Broken seacock valve handle

[Bill Seal]

Originally Posted by Cheechako

I
The problem with putting a valve onto a fitting is the leverage and force when you turn a reluctant valve vs how thin the mushroom fitting is at the thread root: You can see how thin the metal is here. Once it corrodes a bit, how much is left?

I can't understand why they (even Groco) don't use schedule 80 or 120 for the thru hull fittings,

[Statistical]

Originally Posted by Bill Seal

I can't understand why they (even Groco) don't use schedule 80 or 120 for the thru hull fittings,

Because the thru hull itself is not suppose to be load bearing. The seacock (valve) flange should be anchored to the hull. Personally not a big fan of extra holes so prefer the backing plate route.



The large flange, bolts, and 4 to 8" backing plate epoxied to the hull is what provides strength. If that breaks well the truhull is breaking as well even in thicker walled.

[Dieseldude]

Originally Posted by Statistical

Because the thru hull itself is not suppose to be load bearing. The seacock (valve) flange should be anchored to the hull. Personally not a big fan of extra holes so prefer the backing plate route.



The large flange, bolts, and 4 to 8" backing plate epoxied to the hull is what provides strength. If that breaks well the truhull is breaking as well even in thicker walled.

Good drawing. But can you provide some more details? Is the Groco valve a plastic compound ? What materials are the bolts and through hull fitting?

[Bycrick]

The Groco seacocks are bronze with a SS ball and shaft. The Groco through hulls are bronze. I used G10 sheet for the spacer block and paid dearly for bronze bolts.

I prefer to use the Groco adapter plate and thread on the valve. That way, if I live long enough to have to replace the valve, it’s a lot easier.

[Statistical]

Originally Posted by Dieseldude

Good drawing. But can you provide some more details? Is the Groco valve a plastic compound ? What materials are the bolts and through hull fitting?

All bronze (the ball in the valve is stainless steel). The rest is bronze. Bronze valve body, bronze flange, bronze thru-hull, and bronze bolts.

The backing board can vary. Not sure what Groco "official" backing boards use but I just used my own fiberglass board cut to shape and epoxied to the hull.

I believe for plastic valves, TruDesign has something similar with a collar that goes around the valve body. I have no experience with it but I assume it works similarly. The goal being that the thru-hull itself is not load bearing.

[stormalong]

Originally Posted by Dieseldude

Plastic has its immunity to corrosion in its favor. But it is just hard to trust it to this life critical application. Anyone know if there exits a plastic valve approved for below water line application? I mean by US Coast Guard or classification society? Plastic threads are easily damaged too.

Marelon exceeds ABYC and ISO standards.

https://www.forespar.com/marelon-abyc-iso.shtml

Plastic threads are not easily damaged unless you abuse them. Tell me why you think they they are.

If you have a reinforced plastic boat, why not reinforced plastic plumbing?

If you have an aluminum boat you have galvanic issues with bronze that requires extra preparation for installation and frequent inspection.

I am constantly amazed that boat owners dismiss plastic valves when they are superior to any metal alloy.

Disclaimer: I have no affiliation with Forespar or Trudesign. I am the 31 year owner of a 36 year old boat with Forespar seacocks, many of them original and working fine.

[Dieseldude]

Originally Posted by stormalong

Marelon exceeds ABYC and ISO standards.

https://www.forespar.com/marelon-abyc-iso.shtml

Plastic threads are not easily damaged unless you abuse them. Tell me why you think they they are.

If you have a reinforced plastic boat, why not reinforced plastic plumbing?

If you have an aluminum boat you have galvanic issues with bronze that requires extra preparation for installation and frequent inspection.

I am constantly amazed that boat owners dismiss plastic valves when they are superior to any metal alloy.

Disclaimer: I have no affiliation with Forespar or Trudesign. I am the 31 year owner of a 36 year old boat with Forespar seacocks, many of them original and working fine.

I have experienced pcv and nylon thread damage. Those materials are just not as resilient as metals. Perhaps there are tougher plastics that I have no experience with though, so maybe I've been too presumptuous about them all. A fiberglass hull is no comparison to a pipe fitting. They are different materials and at different scales of size. Forces on a hull are generally spread over large areas. Forces on pipe work are concentrated. The discussion had been about fiberglass hulls. Of course aluminum boats are a whole different kettle of fish for galvanic corrosion with many challenges. I had a boat builder tell me of how the BC fishing industry went into aluminum boats in great number some years ago. Many of those hulls have been going spongy. Aluminum alloys of those times has not proven well. If there is anything better recently, only time will tell.

