General Info: Through Hull Warning!

[Watercolor]

Eric,

Beautiful boat.

My familiarity with Randex and their PPG (glass filled polypropylene) ball valves, however, I've never had the opportunity to take one apart and their website doesn't have any good specs on the internal design.

Have you ever seen any diagrams of the internals of the valve? I'm curious to know if the ball is a separate item and the handle shaft another.

Also do you know how much glass is in the material and what the material's tensile strength and flexural modulus are? There is only one US made glass filled polypropylene ball valve that actually meets the tensile strength and flexural modulus required by the ABYC. The ISO material standards are lower than the ABYC standard and that may be why it's not available in the US.

Polypropylene is not as strong as nylon initially, but, unlike nylon, only looses a marginal amount of strength in water.

Are your ball valves on stand pipes? If so how tall?

Fair winds

[chala]

Originally Posted by Watercolor

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.

On most of the units the OD is too big and the OD is too small.

Nice
Could you just clarify the above?

[Andrew Troup]

Originally Posted by David M

Seems insane to have what amounts to disposable brass thru-hulls. Why not just make them out of particle board?

+1

It's such a weird decision, I would have to question the judgement of the decision-makers at the company who made it, and their fitness to occupy their positions.

[s/v Jedi]

Originally Posted by Andrew Troup

+1

It's such a weird decision, I would have to question the judgement of the decision-makers at the company who made it, and their fitness to occupy their positions.

I see the dreadful pink fittings everywhere. I always point it out and except once, nobody cares or changes them. One had a water fountain that he could stop (charter captain lol) and one even sank. I even saw boats that couldn't close or open valves anymore and still refused to change them... just live with the valve always open or closed ??!!

I think it is the fear that freezes some into doing nothing, just ignoring the issue.

[Eric50]

Hi Watercolor,

I must admit that, like you, I do not have the specification and datas on Randex products and that my feedback is only based on experience of the valves in situation (which is kind of shame for a guy like me that is working since more than 30 years with specs and standards all the day....).

I opened once a valve and found that it is made of a body close by a threaded flange on 1 side, enclosing the ball with its associated lips, very simple and classic.

The handle is screwed on the ball.

Our valves are of different sizes (mostly 1/2 to 3/4 inch ND) and fitted on stand pipes from let's say (I never measured them to be honest) 2 to 6 inches high, some are above WL, some under due to the flat bottom of the hull.

Apart the spécifications, I must say that due to the previous satisfactory experience we had with these products, we'll certainly choose the same for replacement.

On the opposite of metallic valves users we never experienced any blocked valve or leaking ones so far, and looking around us, never heard about 1 user having trouble other than accidentaly walking on it and breaking the handle.

I'll try to look for the specs and more data if any available and will revert to you when possible.

[Eric50]

Hi guys,

Here is a link to the the catalog of one Randex supplier, with all the standards reference and détails :

http://www.plaisance-pratique.com/IM...gue_influx.pdf

Hope this will help.

[Watercolor]

Chala,

I’ll give it a try.

1. Tensile strength (TS) and flexural modulus (FM), nylon and H2O.

Marelon is simply Dupont Zytel nylon 70G13L-BK. It’s Dupont’s 6/6 nylon resin with carbon black for coloring and 13% glass fibers for added strength. The following Dupont Zytel website will provide you with the data. The two most important items are Tensile Strength and Flexural Modulus. The categories are:

DAM – dry as molded (taken shortly after molding)
50%RH - 50% Relative Humidity
100%RH – 100% Relative Humidity

http://www.valueplastics.com/technic...nformation.pdf

If you look at the numbers from the Forespar ISO/ABYC and comparison tables I cited in my first post, you’ll see all of them on the Dupont data table.

Nylon is a great product, it is tough, cheap, versatile, and easy to mold. But, nylon is hydroscopic, it absorbs moisture, as it takes in moisture (up to 10% of its weight) it degrades in both TS and FM. However, it gains in elongation. The elongation factor it what makes nylon so good as anchor rode for two reasons:

1. In water it elongates, stretches.
2. The water that’s absorbed in the nylon acts as a lubricant against internal and external friction. Even in the air nylon will stabilize at the humidity level of the air. However, in salt water it tends to stiffen. The reason I believe this is the case is that not all of the salt flush out and stays within the nylon resin. I’m not a plastics engineer so I’m happy to be corrected on this issue.

Depending on a variety of factors (material thickness, glass content, temperature, etc.) full saturation, like below the waterline on a boat, will occur within 6 months or less. However, the rate of saturation varies over time with the fastest rates occurring early on then slowing down over time. The fact is that by the time a nylon thru-hull or seacock is installed on your boat it will most likely be at the 50% value or greater. Also, remember that if you take a nylon fitting out of the water, it will seek equilibrium of the ambient humidity.

What about elongation? Elongation it helpful with regard to a static load test, but has little relevance with regard to impact and shear. And impact, according to all the experts is far more critical than static load.

2. “On most of the units the OD is too big and the OD is to small.”

