Keeping out the cold

[discovery2]

Went down to the boat to check her before the storm arrives.......

Opened the engine hatch and was surprised how cold it was in there compared with the saloon and the rest of the interior. Obvously the wind blows through the intakes and makes it quite cold.

On the one hand, low temperatures in the engine space don't particularly concern me as the engine has the recommended strength of antifreeze etc., and our climate is relatively mild, however there have been several postings recently concerning placing heaters in the engine compartment, and it appears that many use the low wattage types.

My questions thererfore are:
Do you find the heaters effective? Having experienced the draught passing through the engine room, I would have thought that the small amount of heat produced by the heaters would soon dissipate with minimal increase in temperature!

Is there a (designers?) formula for heater wattage compared with engine space volume? or do es one just 'guess'?

Does anyone block (close) the intakes to stop the cold air circulating through the engine space? This could probably raise the temperature quite considerable by preventing the cold air circulating (obviously one would have to remove (open) them before starting the engine!).

Thanks
David


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[davedpc]

Block up the vents only with the use of a small dehumidifier. Use a small thermo. controlled heater of approx. 150W. set for about 5deg. c. This will be the minimum necessary to allow the D/H to work. The unit will also add to the temp. in the engine room although the circulated air will feel cooler. If your boat is out of the water you may be able to permently drain the unit down via the removable log sender unit. Dave G.

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[DavidJ]

There will be formulae (al la home central heating) for heat loss though various materials however your main heat loss is through air change (as you say) what we will never be able to guess is how many changes of air volume are taking place every hour in your engine compartment, therefore the formulae is no use.

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[David_J]

I have the same boat as you and pretty much the same questions. Being new to this boaty thing I read numerous posts on here about heaters, dehumidifiers, timers, thermostatic switches and so on. There is so much good advice and experience here that as a newcomer its sometimes hard for me to decide what best applies to my situation. Our boat is on the dealers pontoon at the moment as it was all part of the haggling we did, anyhow we had a discussion with them on the basis they have a stack of boats sitting there and I guess they must have experience and a desire not to lose my money by inviting damage. Possibly I am lucky in that I have Eberspacher heating with the unit mounted in the engine bay. The dealer advice was to run the heating a few times a day and leave at that. I was a bit wary so I put a max/min thermometer in the engine bay and so far so good. Maybe famous last words but so far it has not got near to zero in there. I seem to recall hlb said something on this subject like "just leave the heating on and use the bugger" which sounds good to me.
Sorry to prattle on but I will be really interested to see the replies on this as it may ease my concerns or stir me into doing more.

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[tcm]

Hi

Several reasons for it being colder in the engineroom, first (and mainly) that the engineroom is full of a great big lump(s) of cold metal, which lose heat and then acts as as a cold sink (radiator in reverse) whereas there aren't any such large items in the saloon etc. Secondly, any cold air in the saloon may fall beneath the floor, whereas in the engineroom you are standing in the coldest air.

Any formula would only be of use with regard to an enclosed space. I dunno any formulae, thou i suppose i cd work it out....

I wouldn't (and haven't) closed the engineroom as described. I can do this with closeable vents, but I think it may be of more value to have occassional air change provided that the engineroom is suitable protected against damp, wd40 lashed about and so on.




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