Marlon vs Bronze seacocks

My 30 year old Taiwanese Trawler, is in need of new seacocks. Several are frozen closed (not those for the engine cooling or generator).

The current bronze seacocks are bonded, but I was wondering what is the general consensus(as if that exists)? We had Marlon seacocks on our old sailboat, and they performed as we’ll after 29 years as when new, with the added advantage that bonding wasn’t necessary.

I’d like to replace the seacocks when I haul out early 2019 to paint the bottom.

I replaced a thru hull and seacock and replaced with bronze thru hull and marelon seacock, with a diverter valve above the marelon fitting for salt water wash down/toilet water supply through the same thru hull. My only concern is that it not be in a place where it would be subjected to contact that might break or damage the fitting. If it's in an out of the way and protected place (as mine is) it should be fine. If exposed I would be concerned about it. JMO

I'll use Marelon or Bronze above water. Below water, Bronze. I know that Marelon is NOT Nylon, but I've seen too many nylon through-hulls snap. The idea that a seacock could potentially snap with no means to stop the ingress of water is like a "Pucker Factor: 10" for me.

Try beating on one with a sledge...it will convince you how tough they are.

The bottom of the boat is only cheap glass and polyester.... Lesser materials than the Marelon.

I went thru all 16 sea cocks on my trawler. Most were frozen. In all I cleaned up and used all but one. The old style barrel ones will last longer than the boat.

https://www.practical-sailor.com/news/Seacock-Maintenance-Procedures-10447-1.html

Greatlaker221 said:

I went thru all 16 sea cocks on my trawler. Most were frozen. In all I cleaned up and used all but one. The old style barrel ones will last longer than the boat.

https://www.practical-sailor.com/news/Seacock-Maintenance-Procedures-10447-1.html

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16?

Marelon seacocks are well proven.

Do you really need to replace the seacocks? What type of seacocks are they?

If they are tapered cone type they can probably be refurbished easily.

If they are ball valve seacocks you can probably just break them free and maybe grease them.

If they are the old Groco rubber plug style, replace them.

My two cents on seacock material, I’m not a fan of plastic seacocks. I’ve seen several of the stems that connect the ball to the handle break. I’m also not impressed with Forespar’s customer service. To be fair my dislike of Forespar Customer Service goes back more than twenty years. They are probably better now or they would be out of business.

If you want plastic consider the ones distributed by Raritan. Sorry I can’t remember the name but they are made in New Zeland.

My choice for a new Seacock would be Groco’s SBV US made bronze ball valve. seacock.

"The idea that a seacock could potentially snap with no means to stop the ingress of water is like a "Pucker Factor: 10" for me."

A properly installed sea cock is BOLTED in place and does not require a thru hull to remain in place.

If you can jump on the sea cock it should be strong enough.

The tapered bronze are the best as the can be rebuilt multiple times with little effort, or expense.

A CG and ABYC compliant seacock will take 500 lbs at right angles for 10 minutes applied to its extreme dimension. That doesn't mean you can't break it.

I see many installations of Marelon ball valves on top of a thru hull which people call a "seacock". It is not, and Forespar does not call that a seacock or make any representations for that installation. It does not meet any standard. The Marelon seacocks that are compliant are the integrated ones with a three corner bolted down base. These meet the CG and ABYC standards. They have another compliant line often seen in production boats but these are sold OEM only, not at any chandlers, though you can occasionally find them.

Lots of plastic around the world yachts down this way have plastic thru hulls and plastic valves but I suspect it’s about weight saving (and unlike most of our boats the hulls are too thin to accept a bolt). My understanding is that the off shore blue water and cat 1 boats also have to have wooden tapered bung attached to every under water thru hull to be compliant along with a collar (if plastic is used) to transfer the operating load over a wider area of the hull and reduce the load on the through hull. I could post a pic if anyone’s interested.

While my experience with Marlon has been positive I used all Spartan bronze seacocks on my current boat. If you keep them greased with Spartan grease and pull them apart for a check, cleaning and grease every year or so they'll last a lifetime. Also I never leave the boat without closing all seacocks, not only might it prevent a calamity but it's good practice to exercise them frequently. I also keep appropriately sized wooden plugs attached somewhere handy by each seacock in the event of an unforeseen failure. Spartan bronze is right down the road apiece from me at Robinhood Marine and while expensive their stuff is top notch, actually made by local craftsmen.

