Hi Sbray,
Totally agree withunder cutting the hole but you also need to connect the bottom deck to the top deck to rigidise it othewise you will stuff the bottom up and your finss won't remain the position you set them up to be.
Cheers
Rich
Your proposed super low aspect ratio aluminium channel fins will be grossly inefficient. Lift (which is what you want) comes from the efficiency of the foil, not just brute surface area. I still don't understand your objection to proper SB fins. If it's really that shallow make a plywood skimboard.
I'd be a little wary of aluminium fins not only from a performance viewpoint but on the outside chance of landing or hitting them pete..one of the main benefits of the fcs /futures fin systems is that in some cases they break off at plug level when the f*&ckers hit you hopefully reducing the chance of slicing you like a stuck pig,especially when you are wet..and also minimizing the damage to your board..admire your persistence,i probably would stumped up for 2nd hand one from the buy and sell if i didn't have the collection of surfboards(10+ and a few other various incarnations ,even an old stonker epoxy )in the shed ..something to think about although i appreciate your efforts to keep us entertained !