Chevetter

I don't have a bilge below the cabin - its very small and (unsurprisingly) is situated underneath the prop at the back of the boat. The entire deck drains into it.

I know I might sound thick but I'm not that thick - note the vent pipe!

I think I want it sealed, so no steam etc. can get into the boat, but it won't actually be pressurised. A check valve (or non-return valve) on top of the overflow pipe should solve the siphon problem.

Hmmm, not a bad point about the siphoning. The valves are there because I may want to restrict the overflow as per a few posts back, but agreed, the whole thing could explode if I shut the top one by mistake..... The return will struggle to run downhill to be honest - the stove is well off the floor as I sain, plus the slope of the boat as well.... but I'll make it go down as far as I can. By the way, does anyone have any ideas as to what I can use for a header tank?

Right, been having a bit of a think, conversing with a workmate who has a lot of experience of installing central heating in houses and we've come up with the following: Should the boiler boil up or produce steam in this design it gets dumped into the bilge. That way no messing about cutting holes above the stove etc. I assume you're all about to tell me that this is a terrible idea though....

Does it have to be literally directly above? That will create a heck of a lot of work for me! A better idea from my point of view would be to take-off directly above the stove but actually vent the steam somewhere else.

Hi chaps, Again comments much appreciated, please see heating system design Mk3. Am I getting there? On the subject of the vent pipe: do I really need this to be down the stove end? Can I not just have a vent out from the header tank into the bilge? It would make the whole thing so much easier. Also, you will notice that my 28mm pipe runs past the top of the rad. Is there any need to do this or can I just stick the feed into one side and hang the header tank off the other side hence saving nearly 1m of 28mm?

My thinking was: Make the feed 28mm all the way down the boat in order for good conductivity of heat. In the return there's no need for this (28mm pipe is expensive)..... although I could be wrong. I figured if its got to go uphill anyway then a bit of 15mm pipe isn't a big deal. Can anyone see a problem withmy design? Anything that I could do better etc? If not I'm actually going to build it Hmm, well it certainly saves me having to buy a towel tail thats for sure plus simplifies the plumbing and ensures a nice flow of hot water up the feed pipe. I suppose it will get rather hot and there's only one of me anyway.... My boat is actually fully spit in terms of air flow (although I do keep the doors open) so thats a bit of an issue, which is the problem that the radiators are meant to solve.

How about this revised design?

Ah right, ok. For some reason I was under the impression that the return from the rads had to be downhill. I'll work out how high the top of the radiator in the kitchen has to be to be uphill from the stove and hence if its feasible.

Thanks for the comments. I'm afraid thermocycling just is not going to happen. Like I said the stove's mounted on a hearth which is a good 300mm higher than the floor, plus the tilt of the boat puts it a long way above any potential radiators in the kitchen. I can't start chopping the physical features of the boat about so I guess by Chris Pink's definition I have already failed Anyways I need a pump, in which case is the Bolin the best one? Re: the header tank: how big do they typically need to be? Is it actually possible to buy one? Like I said, I was just going to use one from a car. I'm also not 100% sure what you mean by a 'gravity fed rad'? How would that fit into my system? Things that I can move: radiators, pipes, pump, header tank. Things that I can't move: walls, the stove.

Hi Chaps and chapesses, Long time since I've been on the forum I know, but I've come back to ask for your advice+opinions. Basically I've been doing a liveaboard while re-fitting type thing for just over a year now (which is somewhat of a challenge, if you've ever tried it) and with winter coming I've saved my last week of time off from work for building my central heating system. My boat is 40ft with a 25.5ft cabin containg 3 rooms - a 9ft lounge/bedroom, a 4ft bathroom and a 12.5ft kitchen/diner. I already have a Boatman stove with backboiler installed and it's 'just' a matter of installing the central heating system. Here's a pic of my design - comments, suggestions, criticism etc welcomed (apologies for the shoddy drawing) So far I have the following questions: Reading other topics on the forum, I think that a Bolin pump will be the best choice as it needs to be quiet and be able to go at the lowest point of the system. Is that sensible? Do I need to care about matching the number of BTUs of the rads to the number of BTUs of the back boiler? Is there much benefit to fitting a thermostat to control the pump? I was thinking of just having a switch. Header tank: where do I get one? Presumably it needs some kind of pressure release valve and dump pipe out of the side of the boat? I was thinking of going to the local automotive scrapyard and hunting under the bonnets of various cars until I found something appropriate? None of this is bought or built yet apart from the boatman so the whole design can be changed if necessary. Thanks in advance

WD40 is ok but it isn't the best 'dismantling lubicant'. I use something called PlusGas - works much better.

Can't say that I have no. I'm at work at the moment so I haven't got the time to do it but this evening, or maybe tomorrow evening I will sit down and work out the rate of corrosion in grammes of steel per month based on a set of nominal conditions. When you say chemical corrosion, which chemicals are you referring to? I've noticed that everyone's washing up scum seems to accumulate around my bows

I don't think you're seeing what I mean: 3 Boats: | B---path to earth--------------(||||||||||Boat A||||||||||> a n.......isolated......................(|||||||||mine|||||||||||||> k | --resistive path to earth----(||||||||Boat B||||||||||||> | Boat A and boat B are not properly isolated and are both earthed to the bank. Boat B has a high resistance in its path to earth. Therefore they are 2 electrodes floating in a weak acid with a resistive path inbetween them. So what have we got (assuming the boats don't manage to sit at exactly the same potential to ground - extremely unlikely)? The path of least reistance between the boats (i.e. from the positive to negative terminals of the battery) passes through my boat as it is easier for electrons to pass through my steel than around it in the water. The direction of travel depends on the potential that the two boats A and B sit at but the result is that my metal is pulled from my boat and sticks to either A or B. This could be an explanation for the blacking coming off - as the metal ions move they have to get past the blacking to get to the other boat. Resolution: hang some more reactive metal anodes over the side and provide a good conductive path to the hull, therefore the anode metal is removed instead of the hull metal.

