Ventalation ?

[Bob S]

Now that the oil is changed the water and toilet winterized and the boat is under canvas is it OK to leave the hatches open to improve ventilation. Last season I didn't cover the boat and come spring there were mold spots all over the cabin. Today I visited the boat and saw quite a bit of condensation inside. It has been raining the last few days but the topside was dry. I left the hatch open. I know you can use some type of desiccant to absorb moisture which I need to do. When your boat is wrapped do you close the companionway and windows or do you leave them open to improve ventilation?

 

[Ross]

Now that the oil is changed the water and toilet winterized and the boat is under canvas is it OK to leave the hatches open to improve ventilation. Last season I didn't cover the boat and come spring there were mold spots all over the cabin. Today I visited the boat and saw quite a bit of condensation inside. It has been raining the last few days but the topside was dry. I left the hatch open. I know you can use some type of desiccant to absorb moisture which I need to do. When your boat is wrapped do you close the companionway and windows or do you leave them open to improve ventilation?

My boat is treated in the same manner that fishermen treat their boats. In the winter season it is hauled ashore and blocked up. My solar powered cowl vents run year round. There are four cowl vents, two powered, two passive. The boat doesn't leak from the top or the bottom and mold and mildew hasn't been a problem for ten years.

 

[sailingdog]

You really need to move air through the boat... most boats will act as moisture pumps, and that's why you end up with condensation inside them.

As the boat heats up during the day, the air pulls in more moisture, since it is warmer... then as the boat cools off at night, the now excess moisture condenses off onto the cooled exterior surfaces of the boat... the longer the boat sits unventilated, the more water it collects.

Using DampRid or some other industrial dessicant will also help...but generally, moving the air through the boat is a better idea.

Of course, if your boat has leaks...then you've got to move a lot more air through the boat to keep it dry... fixing any leaks is a good idea...

 

[Dave Groshong]

Air flow is key! We have Dry Z Air here:

http://shop.SailboatOwners.com/category.htm?fno=400&cat=2208

The problem is, they really need to be emptied and changed out every couple weeks depending on how much moisture's in the air.

I used to run (2) of the air driers 24/7 on a 37ft boat during the winter, they are much safer of course than heaters.

 

[Ross]

I have a dedicated 5 watt solar panel and use that to drive 3 inch computer fans in my cowl vents and to drive a couple of smaller fans in compartments that need forced ventilation. The 3 inch fans are rated at 24 CFM so I get several air changes per hour during the daylight hours year round.

 

[Maine Sail]

If you..

If you have not done this already.... Dry the bilges!! I mean dry them completely and then add a solar vent or leave a hatch cracked a little bit to create a chimney effect.

A wet bilge and a sealed boat with no possibility of air movement will create mold very quickly..

P.S. A couple of kitty litter boxes filled with kitty litter will effectively work the same or similar to the expensive stuff like damp rid and kitty litter is cheap..

 

[Ross]

Re: If you..

Ventilation is so effective that if I spill water in the boat within a week the bilge will be bone dry.

Edit to add:
An example of how we trust our ventilation, after we wiped some sloppy off the deck Friday and rinsed the rags Nancy hung them in the cabin to dry. I was going to leave them outside but if it rained they would just get wet again. They will dry just as well inside and the boat won't be the worse for that.

 

[Bob S]

Ross, Does the solar panel run the fan directly or need a battery set up? If the fans work directly from the solar panel then they only work during sunlight or 4 hours on 20 off? I have removed the batteries for the winter.

Maine Sail, I have washed and pumped/vacuumed the bilge bone dry. Not as clean as your. I will put a few containers of kitty litter, good idea.

What is your opinion about keeping her plugged in? I can leave a heavy duty extention cord connected to the shore power cord and put a small fan on low. I vaguely remember reading something negative about that.

 

[Ross]

bsmith, No battery. they start running about an hour after sun-up and run until about sundown. I have considered putting a 12 volt portable tool battery into the circuit but I don't think it would have a net gain in the winter months. The fans draw .8 watts each and there are 3 on the boat. 2 in the cabin and 1 in the lazerette. The lazerette occupies the aft 4 feet of the boat and is isolated from the cabin by a water tight bulkhead. When ever we go aboard the reletive humidity is in the 50 per cent range.
edit to add: the fans will run on 8-15 volts and are rated at 12 volts.

 

[Maine Sail]

What is your opinion about keeping her plugged in? I can leave a heavy duty extention cord connected to the shore power cord and put a small fan on low. I vaguely remember reading something negative about that.

I thin you'll find that most boat yards don't allow that? Mine does not.. The best money is a Nicro Day/Night solar vent. My boat is buttoned up tight other than about a 1cm crack in one hatch and the Nicro Day/Night and I get zero mold growth and don't use any sort of desiccant.

 

[Bob S]

I assume these solar vents are permanently mounted into a hatch. Ross, yours in a cowl. If your boat is wrapped how does the sun run the fan?

 

[Ross]

Let me see, if I am drawing 2.4 watts to run my fans then that amounts to .2 amp hours/ hour. My solar panel puts out about .4 amp hours in peak sunlight for let's say 6 hours I get 2.4 amp hours total . If I run the fans day and night I will need .2A time 24 hours or 4.8 amp hours, so my panel is at best half big enough and for a bit of a cushion probably only one third big enough.
All of that considered the set up as is works well enough and has been completely trouble free for 10 years

 

[Bob S]

Ross,

Your panel is obviously outside your cover. I googled the Nicro fan Mainesail was taliking about and it looks like one that would be mounted directly to a hatch. Great idea but I'm under a canvas. I would need to find a way to mount a panel outside the canvas. I have a "to do list" a mile long unfortunately money and spare time are limited. This year I shot my ward on a custom canvas cover that I hope to get 10-15 years out of. I love the idea of a permanent solar vent. I hated sleeping on the boat when my pillows are damp! Humidity up here can be opressive.

 

[sailingdog]

Bsmith-

I have two of the Nicro solar-powered vents on my boat. The first one was installed just after I got the boat, and it had two major effects: first, it dropped the temperature of the boat about 15˚ in the summer time; second, it kept the boat much drier. I installed the second about a year later... and it really does keep the boat much more comfortable in the summer time, and prevents condensation problems when the boat is closed up for long periods of time. One is setup as a exhaust, the other as a intake.

 

[Ross]

You can find surplus Volkswagon solar panels on Ebay for about 20 bucks. You can scavange fans from junk computers. The VW panels are about 3.5 watts. Mine is a Seimans that I bought before I learned of the surplus ones. My panel is mounted on the stern pulpit (or is that the "pushpit"?).

 

[Bob S]

Thank you everyone!

 

[Maine Sail]

Sorry

Sorry, we shrink wrap with white shrink material and it lets enough light through so the Nicro works.. I'd guess with a dark colored canvas it would not work or be marginal at best..

 

[sailingdog]

You could ask a sailmaker to install a vinyl or isinglass window over the vent locations...so they'd get enough light to operate for at least part of the day.

 

[Bob S]

Thanks again

I have a small 5 watt solar panel I will mount outside and try running a 12 volt fan. I think the green cover is too dark to permit a solar panel to work from the inside. Any reason why I couldn't leave the companionway doors off?

 

[sailingdog]

I would worry about theft... and also if the cover doesn't seal to the hull tightly, you may get wildlife inside the cabin... that could be very bad.

I have a small 5 watt solar panel I will mount outside and try running a 12 volt fan. I think the green cover is too dark to permit a solar panel to work from the inside. Any reason why I couldn't leave the companionway doors off?