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new ply build

Postby csim on Mon Nov 21, 2016 9:27 am

Hi

Just started a ply build based on paper templates sourced from the association. I cut out all the hull components over the weekend. However, the templates for the cradle referred to in the plans weren't included. I'm thinking of making a couple of female moulds based on the transom and the two bulkhead patterns, but adding the thickness of the hull ply. Probably set each mould at a height corresponding to the appropriate rocker...

Any views on this approach?
Last edited by csim on Wed Nov 30, 2016 7:51 pm, edited 1 time in total.
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Re: Cradle

Postby csim on Tue Nov 29, 2016 9:54 pm

Decided to just go for it using a combo of the patterns and rules/measurements to come up with some basic moulds and rocker measurement points that I attached to a basic building frame. Checked the rocker measurements for fairness using a pine batten, and it looked pretty sweet. 2oz fibreglass on the interior with a couple of coats of resin then loaded the hull panels on the frame. Gradually pulling the panels into shape with a few lines, but looks like it will be a good fit.

Most panels will be made with 4mm marine hoop pine, which I weighed before purchase, and found them to be 6.2kg per sheet. I have cut the transom and centreboard case out of 6mm as I had some spare...


Image
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Re: new ply build

Postby Rumblefish on Fri Dec 02, 2016 7:47 am

As as owner of an older ply boat and reading a little around here, ply boats flex along the top of the board case.

I don't think that can be fast and I'm sure glass boats don't flex as much so I would be doing everything i could to stiffen up the timbers running from the main sheet thwart to the bulkhead.
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Re: new ply build

Postby csim on Fri Dec 02, 2016 12:19 pm

Yup I got that impression too and was thinking of increasing the cross section of those timbers, or even using hardwood. I can't find a specific rule prohibiting this, only that that timber dimensions are recommended (unless specifically stated).

Was also hoping the 6mm centrecase panels would help there too...
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Re: new ply build

Postby csim on Fri Jan 27, 2017 1:12 pm

What is the general consensus on the material and number of stringers used at the top of the side tanks?

Instructions say at least 1, and up to 3 hardwood stringers. But looking at various build images around the traps, two seems to be the go, and more often using Cedar rather than a hardwood. This would give an obvious weight advantage, but is it enough to support the 4mm side tank decks?
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