Further to what I just said, to combat this problem (or to make sure anyway) I was thinking of getting some hanging anodes: http://www.mailspeedmarine.com/anodes/hang...3kg128413.bhtml However these cost an effing fortune for that they are, if you'll excuse my implied french. Instead I think I might get some of these: http://www.aquafax.co.uk/html/product_details.asp?ID=21647 in the 0.68kg variety and sort out the wire myself. I was thinking of getting 6 and hanging them off the hand rails on bits of wire. Bit of a kerfuffle I know but for the cost of the anodes vs. the cost of the hull I think its worth it!

Yes but our marina has a long line of 40ft narrow boats in it, parked side by side, of which I am one. My near neighbour has 240v and the bloke 3 moorings away has 240v, so in theory (as the hull of my boat is a path of less resistance than water) if there is a circuit between these two boats then mine could be in the middle of it!

Thanks for all your responses everyone, I don't think I made the original post very clear, the blacking is coming off along the entire side as far as I can tell, at all points where the boat is in contact with the water, right down as far as I can get my arm. It starts right at the very bows and continues right down the side and along the counter right to the point where the stern starts to curve. One other variable is that this side of the boat which is in the sun every morning. Along the other side its not and as far as I can tell the blacking isn't coming off. I think I have the 'let it rust' thing covered Tony So what's the preferred brand of blacking of everyone here?

I don't recall a blueish tinge no. Furthermore there was a fella blacking a newbuild boat next to mine and he just slapped it straight on as I did. But for arguement's sake lets say it was 'millscale' - what should I do now when the boat comes out of the water to ensure that the blacking does stick? Panel wipe and then rough it over with a wire brush/sand paper or something?

In February I had my narrow boat fully overplated (bottom and sides) by AndiCraft Fabrications. Part of the deal was that I would black the boat myself, something which I was quite pleased about at the time as it's always seemed a waste of money to me to pay someone else to do this job. So anyway yesteday I was fitting the first of my new windows which required me to go round the side of the boat which I don't usually look at and I noticed that some little bits of blacking were flaking off around the water line. Closer inspection showed that a couple of pieces the size of saucers had come off. So I got out my dinghy and rowed round to take a closer look - basically all of the blacking down the entire of one side of the boat is coming off in big sheets leaving bare metal exposed to the water. There is only minimal surface rust at the moment but obviously I want to get it out and sorted before the rust takes hold. So my questions are threefold: 1/ Why did this happen? - Did I not prep. the metal properly when I blacked it? - Is it perhaps caused by not alowing enough time for the blacking to dry? - Is it perhaps because that side of the boat was in the shade and it was February so the bitumen didn't go off properly? - Is it the blacking itself (I used Intertuf, which even says on the tin 'for new metal do X, Y and Z', which I did). - Is it because of galvanic corrosion? I am a bit parandiod about this one as I have 240V plugged into the boat all the time, but I have a Victron Isolation Transformer which in theory should stop it happening. However the boat which is only 2ft away is also plugged in all the time and is blatantly not isolated properly. 2/ More importantly how do I stop it happening again? - Is it a good idea to put primer or similar on the hull before I black it? - Should I clean it down with panel wipe or something first? - Should I leave a longer drying period between and after coats? - Is the application of blacking something which is very temeprature critical? 3/ Galvanic corrosion: - How can I do a thorough test to make sure that everything is tickety-boo? I stuck some wire connected to a DC voltmeter in the water either side of the boat yesterday and basically read nothing but I don't reckon this is a thorough test. - I've heard about 'fishtail anodes' which go down the sides, but does anyone have any experience with these? Sorry for the barrage of questions but I'm feeling lost, confused, fearful etc. right now! Oh also, how desperate is it to get the boat out of the water, someone I know said 'ah it'll probably be ok 'til the spring' but this seems rediculous to me. Thanks in advance.

I've got a very bright head torch - maybe that will help?

Actually I dried it out first using some rags and then a hot day. I had to spend a good long time scraping before I could get it dry though because there were these big rusty blobs full of water all over the bottom. I've got it completely baremetalled and painted in rustbeater now, so its just the water tank paint to go. I'm interested that everyone refers to it as balcking - I've not taken the lid off my water tank paint yet but I guess its bitumous?

What's the worst job you've ever had to do on a boat? I'd say that cleaning out and painting my water tank, which no-one has been in since 1978, has got to rank pretty highly. Lying in a metal box twice the size of yourself with rusty metal on all sides scraping old paint and rust off above your face is not fun! I had to wash my hair 7 times afterwards

Yes I think it is. I am currently preparing for the re-insulation of half of the boat with sprayfoam which should be a significant improvement on the poorly-cut polystyrene that was in there before. I am also making the new bathroom wall insulated and constructing new cratch doors with insulation inside them so the lounge/bedroom should be insulated on all sides. Yeah I had thought of this, but I figured that it would be a lot of messing about. However when you consider that its going to save me £400 minimum then it would be well worth looking into. Another point is that this apporach would allow me to have S type windows or similar for the summer (ones with removeable glass). I have a feeling it wouldn't perform as well as 'proper' double glazing though. Thanks for the info on refurbishment prices. I live on my boat full time which is why I am considering double glazing.

£15 sounds more like it - 12x1200x2400 of Suaplux costs £75!