In looking at the US Sailing portsmouth tables I am confused. I have a Hobie 18 magnum. Am changing to a 29'6" stick, from a SX. Will be running a Tiger main and spin. I believe the main is no more than 5% larger so a .995 d-pn correction? Table states Hobie SX-18 spi. The tiger spi is less sq area than a SX spi, I think. So dp-n of 71.3 + .995? Will take the wings off to race. Please help me get this right so race officials will not get upset if I am wrong. Everything else will be standard Hobie production 18 parts. Downhaul and main purchase will be at class limits for 18SX.

I would start with a normal Hobie 18 (71.4 dpn). It'a not an SX so can't start there. I would take all of the mods below. I come out with 67.86 DPN


Hobie 18 & 18 Magnum TheMightyHobie18 71.4 76.8 73.5 69.5 66.8


Class normally without spinnaker, genoa, reacher, hooter or wire/rope luff headsail attached to a pole, carrying one or more 0.960 0.953 0.958 0.960 0.960

MN For non-class legal mainsail, of same sail area or less than class legal mainsail (formerly square top adjustment) 0.995 0.990 0.990 0.995 0.995

MT For taller mast than standard 0.995 0.990 0.990 0.995 0.995