PocketShip.net

Hi all!
I was interested in cowl of the dorade ventilation device.  I see that there is a standard type, as recommended in the assembly instructions, and also there is mushroom-type ventilation.
I would like to understand how air flows and what are the benefits.
In the standard case, as I understand it, it works like an air intake.  That is, air enters only when it blows directly into the pipe.  If you have a pipe looking forward, and the wind is blowing from the side or behind, then this will be ineffective.  Right?
Another case is mushroom-type ventilation device.  This is a round device, it does not require a specific wind direction.  When the wind blows from either side, it works to extract air from the cabin.  Why is it not so popular?
Why is it preferable to force air into the cabin, rather than pump it out through the ventilation?

Most of the time the wind will be blowing from ahead of the boat, and you can just leave the scoop-type ventilators pointing forward.
If the companionway is left open, the same wind will tend to pull air out of the cabin.

BTW, I leave my ventilators off, with the holes capped, unless I feel the need for ventilation.
And last season that never happened...

Doug

TL;DR: Dorade vents might provide better ventilation but we finally decided for mushroom vents

Long version:

The dorade vents of PocketShip are designed to serve for ventilation AND drainage for the anchor well. While we visited this Pocketship the owner mentioned that at some time the drainage holes to the outside (!) got clogged and rainwater made it into the cabin. Yes, the dorades can be closed as described by Doug, but we definitely want to keep the cabin ventilated when not sailing and the boat sits on the trailer, possibly unattended for an extended period of time.

There is also a video on youtube by jbratt that shows a wasps' nest in one of the dorade boxes

We have chosen mushroom vents of stainless steel that can be opened/closed from inside and outside; they are equipped with a fly screen and have a height of only 25mm when closed.

Dietrich

Thanks for the advice friends! I see that opinions are divided. The exact same thing happens in my head )))

dbeck wrote:...
We have chosen mushroom vents of stainless steel that can be opened/closed from inside and outside; they are equipped with a fly screen and have a height of only 25mm when closed.

Dietrich

Dietrich,

Do you have a link for these stainless steel vents you could share?

Thanks!

Hello Bill,

we've bought ours here (you'll find a pdf drawing)
https://www.svb24.com/en/mushroom-vent.html
They are produced by a Dutch company, http://www.vemefa.eu/indexe.html
I'm not sure, if they are available in the US.

We are still building and we have no experience with those.

Dietrich

Thanks Dietrich!

A quick search 9n my phone found them on eBay. I'm sure they are available elsewhere, now that I know what I'm looking for.

https://www.ebay.com/itm/285177076667?c ... 12b207126c

Bill,

please be aware this type of mushroom vent is only A304 steel, not A316. Thus, they are less resistant to saltwater (our PS will mainly see inland waterways so that's ok [1]).

For the smallest version of this mushroom vent, the opening on top the dorade boxes is a few millimeter smaller than the one required for the cowls proposed in the manual. If this solution does not work out, we could easily exchange the vents after a few years.

Dietrich

[1] All other screws and hardware on our boat are made of A316 (A4) steel. These vents are an exception.

dbeck wrote:please be aware this type of mushroom vent is only A304 steel, not A316.

Weird. Description on eBay website says it is AISI316

Dmitriy,

the ones on ebay seem to be a different brand. Ok, for my next PS I might go for the the AISI 316 ones too.

Dietrich