffle plates inside to ensure the cooling water can not take a short cut between the inlet and outlet across the tank.

I have seen it stated that the "trade" work on a tank size (one side only) of 1/3 of a sq ft per horse power. Having tried to deal with overheating narrow boats coming up river at Maidenhead, every year and found nothing wrong, I am a bit sceptical about this size.

Remember, the only time you will need full engine power, and therefore full engine cooling is when you are in some kind of trouble (fast stream, being pulled towards a weir etc), and that is the last time that you want insufficient cooling to to raise its head.

Before I started our courses, I asked our physics lecturers to work out a mild steel tank size, and they came up with about 1/2 sq ft per COOLING horse power (This size is roughly confirmed out by my ex hire boat). A diesel passes about 25% of its power to the cooling system as waste heat and 45% as power, so a 30hp engine needs about 15hp of cooling (all very rough and ready).

My tank, with a 32HP engine is about 5ft x 2ft x 4ins. This appears undersize, but, even on the Thames, the boat reaches its hull design speed well before maximum power, so it probably never develops the full 32hp. (There is a lot more to cooling calcs than meets the eye).

Over cooling will not be a problem because the engine thermostat will ensure the engine runs at optimum temperature.

Try to ensure there is a way for any gas that may be trapped in the cooling tank can escape - either by providing a "bleeding" plug in the top, or by providing pipework to bleed it back to the header tank.

Other points to watch are that if you intend to use a modern engine, it retains its pressure cap - this prevents something called localised boiling at high powers (the temp gauge shows normal, but boiling on the exhaust valve seats blows water out of the filler); that as nb installations often contain far more water than the vehicle/industrial counterpoint an adequate expansion tank is provided to accept the greater volume of expanding water; that any "high points" in the pipework are provided with air bleed points.

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I am looking to buy some tools to start up his tool box for the boat. In the documentation he brought away from the course there are some suggestions that I have looked.

Are you able to suggest a local place that would be ideal to purchase some tools from and do you have a suggestion as to the most useful things to be buying to start with? Many Thanks, Ann

I suspect the engine may be based on a Jap unit, so the nut sizes are likely to be metric.

I assume you are only thinking of basic maintenance & possibly emergency repairs. The best advice I can give is to tell you what I have purchased for JennyB, my professional tools remain at home.

A mixed AF & metric set of combination spanners from Halfords' budget line, I think they cost about £12 or so. Also a similar socket set in 3/8 & 1/4 drive, again from Halfords for a similar amount. A set of B&Q screwdrivers. A pair of "universal grippy things" from the spring Birmingham show for plumbing etc £10. A plier set, again from B&Q containing a pair of water pump/gland nut pliers etc.

Most of the above are available from Screwfix - www.screwfix.com , and I would advise a first purchase of spanners & screwdrivers.

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Yes - do you have a mains shoreline - if so, fit a galvanic isolator (zinc saver), this may not fully cure the problem. Even if you do not have a shoreline, an adjacent boat may be causing the problem, if you are mainly suffering on one side (the one closest to the offending boat).

It could be Mill Scale (produced when the steel is rolled and also when heated (welded) flaking off. If this is the cause, then I am afraid it needs sand blasting to remove the scale and recoating.

Wet blasting is the "new" low mess method. Whilst you are paying for the blasting, you would be well advised to pay the extra for a more durable hull coating like epoxy-tar. I suppose a thorough
pressure was off, followed by much angle grinding might do the trick, but I would favour wet blasting.

Finally - remember certain cars of the 70s, rusted before sold. It could be poor quality steel. If you have a well known, high quality shell builder, this is unlikely. If you, or the boat fitter, bought on price then it must be considered.

Bearing in mind the cost of repairs etc, I would advise you to hope for the best, but prepare for the worst (suing the builder) and instruct a surveyor who is both professionally qualified, and a member of a trade body to inspect and advise you.

If you have a shoreline, my main suspect would be that - tell the Marina to get their earth and neutral circuits checked.

Water may be considered incompressible, so when a pipe is full of water, and a pump tries to push some more in, the pressure rises very, very quickly with only a drop or two of water added to the pipe. This would cause your pressure switch to cut the pump out.

