| Can i get a quick clarification here. Not following the treads totally, but you are talking about XPS, is that meant to be Expanded Polystyrene?

eXtruded PolyStyrene is XPS. It is a true foam, in that it is the same throughout. As opposed to bead foam, which is called EPS, fir Expanded PS, that you have seen coolers and things made out of, which are little plastic beads that are inflated and squished together into shapes. This process leaves voids, and have generally poor structural properties. Usually white, and very light.

That is what Rob is making the cheap wing sail fairing out of. It is generally considered junk from a composite core materials point of view, but Stone Tool has suggested there are high density versions of that too! So now it is even more confusing.

| And so PS is meaning Polystyrene?
Yep. And by that i meant the cheap white foam Rob is playing with. To differentiate it from the higher end XPS foam he will be playing with after El is sailing.

| And the usual expensive foam is called what?
H100, H80, and all the rest are PVC, like plumbing plastic, which are foamed into sheets. Also there are other foams made of other plastics, like the clear water bottle plastic, which is PET. And other types.

| I used ordinary polystyrene to do the sun roof on Sidecar. Worked out well.

Was that white bead foam, or the insulation grade XPS?