Composite thru hulls: good or bad idea ?

[Mambo42]

By coincidence I stumbled on 2 videos this last week talking about the benefits of composite thru hulls. There is a brand called Trudesign, they are from New Zealand and they apparently specialize in these thru hulls.
Since the are composite they don't corrode and since some of my thru hulls don't look in such good condition anymore (boat is 45 years old) I am thinking of changing those into composite thru hulls. The ones that are still good I will simply keep as they are.

Does anyone have experience with composite thru hulls ? Are they really so much better ? Is there a negative side to it as well or is it just a positive innovation all around ?

 

[rslifkin]

I use the composite Marelon thru hulls pretty much everywhere above the waterline. I stick to brass below the waterline though, as I've heard mixed reviews on the composite valves (as far as issues with sticking) and I wouldn't want to put a metal seacock on a composite thru hull. Plus, properly installed and maintained bronze parts can easily last 30+ years below the waterline, so needing to replace them probably once in the boat's life isn't a big deal in my mind.

 

[heysteve]

I had Forespar Marelon seacocks on a previous boat that was 18 years old. They looked good as new and worked fine.

 

[Mambo42]

I use the composite Marelon thru hulls pretty much everywhere above the waterline. I stick to brass below the waterline though, as I've heard mixed reviews on the composite valves (as far as issues with sticking) and I wouldn't want to put a metal seacock on a composite thru hull. Plus, properly installed and maintained bronze parts can easily last 30+ years below the waterline, so needing to replace them probably once in the boat's life isn't a big deal in my mind.

Most of them are still good, but some, difficult to reach valves, don't function anymore. That means this winter I will have to get to them when the boat is out of the water and most likely I will have to take them out anyway. I can either go with brass again or go for composite.
Composite seems to be much easier to install, but I have no experience with them as underwater thru hull. I have see the composite thru hull of my old depth meter, that one was not completely intact anymore. I have changed that one for a new one, but if that will happen in a few years to new composite thru hulls, it is something to think about.

 

[C lectric]

2 or so years ago I was required to remove all my Nylon through hulls and replace them with bronze units. Reasoning was they were to low and on the hull sides so subject to being broken by a wayward log. Hard to argue with both insurance co. and the surveyor.
I was a wee bit annoyed as it was a LOT of work and a fair bit of expense but it was done.
What really put me off is I took a couple of the original through hulls and smacked them solidly with a sledge hammer. They flew but did not break or crack .

The boat was launched in 1,977 and is now 47 years old.

Oh well, sometimes you can't win.

 

[lwarden]

I have all Marelon thru hulls on my boat and they are original (22 years). They all operate perfectly and when I added a new one for a dedicated raw water washdown I used the same type. I'm more worried about de-zincification of bronze over that period of time than I would be any issue with the Marelon ones.

 

[Comodave]

Some are referring to brass through hulls, never use brass below the waterline only true bronze or a quality composite. I have seen some very old bronze through hulls that were in great condition. My feeling is why mess with a proven product. I know that composites have been around a long time but I still prefer bronze. Your opinion may vary…

 

[mvweebles]

The only time I've used Marelon was for a Y-Valve in a sanitation system. Handle broke a year or so later. I'm surprised to hear they work fine as below waterline skin fittings. Are they as strong as bronze for side-loading? Tool chest sliding into it?

I'm with Comodave - Groco bronze have served me well. But keeping an open mind so curious about composite.

If memory serves, topic comes up frequently on CruisersForum as sailboats seem to have composite more often. Might want to check there too.

Peter

 

[Comodave]

Through hull fittings are supposed to withstand 500 pounds of pressure for a period of time, forget exactly how long. That is one reason I like a quality bronze fitting.

 

[Mambo42]

Thanks for the replies, my boat was launched in 1979, still has the original through hulls, plus some additional ones which were put in later. Now that I know I have to exchange a few I was asking myself which quality should I use. But I understand the overwhelming majority says bronze and since an insurance company demanded it of C-Lectric I think I will go for bronze again. As long as they are good quality, are safe and work fine I will be happy.
Thanks.

 

[jgwinks]

2 or so years ago I was required to remove all my Nylon through hulls and replace them with bronze units. Reasoning was they were to low and on the hull sides so subject to being broken by a wayward log. Hard to argue with both insurance co. and the surveyor.
I was a wee bit annoyed as it was a LOT of work and a fair bit of expense but it was done.
What really put me off is I took a couple of the original through hulls and smacked them solidly with a sledge hammer. They flew but did not break or crack .

The boat was launched in 1,977 and is now 47 years old.

Oh well, sometimes you can't win.

Insurance companies don't know anything about boats, that's why they require surveys. If you get a surveyor with a personal bias for or against anything, the ins company will make you go with whatever the surveyor said, right or wrong. I'm sure there are just as many surveyors out there who would be perfectly happy with composite through hulls. The last boat I sold had all Marelon seacocks and through hulls below the water line. Buyer shared the survey defects page with me, the though hulls were not mentioned.

 

[mvweebles]

Thanks for the replies, my boat was launched in 1979, still has the original through hulls, plus some additional ones which were put in later. Now that I know I have to exchange a few I was asking myself which quality should I use. But I understand the overwhelming majority says bronze and since an insurance company demanded it of C-Lectric I think I will go for bronze again. As long as they are good quality, are safe and work fine I will be happy.
Thanks.

Question. Are Groco bronze fittings available in Europe? What are your options? I've seen chatter on the sail forums that some of the builders use brass (Beneteau) and I wonder if it's cost or availability driving the decision ---- assuming it's true.

Peter