Through Hull Transducer Mounting

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Mac

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Jun 7, 2006
436
MacGregor 25 KEUKA lake NY
I'm a new owner of a 1989 C-25 that sports NAVICO DL200 Wind, Speed, and Depth indicators. The through hull transducer mounting for the Speed Indicator is seeping water, around the base. Does anyone have any experience in how this mounting is installed, the book calls it a skin fitting and it appears to be threaded with an inside plastic nut. I don't want to start twisting and turning without knowing the possible consequences. I am thinking about a temporary fix by trailering the boat and cleaning the outside mounting and applying 3M 4200 until I pull it for the winter next December. Any information or advice will be appreciated.
 
L

LaDonna Bubak - CatalinaOwners.com

Trailer it

If you're going to go to the trouble of trailering it to do a "temporary" fix, why not just do it right? Won't take much more of your time (assuming you've pleased the boat repair gods this season) and you'll be comfortable knowing it's good for awhile. Once you're hauled, you should be able to remove the fitting by backing off that nut and prying it loose from the sealant. You'll have to clean off all the old sealant but a good knife & some acetone should do that. There might be some contention on this so go with your gut but I've always been told to use 5200 under the waterline. Apply gobs & gobs so there are no air pockets or voids & tighten the nut up again, but just enough so the goo oozes out just a little. When it's cured (a day), tighten it down all the way & trim off the excess goo. See how easy that was? ;-) LaDonna
 
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John Buckham

C-25? Trailer?

Yes, don’t get a wrench near that through hull until the boat is out of the water, a small trickle can become a huge hole in seconds flat if that plastic transducer decides to break in two. When you re-bed the transducer use something like Life Calk or Sikaflex, it seals well and is easy to remove when it’s time to upgrade. It may not be what's leaking though! The transducer holder is like a mushroom with a threaded stalk with a hole in the center that penetrates the hull through a large-ish hole. The transducer is calked then pushed through the hull then a nut is threaded down and the whole mess cinched up. May that part never leak again! Most speed transducers (okay then; all I have seen) can be removed from inside the boat to remove marine growth. Usually the center of the transducer can be removed by pulling a pin, then removing the transducer by pulling up. Once the transducer is pulled out you will need "the" or "a" plug to replace the transducer pronto to quell the inrush of water. The transducer will have a couple of O-rings that keep the sea at bay, and most likely these are worn and need to be replaced. If you have "the plug" you should be able to do all this right at your slip. With a C-25 you ought to be able to pull it out with a trailer and boat ramp. You won’t need to unstep the mast, as the repair is quite easy.
 
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Les Murray

Check for water in the hull while your at it

I once had an old Hunter 20 that had a leaking thru-hull. When I removed it to seal it, the hull core was saturated with water and I could never reseal it. It appeared a previous owner drilled the hole, but never sealed the core. You should make sure your core is well sealed (with epoxy) prior to resealing the thru-hull back on. This could take several weeks for the core to dry out. Good luck. Les Murray s/v Ceilidh '86 C-36 #560
 
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