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Old 26-04-2013, 00:31   #61
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Re: Through Hull Warning!

Keep it up Main Sail, if there are products out there we all assume will work but fail well short of practical use everyone needs to know, keep on testing

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Old 26-04-2013, 02:04   #62
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So if i replace with good quality bronze, how long should the thru hull and valves last???

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Old 26-04-2013, 03:16   #63
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Re: Through Hull Warning!

I think its fantastic that Maine Sail takes the time to actually go and test these things with some proper scientific method, unlike the superficial test reports we typically get in yachting magazines.
The fact that we can question the author directly is a privilege that should not be abused.

My only request Maine Sail is can you do some more please!
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Old 26-04-2013, 03:20   #64
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Re: Through Hull Warning!

The Cruiser Forum has gained greatly from subject matter experts and their contribution is greatly appreciated. Their credibility was established a long time ago.

New comers to the forum would be well served to establish their own credibility before attempting to act as a one person peer review panel. Rather than questioning motives, it may serve those newcomers to review our Be Nice rule.
If your attitude resembles the south end of a bull heading north, it's time to turn around.
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Old 26-04-2013, 05:18   #65
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Re: Through Hull Warning!

Originally Posted by dirkdig View Post
So if i replace with good quality bronze, how long should the thru hull and valves last???

You can get easy 10 years if properly greased and serviced... In my boat we replaced 6 years agoo all the fittings for the IBV series from Groco , today are shining as the first day , good thing about this valves is they have a side plug to fit a grease gun and lubricate the ball inside ... real nice stuff!!!!
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Old 26-04-2013, 06:44   #66
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Re: Through Hull Warning!

Caracal is being rude and argumentative with no cause and not adding anything. I am really suspicious of the motivation for his posts. I think MS's tests pretty much speak for themselves. Anyone who has had *any* experience with working on boats, thru-hulls, or even basic plumbing can see the obvious conclusions here.

Mainesail: Thanks for doing the tests and putting the videos together. We appreciate both the time they take and more importantly the information they yield.
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Old 26-04-2013, 09:04   #67
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Re: Through Hull Warning!

MaineSail - thumbs up for your good work.
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Old 26-04-2013, 10:31   #68
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Re: Through Hull Warning!

Okaaaayyyy.. who wants a drink from the "drinks aboard" thread?! Come on by Jedi and we'll have some fun time
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Old 26-04-2013, 10:42   #69
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Re: Through Hull Warning!

Originally Posted by Caracal View Post

I'm out of this thread.

sniff, sniff. and I was starting to enjoy watching you try to convince us that sealant would change the test. As for sharp edges- I am 100% certain that when holes are cut in hulls and backing blocks, the edges are not rounded off. For those of us who have installed or removed a throughhull this is obvious.

Nice work Maine Sail!

To comment on the post, my bronze throughhulls are original to my 1966 hull. Bronze. Unbonded. all in near perfect shape and I have inspected all carefully.
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Old 26-04-2013, 10:46   #70
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Re: Through Hull Warning!

I just think it stinks when people pay good money for what appears to be a nice product, then find out at a later date the manufacturer cheapened internal components.
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Old 26-04-2013, 11:42   #71
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Re: Through Hull Warning!!

Originally Posted by Maine Sail View Post
I have spent thousands of dollars out of my own pocket to get an idea of what is what, what meets a standard, what may not meet a standard. I have shared much of that with the general, boating public at my cost.

So no I don't only do this only if people send me product.. Forespar sent me two OEM/93 series valves and Groco sent me a flanged adapter. The first one, that I purchased, I had not pressed hard enough when hitting the record button on my camera and ruined it without capturing the video. Seeing as they cost $40.00 each I was not in a huge hurry to buy another and destroy it. Every other valve tested came out of my own pocket and was purchased at Hamilton Marine. Before doing any of this testing I consulted with the ABYC, Groco, and Chad G. of Forespar.

The only real question out of that particular video should be "does that assembly meet the minimum ABYC strength safety standards?".

If you feel that by not having a sealant there is me being "intellectually dishonest" about that assembly meeting or not meeting the minimum safety standard then this is an open ended circular argument..
Maine Sail:

I appreciate your testing, I think you are performing a great service.

The only flaws I see in your testing of the Marlon Valve is that it was used, previously damaged, and you installed it onto a Groco adapter with a tapered thread. It is my understanding that the Forespar valves all have straight threads. This would damage the valve before the test even began.

I would also be curious to know what load it took to break the Groco flanged base adapter. Too bad that video did not work.

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Old 26-04-2013, 12:29   #72
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Re: Through Hull Warning!


Your question was:

I'm looking for the pros and cons of Marelon polymer composite versus Groco Bronze hardware for replacement. Here's a few:

1) The breaking strength of Bronze is over double that of Marelon.
2) Marelon doesn't corrode.


