Balsa vs Foam Core

[snort]

I think load carrying capacity and performance are, at least, somewhat mutually exclusive functions of design. The performance of a Catalac built with super-buoyant foam would probably be just as sucky. Catalac owners may beg to differ, and I know there are a few here. I've never sailed on one, but have read enough to accept the notion that they're not too nimble to wind.

[Event_Horizon]

Foam cores had a very distict advantage. If you ever have the pleasure of fliping your catamaran (or filling it with sea water)...foam core boats float higher in the water--upside down or filled with it. You can dry your feet while waiting for rescue! Personally, I think this is not a bad safety feature.

Disclaimer: This is assuming all other things are equal, different model boats could have different properties that might allow for the wood boat to float higher.

[Joli]

Well,,,,,that kind of depends. Balsa is about 9 lbs/cu ft. PVC foams can range from 5 to 19 lbs/ cu ft. When building with foam you may or may not end up with a heavier core compared to balsa. Clear as mud huh?

Originally Posted by Event_Horizon

Foam cores had a very distict advantage. If you ever have the pleasure of fliping your catamaran (or filling it with sea water)...foam core boats float higher in the water--upside down or filled with it. You can dry your feet while waiting for rescue! Personally, I think this is not a bad safety feature.

Disclaimer: This is assuming all other things are equal, different model boats could have different properties that might allow for the wood boat to float higher.

[Sonosailor]

Question for Cat Man Do:

You seem down on polyester resins. Are isophthalic polyester resins better, or are all polyester resins used in the marine industry isophthalic anyway. FP has used isophthalic resins for years, and says their boats do not need barrier coats (now called primer coats by nervous yards) below the waterline and/or under bottom paints, as they are much less susceptible to osmosis than the regular polyester resins. How does isophthalic compare with vinylester?

[Marinheiro]

there are still alot of boatbuilders using orthothalic resins. Isothalic resins have somewhat better mechanical properties but are far beind Vinyl Esters, particularly for Osmosis resistance. In industrial applications Vinyl Esters are almost always used - have alook at web sites for Dow Chemical's Derakane range and similar for Huntsman. Interestingly I believe you can only obtain Isothalic gel coat (ISO-NPG), nothing better. For a new build unpigmented gel coat is better below the waterline.

[cat man do]

Originally Posted by Sonosailor

Question for Cat Man Do:

You seem down on polyester resins.

Only if used on a timber core.