I don;t know, I may have been a little closer to centerline than 7" with the hole, I did not want to line it right up with the water intake.
Does not catch with the gasket off. When I take the locking nut off, I can add the rubber gasket and screw the cap on and it gets a really tight fit against the gasket. and the 2 orings are really seated into place well.
I don;t think it's going anywhere. The sleave was REALLY tight going in from the bottom. To prep the hole, I sprayed foam waterproof insulation in the hole. I had no green goop in there, It was completely hollow except on one side I could see where I cut through a layer of foam insulation or whatever. It was white and the liner was bone dry. Maybe the green goop is algae growing in the insulation on yours?

I put tape over the bottom of the hole and squirted expanding waterproof gap and crack filler foam insulation from the top. Once dried I removed the tape and used the blade of a coping saw to cut the foam out even with the hole. Then covered the inside with a layer of epoxy with my finger. Sanded a bit and screwed the sleave in. I think i'd have a hard time getting it out if I had to.
Anyway, I think I'll try this out watching very carefully for leaks and staying close to the ramp. Worste case is that I'll have to drill a larger hole in the liner and inset the locking nut like Derek suggests, but I 'm not sure the liner is thick enough. If it leaks I'll worry about it. Bilge pump works great. Bubba Joe, take your best shot.
Stay tuned for the test run.