Can " tannoy" vents ever be waterproof?

graham

graham

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We have a "tannoy "vent above the berths in the forepeak which has leaked a bit in the past.

I have just taken it off cleaned up all the bits and refitted with new sealant so it shouldn't leak around the base now but I cant see how it can ever cope with a big dollop of water on the foredeck?

I think the bedding is still going in bin bags unless it proves otherwise.

Should get more air through it now I have cleaned 42 years worth of dead flies out of the gauze filter . :-)

You can see it in these pics in case I have got the name wrong for this type of vent.
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IMG_0110CROP%205_zpsi7l6jetg.jpg
 
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We never had any trouble with ours on previous boats, but they were on the coachroof and not as exposed as yours. You could try not going out when it is likely to be rough, or maybe find a way of blanking it off when under way, which is what I think I would do.
 
For a quid or two extra you get the closeable version; this has a sliding collar inside which when pushed up makes the thing pretty watertight.

I have 2 of these on my boat, one above the cooker in the saloon - a standard place for the design - and one above the fuel locker.

Unlike the solar fan version it retains the translucent central bit for daylight - it has always been a mystery to me why the closeable version is not more widely known and used.
 
Thank for the replies.

May be able to make a bung to go up from the inside Or even a flap with wing nuts to pull it up onto a sealing strip.

For the small amount of air it provides I may just cut a circle of teak with the Perspex bit set into it to let a bit of light into the dark forepeak then fasten that down permanently over the hole.

In the place it is fitted a conventional vent and dorade box would probably give the jib sheets something to catch on and its my favourite spot to sit and watch the sun go down.
 
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Alpha22 said:
They cannot handle big lumps of water. To retain ventilation and be water proof you need a dorade box.
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What about the closeable ones Seajet talks of ?

Described in the catalogue as completely waterproof, but of course the ventilation is shut off when they are closed
 
I have looked at the description on some chandlers sites.

They describe the closable one as "waterproof except when submerged" doesn't really fill me with confidence.

The last time it let water in my wife had wedged her (open) bag of clothes directly under it . The bag was more waterproof than the vent .Fortunately there was a laundrette at our destination ,

The soaked in Bristol Channel Brown Stuff look may yet come into fashion making her a trend setter. This idea didn't actually cheer her up much at the time :-)
 
A Dorade Box is certainly not waterproof if submerged, ie if the boat is inverted; hopefully with a decently ballasted monohull that should be a very short roll period even in heavy seas.

The bible on all this sort of thing is 'Heavy Weather Sailing ' by Adlard Coles; recent editions are by Peter Bruce who no doubt is a great sailor but I prefer the earlier A.C. versions.

In theory the closeable version of the EC Smith tannoy vents should be waterproof when inverted.

So under pressure from outside - and while I have various Plans B,C, D, etc I think I'd trust the closeable tannoys more than bunging a bit of sponge in.

Though if in such conditions I'd be happy to try anything and everything though, right past whisky to even maybe religion !

Incidentally I was lucky enough to see the actual Olin Stephens ' Dorade ' which the vents were invented for, at Cowes this last summer; naturally I was helming a chum's boat and didn't have a bloody camera to hand ( I'm supposed to be a photographer but I leave that ashore as my work is usually aerial ) - I felt very honoured to be in the same bit of water as such a piece of history, gorgeous boat !
 
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Seajet said:
Mushroom Vents are certainly closeable, but have the snag of leaving nasty metal pointy bits protruding underneath at scalp level.
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The secret is to use ones which don't have "nasty metal pointy bits protruding underneath" and/or position them where ones scalp wont come into contact with them.

I have two, One is over the galley where only a dwarf sitting on the stove would come into contact with it. The other is in the forward cabin off set to one side. In nearly 40 years I am not aware of my head coming into contact with it. It barely protrudes below the headliner even when closed. Anyway neither have " nasty metal pointy bits protruding underneath".

One of the nice things about my boat is the thought and care that has been put into its design, construction and fitting out
 
VicS,

every mushroom vent I can remember seeing uses a buttress style thread in the centre, so there is always a bit protruding from the inside - especially in closed mode.

How do your mushroom jobs avoid that ?
 
Seajet said:
VicS,

every mushroom vent I can remember seeing uses a buttress style thread in the centre, so there is always a bit protruding from the inside - especially in closed mode.

How do your mushroom jobs avoid that ?
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By the time you add together the thickness of the foam backed lining, the ply panel to which its glued the the battens to which the ply boards are fixed. the inner skin the foam core and the outer GRP moulding it all but equals the dimension from operating handle to the mounting flange.

Not clear enough on the pictures I have .... will try to remember to take some more next year.
 
I'll be intrigued to see the pics, as the handle and at least a bit of thread will always be below the inner mounting on the designs I'm familiar with; the only mushroom vent on my boat is in the forepeak into the anchor well moulding, effectively using the well as a huge dorade box.
 
Can they ever be waterproof? To all intent and purpose, yes - at least, mine appears to be although, I readily admit, my boat hasn't been upside down.

I have a closable "Ventilite" tannoy vent from E.C.Smith, mounted in the middle of my boat's forepeak hatch rather like that on the OP's boat. It features a simple internal closure sleeve, which has a rubber seal on its top edge that presses on the top of the unit and thereby stops the ingres of water - push it up to close the vent and render it "waterproof" and pull it down for fresh air. The sleeve does close and does seem to keep the water out, although it seems quite a loose fit. I don't think I'd trust it for a long beat to windward in a big sea, with regular dollops of green water over the deck, as I feel the closure sleeve might work its way open if/when the boat slams. That said, I suspect that in most circumstances I'd only have to use a bit of strategically placed sticky tape to ensure the sleeve stayed up in the closed position.
 
Seajet said:
VicS,

every mushroom vent I can remember seeing uses a buttress style thread in the centre, so there is always a bit protruding from the inside - especially in closed mode.

How do your mushroom jobs avoid that ?
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By the boat designer including something called "headroom".

Tannoy vents are very waterproof and very ventilation proof. Mushrooms are great, open windows and portlights much better still.
 
Oh dear, there was me hoping for a useful reply...

I don't have a shed on my boat, but I do have Lewmar Ocean forehatch & opening portlight, it seems my closeable tannoy vents + closeable mushroom vent remain all that is available for the applications where I use them.
 
I have a dorade type vent on my 7m boat, always waterproof, boat kepted in beautiful condition inside, all grip dry and shining.never any bilge water either.
 
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