Normal
Preferably right at the water line to get benefit of the buoyancy - they don't support anything until they displace water - ie you don't get the max 470lbs of buoyancy unless they're totally submerged - however they will create a lot of drag when you're under way if you set them totally submerged - even if you get the contour of the cone such that it doesn't spray up in your face the whole time - so it's a trade-off. I'd set them so when the boat is sitting in the water without a load in it they're not much more than 2 or 3 inches in the water. This way the more you load the boat the more they support.Your boat sides aren't parallel over the full 10' run of the pipe - but you should be able to soften the pvc with a torch carefully and contour it to the side of the boat using indirect heat - wrap the PVC tightly with a heavy aluminum foil (you'll need a hose clamp or two to hold it on) then apply the heat from a distance to the foil. Probably need a 2nd person to apply pressure to the end of the pipe to get it to bend. Once you have it in place while it's still warm spray it with a garden hose to get it to hold the shape. Trick is to not overheat it.
Preferably right at the water line to get benefit of the buoyancy - they don't support anything until they displace water - ie you don't get the max 470lbs of buoyancy unless they're totally submerged - however they will create a lot of drag when you're under way if you set them totally submerged - even if you get the contour of the cone such that it doesn't spray up in your face the whole time - so it's a trade-off. I'd set them so when the boat is sitting in the water without a load in it they're not much more than 2 or 3 inches in the water. This way the more you load the boat the more they support.
Your boat sides aren't parallel over the full 10' run of the pipe - but you should be able to soften the pvc with a torch carefully and contour it to the side of the boat using indirect heat - wrap the PVC tightly with a heavy aluminum foil (you'll need a hose clamp or two to hold it on) then apply the heat from a distance to the foil. Probably need a 2nd person to apply pressure to the end of the pipe to get it to bend. Once you have it in place while it's still warm spray it with a garden hose to get it to hold the shape. Trick is to not overheat it.
