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Old 23-03-2018, 04:20   #1
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White Marelon - UV stable? Expected life?

My boat was built in 2001 and it has white Marelon thru-hulls above the waterline (for drains and scuppers). They appear in good condition, but at 17 years old I’m wondering what the expected life should be. Most are in the engine compartment, and the engine is out for service. The connected hoses also appear flexible and in good shape, but I’m thinking I might replace all (as preventative maintenance) while I have access.

It’s going to add a few hundred dollars in materials and a few days of contorted labor, and I’m wondering if I’m just making work for myself.

Am curious about expected life and experiences of others with educated opinions.
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Old 23-03-2018, 04:25   #2
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Re: White Marelon - UV stable? Expected life?

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My boat was built in 2001 and it has white Marelon thru-hulls above the waterline (for drains and scuppers). They appear in good condition, but at 17 years old I知 wondering what the expected life should be. Most are in the engine compartment, and the engine is out for service. The connected hoses also appear flexible and in good shape, but I知 thinking I might replace all (as preventative maintenance) while I have access.

It痴 going to add a few hundred dollars in materials and a few days of contorted labor, and I知 wondering if I知 just making work for myself.

Am curious about expected life and experiences of other with educated opinions.
Buy a new one, then remove one through hull, then hit it with a heavy hammer. Then hit the new one with the hammer. They should distort slightly but not break.
If this is the case then keep the new one as a spare and reinstall the old one.

Then report the results back here so we all learn something.
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Old 23-03-2018, 05:23   #3
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Re: White Marelon - UV stable? Expected life?

At around 40 years of age they池e still a royal PITA to break apart.
I知 assuming that ours are original equipment.
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Old 23-03-2018, 05:41   #4
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Re: White Marelon - UV stable? Expected life?

Our boat was equipped with all Marlon thru-hulls. The above the waterline ones had begun to get powdery on the surface after 12 years.

I opted to replace all my thru-hulls when I did a refit.
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Old 23-03-2018, 09:21   #5
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Re: White Marelon - UV stable? Expected life?

FYI - I just heard back from a sales engineer at Forespar. Quote from his email: "Marelon is not a plastic. It has a life of more than fifty years. Attached is some further information." (He included about 8 MBs of attachments.)

I think I'm going to check each of the hoses carefully and leave the thru-hulls.
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Old 23-03-2018, 09:33   #6
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Re: White Marelon - UV stable? Expected life?

I agree with Forespar. I have had no trouble whatsoever with Marelon seacocks and thru hulls. They are tough and durable and I am glad to hear him repeat that it is NOT a plastic. And they do not disintegrate from electrolysis. As long as they have been bedded properly in polysulfide or some other below the waterline sealant, they will last forever!
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Old 23-03-2018, 09:59   #7
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Re: White Marelon - UV stable? Expected life?

Hhhmm... I very much disagree with the Forespar "engineer". Forespar's own wesite also disagrees as well.
https://www.forespar.com/marelon-history-1.shtml

Marelon is a UV stable composite reinforced polymer, or in laymans terms, a plastic with fiber reenforcing mixed in that has limited degradation in the sun.

Yes I was also told when I called Forspar that their stuff was designed for 50 years and asked why I was replacing it after 12. I simply asked the engineer if 5200 lasted 50 years. When he said "no", I asked him if he ever tried to remove a Marelon fitting from 5200 without destroying it. His response, "I understand, let me send you to our sales department".
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Old 23-03-2018, 10:10   #8
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Re: White Marelon - UV stable? Expected life?

If your white fittings really are Marelon I don't think you'll need to replace them, but if they are some other kind of white plastic, yes the'll need to be replaced.
I had an above waterline white thru hull that was my bilge pump discharge became brittle and snapped off after 10 years.
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Old 23-03-2018, 12:05   #9
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Re: White Marelon - UV stable? Expected life?

Quote:
Originally Posted by SailFastTri View Post
My boat was built in 2001 and it has white Marelon thru-hulls above the waterline (for drains and scuppers). They appear in good condition, but at 17 years old I知 wondering what the expected life should be. Most are in the engine compartment, and the engine is out for service. The connected hoses also appear flexible and in good shape, but I知 thinking I might replace all (as preventative maintenance) while I have access.

It痴 going to add a few hundred dollars in materials and a few days of contorted labor, and I知 wondering if I知 just making work for myself.

Am curious about expected life and experiences of others with educated opinions.
If you have better access at this time, it may be worth it for your piece of mind ? Apparently its a concern of yours. I doubt it would be for me above the W/L. but that is me.
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Old 23-03-2018, 13:28   #10
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Re: White Marelon - UV stable? Expected life?

They are above the waterline. Trimarans are never going to roll to that level. Why make trouble for yourself? Also your boat is deluxe. I would replace all hosing since engine is out of the way. Ozone degradation of rubber to me is always a concern. Busted hose at the wrong time could be a real nightmare. Leave thru hulls alone.
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Old 23-03-2018, 13:50   #11
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Re: White Marelon - UV stable? Expected life?

I have an above the waterline discharge port in Marelon that is now 34 years old and shows no signs of degradation.
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Old 23-03-2018, 15:22   #12
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Re: White Marelon - UV stable? Expected life?

Thump them with a hammer from the inside.
If they move,re-bed them. If they break........

Do the same to your underwater ones.

Now is the time to find out.

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Old 23-03-2018, 15:40   #13
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Re: White Marelon - UV stable? Expected life?

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Hhhmm... I very much disagree with the Forespar "engineer". Forespar's own wesite also disagrees as well.
https://www.forespar.com/marelon-history-1.shtml

Marelon is a UV stable composite reinforced polymer, or in laymans terms, a plastic with fiber reenforcing mixed in that has limited degradation in the sun.
I think black Marelon is more stable, with respect to UV, than white Marelon. I think I've seen slight degradation of the surface of white Marelon exposed to sunlight after about 20 years of tropical sun exposure.

Let's not fool around. Forespar created the tradename. Marelon = marine nylon.

The substance was invented in New Zealand by Auckland Tool and Gauge Company in 1976. ATGC called it GRZ or Glass-Reinforced Zytel.

ATGC developed the tooling to make by injection moulding GRZ through-hulls, seacocks, hose connectors, and other plumbing items.

R. C. Marine Products started importing GRZ products from NZ and wholesaling them into US marine supply stores in about 1980. Bob Foresman (Robert Reiff Foresman, 1925-2012, an orthodontist who had served in the USN as a dentist in WWII and Korea and who was a keen recreational sailor) bought an interest in R. C. Marine Products in 1981. And R. C. Marine Products and Forespar started using the 'Marelon' name about 1983.

Forespar, Bob Foresman's company, bought ATGC in 1986 so they could move the injection moulding tooling to Rancho Santa Margarita, CA.

So what is Zytel?

It's a nylon. Or if you prefer one of the several families of polyamides. It's a mix of nylon 66 and nylon 6; the specific mix of the two gives it certain engineering properties. Zytel is a trademark. Auckland Tool and Gauge Company worked out how to mix glass fibres through it and then to inject it into a mould. No doubt Forespar engineers have made some refinements over the past few decades.
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Old 23-03-2018, 15:46   #14
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Re: White Marelon - UV stable? Expected life?

As I refit and replace, all my new throughhulls and seacocks are Marelon.
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Old 23-03-2018, 16:13   #15
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Re: White Marelon - UV stable? Expected life?

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Let's not fool around. Forespar created the tradename. Marelon = marine nylon.
Correction and clarification:

Marelon = MAriine REinforced nyLON
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