Board - Mast attachment

[ahmthai]

* glass the hole board 2x 5oz top and 3x 5oz bottom.
Flo

I would also put patches of 1-2 layers of glass in the standing areas of the top of the board, otherwise you will probably get dents as 2 x 5oz glass is quite light for impact strength.

[longwhitecloud]

simple engineering would say do something to decrease the torque on the joint at edge of baseplate to board - best suggestion - big pvc foam block in boards with insert in it - or maybe high density pu if you cant afford pvc.

torque force targeted from being at edge of baseplate (cos xps aint worth 5hit!) goes to edge of pvc box inside board so huge reduction in possible torque

[Florian Scharscher]

Thank everyone for your excellent suggestions!

Shaping the board came pretty natural to me but when it came down to the board mast attachment I was simply leaking knowledge on the structural requirements in foil boarding.

Saying that, I have given your suggestions a good thought and have started building a wooden mast attachment block which you can see below.

- The block is larger then the mast foot to distribute sheer forces on the mast foot outline.
- Furthermore the block will be connected to a stringer on each side to distribute the load over the deck.
- The bolt holes are filled with epoxy and I have increased the number of holes for trimming the mast.
- Note how the top plates (6mm marine ply) extend over the core block which again should help to distribute the load into the foam.

Thank you -longwhitecloud- your suggestion will come in handy when I start glassing!



All the best from Perth,
Flo

[ahmthai]

I think 6mm marine ply is a bit overkill (and heavy). 3-4mm should be more than enough if you can get it. The PVC used on sandwich SUPs and kiteboards is normally 3mm and the plywood is much stronger.

[ozchrisb]

Can you make it wider? There's load going into the board from the sides too. Wrap the foam block in glass too.

[downunder]

Hi Florian,

if you like I can offer you my vac pump in yokine. Thinking to start building a foil myself.
I would suggest talking with Kirkside in Osborne park for a closed cell foam.

Good luck

D.

[Florian Scharscher]

Thanks again for your great suggestions!

AHMTHAI, you are right its pretty strong with the 6mm marine ply wood, just some material I had in the shed.
My local store is selling 3mm, yet it looked to flimsy to be honest. You'll be screaming overkill in a second when I give you my final spec. After all its my first board.

Thank you OZCHRISB. Again, the width of the mast-foot came down to the materials I had on hand. You are fully correct in advising to make it wider and the next board will surely be more then the 90mm, currently. Note, the photo in my last post is in fact 3 pieces of wood. To cope with the sideway forces i was milling a pocket around and over the mast foot, using a router.
I didn't spend too much time thinking about the depth of the pocket in relation to how many glass layers it will need to fill up. So I ended up with a 1,8mm depth and filled it with 5x 6.5oz and epoxy, top AND bottom. I surely looks solid now...







DOWNUNDER, thank you so much for your kind offer, I truly appreciate it! After a lot of back and forth I decided to do a hand layup on my first board. I am also still missing a few bits and pieces (vacuum tube, pressure gauge, strainer) to get my own little pump going. Maybe I'll take your offer later on or at least some advice. I'm definitely going to look up Kirkside though, thank you!

Mast foot is in place, I've sanded the hole lot by hand ready for glassing. I'm starting tomorrow and my glass schedule is 2x 6,5oz + 1x 4oz on TOP, same for the BOTTOM.
Any suggestions? More? Less?

Thanks again and good winds,
Flo

[Florian Scharscher]

Hi everyone,

I've finished the mast attachment and I've been glassing the board.
I layed up 2 layers of 6.5 oz on the top and bottom (epoxy) with the additional reinforcement on the front foot.
It looks solid but I'm not sure how strong it has to be, can anyone advice?
Thinking of adding another 4oz on the bottom...?

An overview of the current setup:

[zfennell]

you could think of the problem like this.

While riding, the major forces on your board will be will be:
1- the mast pushing up on the bottom .
and
2- your feet pushing down on the top .

a simple experiment to evaluate the overall structural integrity of your board could be done with the following steps:

-cut a block of wood ( or 2x4) so that one side is the same dimension as the mounting plate of your mast.
-bolt the block to your board using your design attachment method
-place board on the ground.
stand on the board while keeping it balanced on the block.

use less weight if your nervous.
2x 6oz of glass, top and bottom, should be enough to survive the above....but you never really know 'til you try it.
-no worries

[Florian Scharscher]

Thank you zfennell for your kind reply.

My glas schedule ended up 2 layers of 6oz on the top and 2 layers of 6oz on the bottom + 1 layer of 4oz on the bottom.
It definatelly feels solid and I am not worried about breaking it. With the next boards I will try to strip down on the weight slightly but otherwise I'm happy with the construction.

You can see all the photos in this little write up:
http://www.florianscharscher.com/2014/0 ... -room.html

Thanks for your support!