To the folks who are balsa savvy…(Jim P., et. al.)…are there any benefits with respect to BOUYANCY when replacing balsa channel hollows with foam? Follow up question…how does the overall bouyancy of balsa (Yeah, it varies from piece to piece-understandably) compare to foams. (both polystyrene and polyurethane). Third question… benefits of channeling AT ALL. Have I been spinning wheels all along? A lot of folks don’t channel, but I liked the weight reduction (the way I was taught)…Does this (substantially) weaken the integrity of board…even with foam inserts? Your collective philosophies, please. Thanks, in advance…T.
Chambering is a good idea if you have some heavy wood. If done right it won’t weaken it too much. Adding foam does not add any strength to the board. Foam is only used to fill the void, and reduce the amount of air inside the blank.
Look at it this way. If it does not float in air then it is heavier then air… The more air it has in it the lighter it will be. Styro, has more air in it so it is lighter then Poly. I would not add anything to the chambers. Leave yourself enough wood and you will not have any blow up problems. Keep the rails solid.
Tom: Given my limited experience, I would agree with Bagman and Attila. It seems pointless to chamber a board only to replace the wood with slightly lighter foam.If I recall high school physics correctly, a floating board will displace a volume of water that equals the boards own weight. Surface area and shape make the difference-I think I went to sleep when they mentioned prismatic coefficients! The conclusion, however, was that a given piece of foam would provide a greater surface area than a piece of wood of the same weight. As yourself, I chamber the wood. I do this mainly because of the variations in the weight of the balsa I can obtain. Not sure what I would do if I ever managed to obtain a pile of really light balsa. Perhaps then strenght would be an issue. However, since wood is generally much stronger than foam and has good insulation properties I would probably just go ahead and chamber. I suppose the sensible thing to do would to be to do the math and determine at what temperature a given volume of air will overcome the strenght of a given thickness of wood. On the other hand it would probably be more fun to just go surfing. Take care. Patrick
AMEN, Patrick! Thanks for the feedback! (thanks, also, atilla& bagman!).