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

UK Zip Build

Postby sproggy » Tue Sep 26, 2017 3:01 am

I've changed my mind about what I build more times than I can remember myself but with the Ebihen 16, once I started I realised I'd bitten off more than I could chew (it's a BIG boat to build in a garage) so I'm back where I started with a Zip. And I'm just getting on with it, not worrying about it or about having to extend buildings to give me build space. Refreshing.

I'm in the very early stages, cutting out frame members from white oak. The boards are perfectly flat but having cut out sections for two of the frames (2 and 5.5) I've found that they've warped a bit - one of the deck beams and a couple of the side frames. The deflection is around 1/4" on the side frames and closer to 1/2" on the deck beam

I'm not hugely concerned about this having happened - I'm dealing with a natural product and this happens with timber. But how do I deal with its effect on the boat - try to straighten them out with weights/steam/boiling water before frame assembly or just deal with it once the frames are complete and mounted on the building form? The boards have sat in my garage for several months so have had plenty of time to settle - the cause is obviously stresses within the boards that I've now released by cutting.

I can't imagine I'm' the first to experience this issue but a search didn't bring up anything relevant. Is anyone able to offer some advice please?

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BarnacleMike
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Re: UK Zip Build

Postby BarnacleMike » Tue Sep 26, 2017 3:46 am

I experienced this to a degree with some of the frame parts on my Utility. I personally wouldn't worry about a 1/4" warp.

A 1/2" warp would push the boundaries of what I'd personally consider acceptable, though. For me, it would just depend on the specific piece. You may find that once the frame is assembled, the whole thing balances out within reasonable tolerances. A half-inch difference across a fully assembled frame probably wouldn't be worth worrying about.

Are you using vertically-grained wood? That should help with some of the warpage.
-Michael

Built Utility "Perseverance" — completed Aug 2016
Currently building a Zip
My Boatbuilding Blog: http://barnaclemikeboats.blogspot.com/
My Website of Boat Photos: https://michaelsmaddox.wordpress.com

JimmY
Posts: 504
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Location: Brighton, MI

Re: UK Zip Build

Postby JimmY » Tue Sep 26, 2017 5:54 am

Looking at another Zip build, it looks like all the frames have a deck beam. So clamp them flat when gluing them together. If the assembled frame is slightly warped, when you put them on the frame you should be able to secure each frame to the sheer and chine to remove it. It will just take some measuring before mixing epoxy.
-Jim
Nothing says poor craftsmanship like wrinkles in your duct tape!

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BayouBengal
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Re: UK Zip Build

Postby BayouBengal » Tue Sep 26, 2017 6:05 am

On my first build (a Squirt), I was all concerned about getting the frames perfect and had strongly considered using a CNC so that they would be cut perfectly. But after having completed a couple of boats, this type of extreme accuracy with the frames is quite unnecessary. While I certainly don't advocate careless sloppiness or inaccuracy in the frame construction, a bit of inaccuracy is not really a problem because it can be compensated for and adjusted during construction by appending or shaving off wood.

My personal opinion is that more important than dead on accurate frames is an extremely solid, square, and level building platform. Next, accurate alignment of the frames on the platform. Then, constant checking, rechecking, and checking again your alignment and positioning of the outer edges of the frames while fairing using long levels, water tube levels, string, and plumb-bob's (this is where any minor inaccuracy issues with the frames are alleviated). And lastly, ensuring that you have fair lines for your planking.

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BarnacleMike
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Re: UK Zip Build

Postby BarnacleMike » Tue Sep 26, 2017 6:17 am

BayouBengal wrote: this type of extreme accuracy with the frames is quite unnecessary. While I certainly don't advocate careless sloppiness or inaccuracy in the frame construction, a bit of inaccuracy is not really a problem because it can be compensated for and adjusted during construction by appending or shaving off wood.

My personal opinion is that more important than dead on accurate frames is an extremely solid, square, and level building platform. Next, accurate alignment of the frames on the platform. Then, constant checking, rechecking, and checking again your alignment and positioning of the outer edges of the frames while fairing using long levels, water tube levels, string, and plumb-bob's (this is where any minor inaccuracy issues with the frames are alleviated). And lastly, ensuring that you have fair lines for your planking.


Well-said! I couldn't agree more.
-Michael

Built Utility "Perseverance" — completed Aug 2016
Currently building a Zip
My Boatbuilding Blog: http://barnaclemikeboats.blogspot.com/
My Website of Boat Photos: https://michaelsmaddox.wordpress.com

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sproggy
Posts: 111
Joined: Sun Jan 01, 2017 12:04 pm
Location: Welwyn Garden City, UK

Re: UK Zip Build

Postby sproggy » Tue Sep 26, 2017 6:43 am

Mike, I'm not sure how the boards were sawn - I believe they're quarter sawn but don't have the experience to say for sure. Yes, I too think that 1/4" is probably OK but 1/2" probably isn't! But 1/2" on a deck beam can be dialled out when the deck supports are fitted between frames, I suppose.

JimmY, yes, all the frames have a deck beam. The beam is bow-shaped - the sheer points are OK (arguably - depends upon what you take as a datum!), just the centre that's 1/2" too far forward/back depending upon how I mount it. Easy enough to tweak later in the build.

Thanks to you all for putting my mind at rest. I'm not aiming for extreme accuracy, just trying to gauge what's considered acceptable deviation from true. It'll all be OK once assembled :-)


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