Winter cover - dehumidifier or not

[Robih]

Home is now 550 miles distant from the boat so we cannot frequently attend during the winter to wash the crap off so have decided to invest a not inconsiderable sum in a custom build all over winter cover. Being fitted tomorrow.

Previously we’ve left a desiccant dehumidifier running, regulated by the RH monitor, on 24/7 all winter. However the winter cover manufacturer says that other owners who’ve had winter all over covers fitted have not needed dehumidifiers because hatches can safely be left in ventilation mode under the cover.

So we would welcome any real life experience of those who have winter covers - ventilate or dehumidify?

TIA

Rob

 

[Bobc]

Ventilate.

I have found that keeping air flowing through the boat is best.

 

[jwilson]

Keep hatches shut and dehumidify anyway - on mid-dry setting as you've been doing.

If a boat has absolutely no salty splashes/specks/patches on joinery/headlinings/upholstery etc. ventilation alone may be OK, but salt is hygroscopic and attracts/absorbs water vapour, and you will have more of that in a ventilated-only boat than a dehumidified one.

 

[Graham_Wright]

Ventilate.

I have found that keeping air flowing through the boat is best.

Never did understand that. Damp air is going to dump its moisture when it hits a cold surface.

If you close the boat up and dehumidify, the damp air becomes dry air. Why replace it with damp?

 

[neil_s]

Your cover will protect the outside of the boat, but you still need to keep the inside dry. Letting damp air in will just make all your upholstery damp and smelly and precipitate condensation all over your engine. The electrical system will also suffer. I have a cover but I seal the hatches and vents and have four Kilrock moisture traps which seem to be just enough to keep damp at bay. You need to be around occasionally to empty them, though!

 

[lw395]

You can't beat opening up the boat on a sunny day and letting the breeze through.
The other 29 days of the month, a dehumidifier winds hands down IMHO.

Whatever you do it's better not to neglect a boat completely for months on end.

 

[lpdsn]

Never did understand that. Damp air is going to dump its moisture when it hits a cold surface.

If you close the boat up and dehumidify, the damp air becomes dry air. Why replace it with damp?

I think peoples' opinions on this vary depending upon how damp the air normally is where they live. If you're faced with a typical winter RH of 80 or 90% then ventilition is unlikely to be effective.

 

[Nigel_Ward]

My Beneteau first 235 lives in the lake district and has the mast down and canvas overall cover fitted for 5 months in the winter. The hatches and lockers are partly open for ventilation. I do not have a problem with damp or condensation.
In fact the condensation is worse in early spring when the boat is put in the water and I have the heater on.

 

[RupertW]

You can't beat opening up the boat on a sunny day and letting the breeze through.
The other 29 days of the month, a dehumidifier winds hands down IMHO.

Whatever you do it's better not to neglect a boat completely for months on end.

Agree but we leave ours afloat for 4-6 months every year change without attending as it's a bit of a trip to get to. Dehumidifier is left on but how many days or weeks it lasts before somebody unplugs the mains is unknown. Seven years on the worst we came back to was a cabin and clothes full of mould - and that was in September after just 5 weeks away.

 

[lw395]

My Beneteau first 235 lives in the lake district and has the mast down and canvas overall cover fitted for 5 months in the winter. The hatches and lockers are partly open for ventilation. I do not have a problem with damp or condensation.
In fact the condensation is worse in early spring when the boat is put in the water and I have the heater on.

Lake District is probably different from Channel/West Coast where the water is often warmer than the land until at least Feb'ry, resulting in lots of dew?
Anything not heated or dehumidified in Portsmouth goes manky PDQ is my experience.
Best to do what works locally, and keep an eye on it.
Cleaning everything obsessively may may the difference between damp and 'damp and mouldy'?

 

[boatyguy]

Hi I know this is an old thread but i think things have moved on. Someone said (but could show me any evidence ) that there is a new law or rather change in insurance cover for dehumidifiers on boats after one sunk last year due to fire. Anyone know anything about this?

 

[Scomber]

Bump!!!
After a full 6 months away - quite a condensation clean up needed - think enclosed cockpit tent and sealed fore hatch prevented a decent airflow - we do take a bit of 'leak' water- however it was W Coast Scotland ( near Oban) for first time. Recommendations for decent grade of tarp and suppliers much appreciated. I'll check with insurance re dehumidifier as another option maybe if we seal all up. Dehumidifier suggestions also please. Much appreciated.

 

[Sandy]

Ventilate, ventilate, ventilate.

I watched the spray hood get soaked last week in a shower 20 minutes later it was bone dry. All done with air movement and a bit of sunshine.

Why do 99.99% of the population hang their washing out to dry?

 

[BelleSerene]

Ventilate.

I have found that keeping air flowing through the boat is best.

Which is not going to happen under an all-over boat cover.

Dehumidify. Especially if there are fabrics aboard.

 

[BelleSerene]

In fact the condensation is worse in early spring when the boat is put in the water and I have the heater on.

Yes, though it’s likely you, not the heater, that’s doing that. You’re breathing moist air out. You need ventilation while you’re doing that, or all that lovely moisture ends up on the surfaces and fabrics.

 

[Sandy]

Which is not going to happen under an all-over boat cover.

That really depends on the ventilation incorporated in the cover

If the boat was shrink wrapped that is another ball park.

 

[Poignard]

Ventilate.

My winter cover is designed to keep the rain off the wooden coachroof and cockpit whilst allowing plenty of airflow through the boat. I leave the forehatch and companionway doors partly open. I've done this for 20 winter layups and the boat always smells clean and fresh even after months under cover.

 

[Scomber]

Ventilate.

My winter cover is designed to keep the rain off the wooden coachroof and cockpit whilst allowing plenty of airflow through the boat. I leave the forehatch and companionway doors partly open. I've done this for 20 winter layups and the boat always smells clean and fresh even after months under cover.

Could I ask. Are you based in the rainy north ? I must admit your routine seems like our next plan of attack.

 

[Poignard]

Could I ask. Are you based in the rainy north ? I must admit your routine seems like our next plan of attack.

Rainy Brittany.