CS23 Build Config: Open Deck / Closed Transom

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fallguy1000
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Re: CS23 Build Config: Open Deck / Closed Transom

Post by fallguy1000 »

pee wee wrote: Wed Sep 07, 2022 9:40 am You made that sample in a mould off the boat, but you will build it in place, right?

I agree about the straight epoxy being too brittle to use for sharpening the edges, some milled fibers or structural filler added to the resin would be good.
He can mold that off the boat.
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TomW1
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Re: CS23 Build Config: Open Deck / Closed Transom

Post by TomW1 »

He doesn't need a sharp edge on his strakes, the shape he has now will work just fine, I don't know how much sharper you can get them and still cover with the fiberglass. If he wants to, he can add some cabosil or fiberglass fibers to the epoxy to strengthen it, but again they will be covered with fiberglass, and this is not a flats boat and will not be hitting anything where they are placed. Tom
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Re: CS23 Build Config: Open Deck / Closed Transom

Post by fallguy1000 »

Only covered with the glass from his mould...no hull glass on these!
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Re: CS23 Build Config: Open Deck / Closed Transom

Post by rsiedl »

Thanks for all your replies.

To clarify, I plan to make these up off the boat, epoxy glue them to the boat, then lay some glass over it (strips, not the full sheet glass that covers the hull panels - is that what you mean by "hull glass" fallguy?).

I'm also toying with the idea of making the form using glass, half filling with spheres/milled glass/epoxy, then flipping and using spheres/milled glass/epoxy to fill the rest and achieve a bond at the same time. Maybe a picture will explain that better:

Image

Or perhaps spheres/milled glass/epoxy will not create a good bond and I'm better sticking to a cabosil/expoxy mix?
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fallguy1000
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Re: CS23 Build Config: Open Deck / Closed Transom

Post by fallguy1000 »

I don't like the proposed method because it will be hard to shape correct before applying it to the hull.

Just mould them and bond them, but the boat and part need to be scratched good, like I said.

And honestly, I see little reason to glass over them on the boat. You can and it is insirance, but to do it well is hard due to the shape.

Fairing compounds have lower shear ratings than cab and milled fiber. They sand away easy on purpose. This is easy to shape any errors, so I'd use cab.
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Re: CS23 Build Config: Open Deck / Closed Transom

Post by TomW1 »

I would not use glass spheres but use cabosil instead. I would also just build it in one piece and make sure your form is well lubricated, so it comes out easily. Unlike fallguy I recommend you fiberglass them on for easier fairing and better holding power at high speeds. I have been on here longer than fallguy and remember a commercial guide building 3 of these and he fiberglassed his down. Remember with a 250HP motor on this boat you will be reaching speeds in the high 40's to 50's with a lot of force on anything on the bottom. Tom
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Re: CS23 Build Config: Open Deck / Closed Transom

Post by fallguy1000 »

Don't care to argue. It will be hard to glass over the shape unless you have a 3/8" radius on top and fillet the sharp inside edge.

Even under vacuum, the bag will like to bridge the inside turn which would leave voids under the glass without a fillet, but would make the top turn.

See my pencil marks for the warnings is all. The top will be almost impossible to glass over no vac.
8020A5CD-ACA3-49EE-AE2B-271945620147.jpeg
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Re: CS23 Build Config: Open Deck / Closed Transom

Post by TomW1 »

Again, fallguy that top edge can be rounded to 3/8 easily enough it is already 1//8. He can build the 3/8" rounding in his mold. Your rounding is 1/2" or more. Sorry to disagree. Tom
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Re: CS23 Build Config: Open Deck / Closed Transom

Post by fallguy1000 »

TomW1 wrote: Thu Sep 08, 2022 9:22 pm Again, fallguy that top edge can be rounded to 3/8 easily enough it is already 1//8. He can build the 3/8" rounding in his mold. Your rounding is 1/2" or more. Sorry to disagree. Tom
We didn't disagree.

I drew a finger sketch and told him the 1/8" was too sharp! You are gauging my finger sketch as 1/2". Stop it!
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Re: CS23 Build Config: Open Deck / Closed Transom

Post by BarraMan »

Wood flour is hard to come by here so from my research I've settled on a mixture of Cabosil and Q-Cel 5020 (hollow sphere glass micro balloons).
You can buy a 9kg bag of 75 micron woodflour from Micromilling Pty Ltd for A$45 plus freight. It cost me A$115 to land a bag in Townsville - more than enough to complete my build.

Micromilling Pty Ltd
89 Cathcart St, Goulburn NSW 2580
sales@micromilling.com.au

I dealt with Danny Zylsra (02 48221886 danny@micromilling.com.au)

Q-Cel hollow spheres are mostly air, and therefore not suitable for anything structural. Intended for fairing only!

If you must have wide strakes rather than sharp ones like mine illustrated earlier, I would construct them directly on the hull as I did my reverse chines with a timber edge filled in with woodflour/epoxy, covered with 2 x staggered layers of 6oz biax tape.

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