Leon,
Is Pine the only wood you have access to there at a reasonable price? I was in the RSA 21 years ago, but was not into woodworking or building HWS’s then.
I’ve no experience with chambering.
I’ve been using Western Red Cedar for my HWS’s, but those that taught me their HWS build method had dabbled in Pine frames rails with marine plywood decks and hulls. Just going from pine to cedar frames and rails reduced the weight significantly but they were still tanks. One frienf used African Mahogany ripped from an old set of doors some idiot tossed in the trash, instead of marine plywood for deck and hull but with pine rrame and rails, and it is one of the most beautiful surfboards I’ve ever seen, and not all that much, if any heavier than a marine plywood board of the same size would have been.
WRC is mostly grown in the Pacific Northwest so I’d not expect it there, but perhaps you have another cedar somewhat similar whose grain is relatively straight and light weight, as well as dimensionally stable. My HWS’s are basically built from 4 2x4s for deck hull and frame and a 1x12 for the rails, with much wood left over. I get 5 planks from a 2x4( really 3.5 x 1 5/8") when ripped on a tablesaw with a 5/32" kerf blade. I use 4 of 5 those planks for the hull or deck and need 6 on each side.
I use very different method from the single stringer multiple rib, or the rails first, method employed by most others who make HWS. Mine is more like 3 or 5 stringers dictating the rocker and foil, rather than just one, then many ribs dictating the width and deck dome and potentialy bottom contours. My boards don’t come out any lighter than the other methods, but I feel they come out more accurate and stronger/ more durable, but with no real proof other than they are are still rideable after lots of use.
Twisting is a big issue with HWS as the wood itself does not present equal stresses on both rails when bent to the rocker. There are many different HWS build methods/techniques, and not being able to have a consistent levelled table for rocker, or to prevent twisting, is going to be a challenge for you. The most important part is when laying on the deck panel(s) which locks in the ‘twist’. If at this later build stage you have a perfectly level table to prevent twisting while the glue/epoxy dries, hopefully when you remove the weights and clamps it does not take on a bad twist.
On can expend tremedous effort into preventing the twist, and still fail, or take few precautions and get lucky. One can also just not measure for twist afterwards, as ignorance is indeed truly bliss, and many boards the world over are twisted with blissfully ignorant owners who might even consider them magic.
Whatever method you choose, chambering or HWS, after each individual stage you will likely be thinking how you would do it differently the next time. I recommend writing down those thoughts when they occur and board number 2, will come out sooooo much better than board number one.
So look into Cedars available to you, and marine plywood. My 6’11" x 22 x 3 double wing round pin is 15.5 Lbs or 7 Kilos. But people seem to assume it is a lightweight foam veneer when they see me ride it. It feels way heavier underarm, than under foot, and to semi Quote Dale Velzy,
‘There is nothing like the feel of wood in water’.
Do be conscious of the final weight while you build. Try and keep it down without allowing it to become too weak to impact from a knee/foot in the center of a chamber. For a 7’6" I’d really aim at keeping it under 8.5 kilos, but much depends on your weight and ability, and the waves you will ride it in. With Heavier boards one needs to plan their maneuvers a bit further in advance, read the wave a bit farther in its future.
