felizcortez wrote:
Timely thread. I'm replacing our thru hulls during this haulout as well. I'm going to try to go with some of the Trudesign ones where they will fit.
For the engine thru hull, mine is a 3/4, but I'm thinking of converting it to an inch, but using an adapter to get the hose size back down to what it is expecting 5/8
Just the holes in the hull are 1" for raw water engine, head and head sink drain. The fittings are all 3/4" with a 3/4 to 5/8" hose barb to 5/8" hose.
The hole saw bit worked well. Have a couple extra hole saws. I think what I did was plug the 1" holes with dowels with about 1" sticking out, center the bit and made the first cut as deep as I could stand it with a 1" hole saw. Then I went to 1 1/4" ever so lightly to cut through the flange. You might have to put another wood dowel into the hole. Same with the two larger holes - 1.25" first, then 1.5" lightly to avoid cutting fiberglass behind the flange. With the right tools and the RIGHT ARBOR, you can do all 5 in a half hour. Knock them into the boat, chisel off any remaining flange, use a multitool to cut the hoses inside, then replicate what you took out. I'm just not going back to flush flanges and will glass and fill the depressions before putting mushroom style thru hulls in. You'll need to cut (shorten) the new thru hulls a bit, de-burr and re-thread with the nuts.
Helpful tip, new to me. The hole saw arbor with the pins in it is specifically to keep dummies from heating up and tightening the arbor onto the hole saw blade permanently. The pins stop you from over tightening. Never knew that. Youngest son pointed it out after I fried a blade onto a screw-in-only arbor.
Can you build these out with all marelon parts? Otherwise you're going to be mixing and matching. I've got more brass than I'd like, but eh.