Engine Room condensation

[Derik]

It had been about 5 days since I visited my boat, on the previous visit I had run the engines for 15-20 min but didn't leave the dock. Yesterday when I pulled the engine room hatch there was moisture everywhere. I thought at first there was a leak but realized most of the moisture was up high on the engines.

I ran the blower and left two of the hatches off. We have had a little rain so the bilge has been damp then fog followed by warm days, but I suspect it's condensation from me running the boat at the dock?

Any solutions to keeping the moisture off the engines?

 

[C lectric]

More likely that there is high humidity in the engine compartment.

High ambient humidity [outside air] can cause this when that air is drawn in during the engine running and then after the shutdown that air cools. When it cools the moisture will drop out covering what ever it is in contact with, typically the higher areas.

Ever watch the dew on your car. The upper parts can be soaked with water running off yet the lower parts have none or only a very light wetness.

To much bilge water can also cause this by providing a constant source of water.

I doubt it as a direct result of the engine actually running or you have bigger problems such as an exhaust leak.

Leave the hatches open in future, at least one, leave a couple of fans running in the E.R. , consider a dehumidifier adapted to drain to the galley sink which will condense and drop the excess humidity. Use a timer as I doubt it need run 24 hrs daily, maybe 5 or 6.

 

[psneeld]

https://www.envirovent.com/help-and...ndensation-problems/what-causes-condensation/



Condensation occurs when warm air collides with cold surfaces, or when there's too much humidity in your home. When this moisture-packed warm air comes into contact with a chilly surface, it cools down quickly and releases the water, which turns into liquid droplets on the cold surface.

 

[sunchaser]

A safe electric heater in the ER set to 50F keeps condensation at bay for us. Also, we do not seal up the ER ventilation. Boat is in the very damp PNW.

 

[OldDan1943]

A safe electric heater in the ER set to 50F keeps condensation at bay for us. Also, we do not seal up the ER ventilation. Boat is in the very damp PNW.

Leave the engine room hatches open then, if necessary, dehumidifier draining into the sink.
In FL, I leave an A/C on.

 

[DDW]

This can happen in changeable weather conditions, which in some areas is common. Boat sits overnight and engines cool. Next morning moist, high humidity air moves in. Engines are still cold and below the dew point. They will be soaked in minutes in those conditions, and wiping them off will do nothing - they will be soaked again in minutes.

Either the engines have to be kept at a temperature above the dew point, or the dew point in the engine room has to be lowered. The former can be done with heaters, the latter with dehumidification - and then only if the engine room is well sealed. In changeable conditions, ventilation by itself may do no good as the engines are a large thermal mass that lags ambient temps by many hours.

 

[Choices]

I have a small heater that handles the engine room, and I leave one hatch open so the heated air works into the boat. I have a fan blowing air the length of the boat.

Perfectly dry.

 

[rgano]

I installed two explosion-proof light fixtures in the overhead of my trawler. I switched from 60-Watt incandescent bulbs in the warmer months to 100-Watt bulbs in the winter and left them on 24/7. Never any condensation.

I cannot imagine that running any diesel engine from stone cold to whatever inadequate temperature it rose to in fifteen minutes (I assume this was done in the slip with no appreciable load) would do the engine any good at all. Better let it sit for weeks/months than to do that.

 

[OldDan1943]

Engine block heater or a circulating coolant water heater. I had both on my bronco when I worked in Canada. Nice, getting into the bronco each morning, starting it up and presto, warm air out of the heater.
The engine block heater kept the block warm and in an enclosed engine room it will heat that a little bit too.

 

[FF]

"on the previous visit I had run the engines for 15-20 min but didn't leave the dock."


This is NOT considered good practice , a run underway will warm up the engine , idle with no load does more harm than good.

 

[Pete Meisinger]

It had nothing to do with running the engines, unless you have a water leak on an engine.

You need a little bit of warmth and some circulation. Any of the above suggestions will work. Especially leave the hatches open.

pete

 

[OldDan1943]

What was your overboard temp?
Did you exercise the transmission too?

 

[twistedtree]

I think running the engine may have contributed to the problem. When you ran it, it would have warmed the engine and compartment. The air in that warmer space would have absorbed more moisture. Then as the engine and compartment cooled, the moisture would have condensed out. Had the engine not been run, the extra moisture would never have been accumulated in the compartment.

 

[lwarden]

Here is what's working for me in the PNW:
1. Make sure your bilge is totally dry.
2. If you are in a cold environment (if you are in the La Mesa as in San Diego ignore this) block off the engine room vents in winter.
3. Install a 250W oil pan heater, Wolverine or similar and put them on a thermostat.
4. Put a small dehumidifier in the engine room, one of those West Marine round silver ones works fine.

It's probably got 6" of snow on it today and I wish I could check it out and see if there is any condensation on the engines, but I'm 1,400 miles away so that's not going to happen.

 

[firehoser75]

Here is what's working for me in the PNW:
1. Make sure your bilge is totally dry.
2. If you are in a cold environment (if you are in the La Mesa as in San Diego ignore this) block off the engine room vents in winter.
3. Install a 250W oil pan heater, Wolverine or similar and put them on a thermostat.
4. Put a small dehumidifier in the engine room, one of those West Marine round silver ones works fine.

It's probably got 6" of snow on it today and I wish I could check it out and see if there is any condensation on the engines, but I'm 1,400 miles away so that's not going to happen.

+1!
Dry bilges!! Keep moisture out of the boat.
Block ER vents to keep moist outside air out (like fog).
Wolverine 250 watt oil pan heater will then keep the engine warm and the entire ER warm and DRY. Other benefits as well. Just leave the Wolverine on any time you are plugged in. Engine will be warm, start easy, and will smoke less at start up.

Leave ER hatches open to allow for (interior) air circulation.
If still a moisture problem, then run a dehumidifier draining in the galley sink and overboard.

This system works great in the very damp PNW, BC coast where in winter outdoor humidity is close to 100% all winter.