This is what I did on Grace (1983 M17 #400): The original thru-hulls appeared to be thin-walled aluminum tubing glassed into the hull. I believe the tubing was primarily the form around which the glass was placed as well as the attachment point for the flexible hose. I chose to replace them with 1-1/2" stainless steel tubing which has a 1-1/2" outside diameter and is much sturdier than aluminum. I ground out the remnants of the aluminum and glassed the ss tubing in place. I am confident that no amount of banging around will damage my new thru-hulls (at least not before the hull itself would fail). I believe that bronze (not brass!) or stainless tubing would be best. Don't try to glass in the rubber hose directly. That would be asking for trouble (and you would be certain to have that trouble show up at the absolute worst possible moment). Mark Dvorscak -----Original Message----- From: montgomery_boats-admin@mailman.xmission.com [mailto:montgomery_boats-admin@mailman.xmission.com] On Behalf Of wayne yeargain Sent: Wednesday, October 30, 2002 8:25 PM To: montgomery_boats@mailman.xmission.com Subject: M_Boats: cockpit drain thru hull fitting I had a leak at the bottom end of the cockpit drain on my '76 M17. The metal pipe that goes thru the hull had corroded. I cut it out (6" dia. hole in the bottom) and the metal tube had two small holes just below the clamp from corrosion. (26 years old) Does any one know what is the best type of tube to replace it with, or if a clamping tube is necessary ? Maybe I can just glass the rubber hose directly to the bottom. Some options for the tube are Stainless, Brass, Copper or Marlon fittings from West Marine, or perhaps a section of PVC pipe from Home Depot. My only concern is which materials are most compatabile with fiberglass and will develop a strong bond. Also is it better to re-install it in the new fiberglass as I repair the hole, or would it be better to install it in an adjacent area of uncompromised (original) fiberglass. The hose is long enough that I can route it to a different location. The old tube looked like thin wall aluminum, it was glassed into the bottom with the rubber hose clamped to it. Bob if you have any suggestions I would greatly appreciate your input, or anyone who has dealt with a similar problem.. Wayne "76 M17 "Intrepid"