Fish53 said:

Spartan bronze is right down the road apiece from me at Robinhood Marine and while expensive their stuff is top notch, actually made by local craftsmen.

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I've been there are seen their work. Absolutely top quality.

Ken

I agree with 'are you sure you need to replace them?'
I thought some of mine were frozen - somebody smarter than me told me to pump the brakes and make sure they can't be serviced before replacing them.

Turns out, if they're the tapered cone variety (likely from the age of your boat), they are almost surely still serviceable. Take them apart when the boat is hauled. Get some lapping compound from spartan marine, and some of their seacock grease. Do them a service and you'll be golden for years. It'll take a lot less time & money than getting new ones.

"Take them apart when the boat is hauled. Get some lapping compound from spartan marine,"

A turn or so in the lock nut will usually allow the tapered bronze sea cock to be tapped loose enough to turn while afloat.

So what if it leaks for a few seconds.

Retighten the lock nut , and try to not operate the unit as the growth that jammed it may scratch the tapered bore.

Fine grade "valve grinding" compound is at most auto parts store, in a small tin.

Old thread I came across when researching thru-hulls - feedback was much different than expected, so I'm rejuvenating.

I expected consensus "avoid Marelon, especially underwater." Why? Just seems that 80% of the Y-Valves I've seen on head systems have broken handles. Are these not Marelon? When I've tried to exercise a stiff valve, I can feel the shaft twist and flex - wincing slightly as I wait for the 'snap.' What am I missing? When needed, can you really womp on Marelon the way you can a proper flanged-base bronze seacock, especially a 20-year old fitting?

My experiences and those related by other experts is the larger ones are not as likely to break at the handle.


I just has a Bronze Groco 1.5 inch Full through less than 5 yrars old break off at the handle nub that turns the ball.


That was a first in 55 years of boating including 15 years of commercial marine work.


I would not worry about a Marelon seacock over 1 inch.... yet I did go with the flange/screw on ball valve concept. It came in handy when that ball valve handle broke off (which I hope was a freak).

mvweebles said:

Old thread I came across when researching thru-hulls - feedback was much different than expected, so I'm rejuvenating.

I expected consensus "avoid Marelon, especially underwater." Why? Just seems that 80% of the Y-Valves I've seen on head systems have broken handles. Are these not Marelon? When I've tried to exercise a stiff valve, I can feel the shaft twist and flex - wincing slightly as I wait for the 'snap.' What am I missing? When needed, can you really womp on Marelon the way you can a proper flanged-base bronze seacock, especially a 20-year old fitting?

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I think you've exposed the real issue here which is regular maintenance. Seacocks and valves are not install and forget parts of their systems, a properly installed/maintained bronze seacock will last longer than you and regardless of age never require getting a "womp". Marelon may have it's uses but for me I don't see it as replacement for bronze below the waterline.

Hull values need to be cycled a few times each year (maybe once a month or when you are in the ER doing other stuff) and serviced when having the bottom painted

Personally, I've used Marelon for anything above waterline that I've added or replaced. It's better than the cheap plastic stuff and easier to paint than metal (some of my discharge thru hulls are in the boot stripe, so they get painted). Underwater, I've stuck to bronze. Mostly because it works and I've got no reason to change. I can't see Marelon stuff having a longer lifespan, so no reason to use it.

The Forespar Marelon Y valves are floppier than the thru hulls. As was said above, the larger valves are more robust than the smaller ones. Both bronze and Marelon valves can break - but Marelon do not corrode, bronze does. On my custom built sailboat, cost was not considered and I did the opposite - Marelon below the waterline, bronze above. Why? Plastic does not last above the water (in the sun) while metal lasts forever in the sun but not in seawater.

Marelon is interesting stuff, and has a use. Sadly it has a failing, in that if you have a barnacle or any debris in the rotating ball, it can gall or seize the valve in a heart beat. I've had them on 2 of my yachts upon purchasing them , and changed them out in a year below the waterline. Because of galling / seizing.

