Round over chines

Dinghies, day sailers, world cruisers. Many small sailboats make ideal rowboats or low-speed power boats.

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joewis
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Round over chines

Post by joewis » Wed Mar 30, 2016 11:01 am

I was watching an YouTube video of a stitch & glue 14ft sailboat and they rounded over the chine and the transom. Is there an advantage to this other than making the hull easier to fiberglass?

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hoodman
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Re: Round over chines

Post by hoodman » Wed Mar 30, 2016 11:05 am

It's to prevent air gaps from the cloth laying over the sharp edges. On a planing hull the transom has to be built back up to a crisp edge after for performance reasons.
Matt

Building a Geronimo......!
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joewis
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Re: Round over chines

Post by joewis » Thu Mar 31, 2016 9:06 am

Does anyone round over their chine?

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vupilot
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Re: Round over chines

Post by vupilot » Fri Apr 01, 2016 8:29 am

Yes, most round over to the curvature about like a pen so the fiberglass will form over the chine without bubbling and seal over the joint with an overlap of cloth. If you wish for a crisp chine, just build up with epoxy and sand crisp after fiberglassing just as us power boats do to the transom after fiberglassing to prevent porpoising.

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Stuart
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Re: Round over chines

Post by Stuart » Fri Apr 01, 2016 9:27 am

The problem of running fiberglass over a 90 degree edge is significant and it comes up often. Running the fabric over a 90 degree seam can make a much stronger joint. I have been running the glass fiber almost 180 degree over joints with some success using a questionable method but it does work. We all know that Epoxy can be thinned with Acetone, an aromatic hydrocarbon which also can be used as a thinner for Contact Cement. While Acetone does reduce the strength of the Epoxy I am not sure what effect Contact Cement has on Epoxy. What I have been doing is using a small strategically placed amount of Contact Cement on the cloth and thereby fixing an overlap over 180 degree corners. The Contact Cement is placed about 2 inches from the corner and then pulled tight to the edge. The epoxy is then applied to the cloth and allowed to harden. Looking at the completed application following hardening did not show any problems. The seam was pulled in tight bubble free and filled all voids. However, the Fiber Glass when the Contact Cement was applied, this lip was faired so in my application very little of the Contact Cement contaminated fabric remained. But outwardly I can not know how much weaker the joint is over time. The problem here being that there are times when the fabric must run over a lip, and you must do it. Some of us just say No while others just wait until no one is looking. :D

Stuart

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Mark Chadwick
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Re: Round over chines

Post by Mark Chadwick » Thu Apr 21, 2016 10:13 am

Another alternative, which avoids the use of other chemicals....but needs equipment is to vacuum bag it. Not saying it is cheap and/or easy!


BTW - Hi Stuart! How is she coming? Water this year?

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Stuart
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Re: Round over chines

Post by Stuart » Sat Apr 23, 2016 6:44 am

Mark, will post some pictures.

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