C17 Interior Lamination Schedule Questions

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rezab
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C17 Interior Lamination Schedule Questions

Post by rezab »

Hi all,

I had a couple questions regarding the interior lamination schedule for the C17. By my copy of the plans, it seems to me that between all interior joints between the transom should have two layers of biaxial tape.
Screen Shot 2022-12-28 at 2.14.39 PM.png
Yet looking at WobblyLegs build, he mentions 3 layers. viewtopic.php?p=87689#p87689
WobblyLegs wrote: Wed Sep 20, 2006 4:25 am
Lucky_Louis wrote:I think we should stick to the scantlings spec'd by Jacques.
I agree, but a while ago I asked about putting glass on the outside and the answer I got from Jacques was that the transom was considered part of the bottom, and suggested putting glass there, so Im wondering about treating the inside the same.

I have glassed the inside (inboard of the motorwells sides) for durability and extra strength for bolts going through it... or, at least thats the way I see it - no harm done, very little extra weight and glass really...
Lucky_Louis wrote:I'm not sure about the C17 but the OB17 was 3 layers of tape on the bottom-transom interior joint and 3 on the side-transom interior joints and two each side of the stringer-transom interior joint.
Ditto. Same specs.
Am I misunderstanding my plans, or was there a change in plans since then?

I was also wondering, under step 3, what was meant by "Around the motorwell bulkhead and main-cabin bulkhead."

Thanks all for your help!

fallguy1000
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Re: C17 Interior Lamination Schedule Questions

Post by fallguy1000 »

I would err on the side of caution and 3 tape the transom to sides and transom to bottom, just avoid overlaps.

Most likely the ref to the cabin and motorwell bulkheads was cut and paste from another set of plans.

The motorwell bulkhead, if you have one is part of the system that transfers load from the engine to the hulls and is always best to build any knees and attachments to hull real strong.
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OneWayTraffic
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Re: C17 Interior Lamination Schedule Questions

Post by OneWayTraffic »

The plans clearly say two layers of tape both sides around the transom both in the C17 and the OB17. To my knowledge this has never changed. The wide fabric overlaps over this and makes a third layer. The only place where three layers of tape are specified on that boat is the inside keel.

Two layers is plenty imo. If you've got a nice radius and no air bubbles, that will be more useful than another layer of tape.

Motorwell bulkhead is frame E, main cabin bulkhead is frame C. Both of these get a layer of biaxial all around, including above the sole.

You can do the other frames above the sole with woven tape, though I'd use biaxial there as well. Not a lot more weight, and much stronger. Also easier to lay down on a curve.

TomW1
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Re: C17 Interior Lamination Schedule Questions

Post by TomW1 »

Agree with OWT. I would also use biax above the deck in one continuous piece. You can use the woven tape on the cabin. Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

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