nb.Stealaway

Hi MJG, I also have a Mastervolt charger & know what you mean about the fans. This is a completely different sort of sound though. Sorry Gibbo, what I meant was that I absolutely trust your technical expertise on all things electrical - so if you say it's normal, then I'm sure it is & in this instance don't need to know the ins & outs of why it does it. Ta for expanding on your answer anyway. Thanks very much to everyone for all the replies, Charles

That's a technical enough anwser for me Thanks very much JR & Gibbo for putting my mind at rest. Charles

Quick question about inverters. A while ago I was given a 'Moore Power MSW 1800W Inverter' which does work & has been used for several hours. However, when running the unit itself makes a continuous buzzing type sound. Just wondering if anyone knows if this normal for this model or if there is something wrong eg. fan not running right or some other issue? Regards, Charles.

Thanks Tony. Charles

Interesting point there David. It hadn't occurred to me before (amazing how blindingly obvious things can be missed) that if my tank does indeed have vertical baffles, it will be virtually impossible to drain! I suspect it may still drain through whichever side of the baffles that is not welded. Might still be worth trying some sort of pressurized flush & seeing how much crap comes out. Blacking wise, there's quite a bit of paint on the hull, 3-4 coats of Primocon built up over the years as well as 2 coats of Premium Protection & coat of Rytex in between. I like to take care of the old girl. She looked really good when she was out last week for her biennial blacking, almost NO (new) rust or pitting How much difference can that really make though? Several mm's maybe, but I wouldn't have thought that 1-2mm overall of coating would impede cooling significantly? We're talking about a 60-70ºC temperature differential. I'm also not sure I like the idea of a naked swim - I even black the 8mm base plate! Alan - totally agree 100%. Unfortunately it'd be a major headache for me to retro fit horizontal ones to the existing tank - which as we already have established is undersized anyway. I'm not sure I can afford the time off work (& the expense) of taking my boat to a proper yard. That said, I do work at a marina, hence the frequent (subsidized) blacking, but we don't really do steel work here. There are a few welders/fabricators about though, so I am leaning towards an additional external tank (with horizontal baffles) for simplicity/ease. I touched upon this earlier, but do you cut them to match the curve of the swim, or somehow bend flat bar round it? Would it be a good idea to alternate which side of tank the baffles are welded to (ie. one to the swim, the next to the plate side, then the next back on the swim & so on)? The idea being to make sure the water can't simply go 'around the side' of the baffles. I can't see how it's possible to have the baffles welded to both surfaces. Charles.

Hi Mark, Stealaway is a 45ft trad built in 1994. She has an oval brass plaque fixed to the front of the well deck stating 'Steel work by Shotbolt Eng Ltd, Ramsey, Cambs' with a central area stamped '029'. I assumed all Shotbolt boats would have one, originally at least. I've not seen any of his other boats in the 'flesh' though, so I suppose someone could have just stuck the plate on! Does yours have a big prop as well? Also, I take it your external tank must be on the other side of the swim? Did you have to fit an expansion tank due to increased coolant volume? Regards, Charles.

The flow into the tank is at the top & the return to the engine is at the bottom. As the baffles are vertical I don't think this makes much difference with the vertical baffles. With horizontal ones, wouldn't the water be inclined to sink as it cools anyway? The heat does seem to progress across the tank until is is all pretty hot. From memeory one corner was a liitle cooler, but not much. I totally get that the temperature differential is too close - I believe it's an inverse square law as well, ie. the greater the difference the faster things cool or heat. Hadn't thought about crud accumulating, maybe I should try & blast it though? Charles

I think the tank has vertical baffles, my reasoning being I can insert a rod down through the bleed vent, but when you try to rotate it, you can feel it hit a solid obstruction. Hope that makes sense. I'm not sure how else to tell, there's no discernible weld marks. Perhaps an ultrasonic tester would work, other wise I'd have to cut the tank open Haven't seen those sender housings before, but my system already seems to indicate that coolest cooling water is hotter than desired. They're a lot prettier than my jubilee clips though. Unfortunately my boat has concrete ballast so at the rear of the cabin bilge there are two vents/drains which allow the concrete to breathe & drain after any accidents. As a result though, I prefer to keep the bilge bone dry if I can help it. The idea is very interesting though. I'd have though the water would evaporate, but perhaps not? It's looking more & more like the engine will have to come out if I want to fix this. At least I might finally stop that oil leak? Maybe not, it is a BMC after all p.s. To fit horizontal baffles do you cut curved strips (matched to the curve of the swim) out of flat plate, or is there some 'boatbuilder magic' way of bending flat bar? Charles

