Breathers / Drain holes |
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iGRF
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Joined: 07 Mar 11 Location: Hythe Online Status: Offline Posts: 6499 |
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Topic: Breathers / Drain holesPosted: 08 Aug 17 at 8:41pm |
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Anyone ever considered/experimented with Goretex breather valves?
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maxibuddah
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Joined: 06 Mar 09 Location: United Kingdom Online Status: Offline Posts: 1760 |
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Posted: 08 Aug 17 at 9:57pm |
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we have them on things in work to help along those lines so don't see why they shouldn't work in this instance. There will probably be some class rule preventing them though as exotic materials
![]() Edited by maxibuddah - 08 Aug 17 at 9:58pm |
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Everything I say is my opinion, honest
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JohnJack
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Joined: 12 Mar 13 Online Status: Offline Posts: 246 |
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Posted: 08 Aug 17 at 10:03pm |
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Do you really need a breather hole?
You aren't building up that much pressure are you? Boats should be stored with hatches open to let the air circulate Wouldn't more pressure make a boat stiffer/panels less likely to flex under load?? |
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423zero
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Joined: 08 Jan 15 Location: United Kingdom Online Status: Offline Posts: 3420 |
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Posted: 08 Aug 17 at 10:23pm |
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Johnjack,
when pressurised hull is placed in water, cooler water reduces pressure in hull causing a vacuum, this can suck in air/water to equalise pressure.
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PeterG
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Joined: 12 Jan 08 Location: United Kingdom Online Status: Offline Posts: 823 |
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Posted: 09 Aug 17 at 10:57am |
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You aren't building up that much pressure are you?
You don't need a large pressure difference across a hull to end up with a significant load on the deck/hull seam (or elsewhere). If you have any sort of weak point it's likely to be made worse if you don't have a breather. Assuming your hatches are vertical, and only under water exceptionally, a 2-3mm hole drilled in the middle of the cover should be all you need to prevent damaging pressure differentials, with little likelihood of significant water influx.
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Peter
Ex Cont 707 Ex Laser 189635 DY 59 |
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Cirrus
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Joined: 29 Oct 15 Location: UK Online Status: Offline Posts: 590 |
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Posted: 09 Aug 17 at 11:15am |
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Boats can very easily leak without a breather. Cold water and a warm day when you seal the hatches creates a partial vaccum as already described. Additonally as you move abround the deck it flexes very very slightly and guess what you can pump air out and .. water in. This can happen anyway, which is why sometimes it is very difficuly to find some leaks when off the water but you are loading the dice if the sealed hull is already likely to be at -ve pressure.
So always have a breather .... btw some of the most common causes of leaking are 'O' ring seals around hatches and drain bungs. Consider replacing the 'O' rings just occasionally ! |
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zippyRN
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Joined: 14 Sep 06 Online Status: Offline Posts: 437 |
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Posted: 09 Aug 17 at 11:20am |
iirc the breather hole on the Laser is at the the front of the cockpit just under the toestrap plate , presumably that was felt t o be a place that matched that description ... also intetersitng to note that how even quite old GRP boats can have that styrene smell smell if you ope nthe bungs / hatches after a long time ... |
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zippyRN
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Posted: 09 Aug 17 at 11:27am |
and what if any advantage would they offer over small holes or a u-bend on a larger breather? |
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PeterG
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Joined: 12 Jan 08 Location: United Kingdom Online Status: Offline Posts: 823 |
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Posted: 09 Aug 17 at 12:17pm |
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and what if any advantage would they offer over small holes or a u-bend on a larger breather?
Probably depends how much time you spend upright!
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Peter
Ex Cont 707 Ex Laser 189635 DY 59 |
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GarethT
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Joined: 21 Apr 07 Online Status: Offline Posts: 714 |
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Posted: 09 Aug 17 at 1:48pm |
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From memory my old moth (magnum 9.9 I think) had a piece of thin rubber membrane glued over a reasonably large breather hole, so it would move in and out like a diaphragm but stay waterproof.
I may have this completely wrong, but it's what I assumed it was for! |
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