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.
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
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
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