Mushroom / deck ventilators

[jambaman]

Not had any success finding previous threads on the subject so,…I wish to install either a mushroom or flush deck ventilator to one of our hatches. I would appreciate views on their usefulness and more importunately, their weather ability, i.e. do they keep water out. I see from the new Vetus catalogue, that there are two main types, ones that can be closed and ones that are permanently open. My first thoughts are to opt for the ones that can be closed. Any advise and experience with these would be most welcome.

many thanks
Julian

 

[yourmomm]

i have the permanently open types-they have NEVER let water in-even when hosing down the deck-however, im not sure how much ventilation they provide either....there doesnt seem to be much fresh air down below when the windows and hatches are all shut. my advice would be stick to dorade boxes-but if you do go for these, then the closeable type would be preferable as i assume they can allow more airflow....(?)

 

[ColinHuggins]

I've had bog-standard Tannoy vents on several boats. They never let water in, nor much air either!

 

[Krusty]

I had to install ventilators for use of my vessel under the (then) Sail-Training Code of Practice. It was a real pain getting enough air in and keeping water out (not rain and spray, but real water). I went for the Vetus screw-down-closure mushroom type in stainless steel: two on foredeck, two on coachroof.
These had a plastic ring inside the cap which was supposed to make a seal on the rim of the upstand, but in no time the inevitable contacts by ropes, feet, etc strained the alignment of the central screwed shaft (because its bush mounting was flimsy) so the cap did not sit evenly and let water in. Of course people then screwed it down harder and the end flange of the screw broke away from the cap because it was only lightly spot-welded. These vents were simply not well enough engineered for serious duty.
HOWEVER: after a few 'mods' mine are now very satisfactory:
The plastic seal was replace by a disc cut from 4mm closed-cell-foam sheet (as used for tent ground-insulation, etc). It compresses more easily and deeper.
The spot-welding has been replaced by scouring the whole contact area between the flange and cap until grey and using Araldite; much stronger.
To protect from feet, spinnaker poles, etc, the mushrooms are now housed within swivelling cowl-type vents on deck.
Our 'make ready for sea' routine includes turning cowls to face aft and srewing down the mushrooms, from below of course.
On anchoring we turn cowls to face forward and open mushrooms.
Results for last fifteen years: no salt-water ingress, airy cabins.
I hope Vetus have raised their design and manufacturing standards, but I doubt it.

 

[thalassa]

Vetus and ECS ventilators are basically the same. The best ventilators I had on my boat(s) were Goïot ventilators. Though as nails, they do close off completely, and they actually let air in!

http://www.goiot.com/pdf/p35-aerateur.pdf

 

[William_H]

It seems to me as described any of the mushroom vents are susceptible to damage especially when open. ie big feet. On a small boat I think I would rather consider fan ventilation through a duct from a point near the main entrance or rely on an opening front hatch. olewill

 

[jambaman]

Cheers guys. I can see how the mushroom type would get caught on sheets etc, but would the Vetus flush mounted UFO range? However, if they do not let much air in, then what’s the point!! The Goit ones look and sound superior and as such will investigate further. I wish I could install dorades, but at the cost of ripping out much of the wood interior headlining, I’m reluctant at this stage to carry this out.
Many thanks, Julian

 

[Malish]

The Vetus mushroom type (the smallest one anyway) fits inside a Vetus cowl to give you a dorade type vent - see Piotaskipper's post