Responding to this older message in the thread:
Originally Posted by OldDan1943 View Post
I would think the through hull opening would plug up first.
Never saw it happen.
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Rich Gano
FROLIC (2005 MainShip 30 Pilot II)
Panama City area
I can tell you that we ABSOLUTELY have zebra muscles in Lake Travis choke thru hulls. Several years ago, I never worried about it. That was before zebra muscles took over the lake. Now I have to have a diver scrub the bottom on a regular basis (quarterly - and some do it monthly).
Bottom paint is VERY effective at keeping them off, which is the GOOD news.
Boats with true inboards do much better than I/O boats.
Zebra muscles will definitely attach to the outdrives, trim tabs, shafts, supports for swim platforms, and as indicated above - they will definitely clog up thru-hulls.
I'm still mixed on using bromine tablets. I'd be more willing to try it on the AC sea strainer first. My thru-hulls are marelon, the hose is plastic, the plumbing in the AC should be copper - and is far enough upstream that lack of light would HOPEFULLY prevent growth up there...
If the bromine tablets would dissolve important things - the AC system would be much easier and cheaper to replace than the engine! Though again, since the AC system is so simple (and probably all copper) - the result of bromine on the engine might be MUCH worse than the result of using it on an AC system.