Seasense
New member
I am replacing a skin fitting and seacock below the waterline. I was going with bronze but is there an argument to be made for plastic over bronze?
Bronze or plastic skin fittings and seacocks?
- Thread starter Seasense
- Start date
vyv_cox
Well-known member
Plastic seacocks tend to be more bulky but if you have space there is no reason not to fit plastic. Bronze valves mostly have a brass ball, which corrodes. DZR is a better material now as every component is made from it.
Bouba
Well-known member
I would say not generic plastic but only TruDesign
rogerthebodger
Well-known member
I have 316 stainless steel skin fittings and ball vales on my steel boat but I have generic plastic on my ferro cement boat
The trick with 316 stainless if to fully seal and fill any threads to prevent any crevious corrosion
The trick with 316 stainless if to fully seal and fill any threads to prevent any crevious corrosion
Baggywrinkle
Well-known member
Another vote for Trudesign.
Sandy
Well-known member
Why put metal through hulls in a plastic hull?
vyv_cox
Well-known member
Because, as I said previously, they are more compact. It would be impossible to replace most of my metal seacocks with plastic. But there is a very long history of metal fittings underwater in plastic hulls, in the vast majority of cases without problems.
Plum
Well-known member
Another vote for DZR ball valves and skin fittings. I buy from ASAP Supplies. My oldest DZR ball-valve is 25 years old and is still working well.
Tranona
Well-known member
Huge amount of metal attached to a GRP hull apart from through hulls s not sure why you are asking such a simplistic question. There is no direct contact between the metal and the GRP so again not sure what point you are making.
Trident
Well-known member
TruDesign, I've fitted hundreds and I'll never need to replace one on any boat I've put them on - they last forever and work perfectly
Sandy
Well-known member
Sorry to confuse everyone in the way I posted the comment.
While traditionally metal fittings were used with modern plastics I see no logical reason to fit metal ones.
I have one metal through hull for the raw water inlet, which might get replaced should it fail before I die. That and the fittings for the anode.
Tranona
Well-known member
Simply cannot see any logic at all. Metal through hulls and valves perform exactly the same function as non metallic and if the correct grade material is used will last just as long and are generally cheaper. The fact that they are attached to a GRP structure is completely irrelevant. The non metallic valves are a different material to GRP and are isolated from the hull in exactly the same way as metal valves. If you are worried about your engine water intake simply replace it with a DZR (as I have just done) and it will outlast you.
So no logical reason for using non metallic valves and I am afraid it is you that has confused "logic", not others.
Bouba
Well-known member
The TrueDesign plastic use some kind of polymer ball valve….so it should always be easy to use and not get seized
Zing
Well-known member
Because they are much stronger, tougher and more resistant to getting bashed in by things your boat may hit. Especially so with bronze. I have bronze thru hulls for that reason. I also have DZR brass valves as I don’t need the strength of bronze in the valve and like to save a little bit.
BTW Vyv you can get bronze balls in bronze valves. I think by Apollo, but in a US thread fitting. V. Expensive.
I also have a few TruDesign valves. They are very light to operate and not a bad choice if you can protect them from damage. With their collar fitted they are a lot tougher than without.
Tranona
Well-known member
Can you explain exactly what sort of circumstances would result in a sound metal skin fitting or valve breaking? How would your boat hitting anything damage the through hulls or valves without damaging the hull? Suspect you have a vivid imagination. DZR is probably equally as strong as bronze. Watertightness and corrosion resistance are the key properties of through hulls and valves and bronze, DZR and composites all have those properties.
Bouba
Well-known member
From my experience the fittings break from the inside not outside the boat…it happens when you try an open/close a seized valve
Tranona
Well-known member
Only if it is dezincified brass and it is the threaded fittings that usually fail. Have you actually tried to do it just by using the lever??
Bouba
Well-known member
The lever snapped off…closed….my boat had to be towed to the takeout
Elessar
Well-known member
1 possible reason.
Metal fittings are compulsory in the “machinery spaces” of coded boats. For me that’s 6 of my 8 seacocks.
This is despite the fact that composite depth and speed through hulls are allowed in those spaces.
xyachtdave
Well-known member
Would anyone’s opinion change if Sea Sense had let you know his boat was made of steel? Galvanic corrosion and all that?
I’ve read on here people were worried about UV rays being reflected off the seabed and shortening the lifespan of plastic fittings. Not an issue on the East Coast of the UK I’d imagine but elsewhere?
I’ve read on here people were worried about UV rays being reflected off the seabed and shortening the lifespan of plastic fittings. Not an issue on the East Coast of the UK I’d imagine but elsewhere?