Thanks to everyone for they're input so far. I have accurately measured the tank & it is only 5 sq feet I have re-checked and the engine in fact actually revs to 3800 out of gear (tacho works of the injectors so should be accuate) so hopefully the engine at least is ok Sorry for the mistake earler. Thanks for the pointers anyway Tony & Nose, glad I don't have to strip the engine! I did buy an infrared thermometer specifically for the purpose of seeing how hot different parts of the tank/engine get. I also bought one of these http://www.quickerbuy.com/products/digital-blue-auto-thermometer-panel-meter-two-external-882453926 , although I got mine off fleabay. I have the probes clamped to the hoses in & out of the tank so I can monitor while cruising. Obviously though these will read slightly lower as they are not immersed in the coolant. I have found that at canal speeds the flow sits steady at about 75ºC with the return water temp of 50-55ºC. When I 'open up' the engine (albeit tied to the quayside - so not an ideal simulation I know) first the return temp rises. After a little while the flow will then begin to rise as well and after about 30mins the flow is up to 95ºCish but the return (cooling) water is 80-85ºCºC! At this point I normally bottle it as I don't want to knacker my engine No steam has ever come out though - am I ok too really push it that far? I already kind of knew my tank is undersized but have only had the gauges to monitor what's happening for the last couple of cruises & wondered what part my prop had to play in all this. From what I can tell so far, it'll have little effect other than noisier cruising on the cut!? Unfortunately it looks like I'm back to thinking of cooling ideas. The car heater sounds interesting but the boat is a trad stern so I'm not sure where I could mount it? Charles

I will measure the tank accurately tomorrow but it is definitely around that size or slightly smaller Your logic sounds pretty reasonable to me, as I say, I was just hoping to find a more straight forward fix/improvement other than engine out/welder in as well as plumbing and expansion issues. I have given alternate cooling some thought over the last year or so; -Second skin tank locations (plumbing & expansion issues) -External tank/tubes (don't like tubes and not sure how much bigger an external tank could be - I have polystyrene insulation so it can't extend much past where it is now) -Even pumped raw water cooling for the engine side of the skin tank - a tank on a tank! Wonder if anyone's done this? Don't know how much heat could be dumped through the domestic rad via the calorifier & circ pump? Probably not much & also not good on a hot sunny day . Hence my attention turned to the suspect monster prop I know every boat is different so it's impossible to say definitively but would changing the prop really not help at all? It does seem to have quite a lot of pitch? Is it really essentially that my engine has only sufficient cooling to propel the boat at 4mph for any extended period of time whatever the propeller? Charles.

Thanks Alan, that seems to be my thinking too. Would really prefer not to have to have a second tank fitted & the associated costs/complications and was wondering what effect changing the prop would have? It's nice to have the low revs (noise wise) on the cut, but I would like to get out on the river. It a John Shotbolt Hull, no. 29, so he should have hopefully got things sussed.

My BMC is fine on the cut under normal cruising conditions (generally between 750 - 1000rpm) but will only go significantly beyond this for about 30mins before the temp gets too high (90ºC+). I would like to go on the Thames (Limehouse to Brentford) at some point but am concerned that at the moment the engine may not have much in reserve in case of emergency. Basically I think I'm probably over propped, and with too small a skin tank. If I reduce the prop size, will this help at all, or would I find when going against a current that I would have to rev proportionately higher & that the over-heating issue would remain unchanged? The stats; 45ft boat, BMC 1.5 with ZF 2:1 gearbox. Revs out of gear to about 2500 (from memory). In gear only revs to 1400 (Achieved while tied up - can't see if it'll go higher on the cut as by that time the boat is really shifting so I have to throttle back.) Prop is 17x16.5. Skin tank 5.5 square feet. What do people think?

Thanks Phylis, I admit I wasn't aure wheter the guy who told me had had his leg pulled, but you've comfirmed that this is a known practice - albeit possibly not a very effective one. As mmentioned earlier, I've decided not to try it this time due to needing so much for this 'experiment'. I will try and pick some up next time I'm shopping & make a test piece so I can report as to how well it might work with bitumen. I would have thought if it was really that good the paint manufacturers would already be putting it in? Thanks for all the replies so far, I shall report back in time how the test is turning out. Regards, Charles.

Comastic is evil stuff - I hate it when I have to use it at work! Have you seen the warning on the tin, it's worse than cigarettes! It manages to soak through cloathing and chemically burns any skin it comes into contact with. I appreciate it is supposed to be better than bitumen (though how much i'm not sure) but it's just too nasty for me. The primocon/bitumen combo seems just as good without me ending up burned & infertile!!!!! regards, Charles

That Perago looks very interesting having spent hours on friday & saturday with a bladed scraper trying to get bitumen off. Why couldn't we have had this post a week or two ago? Thanks Tony, regards, Charles