From: ludwig@cm.deakin.OZ.AU (Ludwig Omachen)
Newsgroups: alt.surfing
Subject: Re: Surfboard Construction
Date: 1 Sep 1992 23:19:38 GMT
Organization: Deakin University, Geelong, Australia
NNTP-Posting-Host: aragorn.cm.deakin.oz.au

G'day Brian,

In article <24438@oasys.dt.navy.mil> you write:
>Well, being that there is no surf to speak of here....
>I'l start thinking about board construction again. I was talking with
>a guy who works here about his homemade windsurfer project. He is building
>a hollow graphite board with two webs. I didn't think this would work
>for a surfboard,

There was a manufacturer here in Oz. that was doing a similar thing
for surfboards, he took a mould off a pro's board, layed up the
cloth/resin on the inside of the two halves of the mold (vacuum bagged
as well for the reasons you mention) and then stuck the two halves
together. But... I seem to recall that he then filled it with a low
density foam ?, not 100% sure on that though.

The problem with hollow boards is the change in air pressure inside the
board due to heating cooling, so most of the light weight construction
still uses some sort of lightweight foam core, either shaped first or
pumped in later.

Ended up with a very strong , light board, but again you can't
customise a board economically with that sort of construction, which I
see is a big drawback for the surfing (non-pro) market.

>but his fabrication technique was intriguing. He uses
>a vacuum bag to consolidate and squeeze out the excess resin from the
>skins. This will give a higher percentage of glass fibers vs. resin.
>The vacuum bag is a tighly fitting plastic bag. A vacuum is pulled on
>the bag, making it hug the contours of the bag squeezing the excess
>resin out.

That's pretty much a "standard" construction technique for the
"better" high performance sailboards.

>This will equate to a stronger/stiffer/lighter board. The problem might
>be the installation of the skegs. How is this done regularly? (Lud, help
>on this question.)  Are the cured fins just stuck into the
>foam and glassed over? 

The fins are nornmaly "stuck" ie glassed onto the board after the
shaped blank has been laminated, though with the construction I
mentioned above, I think the fins went right through to the underside
of the deck, very strong !.


>To use this vacuum bag process, an investment
>of about $1000 (US) would be needed for the vacuum pump and assorted
>accesories.  This would be prohibitive for a backyard shaper, but a
>big time manufacturer could make up the bucks quickly.
>Using the regular hand
>layup process, the percentage of glass in the skin is probably near
>30-35%. Using the vacuum bag process, you can get near 60%, almost double
>the glass in the same thickness.  The weight of the board would be the
>same, but it would be stronger and stiffer.  When I'm down at the beach
>next weekend, I'm going to try to find John Ashton, a local shaper.
>I'll give him some of my ideas and see if he laughs me out of the shop.
>I heard that he won the Da'Bull longboard contest in Costa Rica. He
>was down there and was cajolled into competing and ended up winning
>the bitch. The winner received a free trip to Costa Rica. Not bad for
>a contest you didn't plan on entering. Not as cool a prize as Nigel's
>video, but It'll do.
>   O
>   I\   Brian Kiviat (301)227-1833       Sometimes the truth is hidden,
>   I \  kiviat@oasys.dt.navy.mil         Like a shadow in the darkness.
>  /     David Taylor Model Basin                  -Master Po
>   \___________________________
>			     \\

cheer's, keep surfing,
Lud.
Newsgroups: alt.surfing