Under way on every point of sail except DDW or very broad reach it's nearly impossible to have a hatch or portlight open unless it has a dodger if there is enough wind to make good speed. The wind will drive spray in almost any opening it can find in the boat. The one exception is the main hatch if you have a dodger that extends well past the companionway. Have found ventilation not to be a problem except in the Doldrums. For us, when there is enough wind to sail, a few dorades and the main hatch give enough ventilation for it to be comfortable below even in the tropics.
In light conditions, you can open the hatches and ports to increase ventilation. With enough wind to make a couple of knots, it's usually not a problem.
In the doldrums, nothing but fans and air conditioning suffices with the ghosting conditions and that might be enough.
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Peter O.
'Ae'a, Pearson 35
'Ms American Pie', Sabre 28 Mark II
Boat: Building a Max Cruise 44 hybrid electric cat
Posts: 3,198
Re: Ventilation for Voyaging
One of the thousands of things Dashew does right on his boats is ventilation for offshore. The Sundeer series has combing boxes running along both sides of the cabin top. 4 large 5" dorade vents are lined-up on each side funneling air into the combing. Inside, adjustable "eye" vents allow you to position the air flow wherever you want.
The boats aren't real pretty, but function is awesome!
My centre cockpit aft cabin has two dorades, a 12 volt fan, two opening portlights, and an overhead hatch/skylight. All openings have bug screens to keep (some of) the bugs on the outside. Ventilation is pretty good in my aft cabin, probably better than my forward cabin (it's wetter up there).
One very nice feature my boat has is two portlights that open inboard into my cockpit, and therefore under my dodger. I keep these open in all but the roughest weather, they provide great ventilation. The downside is one opens into my head (stbd side) and the other into my workshop (port side), neither place do I spend a lot of time.
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Location: Paradise Village Marina, Puerto Vallarta
Boat: 1975 CT-41
Posts: 18
Re: Ventilation for Voyaging
I'd like to see what the air vent looks like inside the cabin. What type of air controller/screen is installed? We just put the dorades on the boat, they were closed off when the boat was purchased and the headliner covered up the vent holes. We took the headliner down and now it is just the bare fiberglass with a hole.
Our Dorades have teak-like (actually they are PNG rose wood) trim rings where the air enters the cabin. You could use teak for a more finished appearance.
You can retain the convenience of no headliner and improve the situation visually by using timber covers (varnished or oiled) over the inside of sail tracks and to make "conduit" for otherwise exposed wiring. This allows the convenience of instant access to leak sources, and gives a more finished appearance.
__________________ Who scorns the calm has forgotten the storm.
Since we're reviving this thread, I just wanted to say that I find the placement of fans in all the areas to matter. For sleeping, I like the flow of air to come past my nose from my feet. The feet don't have to have it directly, but the rest of my body wants that flow.
In the saloon, I like one for the cook, and two for the saloon table.
The dorades really do a good job under way, and I made a forehatch dodger that works like a dorade so that we can leave the forehatch open in a tropical downpour...
Cheeers, guys,
Ann
__________________ Who scorns the calm has forgotten the storm.
I'm sure some must have a closing feature but I just stuff rags in mine if I'm worried about the cold. As far as screens go, I have screens for absolutely everything, mosquitoes are a big problem in some of the areas I sail. We nearly got eaten alive last week on the Bay of Quinte with our screens in.
My boat came with screens for most of the openings, but my wife made the rest. She bought screen material from Canadian Tire and cut it to shape. Then put on Velcro strips. Hot glue gun to attach to the boat. She tried a glue gun to attach the Velcro to the screen, but that didn't work. In the end she resorted to a needle and thread.
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ATN, best known for the ATN Spinnaker Sleeve and Tacker, makes a very clever device called a Dorcap which is a reefable wind scoop for deck hatches. It is adjustable so you can draw the top down and raise a small panel to prevent rain from blowing in while still allowing air to enter. I’ve seen it at the Annapolis Boat Show and have been tempted to get one or two for my boat. Anyone who has ever sailed in the Caribbean knows the nightly routine of waking up to rain spritzing your face, getting up to pull the hatch down, getting hot, getting back up to open the hatch, etc. several times a night. I think it would probably work well to prevent rain from blowing in, but underway a wave breaking over the deck would flood right in.
Sailboatowners.com sells a “Hatch Umbrella” which is actually a small tent that you suspend from a halyard over your hatch and secure to the lifelines. I bought one when they were still reasonably priced to use on my Hunter 26. It worked well in gentle weather, but a blowing rain would still get under it and through the hatch.
It is really ventilation while underway that concerns me the most, and it seems that the answer that keeps coming up in this thread is “dorades.” And fans. I’m not too impressed with the Hella and Caframo fans that you usually see on production boats, because they usually make an irritating rattle and too much noise for the air they put out. But West Marine and Defender have a Caframo Sirocco 807 fan that looks promising. It claims to be quiet and use little power, but its best feature is the swivel base that lets you pull it out from the wall and point it where you need it. And you can set a self-timer for 2, 4, 6, or 8 hours. Has anyone used this fan? If so, does it live up to its claims? Or has anyone found a better fan that is quite, adjustable, and powerful?
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