anchor locker drain hole, outside cover plate

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Neeves

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Two questions:

Is there an official name for the cover plate sometimes attached to the outside of the hull to deflect or reduce the amount of water entering a chain locker when the yacht is at sea

For these that have yachts fitted with these plates/deflectors - do they actually work?

Jonathan
 
This sort of thing ?

21871-9497675.jpg
 
VicS said:
This sort of thing ?

21871-9497675.jpg
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Vic, Yes, the very things.

Rob, thanks, 'shell vents' - descriptive!

I agree they look much neater then a simple hole.

I note that many AWBs simply have 'ugly' holes (and I don't see that many with shell vents) but this might be part of overall economy rather than ineffectiveness - so wondered.

That was quick, easy and non contentious (despite the word anchor appearing!) :)

Jonathan
 
billybiltong said:
Ps Very sorry trying not to contentious!!!! ������
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Not contentious at all - our anchor locker is in, or on the bridgedeck and sits 1m above the water, with 2 x 20mm drain holes, one in each of 2 corners.

I was simply trying to increase my limited knowledge of nautical terms, clamshell vents, and whether the said clamshell vents were advantageous. It appears they might be aesthetically pleasing - whether they have any other advantageous function has not been mentioned.

Jonathan
 
bitbaltic said:
I thought that too, but have seen both 'shell' and 'clamshell' used on different chandlery sites, so I think you are both right.
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I'm happy to know they are either 'clamshell vents' or 'clam shell vents' - for which thanks.

Semantics apart - the question of whether they do anything other than look more attractive than a plain hole - is unanswered.

Out of interest - bitbaltic aka Karisma - how is your Hanse kitted, with or without 'csv' - and is the actual hole in the bottom of the locker - or do you enjoy a 'puddle'? I'd ask the same of Paul, except I assume you do not have a Hanse :)

Jonathan
 
My chain locker has a clamshell vent on each drain hole. (One on each side, and as near to the bottom as possible).
The drains are less than a foot above the static waterline, so when sailing, are often submerged. I would imagine that when pitching at all, if it wasn't for the vent covers, jets of water would be injected into the chain locker. Would that matter? Maybe it would be a good thing, and help to flush out any accumulation of mud in the bottom of the locker.
I've never given them much thought, but I suppose that they look better than just a hole.

I have a matching pair of the same vents aft, to encourage water into the cutless bearing for the prop shaft. :D
 
Neeves said:
I'm happy to know they are either 'clamshell vents' or 'clam shell vents' - for which thanks.

Semantics apart - the question of whether they do anything other than look more attractive than a plain hole - is unanswered.

Out of interest - bitbaltic aka Karisma - how is your Hanse kitted, with or without 'csv' - and is the actual hole in the bottom of the locker - or do you enjoy a 'puddle'? I'd ask the same of Paul, except I assume you do not have a Hanse :)

Jonathan
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She has a single clamshell on the port side and the hole is at the bottom of the locker, to be honest I haven't ever given it much thought as to whether the clamshell itself is lower down than the hole (i.e. Is there a pipe beneath the bottom of the locker or not?) the clamshell is however at the perfect height to be crushed should you get it wrong coming into a pontoon... this is how I found out the name myself because when I crushed it I did not know the name of the replacement part I needed :)
 
bitbaltic said:
She has a single clamshell on the port side and the hole is at the bottom of the locker, to be honest I haven't ever given it much thought as to whether the clamshell itself is lower down than the hole (i.e. Is there a pipe beneath the bottom of the locker or not?) the clamshell is however at the perfect height to be crushed should you get it wrong coming into a pontoon... this is how I found out the name myself because when I crushed it I did not know the name of the replacement part I needed :)
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Its a comfort to know I'm not the only ignoramus :)

I have seen 2 new AWBs at boat shows with a puddle of water in the chain locker and the drain hole, maybe, 200mm above the locker base. I wondered how widespread was the design (I did not think to look as the whether they had clamshell vents). The water in the locker could have been rainwater, water from washing the decks down (though it looked like brown Windsor soup - if you are old enough to understand) - but it would be fairly permanent - as unless you mopped it out there was no other way of drying it.