I used all Forespar Marelon seacocks, the triangular flanged ones, 4 below the waterline, and one in a sink drain slightly above the waterline. The one in the sink drain froze open, I tried lubing it as much as was possible but with little improvement. I called Forespar for ideas, their attitude was ya, if you don't exercise them regularly they do that. They also said that there is no fix other than replacement. Their attitude was just buy another one.
The ones below the waterline still work, but now I'm just holding my breath waiting for one of those to freeze, knowing that would entail a haulout and a whole bunch more work to fix.. When I replaced my thruhulls I was all excited to use all Marelon,no corrosion and all that. After my experience I'm less enthused, after my conversations with Forespar even less.
Another thing which I think is a big drawback is that there is no way to lube the ball other than squirting something in the ends, seems like there should be a grease fitting in the side or something.
Here is a serious weirdity. On the Forespar Marelon triangular flange seacocks there is no specific orientation between the flange bolt pattern and the valve lever. I found this out by using one seacock as a pattern to drill the mounting holes for all my seacocks. Then when I went to mount them the handle directions were all over the place. I called Forespar on this also, they said it's correct that there is no specific orientation between triangular flange and lever. They have multiple molds and they're all different. That one I really don't understand.
If I was to do it again I don't think I'd use Forespar Marelon again. Seems like a good idea but I think the execution is lacking.
This got me thinking. Whatever happened to that Tru-Design line of glass filled composite thruhulls that Raritan picked up? It doesn't show up on their website anymore. Looked like nice stuff, Raritan is a great company. I think Tru-Design is out of NZ and originally it was all metric, I thought they then added imperial.

Sean9C
AS you can see in my previous post I like you am not a fan of Marelon. I was probably kind in my previous comments. I used to run boatyards and in the late 80's all the racing yachts started using them. The problem was one barnacle and if it got in the valve, they would break up and engrain in the ball of the valve and seize it up. I worked in Bermuda and no shortage of barnacles there.

Sadly these were new yachts. Over a period of time we changed them to bronze.

OldDan1943 said:

Hull values need to be cycled a few times each year (maybe once a month or when you are in the ER doing other stuff) and serviced when having the bottom painted

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I close all of mine every time I leave the boat unattended, sorta makes sense when you think about it. I also take mine apart at least once each year to clean and grease them, more if I haul out for any reason.

Fish53 said:

I close all of mine every time I leave the boat unattended, sorta makes sense when you think about it. I also take mine apart at least once each year to clean and grease them, more if I haul out for any reason.

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And some go to the extent of flushing all the systems with fresh water too.

On the yearly haul, I grease my Marelon seacocks with plastic safe grease (Superlube or the Forespar product sold for this specifically). This can be done from the bottom without removing the hose. Buy some flux brushes. Trim the bristles short, to about 3/8" to make is stiffer. You may need to tape the brush to a longer stick. Close all the valves and go around smearing a bit of grease on the balls. Now operate all the valves a few times, then leave them almost all the way - but not quite fully - open. Bend the very end of your brush over about 160 degrees, tight bend. Push the brush past the ball and smear some grease on the edge of the back side of the ball (exposed because you left it slightly closed). This lubricates the top of the ball. Again operate the valves a few times.

This takes about 15 minutes to do on 7 seacocks.

I thought, at some point, that Forespar also had a heavier than water liquid lube that you could pour in from the top. I don't see anything like that on their website now.

DDW said:

On the yearly haul, I grease my Marelon seacocks with plastic safe grease (Superlube or the Forespar product sold for this specifically). This can be done from the bottom without removing the hose. Buy some flux brushes. Trim the bristles short, to about 3/8" to make is stiffer. You may need to tape the brush to a longer stick. Close all the valves and go around smearing a bit of grease on the balls. Now operate all the valves a few times, then leave them almost all the way - but not quite fully - open. Bend the very end of your brush over about 160 degrees, tight bend. Push the brush past the ball and smear some grease on the edge of the back side of the ball (exposed because you left it slightly closed). This lubricates the top of the ball. Again operate the valves a few times.

This takes about 15 minutes to do on 7 seacocks.

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The problem for me is metal is tougher than plastic.

Intakes for the engine or toilet are seldom exercised enough to stay totally clear of growth.

A rotating bronze sea cock will close , even if it needs persuasion , the plastic ???

The exercising required is every 6 or 12 months. Shouldn't be all that burdensome. If you don't do that on your bronze seacocks, you are asking for trouble anyway.