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First Build

Posted: Sun Sep 05, 2021 9:59 pm
by nkdly
Hi all, I'm a guitar builder and plan on building a couple of Paipo style bodyboards for myself and my teenage boys for the upcoming Aussie summer.
The boards will be solid pine, used in 2-4 foot waves (mostly choppy), mostly standing takeoff (no swim fins). I'm 6"6 & 100kg with my sons fast approaching.
A curved nose tapering to a flattish tail is a style I was going for.
I'm after some input on shaping and sizing. What dimensions would I roughly need to build the boards. Would I bother with concaving the bottom or just keep things simple.

Re: First Build

Posted: Thu Sep 09, 2021 1:36 pm
by OG-AZN
My experience with boards like this is stuff like concaves and channels look cool, but they don't provide a dramatic impact on board performance. You'll have as much fun on the simple design as a more complicated one. A good guide for width is to stand with your arms relaxed, elbows bent up like you're holding something, and measure across your elbows or wrists. For standing take offs in the shorebreak, you don't need a lot of a length. Even a 1.5-3ft kickboard size would work, but if you want a more versatile board, I'd start with bodyboard range lengths of 42"-44".

Re: First Build

Posted: Sat Sep 11, 2021 8:41 pm
by nkdly
I’ve made a start on the board, Using an old dining table I picked up cheap.
I’ve made it quite big, with the idea that I’ll trim it down and reshape if it doesn’t function. It’s 57” x 21” and 18mm thick. I’m unsure of the wood, all I know is the table was made in Malaysia.
I’m concerned with the weight, it currently weighs 8kg. I’m thinking of planing it to 12mm which will bring the weight to 5.5kg.
What are some thoughts on this so far?

Re: First Build

Posted: Mon Sep 13, 2021 5:25 pm
by zensuni
By reducing the thickness you will gain flex, you can also make a concave to make the board lighter.

Re: First Build

Posted: Tue Sep 14, 2021 3:17 am
by OG-AZN
The shape is fine & it will work at its current length or shortened. 8kg is pretty heavy, but I'd try it as is before planing it down. Once you get it in the water the weight issue won't be as noticeable. Not sure how a board made with that kind of glue joint flexes or how durable it will be.

Re: First Build

Posted: Tue Sep 14, 2021 3:38 am
by bgreen
8kg would be too heavy. Do the waves have power? Given you are doing a standing start, you just want something that will get picked up. Have you seen UK bellyboards?

Re: First Build

Posted: Tue Sep 14, 2021 3:42 am
by bgreen
I thought about this some more - my fibreglass boards are some where like 6KG. You might even get away with 1/2" . What were you going to seal it with - if it was oil you could always test and refine. If varnished, you pretty much got what you have.

Re: First Build

Posted: Tue Sep 14, 2021 10:25 am
by nomastomas
My prone boards weigh about 2.5kg, so even a 5kg prone board seems too heavy. Without getting into the whole buoyancy vs. mass thing, I've found that better buoyancy = better performance. But, you gotta use the materials available I guess. I would think 1/2" or 5/8" marine plywood would be a better choice. Ply is readily available, strong and much less dense than that Malaysian wood (heaviest table I ever owned was a wood table made in Malaysia...what is that stuff?) Maybe not as pretty? In general, for prone boards, any material less dense than water will work to some degree. As a luthier, you may find more advantages to using Hollow Wood Surfboard (HWS) construction technique. Lots of how-to on the internet. Just Google "HWS". There is even a program to convert Aku cnc files to HWS template for ribs and spine templates. I 've helped a local Middle School wood shop teacher who has his students build them as a project.
I disagree with OG-AZN on the performance impact of bottom contours. Its been my experience that when done correctly, there is indeed a noticeable difference in performance. That said, a contour-less bottom will of course work, just not as well. Pretty rare to see a modern surfcraft with no bottom contours...regardless of shape or size. Maybe the message is walk before you run.

If your willing to step away from wood, EPS wall insulation panels glassed with epoxy resin is a cheap and functional construction technique. One 4ft x 8ft x 1in sheet can do four 1" thick boards or two 2" thick boards. Minimal "shaping" required and no special tools. Two layers of 4oz cloth, deck and bottom, free-lap the rails and go finless. Won't be the prettiest but will work. Of course, there would be some new skills to acquire...

Re: First Build

Posted: Tue Sep 21, 2021 9:28 pm
by nkdly
Thanks for your help and input everyone. I’ve planed it down to about 11-12mm, reducing the weight to 4.5kg. It feels quite good so I don’t think weight will be an issue. There’s a small amount of flex in the board. I used the router to cut a small concave, this wood is super hard and that was the only way to efficiently remove material.
I’ve just finished sanding and will coat it in marine spar.

Re: First Build

Posted: Wed Sep 22, 2021 9:38 am
by nomastomas
Nicely done...very traditional. You gotta use the tools that work. Shouldn't have any trouble with speed, with flat rocker and parallel rails. Might be a little stiff when turning. You'll need to learn to heavily weigh the tail when turning to bring that rail-line up and out of the water. Like riding an old school longboard. How are you going to finish/seal it...oil? varnish?

Re: First Build

Posted: Wed Sep 22, 2021 9:42 am
by nomastomas
Actually, very similar to the planing hulls Lindsay Lord used for his research, including the exit concave to reduce pressure/drag in the rear third of the bottom.

Re: First Build

Posted: Sat Sep 25, 2021 4:54 am
by nkdly
Hi Nomastomas, I’m finishing with a marine grade varnish

Re: First Build

Posted: Mon Sep 27, 2021 2:46 am
by bgreen
Send a ride report, once you've surfed it a few times.