Marelon Thru Hulls
- Thread starter Bob S
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Not a good idea
Not a good idea ...because plastic and bronze--all metals--have different thermal coefficients...iow, they expand and contract at different rates and in different amounts...resulting in leaks and/or cracked plastic.
That's a great point from Peggie, also
consider the matching of the right threads. MS did a great writeup of that, and it may be on his own website, too.
consider the matching of the right threads. MS did a great writeup of that, and it may be on his own website, too.
While this is safer than using Marelon on Bronze thru-hulls it is still not the best idea.
Using a Bronze marine ball valve on a plastic thru-hull will usually only result in a leak but using a Marelon ball valve on a male Bronze thru-hull can result in the splitting of the Marelon valve. While rare there are a number of repoted cases of split Marelon vlaves that were installed on Bronze thru-hulls. IIRC Sailnet had a guy about two months ago who had this happen to him.
Unfortunately cracks like this, in Marelon ball valves, are hard to see and hard to diagnose due to locationa nd lighting,. It is quite possible to mistake a cracked valve for a loose one and then over tighten it more..
If you have Marelon I would suggest using Marelon valves..
Metal on Outside of hull - grounding difficulty
From the original post ".... it looks funny on the Marelon..", I assume the metal is on the inside of the hull, but this is just an assumption.
If, however, it is on the outside of the hull, and I mention this because I've seen an instance where this existed, there is a problem with grounding the metal part because you can't get a wire to it.
Just thought I'd mention this to help fill in on the details.
From the original post ".... it looks funny on the Marelon..", I assume the metal is on the inside of the hull, but this is just an assumption.
If, however, it is on the outside of the hull, and I mention this because I've seen an instance where this existed, there is a problem with grounding the metal part because you can't get a wire to it.
Just thought I'd mention this to help fill in on the details.
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