Engine bay condensation - Tube heater on a timer?

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vodzurk

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Hi all,

Apologies for what's probably another dumb question, this is our first winter with a boat (6.5m Sealine).

We were told that basically, if the temperature stays above -5C, then a duvet over the engine is fine. Lower, and i need to winterise the engine, which I now know how to (but haven't because the weather hasn't prompted me to yet).

However, on Thursday I went down to do my 2-week start-her-up-for-15-minutes... and on removing the duvet, the whole engine was covered in moisture.

This can't be good right?

So what I'm thinking is one of these 40W tube heaters, duck-taped (to its bracket) into the engine bay, probably on top of the battery covers to give it some height in case of flooding. Then to slap it on a timer, to come on at the warmest part of the day ~1400h for an hour, just to push out any built up moisture.

Also thinking to do the same in the cuddy, as the fabric feels a bit damp.

Is this a kinda normal plan and the right thing to do? Or mostly pointless?
 
80watt twin inboard shaft boat 30 ft so fairly big engine space . Electric bill is a pain I guess it's cheaper than a corroding engine
 
Yes best to let air move around I also block off air intakes to stop damp blowing in .also use a dehumidifier .
 
I'm not too sure what the duvet does. On a human it holds in body heat, but an engine has none, it'll still end up at the same temperature. All it will do is reduce air circulation, which maybe explains the condensation?

Everyone has differing views on this subject, but personally I'm not a fan of starting the engine for 15 mins and running it on the berth. Unless you're taking the boat for a blast and getting it right up to operating temperature I'm in the camp that feels you're probably doing more harm than good getting a partial bit of warmth in to it and then shutting it down.

I'm another who puts a 40w tube heater in the engine space in the winter and just leaves it on. It's only like having a 40w light bulb on, not ruinous.

Last thing, make sure your bilges are dry. That moisture is coming from somewhere.
 
Brilliant tips all you guys! Thank you!

My plan is now to buy 2x 40W tube heaters in a few mins, one for the cuddy, one the engine bay.

Also gonna take some cling film down for the cuddy air vent. Think I might put the cuddy on a 12 hour timer as it's probably a losing battle there, but hopefully the odd warmer day + heater should make a difference.

And I can't believe what an imbecile I've been with the engine bay... yep, there is a 1cm pool below the engine which is a sod to get to, and I thought nothing of it. Will get it sponged out and dried tomorrow. Then blanket out, heater in.

Blanket is because the broker told me to, said that's enough to prevent too much cold setting in.

The engine turnover every 2 weeks is just so it doesn't all lump up from 4 months of non use, not for damp prevention. It's a 35yr old Penta. I've had banger cars before and know if left too long, they give up the ghost permanently, so figured I'd better do the same with boat engine.
 
What I would do run it up for at least 30mins at 1800rpm and poar little redex down the air filters to stall engine this will coat valves and rings in an oil based product then give the whole engine and electrics and pulleys a good spray with duck oil . I have had many years with old aq151 volvopenta engine and this always seemed to look after them for the winter .
 
Hi, as an alternative to tube heaters, I use two of the smallest available oil filled radiators. One in the engine bay and one in the cabin.

I use them because they are simple to just stand in the engine bay and cabin, as they are oil filled, if the thermostat ever stuck closed, they wouldn’t of gone so hot as to cause damage.

I put them on a low setting, cost around 50 quid to run from November to March.

Btw, all the duvet is going to do is get damp and rust your engine -
 
Loose the blanket. It's preventing air circulation.
Make sure you have some natural ventilation.
Keeping the bilges dry.
A little bit of heat plus ventilation should ensure boat stays dry. Even with no heat good ventilation should work.

My theory. If my boat is in the water all winter, The water won't freeze, there will be enough heat transfer from the water the boat is floating in to prevent my tanks ,engine, hoses, freezing. So far it has worked. Snow & frost on top of boat but sea underneath keeps it just above freezing inside.
 
ari said:
I'm not too sure what the duvet does. On a human it holds in body heat, but an engine has none, it'll still end up at the same temperature. All it will do is reduce air circulation, which maybe explains the condensation?
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Click to expand...

I don't do it myself but know quite a few who do. I imagine it's done on the same principle why some similarly cover car windscreen in winter. They still get wet but somehow do seem to prevent frosting up. I can't quite get my head around how? either.
 
adey said:
Don't do that unless you're going to use a de-humidifier.
Click to expand...
It's still gonna be pretty far from airtight. It's a 1ft square piece of slatted wood. Might as well try and raise the temperature of the world with it in place in the cuddy.

I'll have a think about leaving an inch of it clear/open to let some condensation equalise out.
 
Can anyone see any for and against from my input below to help vodzurk.

My observations are :- 1) How does a timer eliminate condensation? Is it linked to a dew point sensor?
2) What purpose does a thermostat serve? If you have fresh water to protect then would a frost stat be a safer more economical solution instead of a temperature rise stat? Or drain with winter lay up.
3) What in an engine room needs warm air? Few if any ER's are thermally insulated anyway. Energy and environment issue?
4) What are the benefits of running a winterised engine? Apart from causing horrendous air pollution due to incomplete combustion, emulsifying the sump oil as the engine cools, light load mechanical damage, and defeating all the earlier winterising procedure's, which you then have to reinstate?

In conclusions all we are trying to do is eliminate moisture in the ER air space just before the dew point occurs. My only answer would point towards a permanently connected automatic adjustable de-humidifier. To function without the core becoming blocked with frost a small tubular heater controlled by a FROSTSTAT in front of the air intake should work with fine tuning. For this procedure to work really efficiently the ER has to be completely air tight. Not easy in the water but achievable on the hard.
Secondly if you can achieve the afore mentioned then a fully wintered boat should easily last for at least six months without resorting to running, given the latest good quality oil additives.

I stand to be corrected.
 
Thanks again to everyone for the tips. It's great to hear so many views, and have a source of info for all this :).

Surfacesub:
Thanks for your feedback, muchly appreciated! In response:
1) The timer was me thinking that having heat available at the hottest part of the day would push out any buildup of moisture. Seems from the other posters though that a 40W tube left on 24/7 isn't exactly gonna break the bank.
2) The tube heaters come with a thermostat on them (though mostly annoying as it'll be 1-10... not anything measurable?). But if there is a warm day or two in double digits... then it might stop using electric when it's already plenty warm.
3) One where the engine is covered in moisture? The dew point is a mix of air moisture and temperature. I've had many battles with condensation in my garage, trying to stop my tools from rusting up. The engine bay is quite small. But it's not airtight. So I'm thinking that unlike my garage, that it'll be better at holding in a small temperature rise over keeping up with dehumidifying.
4) My engine isn't winterised. It has a seawater cooling system (Penta AQ151), so if the outdoor temperature goes below -5C, then there's potential that the seawater cooling could freeze. The obvious solution to this is to replace it with antifreeze and leave for the whole of winter. However, the wife was determined that we'd go out and do more with it in winter... turns out she doesn't like that anymore, as it's COLD as heck. Plus I'm expecting it to be lifted out in a few weeks, so gotta get it to the hoist. A 40W heater would probably help against freezing mean i can avoid winterising until possibly -10C.

Regarding starting her up and running for 15-20 mins every 2 weeks... I do that from habit with old cars. The engine is 35 years old. It's noticeably easier to start after 2 weeks than 4.
 
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