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Breathers / Drain holes

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Jack Sparrow View Drop Down
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Post Options Post Options   Quote Jack Sparrow Quote  Post ReplyReply Direct Link To This Post Topic: Breathers / Drain holes
    Posted: 08 Aug 17 at 11:35am
I've just bought back Sacré Blue the Farr 3.7 I imported to start the class a few years ago, and the boat has had the drain holes in the stern filled in. But has been made water / air tight. i.e undo hatches and get a rush of air.

Question - is this going to make the boat over pressurises and do something bad? Does it need a breather pipe. Farr 3.7's are built quite light - 4mm ply hull skin. The only boat I've had that was like this was a Moth and it had a breather. But then again I think it also had drain plugs?
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JimC View Drop Down
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Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 08 Aug 17 at 11:57am
I can't imagine the pressure doing any good at all. I'd definitely put a breather in. How odd to fill in the drains. Wooden self draining boats are enough of a rot trap as it is.

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Post Options Post Options   Quote peterthomas Quote  Post ReplyReply Direct Link To This Post Posted: 08 Aug 17 at 12:15pm
Many of my previous grp boats had breathers in the hatch cover so I think, as a start, I would drill a very small hole in the centre of your existing hatch cover.  Then think about reinstating the drain holes for the reasons Jim has mentioned, depending I suppose on why they have been filled in.  Might be worth asking that question.

Peter
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Jack Sparrow View Drop Down
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Post Options Post Options   Quote Jack Sparrow Quote  Post ReplyReply Direct Link To This Post Posted: 08 Aug 17 at 12:29pm
Yes, what I thought. Just needed to check I haven't missed some new way of doing things. I think the idea was to make the boat water tight. But of course this eventually is always never the case. And then you have the internal condensation which can't get out to consider. Oh well another job to do.

Jim / Peter - breather worth it on a lightish ply hull as well as drain holes?
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Post Options Post Options   Quote Riv Quote  Post ReplyReply Direct Link To This Post Posted: 08 Aug 17 at 12:31pm
Reminds me of my topper silliness post a few weeks ago. I expect a build up of pressure in a light boat will add volume to the underwater shape and so it will go quicker on hot days when there is little wind as it will float higher out of the water. On the other hand the moment it goes in the water the air will cool and contract and you might get the opposite affect.......I dunno.
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Post Options Post Options   Quote peterthomas Quote  Post ReplyReply Direct Link To This Post Posted: 08 Aug 17 at 12:47pm
Thinking about it a bit more, I would doubt it was the most recent owner (given his occupation and the repairs he made) so must therefore have been the one before.  The most recent owner would however perhaps have a view on it.
I don't think my boat has a breather at the moment so perhaps just drain holes will do.  I will check tomorrow (if I remember).
Peter
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JimC View Drop Down
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Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 08 Aug 17 at 12:57pm
Oh yes, I'd definitely put a breather in. Don't know about a hole in a hatch cover though, I'd look for a spot which is never under water and never sitting in a puddle - or else, as you say, going through a tube to have the same effect.
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423zero View Drop Down
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Post Options Post Options   Quote 423zero Quote  Post ReplyReply Direct Link To This Post Posted: 08 Aug 17 at 1:02pm
What can happen without a breather is hull expands goes in water cools and can suck in water, put a permanent breather somewhere similar to a Laser, stop hull panting.
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Jack Sparrow View Drop Down
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Post Options Post Options   Quote Jack Sparrow Quote  Post ReplyReply Direct Link To This Post Posted: 08 Aug 17 at 2:09pm
Originally posted by peterthomas

Thinking about it a bit more, I would doubt it was the most recent owner (given his occupation and the repairs he made) so must therefore have been the one before.  The most recent owner would however perhaps have a view on it.
I don't think my boat has a breather at the moment so perhaps just drain holes will do.  I will check tomorrow (if I remember).
Peter

Pretty sure it was most recent owner, we discussed it. Sort of why I was checking things out here.
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Jack Sparrow View Drop Down
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Post Options Post Options   Quote Jack Sparrow Quote  Post ReplyReply Direct Link To This Post Posted: 08 Aug 17 at 2:18pm
Originally posted by JimC

Oh yes, I'd definitely put a breather in. Don't know about a hole in a hatch cover though, I'd look for a spot which is never under water and never sitting in a puddle - or else, as you say, going through a tube to have the same effect.

Previous ply hulls have had then on the foredeck near the king post. Not had them in any of the Cherubs I've had or built though.

Is there a relationship between tube diameter and air pressure? i.e whats the max / min silicon / pvc tube internal diameter you can use to create the breather with so when you make the loop in it and instal it, it breaths. But creates the air bubble necessary to keep water out.


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