Condensation issues with our Jeanneau SO 33i

[NPMR]

We've just had our first reminder of the winter(!) that below 10 degrees C in the cabin, condensation is a massive problem if sleeping overnight on the boat.

The "33i" is a brilliant boat in so many ways but it feels absolutely as though the designers never sailed in anger (or perhaps not away from the med) and spent no nights in cooler climes. Sadly, the biggest condensation build up we get, is exactly above the heads of sleepers in the double cabin, with an inevitable 'splat' on the face starting at about 4.00am!

The problem is the single skin make up of the boat (she's injected injected into moulds not laid up - makes her strong and light, so jolly quick).

I've considered covering the inner surfaces with something but there are complex double curves, so wood and/or carpet (used on my last boat) are not practical.

I remember seeing eons ago, a product made by, I think, 3M, which was minute glass balls that would be put in some kind of paint, to create a kind of insulating layer that was painted on.

Are there more modern alternatives that anyone knows of?

 

[pvb]

Ventilation would help.

 

[maby]

Ventilation would help.

But only with the humidity - at the expense of the temperature! Heating would also make a difference - we had one of the first 33i in this country and spent a lot of time on it throughout a reasonably cold winter - the Webasto was running most of the time and condensation was not too much of a problem.

 

[VicS]

We've just had our first reminder of the winter(!) that below 10 degrees C in the cabin, condensation is a massive problem if sleeping overnight on the boat.

The "33i" is a brilliant boat in so many ways but it feels absolutely as though the designers never sailed in anger (or perhaps not away from the med) and spent no nights in cooler climes. Sadly, the biggest condensation build up we get, is exactly above the heads of sleepers in the double cabin, with an inevitable 'splat' on the face starting at about 4.00am!

The problem is the single skin make up of the boat (she's injected injected into moulds not laid up - makes her strong and light, so jolly quick).

I've considered covering the inner surfaces with something but there are complex double curves, so wood and/or carpet (used on my last boat) are not practical.

I remember seeing eons ago, a product made by, I think, 3M, which was minute glass balls that would be put in some kind of paint, to create a kind of insulating layer that was painted on.

Are there more modern alternatives that anyone knows of?

International once marketed a paint call Corkon but is was pretty useless and unattractive on any visible surfaces.

The only solutions are to eliminate cold surfaces or reduce the humidity. Increased ventilation will help to reduce the humidity but some insulation of cold surfaces will probably be necessary.

 

[James_Calvert]

Heating is the answer, also you could possibly reduce humidity by sleeping in a less enclosed space like the main saloon? An Eber or equivalent drawing air from the outside will also help keep humidity down by increasing ventilation.

You need enough heat to keep the temperature of your colder surfaces above the point of condensation. So the less insulation they have, the hotter the air temperature needed.

How about trying to reduce heat loss by insulating the other side of these single skinned surfaces, eg if your problem is with a cabin under the cockpit, put cockpit cushions over the cold spots? And a cockpit tent or enclosure could also help.

 

[lw395]

Cockpit cover is a good call.
More ventillation.
Thick duvet.
Eberbasto that can be switched on from within duvet.

A decent vehicle trimming person might be able to work wonders though. It can't be much harder than some kit cars?

 

[RupertW]

If you are at a marina then a dehumidifier is fantastic and much much more energy efficient than heating if ventilation alone doesn't solve the problem. We have cooked meals and dried clothes aboard with rain pelting down and felt comfortable and dry, with dehumidifier fans then turned down a bit afterwards.

If you are away from mains then I think heating combined with ventilation makes the most sense, helped of course with internal insulation where you can.

 

[[70521]]

As other posters have said ventilation is the key! Open your hatches and all doors in the boat.

The human body releases about 200 ml of fluid in 8 hours sleep. I quite enjoy sleeping in the cockpit, but this is after years of bivouacking on mountains and not everybody's cup of tea.

 

[ctva]

If you have access to 240v, then a dehumidifier is the only solution. We have a 342 and in the cooler periods of the year (Oct - April) we run it overnight with only minimal trickle ventilation. Heating does not work, at least in practical amounts, on a boat. The only other option is ventilation, ventilation and ventilation with the best being a solar ventilator that charges during the day to run over night.

 

[Spyro]

I can't see glass balls in paint being any good. There's not going to be any insulating properties in that. Some sort of layer of insulation is the answer but it's not going to be pretty. Foam backed headlining is the work of the devil but it did have a purpose.

 

[Cactus Sailing]

different boat but yes condensation can be an issue during the colder months...

If you're lucky the condensation wont drip, if you're unlucky well yeah it wakes you up.

As others have said your options are, heating / de-humidifier / ventilation and wrap up

the diesel pump for our heating is in the aft cabin so its noisy, we tend to plug in a small radiator about 0.7kw & a de-humidifier - it wont feel like the tropics but its condensation free & don't use too much power.

out of the box idea I tried early this year is the hydrophobic coating sprays which do work surprisingly (the one I tried purchased via work for some crazy innovation nonsense and also crazy expensive worked well) but where the condensation goes I have no idea, the thought is water cant collect on the surface as it cant cling to it, it don't last forever and needs re-applying.

