ICMS - a method of measuring the stiffness of a mast.
www.peterman.dk/mast-imcs-formulas.htm

SDM - Standard diameter mast
RDM - Reduced diameter mast (commonly called a skinny mast)

Xply is a monofilm sandwich with a layer of scrim (or ripstop). Go a google search for "xply and sail" in images.

JB

I can tell you from recent experience that water in a board makes the styrofoam break apart.

I am still repairing a board that had bubbles coming out of the footstrap inserts. When I cut out the old inserts and looked in there the styrofoam was soaking and came apart quite easily.

In fact the more I look at the way some boards are made I wonder if they intend them to fail after a number of years... who would have thought?

Boards have vents when they use expanded polystyrene. I believe this is meant to reduce the stresses caused if a board repeatedly expands and contracts with temperature changes.

I am not sure if other foams (polyurethane or extruded polystyrene) also need vents.

Expanded polystyrene is an open cell foam and will absorb water easily.

Having said all this, I think ASA (plastic) boards also have a polystyrene core, but they don't have vents. I don't know why.

If the core is open cell, and the air pressure out side is less than the air pressure inside the board, all the air in the board can travel to any weak point, causing a big delam. If it's closed cell foam, the air is not free to travel around, (and nor is water for that matter), so delamination is not a problem. Also if the pressure inside is less than that outside, and there is a small hole, it will suck in thru the hole, if that's under water, the board can get very wet inside!!!
This adds to weight, I'm not convinced it deteriorates the foam though. I think the foam damage and the leak were caused by the same thing, there's water in there because there's mechanical damage not vice versa.

Some of the old plastic boards I've worked on were closed cell poly urethane, but I haven't pulled many apart.

Old polyester/urethane (for some reason commonly termed "fibreglass boards") boards are closed cell so don't suck in water or delam due to heat.

Most modern boards are expanded styrene core (open cell), with a sandwich skin. The sandwich usually has fibreglass on the outside, and either high density foam or timber on the inside, (there's just as much fibreglass in a modern board as an old board, so distinguishing between the two by calling one of them "fibreglass" isn't very accurate.) There's also varying amounts of carbon, and or kevlar at stress points.

This form of construction is much lighter than the old way, but does need a vent of some sort.
Although I have seen boards that are fairly old made this way without vents, and no problems, but these are painted plain white with no graphics.

So gesty, is it a pure white board????

Yes the car would be the killer, may be best to drill it just to be sure.

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Gestalt said...

my new board arrived today with vent not drilled out.

was told to always leave it upside down on the beach and drill the vent if i fly anywhere.

i guess i better not leave it in the car either.

voodoo ....