Youngsville NC supersized OD18 build

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fireturk41
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Re: Youngsville NC supersized OD18 build

Post by fireturk41 »

TomW1 wrote: Tue Jun 14, 2022 12:57 am
fireturk41 wrote: Mon Jun 13, 2022 10:56 pm I’ll have some more pictures in the morning, I cut the stringers today, epoxying them to the plywood was a nightmare! I need to take a drive next week and get some more wood. (There’s a lumber yard about 100 miles from me that sells marine grade ply 80 bucks a sheet less than the local guys) I got the stringers epoxied to the ply, even though it’s ugly it’s solids I’m going to add some fillets tomorrow and start making the butt blocks for the ply and start working on the forms. I realized today I’m a little slow and added 10% everywhere except for length, so I made a panel B and a half lmao.
Did you put a layer of 12oz biax on the plywood before glueing the stringers down. You should have. You need a layer of biax on the inside and outside of the hull. The Study Plans call for 85 sa. ft. but that is not enough for your stretched OD18. As far as tieing the stringer the answer is yes you need to use tie them to the bottom, this is a planning boat. Your plans fiberglassing lamininating page should tell you what to use it is page B212_6. Since your a tirst time builder I think, you need to slow down and re-read the plans again, so that you do not make any critical mistakes. We are glad to help you and willig to do so. :D Please keep asking the questions I want to see how this big boy compares to my little OD18. :lol:

Tom

I did not, I thought the lamination came after the stringers were installed before affixing the chine panel

OneWayTraffic
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Re: Youngsville NC supersized OD18 build

Post by OneWayTraffic »

Almost every single planing boat in this list of plans has the inside glass before stringers and frames. This allows an unbroken continuous run of inside glass, which is apparently stronger.

However I think that the dories are an exception. Remember the bottom is twice as thick. There's more strength in the wood. If your plans don't require glass on the inside of the hull before stringers then I wouldn't put it on. Remember in the plans the stringers are simply glued to the hull. I have the HM19 plans (again flat bottom) and no inside glass is specified at all except that tabbing in the frames/stringers and sides. The OD16 build order is similar I think. No inside glass.

As an aside there have been a few boats built with stringers glued to plywood (even 6mm) and then glass on the inside. This used to be an option on the Phantom 16/18 and also there's at least one OB17 built that way. It has not failed. I built my C17 the same way. There's at least one other well regarded designer in Australia that specifies interior frames and stringers before glass, at least in his plywood cored boats (not strip plank.)

So just follow the plans. She'll be right.

Edit: yours is a scaled version. Maybe you might want to beef it up a little.

viewtopic.php?t=19403&hilit=OD18+glass

fireturk41
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Re: Youngsville NC supersized OD18 build

Post by fireturk41 »

OneWayTraffic wrote: Tue Jun 14, 2022 1:39 am Almost every single planing boat in this list of plans has the inside glass before stringers and frames. This allows an unbroken continuous run of inside glass, which is apparently stronger.

However I think that the dories are an exception. Remember the bottom is twice as thick. There's more strength in the wood. If your plans don't require glass on the inside of the hull before stringers then I wouldn't put it on. Remember in the plans the stringers are simply glued to the hull. I have the HM19 plans (again flat bottom) and no inside glass is specified at all except that tabbing in the frames/stringers and sides. The OD16 build order is similar I think. No inside glass.

As an aside there have been a few boats built with stringers glued to plywood (even 6mm) and then glass on the inside. This used to be an option on the Phantom 16/18 and also there's at least one OB17 built that way. It has not failed. I built my C17 the same way. There's at least one other well regarded designer in Australia that specifies interior frames and stringers before glass, at least in his plywood cored boats (not strip plank.)

So just follow the plans. She'll be right.

Edit: yours is a scaled version. Maybe you might want to beef it up a little.

viewtopic.php?t=19403&hilit=OD18+glass
My plans to beef her up were to add some fillets to help distribute the load and then to glass the stringers and bottom to beef it up a little. I was originally going to just tab them, but it won’t hurt to just glass them in

OneWayTraffic
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Re: Youngsville NC supersized OD18 build

Post by OneWayTraffic »

That’s what I’d do. That thread I linked to had some recommendations from the designer directly for an upscale. Extra glass and tabbing and an extra frame.

TomW1
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Re: Youngsville NC supersized OD18 build

Post by TomW1 »

Agree with OWT.

Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

fireturk41
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Re: Youngsville NC supersized OD18 build

Post by fireturk41 »

I’m getting to a stall point (material wise) I’m going to cut molds tomorrow and the transom. For the transom where the motor hangs, although I’m scaling by 10% I leave that dene soon the same height, correct? Also I was reading other builds and saw where others transoms were about an inch short. Should I raise it an extra inch?

TomW1
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Re: Youngsville NC supersized OD18 build

Post by TomW1 »

fireturk41 cut the transom the same height as the sides, 10% higher. if you did the sides higher. Then the area where the motor goes it is cut down for a 20" motor shaft, or made bigger up for a 25" motor shaft and the transom cut down.. Do not use hard angles in the corners, but round them a little. Hard angles can cause cracks to develope in the corners.

Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

fireturk41
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Re: Youngsville NC supersized OD18 build

Post by fireturk41 »

Okay that’s what I had thought and wanted to confirm. I was going to use a soup can on the corners

Fuzz
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Re: Youngsville NC supersized OD18 build

Post by Fuzz »

Soup can will work and look good too!

TomW1
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Re: Youngsville NC supersized OD18 build

Post by TomW1 »

+1 Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

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