hollow paulownia surfboard - advice needed!

General Discussion
1

i’m just looking into a hollow surfboard build made from paulownia, I want to make a 9ft longboard using the rib frame and strip rail method as opposed to shaping and then chambering the board.

what I am wondering is…

  1. should I consider making the ribs etc from paulownia, would it be strong enough at 5mm thick? my alternative is some beech ply i already have which is about 4mm thick but i think i would save a fair bit of weight using the paulownia if it could take it?!

  2. how thick should i consider making the deck and base of the board? i was thinking 5mm but is that too thin, should I go as far as 10mm? weight is obviously a concern but strength and durability are very important too.

anyone out there made a hollow paulownia board before? any advice?

 

thanks all

 

Sam

2

My only comments is to mention Beech wood is highly prone to rot. Probably not the best choice.

 

3

will that matter if it is contained within the board? baring in mind I am planning to have a light fibreglass coat too so its going to be totally watertight. or are you thinking in case of a ding which lets water inside?

4

Yep.

I’d be inclined to use the Paulownia.

5

I see, thanks for the advice, just need to work out if the paulownia will be strong enough to form the ribs of the design as well as the rest of it. 

6

Hey Sam. I’ve built a couple of sub 7ft hollow all Paulownia boards with 6mm ribs and skins. No problems with the strength. The majority of the boards strength and stiffness comes from the rail build up/section. The internals pretty much need to be just strong enough to separate the top and bottom skins under your body weight. Single stringer and cross ribs every 250 - 300mm generally will be no problem in my experience.

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9

Sounds great RDM, I would much rather do an all paulownia build if it will work so that’s good news, thanks for the advice

10

2.5MM is the thickness you want. 10mm paulownia planks with ribbed frame long board will weigh over 30 pounds.

Finished my hollow paulownia 9’1" x 23" x 3 1/8" lb two days ago. 8.1KG with fins. This came out heavy in my opinion. Will do better on next one.

 

 

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11

2.5mm?! Really?!! Seems incredibly thin, I was thinking 5mm minimum or it won’t have the strength to resist a substantial knock. How heavy did you go with the glass? How many coats? 

 

12

I’m using 1/4" on top and 3/16th on the bottom with 1/8th ply for the frame.

This is with about 6" frame spacing.

closer frame spacing allows you to get away with thinner skins.

One layer of 4 oz top and bottom(on outside only) and 2 inch strips of cloth between the frames underneath the top skin adds very little extra weight, but allot of strength.

The only way I can see using 2.5mm Palouwnia is glassed inside and out.Especially on the deck.

Which is a valid approach.I think Paul Jensen uses 1/8" skins glassed inside and out.

I like that board bb30!

I’d like to find out the glass schedule ,frame thickness and frame spacing on it.

I’m on my 14th hollow wood board, and making them as light as possible is my biggest challenge.

 

13

thanks Lazio,

I think i’m going to try 5mm skins with closer frame spacing and frame built from 5mm paulownia too, that way I can keep it easy when milling the paulownia timber and just do 5mm thick boards for the lot. I will probably go down the route of a 4oz glass job top and bottom on the outside only.

its going to be sort of reproduction of a mandala hunter-seeker model, maybe about 9’1. I used to have the board and had to sell it to a mate to fund a long surf trip and iv’e always fancied making a version of it myself, not sure how it will go as the bottom shape and rails are pretty complex but hey ho its got to be worth a try!

i’ll post some pics of the finished board in say… 12 months time!!!