Ventilation and the bulletproof dorade

[Valiente]

I am entertaining suggestions for ventilation solutions on my sailermotor

There are two decent-sized hatches in the saloon overhead, but just two 7 x 14 opening hatches on the cabinhouse sides, one in the head and one over the galley. The rest of the portlights are 1/2" Lexan throughbolted. Same with the pilothouse: the center windscreen opens forward and there's two little hatches overhead, but that's it. Oh, there's a Nicro vent over the galley, too.

As we wish to both travel in the tropics and to have a diesel heater in the main saloon (floor or bulkhead...haven't decided yet), I am looking for ways to increase air flow through the boat. I can use a Windscoop at anchor, but does anyone have a bulletproof dorade design that gets a fair volume of air down the boat but which can also either shed green water over the decks or can be REALLY shut off in storm conditions?

I am reading "The Warm, Dry Boat" and there's a lot of good ideas there, but I am looking for real-world, bluewater-tested suggestions. The boat is steel, and welding stuff on is no object. Here's a picture to give you a sense of the foredeck layout. I would prefer not to block pilothouse visibility, but you can't have everything.

[tdw]

Originally Posted by Valiente

I am entertaining suggestions for ventilation solutions on my sailermotor

V,
On Raven we have two Dorades over the main saloon. They have a decent box underneath them and when we took white water from bow to stern a month or so back not a drop got through. However, the vents themselves are those rotten plastic jobbies that look revolting and are not particularly secure. From what I can see replacing them with those hellishly expensive chromed metal types is the best answer but I'll need to build a cage over the vents to keep lines away from them. We have screw down covers for the vent holes but have yet to need to use them. It does seem to me that the good Dorade (as vertical as possible in my opinion) is still the best thing going round. Somewhere I have an image of what looks like an excellent installation. I'll go look for it and if can find it will post.
Regards
TD

[sailingdog]

While I agree that a properly designed dorade vent is the way to go, you won't be able to design one that can take "green water" over the decks and not leak like a sieve into the cabin.

In cases where you're getting green water over the decks, you need to close off the dorades. Same thing with the Nicro vents... in cases of heavy weather and seas—you need to remove the vent and close off the hole with a deckplate, otherwise, expect some water for company.

That said, four-inch dorades are the minimum size I'd go with.. and if you can install four of them...two forward and two aft.. it would go a long way to keeping fresh air flowing through the boat. The metal dorade vents are the way to go, but you really do need to build line guards for them, as TDW points out.

[soul searcher]

I like the nicro vents they move quite bit of air and our boat never realy feels damp We have three of them and two dorades. we do have deck plates for all of them. Nicros are nice when its dead calm they keep the air moving.



Matt

[sailingdog]

I have two Nicro vents on my boat... and given it's rather limited size, find that they're fairly good at moving the air through the boat as needed...since it is a small 28' trimaran. The ones I have are the more expensive BRS model that have a metal screw-in deck ring, rather than the plastic one.

[TrueBlue]

Not "bulletproof", but our two dorades are the types made from a rigid, yet flexible vinyl material - therefore less prone to breakage. The dorade interiors are finished in a dark blue.

Stainless cages of course, offer additional protection and are very convenient for attaching unused halyards.

[sailingdog]

Stainless cages of course, offer additional protection and are very convenient for attaching unused halyards.

Also good for preventing the jib sheets from sending the dorade cowl into the drink...

[Valiente]

All good suggestions, folks. Thanks!

[Faster]

If you build dorades, you could align them with the rather wide posts between pilothouse windows and minimize their impact on straight-ahead visiblity. Though it looks like one of your Nicro vents is already there....

[sailingdog]

He could always move the nicro vent, as they're pretty easy to install or move since they have no wires and are fairly low profile.

One of the most innovative designs I've seen had dorades that screwed into a deckplate... for heavy weather, the dorade was just removed and the deckplate put in its place.

Another innovative design of dorade box I've seen had the top made of either ABS or Plexiglass, so that it would act to let light into the boat as well as air.