UK Zip Build

Outboard designs up to 14'

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sproggy
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Joined: Sun Jan 01, 2017 12:04 pm
Location: Welwyn Garden City, UK

Re: UK Zip Build

Post by sproggy » Tue Aug 13, 2019 8:32 am

It's an interesting idea. And would be more viable if I had a thicknesser! I've got one on my shopping list but for later in the project - I could bring it forward. I would have to test to see whether stripping the outer ply (or two) off caused any cracking issues when bending but it's supposed to be high quality ply so it should cope.

Thanks for the suggestion - definitely worth considering.

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BarnacleMike
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Re: UK Zip Build

Post by BarnacleMike » Tue Aug 13, 2019 6:23 pm

If you have the patience, you can always sand it to match.
-Michael

"How long does it take to build a boat? Until it's finished" — yours truly

Blog (Utility & Zip): http://barnaclemikeboats.blogspot.com/
Website of Boat Photos: https://michaelsmaddox.wordpress.com

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sproggy
Posts: 235
Joined: Sun Jan 01, 2017 12:04 pm
Location: Welwyn Garden City, UK

Re: UK Zip Build

Post by sproggy » Wed Aug 14, 2019 1:43 am

My first thought when I read that was "I don't have the patience"!

But using a belt sander with a fairly aggressive grit could do the job in an acceptable amount of time, I guess. And the advantage of sanding ply is that it's quite easy to see how far through you're going. It would be feasible.

But having given it some more thought last night it seems to me the easiest method would be to bond 2mm shims to the sheer, chine and stringers (after they have been faired) to bring the 6mm ply out to meet the 8mm. Then fair the shims back into the stem. It would make a few challenges in terms of the butt blocks but I think I can do something about that. Perhaps it's not as much of a problem as it seemed! Sleeping on a problem usually brings perspective.

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sproggy
Posts: 235
Joined: Sun Jan 01, 2017 12:04 pm
Location: Welwyn Garden City, UK

Re: UK Zip Build

Post by sproggy » Wed Nov 27, 2019 7:32 am

It's a year and a day since I last posted a photo. So probably time for another one. Having spent a very long time fairing (and I'm still not done aft, where I have to work upside down) I reached the point where I was ready to stick some skin on the frame. I expect starting in the middle of the boat is somewhat unconventional but these are 'transition' panels in 4mm ply (was supposed to be 3mm) between the single layer of 6mm (1/4") forward and a double layer of 4mm strips aft.

First one with lots of staples holding it in place:

Image

and then I realised how much effort it took to remove staples so on the next one I used more clamps and fewer staples:

Image

The next job was to bond 2mm shims to the sheer, chine and stringers, which were then thinned out towards the forward frame to blend back to the original profile:

Image

Explanation for the shims - 2mm shim + 6mm ply is the same thickness as two layers of 4mm ply.

The first forward panel is about ready to go on. I used a router to thin it from 6mm to 4mm for an approximately 6" overlap with the transition panel. This leaves it proud of the transition panel by exactly the thickness of the ply for the second cold moulded layer and the shim on the frames makes up the difference.

I intended to use 6" wide strips of ply aft but realised that squeezing the transition from flare forward to the barrel transom into a Zip length and low freeboard (a proper Barrelback has an extra 5' or so of length and greater freeboard to achieve this) meant I needed narrower strips to accommodate the fairly extreme twist. I'm working with 5" width at the moment although that may still be pushing my luck. There's more fairing to do before I explore that further.

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