How does he do this? (Resin Infusion)

[markwang]

You should use VARI systerm . Resin Distribution Net, or Flow Media, is most commonly used for vacuum assisted resin transfer molding and resin infusion. Composite bridge decks using SCRIMP technology is one of many examples. The recognized advantage of our media is that is will increase your resin flow rates, in return, reduce your material and labor costs.
my email: markchinawire@yahoo.cn

[sigurd]

Originally Posted by Herman

2 simple ways of making similar rudders:

-1. Fill the moulds with dry laminate, put a piece of (CNC) machined foam in, clamp the moulds, apply vacuum, and fill with resin. Probably 2-4 bars of pressure. This is called RTM (resin transfer molding) and can be pretty efficient. Cycle times of 14 minutes are no exception. (even with epoxy!)

-2. Fill the moulds with wetted laminate, pour in epoxy foam, wait for it to rise a bit (the viscosity or at least the "hanging power" goes up then) so you can turn one mould half onto the other. Clamp and wait, preferably heat up. Many paddle blades are made this way. (or variants of this method)

What about the gas from the epoxy foam, in the second method, it won't bugger the laminates?
Does this method compress the laminate well? Do you make exit holes for excess resin/gas?

How much diagonal (assuming +-45') in relation to longitudal, for a 18cm chord, 10% thick, 120cm long board? Probably 4mm wall thickness.

I'm planning to stitch tow to braided sleeve, then pull another sleeve outside, and stick a bladder inside, put in mold, and pump.
Possible modifications: 1: Use uni sleeve from soller instead of tow (but I already have the tow)
2: use two bladders alongside, each with a braided sleeve around it - to make a shear web.

[Herman]

Gas is not a problem, it is contained in the foam. If it would escape the foam, the foam would collapse. It does compress the laminate somewhat, but not impressive. No exit holes, weigh your materials, and experiment a bit, or overfill slightly.

Layup: no idea.