Buoyancy and balance.

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trebor
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Buoyancy and balance.

Post by trebor » Mon Jul 04, 2016 7:22 pm

I would like to increase buoyancy in Aft section of Sprint, when tacking back of boat goes under scooping up water slowing tacks.
I thought about blocking aft section, fitting through tubes with flaps. this will be approx' 2 square feet of buoyancy, is this enough ? and will it help to stop aft dipping ?
Robert
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Rupert
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Re: Buoyancy and balance.

Post by Rupert » Mon Jul 04, 2016 9:09 pm

Do you mean filling in the self draining bit? If so, it won't increase hull buoyancy, though it might act as an aft deck and transom, so preventing flooding. Doesn't any water that comes in simply drain out as you start sailing again?

Can be a pain in light winds. Maybe transom flaps and a canvas aft deck would be lighter?! Seen that done before, in British Moths, I think.
Rupert

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trebor
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Re: Buoyancy and balance.

Post by trebor » Mon Jul 04, 2016 9:31 pm

Not all of it, I was just planning to make a transom about 10" in from back with tubes through, flaps on outside, the centre spline of Sprint slopes down, I was planning to work with this slope, a block of foam shaped and then glassed into place.
The other thing I thought might work was to use centre board slot to drain cockpit, build transom without tubes.
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JimC
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Re: Buoyancy and balance.

Post by JimC » Tue Jul 05, 2016 11:37 am

Well familiar with this problem!
I'm rather of the opinion, though, that a lot of the slowing down is down to the change in trim creating shed loads of drag when the stern is pushed in the water, and water ingress, though annoying is distinctly secondary. So with Unskol I've concentrated a lot on changes to internal layout so I don't have to shift the weight back to tack.

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trebor
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Re: Buoyancy and balance.

Post by trebor » Tue Jul 05, 2016 6:57 pm

Unfortunately I cannot move anything forward, I thought if I increased buoyancy aft it would allow for crossing over further aft, the new wings I have fitted allow for moving further aft, at the moment unless moving fast, back of boat would sink.
Robert
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Rupert
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Re: Buoyancy and balance.

Post by Rupert » Tue Jul 05, 2016 7:08 pm

Increasing deck height would increase volume, but would require a total rebuild. An ultralight aft deck and stern flaps would be my favourite over foam blocks.
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trebor
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Re: Buoyancy and balance.

Post by trebor » Wed Jul 06, 2016 5:43 pm

Good idea, I will have a look thursday.
Robert
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