Dorades on deck / hatch for front cabins

[nfbr]

I have a catamaran, and the two front cabins need some cross flow ventilation.

I can leave the hatch open but that's problematic for weather, security and it's a very large hartch (2ft) for a custom Dorcap.

I have 4 options

1. Vent or solar vent in large hatch
2. Dorade in deck
3. Dorade in hull under trampoline
4. Ducting somehow into existing boat dorades

Does anyone have experience with fitting dorades that will get a lot of water over them in heavy weather?

I'm happy to have a fan to assist them, but they have to seal well when sailing.

Thanks

[ItDepends]

Originally Posted by nfbr

Does anyone have experience with fitting dorades that will get a lot of water over them in heavy weather?

Based on my experience with dorade vents that get a lot of green water wash... they leak.

Actually with enough water on deck, they do not leak, they pour water into the cabin Once water comes in the cowl faster than it can drain out of the box, an overflow into the cabin is unavoidable. And these were dorade boxes speced by Sparkman Stephens, who invented them!

They are great at anchor in the rain. For ocean crossings, not so much.

[psk125]

For heavy weather can't you turn the cowls on the dorades to face aft? That would help to keep them from getting overwhelmed.

[JPA Cate]

Fans. Possibly oscillating. Retains structural integrity. Won't leak, ever. The Caframo ones are easy to clean, and the spare blades are light weight and easy to store. They do make noise, but even on low, they move enough air to dry one's perspiration.

At anchor, you can have hatch dodgers made on the dorade principle, which will allow ventilation, even in the rain. On our mono, Jim and I made it out of Stamoid (a pvc "fabric" with a 10 yr. guarantee), and if the wind is over 20 kn., we have to close the hatch part way, but it can still stay open. The trick in the design is to have a good overlap between the "dorade" panels, so that bouncing raindrops can't come through. The forward panel goes down almost to deck level, and the aft one close to the top of the dodger. Plan on opening the hatch to about 45 degrees. It won't need to be open all the way.

Ann