Sorry, I meant to say the “ID is too small.” Almost all seacocks and ball valves follow the ASTM standards for thread sizes and other basic dimensions (ID and OD). So if you have a ¾” seacock you should be able to use any ¾” standard threaded thru-hull fitting. That thru-hull fitting should have an ID of about .750” and an OD of about 1.050.” The Forespar 93 series, in order to get around the problem Main Sail exposes in test

Load Testing A 3/4" Marelon Ball Valve & Thru-Hull Fitting - YouTube

on the over the counter 849 seacock, Forespar simply thickened the thru-hull walls by:
a. Increasing the OD
b. Increasing the ID

Compare the ID’s on the 93 series ¾” video

Forespar Marelon OEM / 93 Series Destructive Testing - YouTube

and the 849 video above.


So the Forespar ¾’ 93 series thru-hull instead of requiring a hull opening of 1.050” it requires an opening of 1.100”. This is not a major difference, however, to gain the thickness they need they decrease the ID from .750” to .62.”

On the ½” seacock/ thru-hull system the opposite is the case. The standard OD for ½’ is about .850,” Forespar ½” thru-hull is 1.100.” However, the ID standard is about .500” where the Forespar is .620.” The same thru-hull is used for both seacocks.

This follows through-out the 93 series. The 1” and 1 ¼” share the same thru-hull, and the 1 ½” and 2 “ share the same thru-hull. The ½”, 1” and 1 ½” 93 series seacocks have higher ID’s than standard, therefore better flow rates. The ¾”. 1 ¼” and 2” have significantly lower flow rates. And they all require larger hull hole sizes.

If your genset requires a ¾” seacock and you install a ¾” 93 you could overheat the engine.

I’ll add this to the mix.

a. A 16 lb alternator dropped from 4ft (impact) onto a 1 ½” Forespar fitting will destroy the fitting when a 500lb static load will not.
b. In the Main Sail video on the 93 Series, I would conclude that the fitting did not meet the ABYC/UL standard.
c. What is it you want for a thru-hull and seacock standard?

As I said before, there’s a lot more to this than I’ve mentioned here.

[Captain Bill]

Originally Posted by s/v Jedi

After 5 years? twice the strength?! You must have missed the YouTube videos of MainSail with his strength tests of thru-hulls and valves incl. Forespar Marelon.

Bronze stays good, it is brass that causes the problems described.

start here, find the rest there:

I have in fact seen the video. My valves are the OEM type, not a separate thru-hull and ball valve, so these tests to not directly apply. I have not experienced any swelling/sticking or other problems reported here.

[s/v Jedi]

Originally Posted by Captain Bill

I have in fact seen the video. My valves are the OEM type, not a separate thru-hull and ball valve, so these tests to not directly apply. I have not experienced any swelling/sticking or other problems reported here.

Yes, I have a 1.5" OEM93 valve for the main seacock and it is good. I think the 1/2" and 3/4" standard Marelon valves and seacocks give the most trouble. I also have a 1.5 one of those and it is okay, although the handle feels much softer than that of the OEM93 valve.

I much prefer the bronze Groco valves and seacocks, but I find the OEM93 okay. At 19 years old, they seep through when closed though and I'll have to replace the lot (I have a bunch in 2" fresh water plumbing). I might try the French ones because ai haveone of those at 3/4" with the red T-handle and it feels pretty good. I may even get ones with actuators to make transferring water easier because it is ballast for us. Very hard to get to...

p.s. there is a video for the OEM valves too...

[Watercolor]

To Jedi and Captain Bill - Simple as a point of information, the only thing keeping your Forespar valves from flooding your boats is a nylon nut. The nut that holds the handle to the ball.

Here's the result. It's happened on a whole series of Catalinas.


CRITICAL UPGRADES - DO THESE OR ELSE!!!
Catastrophic seacock failure! - Page 3 - Catalina 36 International Association Forums

[Watercolor]

Let's see if this works.

CRITICAL UPGRADES - DO THESE OR ELSE!!!
Is this a dangerous thru-hull fitting/valve combo, or is this normal? MARELON

[Captain Bill]

Originally Posted by Watercolor

Let's see if this works.

CRITICAL UPGRADES - DO THESE OR ELSE!!!
Is this a dangerous thru-hull fitting/valve combo, or is this normal? MARELON

I had a slightly different but related experience with my overboard dump valve for the holding tank. Since there is no lock mechanism on this valve I attempted to remove the handle to comply with USCG regulations. When I did this I got a small steady trickle of water, but nothing blew out. I simply replaced the handle, tightened the screw and all was well. Perhaps because I have a catamaran and the through hull is not that far under the surface there was not enough pressure to cause a major issue. The information you have provided will make me think more than twice before removing the handles from a couple of valves located in a deeper part of the boat. Thanks.

[chala]

Originally Posted by Caracal

To be fair, the pic only shows a single cockpit drain, and as it is shown in profile, how can you tell it's not crossed?

Because if it was crossed you would see the pipes crossing.

[Therapy]

Originally Posted by Saltyhog

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.

Ditto!

[Therapy]

Originally Posted by Watercolor

Tim,

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.

Thoughts??

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:
http://www.forespar.com/pdf/930136-m...-standards.pdf
http://www.forespar.com/pdf/930136-m...comparison.pdf

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:
CRITICAL UPGRADES - DO THESE OR ELSE!!!
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.

Very interesting.

Thank you.