Comments seem to suggest that most drain holes are at locker base - and the ones I saw were exceptional.

This is not another fettish, just something that seemed topical.

Jonathan
 
Neeves said:
I'd ask the same of Paul, except I assume you do not have a Hanse :)

Jonathan
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I have a Westerly Jonathan. She doesn't have drain holes at the bow so assume the locker drains into the bilge, a horrible idea IMO. I had a previous boat the did this and the bottom of the locker was rather close to the waterline. I glassed a false bottom into the locker to raise the bottom, then drilled 1/8" holes from inside the locker, almost at the bottom. I then drilled them out from outside, at a slight upwards angle so the bottom of the hole was right at the bottom, then i fitted the clamshell vents.

I'll be looking to make a similar modification the my Westerly, with a vent each side. Not that in enjoy hanging upside down through a 46cm x 31cm hole breathing in resin fumes :disgust:
 
I was simply trying to increase my limited knowledge of nautical terms, clamshell vents, and whether the said clamshell vents were advantageous. It appears they might be aesthetically pleasing - whether they have any other advantageous function has not been mentioned.

Jonathan[/QUOTE]

My previous boat had a simple hole to drain the anchor locker about a foot above the waterline. When punching into a head sea for a few hours the locker used to fill up as water was forced into the hole. It eventually found a balance between the head forcing it out and the head forcing it in .... this balance was well above the normal waterline. I only noticed it because I had to go in the locker immediately after a rough passage. Otherwise you get to harbour and before long the water has drained. Anyway I fitted a clamshell over the hole and never had another problem .. I guess the flow past the shell tends to suck out the water like a venturi. So, in a nutshell, (pun) I think the clamshell thingie does do a functional job. Phil
 
PTB said:
I was simply trying to increase my limited knowledge of nautical terms, clamshell vents, and whether the said clamshell vents were advantageous. It appears they might be aesthetically pleasing - whether they have any other advantageous function has not been mentioned.

Jonathan
Click to expand...

My previous boat had a simple hole to drain the anchor locker about a foot above the waterline. When punching into a head sea for a few hours the locker used to fill up as water was forced into the hole. It eventually found a balance between the head forcing it out and the head forcing it in .... this balance was well above the normal waterline. I only noticed it because I had to go in the locker immediately after a rough passage. Otherwise you get to harbour and before long the water has drained. Anyway I fitted a clamshell over the hole and never had another problem .. I guess the flow past the shell tends to suck out the water like a venturi. So, in a nutshell, (pun) I think the clamshell thingie does do a functional job. Phil[/QUOTE]

Yes, I did wonder if your drain hole was orientated to 'come' aft and maybe 'down' and you had a clamshell vent if, as you say, there was a Venturi effect. It would certainly remove or reduce the pressure from the seas into which you are bashing. Which then begs the question - why do some yachts not have clamshell vents.

Since pondering the 'question' I have noticed a surprising number of older yachts have no vents and no holes, and presumably drain to the bilges - as Paul mentions, an awful idea. But presumably it was 'normal' and accepted - so no-one complained. But its hardly rocket science.

I have also noticed, the 2 yachts I saw at a boat show, and others (where they either have exceptionally shallow chain lockers, or more likely a vent well above locker base) that there is a disagreeable opportunity to carry around a few litres of nefarious water - just right to corrode your chain - as the locker will never drain. A new hole(s) seems a very sensible idea - but chain lockers are really the design of the devil (or maybe chain makers).

The trouble being - if your locker is well filled with chain and you never deploy all the chain (or look at the opportune time) you would not know it had a few litres of water in there.

The limited replies do seem to favour clamshell vents - and stick them on with Sika, or something similar.

Jonathan
 
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