This repair is something of a no-brainer... the boat came (standard) with a thru-hull fitting for the sink drain, with a gate valve. This is the kind of valve that you'll find on your garden faucet -- you need to crank it about 10 turns to close it complete, and you can't tell by looking at it whether it's open or closed.
Well, that's what's wrong with it outside of the marine environment. Worse yet, these valves can hold a small amount of water during the winter, causing them to freeze and split. When the boat is launched in the springtime, the tiny leak can be enough to sink the boat. Suffice to say that the valve is history, and is being replaced by a ball valve.
What I'm still confused about, though... I have a new bronze thru-hull fitting. But this one still looks OK. Would you remove this thru-hull? [January 2000]
Update [April 2000]: I did decide to replace and re-bed this thru-hull. As it turns out, there was not much sealant on the outside. I bedded it with Sikaflex 291, and also installed a large high-density plastic backing plate to spread the load.
One item that I have decided to re-bed is the speed transducer. I haven't had a chance to remove it yet, but this combination of silicone and plexiglass just doesn't fill me with confidence about its watertightness. [January 2000]
Update [April 2000]: This is the SR Mariner paddlewheel, re-bedded with a new high-density plastic backing plate. It was bedded with Sikaflex 291, as above with the sink thru-hull.

New Instruments + Thru-Hulls

In January 2001, I purchased a new Raytheon ST40 Bidata instrument. This unit requires two thru-hulls. One provides depth readings; the other provides speed and water temperature.
I re-used one hole from the old paddlewheel. The hole was slightly oversize for the new transducer, so I installed the depth transducer in that hole.
I drilled a new hole the correct size, opposite the original hole, and installed the paddlewheel in that hole. These are bedded with 3M 5200 (regular, slow-cure).
Also, you will notice that the paddlewheel inspection port is 8" in diameter. This is to improve access to the transducer for inspection and removal. This access is less critical for the depth transducer.
© 2018 Melissa Goudeseune