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Jul 17, 2023

Through hull fittings: bronze or plastic?

When it comes to through hull fittings do you opt for bronze or plastic?

When it comes to through hull fittings do you opt for bronze or plastic? Surveyor Ben Sutcliffe-Davies shares answers a Yachting Monthly reader's question

Are plastic composite seacocks as good as bronze?

I recently had a scary experience with one of my through hull fittings breaking.

I want to replace them all and would like some advice on bronze versus plastic.

Can one of your experts help please?

Jeff Wrinch

Ben Sutcliffe-Davies responds:

Great question Jeff and one of my hot subjects that I have regularly warned about in Yachting Monthly several times in the past.

If they are real bronze ball valve fittings then they should last a lifetime, but buyer beware, as sometimes they are not really bronze but made from composite materials.

You also need to know what the ball material is.

On the flip side, Marelon-type composite valves have been in use for over 20 years in the USA and New Zealand.

There are various options with both the Forespar Marelon and the Tur design.

At one time, Forespar did a range like the Tru design that replicated the Dezincification Resistant Brass (DZR) ball valves; they both had some failures caused by incorrect fitting.

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Forespar now has several options of valve available and I have used them in my own yacht for years.

The skin fitting should not be over extended internally.

A support collar is also available in chandleries in the USA and New Zealand and many in the UK.

I would suggest using the support collar to prevent overloading the skin fitting.

If you are not convinced then there are some good bronze options. Perko is a USA brand and is a nice sluice valve.

I still love the Blakes seacocks but be aware, they are actually made from DZR brass.

However, it's a rare day when one fails, just don't use stainless steel bolts!

Lastly there is the Alex valve, which has a bronze body with neoprene seals.

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