Marelon valves

[Fou Du Large]

I want to chage the marlon through-hull valves on my boat
Is someone know the size of these valves 1/2'' npt or 3/4'' npt?
My boat is under the snow...

Thank you.

[Stu Jackson]

The valves are different sizes.  Which ones do you want to change?  All of them?

[Fou Du Large]

Yes all the plastic valves.
2 sinks drain
Macerator
Motor inlet
salt water pump
Toilet inlet, (hull only).
Is stainless steel 316 ball valves is a good idea?

I know that is better to change the thrugh-hull fittings to, but this is a big job.
I'm afraid by the plastic handle of the valves, hard to operate.

Bye

[dgill]

Hi Martial,

If the existing valves are difficult to operate and you feel they are no longer viable, why not replace them with New Marelon valves.  The existing valves have worked for nearly 22 years.  Marelon is not subject to galvonic corrosion.

D. Gill

[tonywright]

I find that the Marelon valves even on a 2003 do not turn as easily as the bronze ball valves do. It certainly makes them feel fragile, so I can understand Martial's concern. But they seem to last.

Before you replace them, take a look at the Forespar maintenenace recommendations (here is an excerpt):

FORESPAR® MARELON® Thru-hull/seacocks are corrosion free and provide great peace of mind in that regard. They are relatively maintenance free. Generally, lubrication is not required. What is required is to open and close them on a regular basis (4 times a year minimum). The frequency this is required is determined by two (2) things, whether the valves are routinely kept open or closed, and the rate of sea growth (weed and barnacles) in your area. If the rate of fouling is high and the valves are not actuated regularly, this build up of growth can cause any valve to turn hard or not at all. If the valve becomes stiff due to lack of use and sea growth build-up, it must be cleaned. The restriction of flow into the valve may cause harm to the machinery it serves and the valve may seize if not maintained. DO NOT DISASSEMBLE VALVE OR LOOSEN BOLTS EXCEPT IN EXTREME EMERGENCIES.

[Jon Schneider]

REVISED (I stupidly forgot to embed the url to which I was referring):

Here's a really good site on replacing thru-hulls (and other projects as well): http://www.pbase.com/mainecruising/replacing_thruhulls.  It's a project site to which many of us refer from time to time and should definitely be on your bookmarks.