First, Forespar calls Marelon a “polymer composite” and a 21st century material. The fact is Marelon is simply a Forespar trade name for Dupont Zytel 70G13L – BK 13% glass-filled carbon blacked 6/6 nylon (that’s not carbon fiber). The nylon 6/6 resin used in Marelon has been around for over 70 years. And the 70G13L – BK can be purchased by anyone. It’s an off the shelf material, nothing exotic.

It has a tensile strength (TS) of 17,000psi and a flexural modulus (FM) of 750,000psi. Both these values are measured “Dry as Molded” (DAM). The DAM measurement is important to remember, especially with nylon. Nylon is great in rode because in water it looses strength and elongates.

Second, you state, “The breaking strength of Bronze is over double that of Marelon.” I’m assuming that you’re getting your information from the Forespar’s Marelon Comparison table. This table has been on Forespar’s website for some 8 to 10 years, and in all that time it’s been in error, or so they claim.

Look at the following Forespar sites:

Besides the obvious mPa “error”, it should be psi, Forespar has provided you with two different values for Marelon. There’s a significant difference in values. Why? Dupont Zytel 70 series comes in several flavors, the 70G13L (13% glass) has a TS of 17,000psi and a FM of 750,000psi (DAM). The 70G33L (33% glass) has a TS of 27,000psi and a FM of 1,300,000psi. The 33% glass material makes a better comparison to bronze than the 13% glass don’t you think.

Third, “Marelon doesn't corrode.” This is an absolutely correct and totally useless statement by Forespar or anyone else. Metals corrode, plastics degrade, sadly we simply give Marelon a pass on corrosion and ignore degradation. Put your boat in the water with a properly installed bronze seacock and a Marelon seacock for 6 months what will happen, a 60% overall loss in TS and FM values.

The bronze seacock will still have a TS of 35,000psi and a FM of 15,000,000psi. The Marelon seacock and thru-hull will have a TS of 7,500psi and a TS of 250,000psi. This is a average 60% loss of strength. These figures are directly from the Dupont data tables. These Dupont/Marelon values are lower than good grade PVC.

Mainsail has done an excellent job testing these seacocks and putting some substance to this long running discussion. Even he will admit that his testing is less than perfect, however, they are a good representation of the facts. I wish Mainsail would explain about why he decided to do his tests, it’s all about impact.
The ABYC in H-27 and corresponding UL 1121 Seacocks and thru-hulls standards have a static load test but no test for impact. Yet impact is the issue of concern of all the marine experts, as Mainsail will attest.

I’ve done some impact testing on marine fittings and Forespar does not fair well at all. A 15 lb alternator or a 150 lb person hitting a thru-hull can do many more times the damage than a 500 lb hanging weight.

When it comes to the fact that some people have never had a problem with Marelon seacocks and thru-hulls is nice anecdotal information, but it’s not something you want to base your decision on. And Forespar seacocks have had a lot of problems that relate both to design and materials. Most people know about the problems with the Forespar 849 seacocks and the stem/handle breaking off. Forespar relegates that to a maintenance problem, that might be part of the issue, the real issue, I believe is a material and design problem. As for the 93 series they have two basic issues.

1. They thru-hulls are non-standard in ID and OD. On most of the units the OD is too big and the OD is too small.
2. The redesign creates a serious hazard. I’ll just say read the following:
Catastrophic seacock failure! - Page 3 - Catalina 36 International Association Forums

There’s a lot more to be said. But I’ll stop here for now.
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Old 26-04-2013, 12:50   #73
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Re: Through Hull Warning!

Originally Posted by s/v Jedi View Post
He's just a troll, sent from some competing forum or may be paid by Dupont or whoever makes Marelon
Obviously some do like myth busters and some do not.
Troll 1. A supernatural creature of Scandinavian folklore. No Siegfreid so what the fuss.
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Old 26-04-2013, 14:08   #74
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Re: Through Hull Warning!

Originally Posted by Watercolor View Post

There’s a lot more to be said. But I’ll stop here for now.
Thanks for chiming in on this. I knew you would so didn't feel it necessary to go down that path. As always excellent information!
Marine How To Articles
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Old 26-04-2013, 14:55   #75
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Re: Through Hull Warning!

Hi everybody,

FYI, we have "plastic" through hull and valves aboard since 1990 and they are still as new nowadays, the brand is "Randex" and are very well known and reputed in France / Europe to be very reliable.

The weak point is the lever of the valve if you walk on it, but it already happend with my athletic net weight of 220 pounds and did not is easy to have spare parts so I would strongly recommand this brand based on our (and many others locally) experience.

Fair winds
Eric - S/Y Azawakh
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