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Author Topic: Racing Sparrow 750  (Read 1817 times)

lakeshore

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Racing Sparrow 750
« on: August 24, 2014, 06:20:13 PM »

Hi there
anyone built or building a racing sparrow 750 as per Bryn Heveldt's book, i'm is the process of planking the one i'm building and wondered how one removes the backbone after planking that the bulkheads are glued onto as there is no removal info in the book. I have posted the problem on the Racing Sparrow forum but wondered if anyone on here had  come accross the same problem and how they removed it.
 
John.
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bill63

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Re: Racing Sparrow 750
« Reply #1 on: September 29, 2014, 06:58:55 PM »

Hi,

The backbone should just twist off. I used a drop of superglue to glue the formers onto the backbone and twisting the backbone off does very little damage to the balsa formers. The deck will hide the damage anyway. The boat is a cracking design and mine sailed  brilliantly on the first outing.

If I built one again I would cut some of the meat off the formers to allow more internal space. When the hull is glassed it is plenty strong enough.

Bill
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tiaki

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Re: Racing Sparrow 750
« Reply #2 on: October 08, 2014, 06:37:18 PM »

Hi,
Once the hull has been skinned in fiberglass and sanded back there is no good reason to keep any of the internals. I remove everything and resin the inside of the hull which gives a fiberglass and balsa sandwich with heaps of strength. I insert a thin ply (1.5mm) frame at the jib attachment point and the keel/side stay point, that's it. The frames are approximately 15mm around the shape of the hull and for the mid ship one it usually has a centre upright section with the bottoms flattened to help with of condensation removal. Useful if the mast is deck stepped although I prefer to mount the masts in a tube which I bond to the frame anyway. I epoxy the decks down rather than polyester resin as it is far stronger than a polyester joint. I use yacht inspection hatches for the hatch which come in 4 and 5 inch diameter here, no messy glue residue from tape, no tape failure and no need for waterproof switches.
Cheers
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bill63

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Re: Racing Sparrow 750
« Reply #3 on: October 08, 2014, 06:55:47 PM »

The racing sparrow was the first plank on frame boat that I built so I followed the instruction to the letter. Since then I have removed all formers in the hulls of other boats I have built, adding internal structure where needed. I am currently buiding an IOM Triple Crown where low hull weight is crucial and all formers are removed.


Bill
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