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Old 13-03-2015, 23:14   #1
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Fiberglass thru hull fittings

First, I am really enjoying this CF site! When I consider this site and the links in it to other sites it is literally a yatching encyclopedia. I spend a lot of time reading it on my iPad.I've read quite a few comments on thru hull fittings commenting that brass and bronze through hull fittings enevitably corrode and need to be replaced. Couldn't beefed up fiberglass fittings be made to replace the metal fittings? Imagine an empty roll of wire with the core being the thru hull component (shorter) and the sides of the roll the inner and outer flanges epoxied to the hull.

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Old 14-03-2015, 00:01   #2
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Re: Fiberglass thru hull fittings

Brass bad, bronze good. Dont confuse the two. There was a bronze age not a brass age.

Good bronze thru hulls will last indefinitely. The stainless balls may degrade.

We've just finished our annual haulout and all our bronze groco thru hulls are in good condition. Next haulout we'll replace several balls which have scored surfaces.

There are a proprietary plastic composite reinforced thru hull typically labelled as Marelon which work well. These are not something you will find in your local hardware store. We have one Marellon thru hull which is in excellent condition.


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Old 14-03-2015, 00:07   #3
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Re: Fiberglass thru hull fittings

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Originally Posted by leftbrainstuff View Post
Brass bad, bronze good. Dont confuse the two.

There are plastic fittings typically lanelled as Marellon which work well.



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What am I missing here? (Many years of experience) I'm going to take a leap here... Seems a no brainer ... Why don't more people use plastic?
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Old 14-03-2015, 00:10   #4
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Re: Fiberglass thru hull fittings

Wouldn't plastic last longer ( no corrosion?), and much cheaper too?
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Old 14-03-2015, 00:18   #5
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Re: Fiberglass thru hull fittings

Quote:
Originally Posted by leftbrainstuff View Post
Brass bad, bronze good. Dont confuse the two. There was a bronze age not a brass age.

Good bronze thru hulls will last indefinitely. The stainless balls may degrade.

We've just finished our annual haulout and all our bronze groco thru hulls are in good condition. Next haulout we'll replace several balls which have scored surfaces.

There are a proprietary plastic composite reinforced thru hull typically labelled as Marelon which work well. These are not something you will find in your local hardware store. We have one Marellon thru hull which is in excellent condi
tion.


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Ok, I'm getting the picture. Good bronze fittings could last indefinitely and the stainless balls can be replaced. And good quality plastic fittings are probably cheaper than bronze, but still somewhat pricey. In terms of over all cost, durability and performance bronze wins out. Thanks for the information.
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Old 14-03-2015, 00:28   #6
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Re: Fiberglass thru hull fittings

I've had Marellon seacocks that lasted over 15 years but I've also heard many stories of them breaking. I've also had plastic though hulls break. Luckily they were above the waterline. I think they didn't have proper ultraviolet protection
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Old 14-03-2015, 02:33   #7
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Re: Fiberglass thru hull fittings

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Ok, I'm getting the picture. Good bronze fittings could last indefinitely and the stainless balls can be replaced. And good quality plastic fittings are probably cheaper than bronze, but still somewhat pricey. In terms of over all cost, durability and performance bronze wins out. Thanks for the information.
Nope, I spoke to quickly, seems the jury is still out on this. I just watched a YouTube video showing a Marellon thru hull fitting being tested for strength. According to the tester the Marellon failed the test. Yet another commenter suggested that the tester had used the wrong ball valve and should have used a ball valve that when threaded to the thru hull component lies parallel to the hull rather than the one in the test which was perpendicular to the hull.
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Old 14-03-2015, 03:34   #8
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Re: Fiberglass thru hull fittings

I replaced all of my trough hull fittings with Marine Products | TRUDESIGN
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Old 14-03-2015, 07:36   #9
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Re: Fiberglass thru hull fittings

I have bronze through-hulls and bronze cone style seacocks (all Spartan) which are beginning their 31st year of service. All are dismantled and lubricated annually. They are in excellent shape and I would reccommend them to anyone who would listen.
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Old 14-03-2015, 07:50   #10
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Re: Fiberglass thru hull fittings

If the fitting is exposed, mechanical strength is very important. When your fitting is flush, you can use plain grp (molded in) fitting. This is often done above the waterline. Below the waterline, you may want some of your fittings to have a valve and then it is much easier to fit metal thru-hulls as they will end with relevant attachment method (mostly threads) for the valve.

So to say grp thru hulls are OK when you know how and why you are building / using them.

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Old 14-03-2015, 09:16   #11
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Re: Fiberglass thru hull fittings

Bronze do NOT last indefinetely. Just replaced one that showed reddish when scratched. When I knocked it a bit, trying to get it off, it broke off clean just behind the flange.
I'm slowly replacing all valves and thru hull fittings (that don't pass the scratch test) with Trudesign. Beware though that the small valve sizes are massive compared to metal ones. They are approved by Lloyds for commercial vessels which is good enough for me! And no, I have no business affiliations with Trudesign.
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Old 14-03-2015, 09:42   #12
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Re: Fiberglass thru hull fittings

Trudesign Easy to install and, when epoxied in they become part of the hull. They are certified and pass the 500 lb test.
I've replaced 2 of my bronze thru hulls and will do the last one on the next haul out.
It just makes sense to use similar materials wherever possible.
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Old 14-03-2015, 10:58   #13
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Re: Fiberglass thru hull fittings

Mainsail is a very knowledgeable marine pro that has published articles and videos on this subject that may be helpful. Check out this video for example [URL=https://www.youtube.com/watch?feature=player_embedded&v=50-tM1JNZ_0[/URL]
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Old 14-03-2015, 11:15   #14
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Fiberglass thru hull fittings

I'm still out on the longevity of Marelon, ball valves, they need to be worked often.
Now, I open and close the thru hull valves each time I'm on the boat.
I know many do not use this practice.
The plastic ball valves, get stiff, and the handles move quite a bit before opening, if left a long time with out working.
Bronze seacocks, can be serviced in water, and adjusted to open/close easier, and without the danger of twisting the thru hull fitting and causing a leak.
That's been my experience, I've had both, on vessels I've had for 10yrs or longer.


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Old 14-03-2015, 15:07   #15
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Re: Fiberglass thru hull fittings

If your Bronze skin fittings are showing a reddish colour you have not had them wired to your boats bonding system, see, http://www.syc.com.au/wp-content/upl...e-Easy-SYC.pdf
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