Hello Tod Mills et al, the old aluminum thru hull was simply a short length of 1.5 inch o.d. tubing...no flange or anything! it was glassed into the hull and was probably quite secure when new but over the years had become covered with a whiteish powdery material and had actually rotted all the way thru in several places right where the rubber hose ended. i was going to do a temporary fix by sleeving the inside by epoxying in a 1.25 i.d. piece but when i drove in the sleeve the whole thing came out with little effort. i am going to now epoxy in a short section of 1.25 i.d. copper water pipe made up by soldering a 45 degree elbow, 2 inches of tubing and a coupling. this will give me the correct outside diameter [ 1.5 in ] to match the 1.5 in. existing cockpit drain. this piece will not have any flange either unfortunately, but i am glassing it in really well with system three and it should be much stronger than the old piece which lasted over 27 years. this winter i may replace the old alum. cockpit drain but it still looks in good shape. since we are sailing now only on lakes and will not get pooped,I HOPE! i will not add any additional drains as jerry suggested in the old archives. hope you find all of this of interest. i think it applies only to the older M17's -pre wet locker. tomorrow morning we will begin the installation happy trails, ron and cathryn goodspeed M17 "hula pie" #o25