# Ventilation and the bulletproof dorade



## Valiente (Jun 16, 2006)

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 (Oct 2, 2006)

Valiente said:


> 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 (Mar 19, 2006)

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 (Jun 28, 2006)

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 (Mar 19, 2006)

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 (Oct 11, 2004)

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 (Mar 19, 2006)

> 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 (Jun 16, 2006)

All good suggestions, folks. Thanks!


----------



## Faster (Sep 13, 2005)

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 (Mar 19, 2006)

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.


----------



## TrueBlue (Oct 11, 2004)

Not sure if it's standard with most permanently mounted dorades, but ours have threaded plastic caps, which are inserted into each dorade's bushing from the cabin side. This provides flexibility during cold or heavy weather without having to go on deck.


----------



## soul searcher (Jun 28, 2006)

SD Can you retro fit the nicros with the screw in plates or are they completely different. we just have the press in plates for them but regular screw in plates for the dorades.

Matt


----------



## sailingdog (Mar 19, 2006)

Unfortunately, the Nicros have to be bought with the screw in plates... since the vent fan itself has a bronze screw collar in it...they BRS model is a bit more expensive than the others for that very reason...that and they come with a stainless steel deck ring and deckplate.


----------



## christyleigh (Dec 17, 2001)

*Nicros*

Nicro has had vents with below deck electrical - AND water ingress shutoffs - for about 5 years called Powervents 24/7 battery/solar and expensive. They are square and I installed them on my forward hatches on my c320 after taking green water into the forward berth with the standard round type pictured in an earlier post.


----------



## sailingdog (Mar 19, 2006)

I've found that even though the Nicro Powervents close off for rain and such... green water breaking over them will pour through them quite nicely...  Replacing the Nicro vents I have with deckplates means green water doesn't bother us at all..


----------



## christyleigh (Dec 17, 2001)

sailingdog said:


> I've found that even though the Nicro Powervents close off for rain and such... green water breaking over them will pour through them quite nicely...  Replacing the Nicro vents I have with deckplates means green water doesn't bother us at all..


Hrrummph.... I never actually got to test the closure of the powervents against pure water. The other 24/7's did fine in pouring wind blown rain or splashover from bow waves but dead into steep 5 footers when the water ran up the bow like a wave up a beach it really poured in. I'm a bit surprized that the powervents would leak that much unless they were totally destroyed. I realize they are just a plastic closure but I would have only expected a few drops to come through - thanks for the info


----------



## sailingdog (Mar 19, 2006)

We had over three feet of water on the foredeck at the time we found this out.. and the little plastic part just blew out from what I recall. Not fun... Wasn't my boat, but I was supposed to be using the v-berth....which was a bit soggier than I like after that afternoon's beat...


----------



## TSOJOURNER (Dec 16, 1999)

*Duct tape for green water*

I know this will sound crazy but duct tape will seal all hatches, and small vents during green water soakings. I know cruisers who put it on at the start of the passage and remove it once they arrive in port at the end. Don't leave it on too long or you get the common duct tape goo remaining. We keep our dorades facing aft, sucking air out of the boat instead of blowing air in. It keeps things drier but doesn't stifle the air down below. Also don't forget the chain hawser pipe.. Plumbers putty (for installing stainless steel sinks) works well, never solidifies, and doesn't get all over your chain.

For in port ventilation, we created squall proof hatch covers that remain open during 25+ knot squalls. Note: Most of the water reflects off the deck, so you need to develop a damper to prevent the deck spray from getting down below.


----------



## Livia (Jul 20, 2006)

Sorry to revive a dead thread again...

We have these in the static version and are considering adding their solar fan. They say "waterproof unless submerged" and I'm curious if anyone has experience with these (or variants) and greenwater. Also curious how these differ from the nicros so that if we replace we can know what we are gaining and losing.

Livia aboard s/v Estrellita, a Wauquiez Pretorien 35


----------



## sailingdog (Mar 19, 2006)

Livia—

Nicros will generally keep out rain, spray and such, but if water breaks over the vent, they will generally allow water to pour into the cabin. Those probably don't stop water much differently than the Nicros do. It also depends on which model Nicro you get. The BRS model of the Nicro vents are screw-in vents, rather than snap-in vents, and have a screw-in deckplate that can close off the opening in really heavy seas.


----------



## Livia (Jul 20, 2006)

Thank you sailingdog


----------



## sailingdog (Mar 19, 2006)

Livia-

You're welcome.


----------



## Steelhull (Dec 11, 2006)

*Steel hull dorade*

Valiente,

I have been musing the same issue on my steel hull. I ended up buying a 4" black iron nipple (12" long, threaded both ends), cut it in half and welded it thru the deck in front of my pilot house on iehter side of the mast. It protrudes into the cabin just shy of the headliner. I will build a nice teak grill to cover the pipe on the inside where the threaded end is. This grill will be hinged so that a pipe cap can be intalled in very heavy weather. On the deck side, the pipe is about 4" proud of the deck. A standard dorade box will cover it. I welded 4 studs to the deck to mount the box to. I was able to get two 4" stainless teardrop dorades for $450.00. The airflow is a terrific improvement. I also installed two 4" nico day/night vents. One in the vbirth, one in the aft cabin. The boat aroginally had vetus vents in the same place so I was able to reuse the stainless mast pulpit that act as protectors for the dorades.

hope this helps...


----------



## Valiente (Jun 16, 2006)

Steelhull said:


> Valiente,
> 
> I have been musing the same issue on my steel hull. I ended up buying a 4" black iron nipple (12" long, threaded both ends), cut it in half and welded it thru the deck in front of my pilot house on iehter side of the mast. It protrudes into the cabin just shy of the headliner. I will build a nice teak grill to cover the pipe on the inside where the threaded end is. This grill will be hinged so that a pipe cap can be intalled in very heavy weather. On the deck side, the pipe is about 4" proud of the deck. A standard dorade box will cover it. I welded 4 studs to the deck to mount the box to. I was able to get two 4" stainless teardrop dorades for $450.00. The airflow is a terrific improvement. I also installed two 4" nico day/night vents. One in the vbirth, one in the aft cabin. The boat aroginally had vetus vents in the same place so I was able to reuse the stainless mast pulpit that act as protectors for the dorades.
> 
> hope this helps...


It does, thank you. It combines the "stock" approach with a custom modification that might do the trick. I would consider modifying the top end of the vent pipe with a scalloped cut facing aft and forward to increase the air flow down from the dorade into the cabin. I would also consider putting in a petcock in that pipe cap, so that if you get a quart of water in there from a severe dousing, you can drain the pipe before you remove the cap. I suppose a rubber bung would work as well...if your cabin top is that far underwater, you have other issues...


----------