[boatpoker]

Originally Posted by BilgeRat

Yeah, just replace it with a bronze seacock. A USCG inspection might hit you up with a fine. What you have is not to code.

And if you have a steel hull put a G10 or phenolic spacer between the hull and valve. That will reduce the electrolysis significantly. That's why your handle rusted off.

1. Please specify which code.

2. "electrolysis" does not occur on boats, what you are looking at is dezincification of a brass ball valve caused by galvanism

[stormalong]

Originally Posted by Dieseldude

I have experienced pcv and nylon thread damage. Those materials are just not as resilient as metals. Perhaps there are tougher plastics that I have no experience with though, so maybe I've been too presumptuous about them all. A fiberglass hull is no comparison to a pipe fitting. They are different materials and at different scales of size. Forces on a hull are generally spread over large areas. Forces on pipe work are concentrated. The discussion had been about fiberglass hulls. Of course aluminum boats are a whole different kettle of fish for galvanic corrosion with many challenges. I had a boat builder tell me of how the BC fishing industry went into aluminum boats in great number some years ago. Many of those hulls have been going spongy. Aluminum alloys of those times has not proven well. If there is anything better recently, only time will tell.

Was that reinforced nylon like marelon. We are not talking about PVC. We are not talking about plain nylon fittings. We are also not talking about household plumbing fittings.

Forces on pipework? At three feet of depth water pressure is 1.5 psi. A fiberglass hull pounding in a seaway easily exceeds that. So does hitting floating objects.

Over the 31 years that I have owned my boat I have replaced about half of my marelon ball valves. Not because they were defective but because they were not properly flanged seacocks. I have also removed and sealed up a couple of thru hulls. As an experiment I took one of those thru hulls and placed it on concrete. I hammered at it for a while and could not crack it. It was at least 20 years old at the time.

Dieseldude: You asked if marelon met standards. I showed you that they did. Even good bronze deteriorates over time. I have seen no evidence that marelon deteriorates. Yes, there were design flaws with early marelon valves, the result being handles breaking off. That issue was fixed decades ago. Show me recent evidence of a failure. No material lasts forever, including bronze.

[redneckrob]

Originally Posted by boatpoker

1. Please specify which code.

2. "electrolysis" does not occur on boats, what you are looking at is dezincification of a brass ball valve caused by galvanism

Careful, @Manateeman will be along soon to denigrating you for daring to question a post that was entirely incorrect. And questioning your service while they're at it.

[sck5]

I had marelon seacocks on two different boats. They did not fail disastrously but the stems of the handles snapped on two that were more than 25 years old. No other signs of deterioration but the stems were the only part that wasnt Marelon. Not sure exactly what they were except they didnt last as long as the marelon did

PS - User error was probably a factor because i didnt "exercise" the handles nearly often enough. It really is a good idea to do what they say and move them back and forth every month or so.(at least)

[Matt Johnson]

Originally Posted by sck5

I had marelon seacocks on two different boats. They did not fail disastrously but the stems of the handles snapped on two that were more than 25 years old. No other signs of deterioration but the stems were the only part that wasnt Marelon. Not sure exactly what they were except they didnt last as long as the marelon did

PS - User error was probably a factor because i didnt "exercise" the handles nearly often enough. It really is a good idea to do what they say and move them back and forth every month or so.(at least)

That would most likely be the 84 series Forespar... It's a flawed design and shouldn't be counted on. Their 93 series is totally different and a great valve.

[boatpoker]

Originally Posted by Matt Johnson

That would most likely be the 84 series Forespar... It's a flawed design and shouldn't be counted on. Their 93 series is totally different and a great valve.

I'm a fan of the larger Marelon seacocks and we excercise all seacocks during surveys but ... testing the smaller 1/2" - 3/4" Marelon units give us the creeeps because they bend so much. If they do not open/close easily we don't push them too hard and we do make note of this in our survey reports.

[Matt Johnson]

Originally Posted by boatpoker

I'm a fan of the larger Marelon seacocks and we excercise all seacocks during surveys but ... testing the smaller 1/2" - 3/4" Marelon units give us the creeeps because they bend so much. If they do not open/close easily we don't push them too hard and we do make note of this in our survey reports.

Are these the bolt together boxy type or the normal valve shaped model?

[boatpoker]

Originally Posted by Matt Johnson

Are these the bolt together boxy type or the normal valve shaped model?

The normal valve shaped units are the ones we're not fond of.