White Marelon - UV stable? Expected life?

Jun 14, 2010
2,082
Robertson & Caine 2017 Leopard 40 CT
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, with some exterior surface weathering, 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.
 
Jun 14, 2010
2,082
Robertson & Caine 2017 Leopard 40 CT
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.
 
May 12, 2004
1,502
Hunter Cherubini 30 New Port Richey
Just replaced an above the waterline thru-hull with Marelon. I'm not sure if it says Marelon on it. Probably does. However. if you place a generic white plastic t-hull next to a Marelon one, the difference is readily noticeable. Much heavier construction and much less susceptible to sun deterioration.
 
Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
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.

Ummmm... Marelon is a plastic and that material, at least when under patent protection, was reportedly Dupont Zytel 70G13L a 13% glass-filled carbon blacked nylon 66 resin for injection molding. A guy I know in VT sent it to a lab for material make up testing. The added glass fibers simply add strength to the Nylon. If nylon is not a plastic...........???

I would personally love to see those attachments because I have seen UV failed "RC Marine" / Marelon above water thru/hulls.

Please forward them along to: compassmarineservices @ gmail dot com
 
Jun 14, 2010
2,082
Robertson & Caine 2017 Leopard 40 CT
Ummmm... Marelon is a plastic and that material, at least when under patent protection, was reportedly Dupont Zytel 70G13L a 13% glass-filled carbon blacked nylon 66 resin for injection molding. A guy I know in VT sent it to a lab for material make up testing. The added glass fibers simply add strength to the Nylon. If nylon is not a plastic...........???

I would personally love to see those attachments because I have seen UV failed "RC Marine" / Marelon above water thru/hulls.

Please forward them along to: compassmarineservices @ gmail dot com
Image attached. The UV damage is obvious. The question is whether it's just surface or structural. The Forespar rep confirmed it's theirs and said the damage is superficial and recommended I lightly sand and paint it with 2-part to make it look nicer.
 

Attachments

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Jun 11, 2004
1,621
Oday 31 Redondo Beach
Image attached. The UV damage is obvious. The question is whether it's just surface or structural. The Forespar rep confirmed it's theirs and said the damage is superficial and recommended I lightly sand and paint it with 2-part to make it look nicer.
I have thru hulls that look like that. Nothing I can see shows that they are Marelon. If they did I would feel more comfortable that they were more UV resistant than regular "plastic/nylon" fittings .
 
Jan 7, 2011
4,727
Oday 322 East Chicago, IN
Image attached. The UV damage is obvious. The question is whether it's just surface or structural. The Forespar rep confirmed it's theirs and said the damage is superficial and recommended I lightly sand and paint it with 2-part to make it look nicer.
I don’t see any markings on the thru hull. How do you know it is Forespar Marelon? I too have similar thru hulls on my 1988 O’Day 322. I am also considering replacing mine as they are 30 years old (unless a PO has changed them).

Greg
 
Jun 14, 2010
2,082
Robertson & Caine 2017 Leopard 40 CT
I don’t see any markings on the thru hull. How do you know it is Forespar Marelon? I too have similar thru hulls on my 1988 O’Day 322. I am also considering replacing mine as they are 30 years old (unless a PO has changed them).

Greg
I sent pictures to Forespar and they said it’s theirs. If you send your pictures, make sure you also show one looking inside. The rep wrote to me that the shot I sent showing the internal bore helped him confirm.