I’m building an EPS hydrofoil board in the near future and have some questions:
The board will be 4’10"x20"x2"
The board has to be quite durable as it has to withstand hitting waves at high speed (25+ kn), I guess the occasional jumps cause a lot less stress.
My previous board was similar size XPS but only 1/2" thick on some areas. That build was 4x4 oz glass on each side with multiple 6 oz patches on high stress areas, but without veneer and lasted a few months before braking… By analyzing the fracture I guess it was caused by delamination of the top deck after hitting a wave at high speed.
By radically increasing the width and using veneer I expect to create a bulletproof board.
The core will be 2lb EPS (could I get away with 1.2 lb EPS? Its easier to source and bending the rocker…)
The layup from top to bottom:
4 oz glass
1/16" (2mm) cork veneer
4 oz glass
EPS core
4 oz glass
4 oz glass
Does this layup look OK?
I’m planning to wrap the veneer around the rails from the top for extra stiffness and durability, does it worth the effort or should I use it on the top only?
Hi Rufusz, I’ve made a few paddle-in hydrofoil boards but instead of using a heavier glass schedule I used two 1/2 in pine stringers 3 " apart so it was never going to snap and it gave a solid place for the Tuttle box to be inserted and its a very solid place to stand. My boards are about four inches thick, 5 foot long.
How are you attaching the foil ?
Hey S R F D C O, I found only a few pics of my hydrofoil, see below.
Lacking proper waves here we need wind to have fun (and a kite). The mast is about 90 cm long (35") and the thing is capable to reach twice the wind speed
The mount is 4 bolts through the board there will be carbon fibre tubes inside the core around the bolts for support.
This lam schedule, on at least 1.5lb foam, is standard for short board surf. For hydrofoil kite make sandwich top+rails and bottom, add more fiber outside, so you can go with 1,2lb foam.
Did not bother with building the foil as the materials alone (full CF) would cost a lot, not to mention the labor and the potential to end up with something unusable. I got a fair deal from one of the local brand reps so got lucky I guess.
A Hydrofoil board build is a lot less complicated then the foil itself or let alone a surfboard as I don’t need to worry about concaves, perfect outline or flex. Most of the board will be dead flat with 3" rocker and the flex should be aimed at a similar sized granite board, hopefully the weight less so. Its as easy as it gets
My previous board was up for a task I blame the XPS for the delamination, so going with EPS (3 times thicker core then the previous board) and the extra 2mm cork all around the core should be more than enough. One thing for sure: it won’t be the lightest board on the planet…
The function of the board is to hold the foil and as a platform to stand on, its hydrodynamic performance is moot. I did the same a few inches of nose rocker and then completely flat out the tail. Light isnt a consideration.
I don’t get why you would use a fixed through bolt instead of windsurfer mast boxes to fasten your foil mast to board,
with boxes you get the ability to adjust foil position forward and aft, especially handy if you are trying different foils.
The reason I use the 4 bolt mount is that my current foil has this mount and the mast is glued together with the mounting plate so changing it is not an option.
Many kite hydrofoil manufacturers use this mount system so swapping to a different foil later will not be a problem.