It follows that if that drop of water could escape from the pipe the pressure would fall equally rapidly and the pump would cut back in for a short while, and so it would go on.

An accumulator is a tank with air at the top, and water at the bottom, usually separated by a rubber diaphragm. This should be pressurised to about half the pump cut out pressure - has this been done and checked? Use a car pressure gauge and foot pump.

What happens now is, that as air IS compressible, the pump forces water into the accumulator, compressing the air, until, eventually, the pump cut out pressure is reached. Now if you loose a drop of water the air simply pushes the diaphragm down and maintains the water pressure.

The first thing to do is to check that the accumulator is pressurised to about half the pump cut out pressure.

However, you still have a loss of water, and I suspect three places - in no particular order of importance.
1. Something stuck under one of the pump valves or a faulty valve, like a bit of pipe swarf, or in an older boat, rust etc from the tank. I guard against this by fitting a gauze strainer and a "plumber's" non-return valve close to the pump inlet. I rather suspect this is the cause.
2. The calorifier's PRV leaking, again a faulty valve or something stuck under its seat. If you twist the PRV cap, your pump should run as you lift tha valve (depending on type), this may flush the seat clear (or it may not).
3. A faulty calorifier allowing domestic water to escape into the engine cooling system. This is not very likely likely, but to check it wait until the engine is cold and fill up the engine system to a fixed pint (like exactly flush with the bottom of the filler neck, then leave the domestic water pump turned on, with the engine off, for several hours or over night. If the water level has risen, you will have found your leak.

First understand that we black to (try to) prevent rust, any cosmetic effect is a very much secondary consideration.

For an iron containing material to rust - like steel - you need water/damp and oxygen.
No damp = no rust
No oxygen = no rust

We can not avoid damp, and to a certain extent we can not avoid oxygen because oxygen will dissolve in water, but the deeper one goes, the less oxygen the water contains.

At bottom plate depth on a typical flat bottomed narrow boat the amount of oxygen present in the water is normally small enough to present a very low rate of rusting, so the chances are that the inside of the bottom plate is rusting more quickly that the outside, at least in some places.

Even if you did black the bottom plate, it would soon be ground off by the bottom, shopping trolleys etc. I do not black the bottom of JennyB and as far as I can see neither did Viking Afloat, yet after 10 years its ultrasound scan gave a bottom plate of 12mm (I suspect it started as 1/2" plate, so, assuming the ultrasound was accurate, it lost 0.5 mm in 10 years - probably due to hirers trying to enlarge the channel.

If your boat has a V bottom I would black as far as I could reach underneath.

The major danger area, because of the abundance of oxygen, is around the waterline. If you are blacking yourself and have time, I would suggest an extra coat for at least 6" above and below the waterline.

Also another point. Do not rotary wire brush off any rust. this will polish the steel and may stop the blacking adhering to the hull. It is probably better (failing shot or sand blasting) to use an angle grinder to get the rust flakes off.

I would expect a high level vent connection, are you absolutely sure you do not have one?

I answer on the basis that this is a normal "dump through" toilet and not a vacuum one - they may well have no vent save the outlet from the vacuum pump.

If the rinse pipes are metal then leave them, if they are plastic or rubber I would advise that you either change them for metal or "toilet" grade plastic hose.

Again assuming a "dump though", I think you need a large bore breather pipe in the top of the tank and venting through the side of the boat. Ideally two - one each end.

If the air in the top of the tank suffers oxygen depletion the aerobic bacteria in effluent will die, leaving the anaerobic ones that produce that smell, so you need a supply of fresh air across the top of the effluent so the aerobic bacteria (that do not produce smells) overwhelm the anaerobic ones and suppress the smells.

My boat has a single 3/8" breather pipe and the tank stunk, so I fitted an additional 32mm (I think - largest easily available copper tube) at the other end of the tank, and just to make sure I fabricated a metal box that sits between the tube and skin fitting, containing an old brushless computer fan. The fan is controlled by a pneumatic push button time switch, so when you sit down you push the switch and ventilate the tank. We can now go several weeks in summer without developing an unacceptable smell.

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