460 dorade vent - what do they do?

[jimali]

Hi

On my 460 there are 2 dorade vents on deck between the mast and solar panel. They are obviously factory fitted and sit above the garage molding for the sliding hatch. Internally there is an air grille near the ceiling lights close to the mast.

I can see no obvious air link between the vents and the grille. The vents just seem to be there to vent the hatch garage, which also has two large drain holes. I am about to take the garage off in the next few weeks but would be interested to see if anyone had investigated their purpose.

I am also hoping to sort out the solar panel which seems to have been fitted in its own swimming pool!!

By the way I have a garden of mould growing inside the garage see photos.

Thanks

jim

 

[centerline]

what you show is a cowl vent... a dorade box is something that a vent, most commonly a cowl sets on.... google is your friend and it can show you pictures.

but to answer your question, a dorade box is an air/water seperator that is supposed to allow air flow into or out of the cabin while allowing any ingested water to return back to where it came from...
using an air vent facing forward on the bow sometimes/quite often will scoop in a bit (or a lot) of water from a wave, and without the dorade box, it would ALL get funneled to the inside of the boat....
any vent, dorade box or not should be strategically placed on the deck to minimize being hit with water, but sometimes it may get wild enough that there needs to be some way to close the vent entirely, such as a screw in plug for under the cowl...

 

[splax]

As a further clarification, it is my understanding that these cowl vents provide engine intake air, equalize humidity with the outside, and allow higher temperature moist air to escape with the boat ports and hatches closed.

 

[Jeff10528]

The Dorade vent does both supply and exhaust air from the cabin depending on the direction the cowl scoops are turned relative to the air flow over the boat. The Dorade box provides a mounting place spilling air low in the box. The internal vents take air from high in the box. Water is thereby separated and returns to the deck through drains (the garage in your case.) The yacht Dorade blazed a trail of significant race wins thereafter, including the 2013 TransPac! Google yacht Dorade for more info.

 

[jimali]

460 deck vents

As a further clarification, it is my understanding that these cowl vents provide engine intake air, equalize humidity with the outside, and allow higher temperature moist air to escape with the boat ports and hatches closed.

hi

Thanks for that information. Have you any idea of the air path from the vents via the garage to the inside of the boat and particularly the engine

Thanks

Jim

 

[centerline]

the garage you are referring to, I would assume you mean the sea hood..... instead of a dorade box, they have mounted the cowl vents in the sea hood. and hopeing it will separate the water from the air....

the air would flow from under the sea hood to the front of the sliding hatch, under it and in to the cabin.....
what goes into the engine compartment will be either sucked in when the engine is running, or you will have to open the engine compartment and place a fan to circulate air into the area....
OR. if you have a cowl on the coaming in the cockpit, as it removes air from the space below it, it will probably pull from the cabin to replace it.... or from a cockpit hatch that has a bad seal. air will always take the path of least resistance.

these cowl vents are passive, and only operated by the wind or other airflow around them... do a search on boat ventilation options and you can learn a lot by what you find...

 

[Jeff10528]

Wow, had this gone wild or what? I'm assuming by "garage" you mean the space where the companionway hatch is stored when opened. On my h430 that space is separated from the Dorade Box , ok, it is really a triangle, by a structural rib. The separation is almost complete except for drains in each of the forward corners of what I have been referred to as the "Spray Shield", translate- cover of the garage. Water is directed from the Dorade Box and off the Companionway hatch to the sides and rear exiting in the channel where sheets and halyards travel to the forward end of the cockpit.

I've already described airflow through the box.

As far as where it goes, it enters or leaves the cabin through two vents located in the forward end of the ceiling light panel. The vents have adjustable flaps which can be opened or closed with a central knob. The air can then be utilized as needed by all uses.

External factors such as airflow around the scoops, wind and boat speed determine the amount of air supplied or exhausted through the Dorade Box. It was simply designed to improve ventilation in the cabin space. I do not believe the technology to be any more complicated then that.