Current practice is not to bond ie connect your underweter thruholes together. Since you ARE OUR researcher on this subject, maybe you can find substance for this. I believe skippers feel that marinas are so hot that it is better not to connect but to zinc.
[John, on the 'sink me zinc me' thread suczincly explains modern zincing]
I really don't think Marelon can be broke. The broken handle story has been around forever. It may be related to the screw that holds the handle on to the body which has been replaced by a fatter one for a number of years. But I don't know what "breaks."
Marelon seacocks cannot be taken apart for maintenance. The only m. you have to do is grease the ball by taking the hose off inside and outside when the boat's out. Once a year. Maintenance consists of 'cycling' the valve. The dirtier and more virulent your marina the more you turn the handle. Wouldn't this be the case for an alloy valve? Exercising the valve keeps the ball clean.
One Marelon guy says he has never had a problem even tho his valves are rather stiff. The handles are balanced in the sense that they project out both sides of the shaft. He doesn't LEAN on the long side but cups (my description) the handle providing up and down turning on the handle.
If you've forgotten to cycle your seacock for three years and you have live barnacles in the hole, and you use a piece of pipe to persuade the handle to open or close, something has to give. What gives maybe is the center(?) I'm going to check this out because I want to use Marelon on 338.
I have not varified this:
Forespar site talks of a "93 series" a heavier form of thruhull. If I understand it, you not only can get a heavier thruhull but also get one with STANDARD PIPE THREAD. You match the NPT with an NPT valve (not sure if that means seacocks also have that option.)
What this means is that you can get many more turns befor it snugs up. I'm going to call them and will ask. I can't see any reason for a pipethread thruhull going into a pipethread seacock - so they must be talking about the questionable practice of using an inline valve as a seacock. And providing a stronger thruhull with the proper threads.
OK. Just talked with Forespar. Yes the handles can break, cecause they are not exercised regularly and the balls load up. Head discharge seacocks calcify and must be REPLACED periodically. The same is true for sink valves related to what you put down the sink.
The 93 series of SEACOCKS were produced in response to new regs (But by whom didn't compute (ABYC?)
You purchase the seacock and thruhull as a unit. They are pipe-threaded ie both are NPT. The thruhull is pared down till it fits into the seacock depending on backing block height. This has to be the most secure setup ever.
For you guys who insist on alloy, maybe Scott can find out if Groco/Apollo/Spartan have a version of these too. It's a whole new ball game
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