Bikers use it on the inside on their visors to stop condensation and it does work, I've not tired the cheaper versions.

if you want I can take a photo of the roof this weekend after a night on-board with a treated area vs non treated (I think I have enough left), as its quite amazing

 

[NPMR]

if you want I can take a photo of the roof this weekend after a night on-board with a treated area vs non treated (I think I have enough left), as its quite amazing

I'm interested in all ideas.

Ventilation is opened up in the cabin as best possible, but there are sleeping temperature issues with this for crew.

My mind is drifting to an awning idea that could, with some imagination, create a 'space' above the sleepers, that would either catch the drips or even act as an insulating space.

But a neater 'coating' sounds interesting.

 

[PabloPicasso]

A tent over your sleeping area (cockpit tent already mentioned) or a cover over the outside of the forepic with an air gap beneath. You could leave the forepic hatch open under the awning for ventilation too.

Some sort of insulation, what type though? most are not water resistant or easily shaped to the weird shapes of boat ceilings.

I like the sound of a coating that would prevent water beading, I wonder how well that would work? I can't see a downside to trying this other than cost, and trouble of applying it.

 

[RupertW]

A tent over your sleeping area (cockpit tent already mentioned) or a cover over the outside of the forepic with an air gap beneath. You could leave the forepic hatch open under the awning for ventilation too.

Some sort of insulation, what type though? most are not water resistant or easily shaped to the weird shapes of boat ceilings.

I like the sound of a coating that would prevent water beading, I wonder how well that would work? I can't see a downside to trying this other than cost, and trouble of applying it.

It's not ceiling insulation that matters, I think. In order of importance I would put below water level hull insulation (because water conducts heat away 80 (?) times more than air, then above water hull insulation and finally ceiling. If you can't have the ideal dehumidifier solution then you want the warm moist air to go up through the ceiling through vents anyway.

I know that the drops condense on the ceiling but with better hull insulation the drops should be a lot fewer as the boat will be warmer

 

[pagoda]

This is something of a perpetual problem on many boats. Our current boat is of the recent generation- without head lining as such. Our previous Jeanneau was cured by lining the interior with closed cell foam and then "van lining". That made a comfortable and warm interior surface. Huge improvement. Removing the old head lining was a hideous job. Heating and ventilation with the newer style interiors seems to be the main solution. And dehumidifiers as well in extreme cases. For heating to work, you have to allow your warm air to vent - and carry away moisture. It's not that easy to raise the interior surfaces to a non condensing state. Try only heating the volume you are occupying- and close doors to other spaces? We don't heat our aft cabin or heads unless they are going to be used.

 

[RupertW]

This is something of a perpetual problem on many boats. Our current boat is of the recent generation- without head lining as such. Our previous Jeanneau was cured by lining the interior with closed cell foam and then "van lining". That made a comfortable and warm interior surface. Huge improvement. Removing the old head lining was a hideous job. Heating and ventilation with the newer style interiors seems to be the main solution. And dehumidifiers as well in extreme cases. For heating to work, you have to allow your warm air to vent - and carry away moisture. It's not that easy to raise the interior surfaces to a non condensing state. Try only heating the volume you are occupying- and close doors to other spaces? We don't heat our aft cabin or heads unless they are going to be used.

That all makes a lot of sense to me. The only thing I'd disagree with is using dehumidifier in extreme cases only. To me it's a tool as useful when connected to mains as battery charger or TV - it transforms the experience of living on board in cold or damp conditions, with a lot less power than the fan heaters we also use from time to time. The difference in smell and comfort between a heated well ventilated boat and a dehumified boat is like walking into a shed in Autumn or Summer.

I wasn't a fan until I rented a old stone built flat for a couple of months when working away and was shown a dehumidifier. The difference even touching towels or upholstery was huge.

 

[maby]

Definitely agree on the value of a dehumidifier. It is not only that it eliminates condensation but also that it reduces the cost of heating - dry air is a lot easier to warm up than wet air.

 

[LittleSister]

The only solutions are to eliminate cold surfaces or reduce the humidity . . .

. . . or to ensure the air temperature in the boat is lower than that of the headlining!

I agree that cushions and or an awning over the deck in the vicinity of the offending area of headlining may well help. The deck will likely reach its coldest temperatures through radiating heat to the sky (especially on clear nights) rather than simply conduction to the ambient temperature air.

 

[blxm]

That all makes a lot of sense to me. The only thing I'd disagree with is using dehumidifier in extreme cases only. To me it's a tool as useful when connected to mains as battery charger or TV - it transforms the experience of living on board in cold or damp conditions, with a lot less power than the fan heaters we also use from time to time. The difference in smell and comfort between a heated well ventilated boat and a dehumified boat is like walking into a shed in Autumn or Summer.

I wasn't a fan until I rented a old stone built flat for a couple of months when working away and was shown a dehumidifier. The difference even touching towels or upholstery was huge.

Couldnt agree more. We use a meco and the small amount of heat and the drying has transformed the experience of living on board. Only need the unit on minimum and the noise is so low we dont notice at night. 32foot AWB and almost no condensation.

PS Its a simple solution but there is a £ cost. However, for us we wouldnt be without if mains electricity is available.
Without mains ventilation was the next best option for us.

 

[guernseyman]

International Anti-Condensation paint.
When we bought the boat there was a little mould in the dead space of an open-fronted locker under the cabin top. After cleaning and applying the paint there has been no recurrence after 25 years.