Its relevant to the spin. Install the chute and attach sheet lines. Pull the lines back toward the hull, you want to sheet thru the middle of the chute so the foot and leech harden at the same time. Too much pull on the foot or the leech will affect sail trim. May need someone to hold the sheet so you can step back and examine. If you are lucky the shrouds will attach where the block needs to be and no holes will be drilled.
Dead on! This is how I determined my spin block locations. Turns out to be about 4 inches infront of the shrouds. I can measure tonight if I think of it. I hard mounted eye straps with #10 screws and nuts. I used carbo autoratchet blocks with stand up springs too. I also reinforced the fiberglass on the interior of the hull lip through the forward deck port. Bear in mind, if you use a longer pole, the spin block location will change also. I have a standard (west marine) 9' 4" long aluminum tube 2 inch diameter, .063 wall thickness. I bought the Performance EO snuffer head which slides into the tube perfectly. Did I mention I have 6 more tubes for sale...LOL!
