Short, undrilled bronze through hull fittings

[tribologist]

I’m going to remove the old sonar transducer in my Albin 25 and replace it with a thrugh hull unit. I was looking for undrilled bronze hull fittings to plug the hole with until next time i need to do some other fiberglass work but i did not find anything. Im probably using the wrong name for it.

Ulf

[WillieC]

I did the same thing, and plan on someday getting around to glassing the hole.

groco-th-thru-hull-bronze_l.jpg

I had to enlarge the hole in the fiberglass a little since the transducer was a bit smaller than the thru-hull. Then I took a rubber plug from the hardware store, shaved it down to fit inside the inner end of the thru-hull. Then put a bronze cap on it. Of course I used some Sika-flex 291 for sealant against the hull.

(Disclaimer: Everything I just told you I will deny in a court of public opinion because this is the exact WRONG way to make this repair. It is quick and easy however.)

[tribologist]

Not sure it’s all that wrong. Doing it permanently by laminating a patch carries its own risks. The boat has a fair number of bronze fittings thats look pretty good. One more or less... the current transducer is probably as bad as it gets. It sticks out quite a bit and all it would take to shear it off would be a log in the water.

Im not sure on how the originals are installed. Looks like they are laminated in place?

Maybe what i do is buying a regular hull fitting, cut it after the nut and put a tapered thread in it like the drain plug. I like to get the area back for putting in a separate start battery behind the two 80 Ah deep cycle batteries.

Ulf

[WillieC]

I agree about the transducer hanging out there. It barely missed the bunks on my trailer, and I tried shearing it off most every take-out. I have replaced a thru-hull and removed this transducer and they were not difficult to remove.

Threading a taper into an already threaded-on-the-outside thru hull would be quite a feat.
I cut mine short and just capped it with an NPT tapered cap, even though the thru-hull is straight cut. Don't tell anyone. Build up your battery rack to fit over it or leave a gap in between the batts and let the thru hull stick into that gap. You'll likely have to build it up anyway to get a somewhat level base for the batts.

[jleonard]

Or just have one machined from bar stock the way you want it.

[tribologist]

I was considering machining one until i saw the price for a 3” long 1-1/2 bronze rod in MCMaster, $32.40 plus shipping...... I have a decent shop with a 13x40 lathe and a Swedish mill (Abene) sharing the garage with our other old Swedish machinery, Pärlan, a -67 Volvo 1800S.

[jleonard]

I don't think that's too bad esp since the labor is free.

[WillieC]

(Ulf, I am posting here since this is about the thru-hull, not the other topic. I am bad enough at drifting a thread without anyone's help!)

"Ordered a Graco 1/2” through hull. When I get it I will take a look to see how to best cap it. 5200 on inside and capped with a brass cap is what im thinking. The brass should not see the saltwater if done right. (Ulf)"


The bronze (not brass, right?) doesn't care about the saltwater. 5200 may present a bit of a problem when you decide to remove the thru-hull, so I read. I used Sika-flex 291 I think it is called.
I just stuffed a rubber stopper inside the tube, cut it off a little proud of flush, and put the cap on with a little anti-seize on the threads. I may have bottom painted the exposed parts, maybe even primed it with leftover two part barrier coat. And then I learned how to do fiberglass work after an unfortunate incident at the boat ramp when I converted the A25 into the A25 Stretch model... A25 Plus 2 Inches. My new bow eye, with severely reinforced backing plates, is a thing of beauty. The next time I try to stretch it, major damage will occur. (I'd show you pictures, but I cry every time I see them.)

[tribologist]

Sounds good! Fiberglass work is fun once you get a bunny suit and a good solvent filter mask. Its amazing how nice one can get stuff with very limited experience by just following basic rules and take your time. (And plenty filler and long sanding boards). I had done some basic repairs on boats in Sweden like replacing rotted floors and repairing small damaged areas. A few years ago i overhauled a -62 whaler 13 and on that one i had to first build up and fair in the surfaces with bondo, make a mold and then cut out the old repair and build it back up. Lots of work but very fun to learn. Bow eye was completely ripped out of that one too. Boatworkstoday on youtube is fantastic inspiration.

I cant find caps made from bronze so i will use a Home Depot brass cap for now. It does not matter so much since its there as a secondary for the sealant. If im lucky the bore might be suitable for a tapered thread so i can plug it.

Ulf

[WillieC]

FYI

BronzePlug.JPG

This from Defender.

My favorite local supplier in Seattle has them too. Negotiating their website to find what I am looking for can be tricky. A phone call usually solves it. Local is good because the 'shipping and handling' usually costs more than the piece.

[tribologist]

Nice!!! Thats a good find!

Thanks!

Ulf

[rebuckley]

Ultimate, due to your excellent choice of locations, Defender is our local stop! And I think I stop there once a week.....

[tribologist]

Darn.... went to the one in Waterford, Connecticut

Had $100 on stuff on list, walked out with $360 worth of parts... that place was very nice. Very well stocked and fantastic staff.

Ulf

[rebuckley]

That's the place, my list when I walk in and my cart when I walk out never seem to match...always more in the cart

[jleonard]

Darn.... went to the one in Waterford, Connecticut

Had $100 on stuff on list, walked out with $360 worth of parts... that place was very nice. Very well stocked and fantastic staff.

Ulf

Only 3.6 times your "plan"? Not bad that's probably my average lol