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Cold Molding a hull

Framing, planking and fairing. Repair, or reconstruction. If it's hull related, you'll find it here.

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Cold Molding a hull

Postby Roy » Wed Jun 12, 2013 2:32 am

"Fairing the old hullsides and cold molding over them using the unremoved originals as a mold will give you better results than molding over the frames... much better." Eric T from another thread.

I am starting from a point where the hull was sheathed in glass, although not quite as thick as Dons. The existing planked hull is in a very poor state and this must be removed to make frame repairs. What would be your plan of action, I would be fascinated to hear your views.
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Re: Cold Molding a hull

Postby Don Ayers » Thu Jun 13, 2013 6:07 am

I think you have to evaluate the existing hull sides and frames. I think you could do it both ways. My hull sides for my Ariston was done on the frames, layer by layer and look great. You have to make sure everything is fair and filled between the second outer layers and the final.
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Re: Cold Molding a hull

Postby Eric T. » Sun Jun 16, 2013 9:48 pm

In your situation, and choosing to mold rather than plank the hullsides, the existing hull can be used as the mold.

EXTREMELY Simplified: To use the existing hull as a mold, you must strip the boat of all equipment and fair the hull. After that is done, you apply a release film to the hull then layup the following layers on the faired original hull. Use of vacuum bag clamping is the best way to avoid voids that will cause problems in the years to come. Especially in the outer, lengthwise, lamination.

Don's hullsides were done in a hybrid method of this... getting the outer, lengthwise, lamination clamped with vacuum bag methods.

You will also note that after the first two layers were bonded, the entire hullside was faired smooth again in preparation for the final layer.

Prior to the hullsides being fabricated, Dons boat framing was also completely and carefully re-lofted and re attached by Northwest Classic Boats in California to ensure that the frames be again attached to each other again and would allow for a smooth hull to be laid again. Carefull attention to detail and experience paid off in the results that Don received.

Roy wrote:"Fairing the old hullsides and cold molding over them using the unremoved originals as a mold will give you better results than molding over the frames... much better." Eric T from another thread.

I am starting from a point where the hull was sheathed in glass, although not quite as thick as Dons. The existing planked hull is in a very poor state and this must be removed to make frame repairs. What would be your plan of action, I would be fascinated to hear your views.
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Re: Cold Molding a hull

Postby Roy » Mon Jun 17, 2013 6:56 am

Sorry if it's me being and idiot but I am assuming that as you apply a release agent to the existing hull then at some stage this (the original planking) is removed and the new molded hull re-attached in its place. As you have obviously done this in the past do you get problems with refitting the new hull or are the original planks that are used as a former not thick enough to present fairing problems.

A question for Don. In one of your posts in your Restoration Journal you mention say that "All deck frames were removed and repaired or replaced and then went back in with epoxy". Were they using Epoxy as a glue because I thought this was a complete No-No or it is if you believe people like Don Danenberg .
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Re: Cold Molding a hull

Postby Eric T. » Mon Jun 17, 2013 8:30 pm

For the question to me... It is a thin film... like 3M plastic film and not a release compound... compound would contaminate the wood.

I have done bottoms this way... and worked with Northwest Classic boats to have Hullsides done like this.

Cheers!
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Re: Cold Molding a hull

Postby Don Ayers » Tue Jun 18, 2013 6:35 am

Roy wrote:Sorry if it's me being and idiot but I am assuming that as you apply a release agent to the existing hull then at some stage this (the original planking) is removed and the new molded hull re-attached in its place. As you have obviously done this in the past do you get problems with refitting the new hull or are the original planks that are used as a former not thick enough to present fairing problems.

A question for Don. In one of your posts in your Restoration Journal you mention say that "All deck frames were removed and repaired or replaced and then went back in with epoxy". Were they using Epoxy as a glue because I thought this was a complete No-No or it is if you believe people like Don Danenberg .



Roy, I made a video talking about different types of construction. You are talking about two totally different methods when discussion hard epoxy vs. 3m 5200 rubber adhesive. Much debate exists but to keep it simple you don't mix the two. Both are far superior to original construction methods but both can be done wrong and incorrect that will result in very poor results.

Hope this helps

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