Marelon Ball Valve Seacocks

[Ward H]

The marelon ball valve seacocks on my 93 C30 are very stiff to operate so I plan to change them out this winter.
They appear to be Forespar Marelon MF850 Threaded Ball Valve. https://www.defender.com/product.jsp?path=-1&id=4210227

Catalina Direct appears to be selling the Forespar Marelon Series 93 ball valves for the C30.
https://www.defender.com/product3.jsp?path=-1|51|2234261|2234264&id=199316

Are the series 93 a better seacock? They are about $35 more than the MF850.

Is it best to change out the thru hull while changing the seacocks?

 

[CarlN]

Yes, the Series 93 (also sometimes called OEM) are an entirely different design and a great seacock. The ones you currently have get stiff and eventually the handle breaks off. I don't understand why Forespar keeps marketing them as it does their reputation no favors. I've been using the Series 93 for over 10 years with no problems or complaints. I exercise the ones that don't get closed regularly twice a year. They haven't needed any lubrication. If you currently have some 3/4" seacocks, consider upsizing those to 1" and using an adapter to connect the 3/4" hose. The water flow through these seacocks is a little less than the same diameter bronze because the tailpipe plastic is so thick. Here's
MainSail testing the Series 93 to the ABYC standard for side loading.

 

[LeslieTroyer]

Ward before you change them out Forespar makes two types of lube specifically for those valves, might save a bunch of work and $$$.

 

[Maine Sail]

The marelon ball valve seacocks on my 93 C30 are very stiff to operate so I plan to change them out this winter.
They appear to be Forespar Marelon MF850 Threaded Ball Valve. https://www.defender.com/product.jsp?path=-1&id=4210227

This is just a ball valve and does not meet the minimum safety standards when used as one by threading it onto a thru-hull fitting.. Here is a 3/4" Marelon ball valve.... Compare this to the OEM series video above and you'll see why I won't use them from below water applications..

Catalina Direct appears to be selling the Forespar Marelon Series 93 ball valves for the C30.
https://www.defender.com/product3.jsp?path=-1|51|2234261|2234264&id=199316

Good to see they have chosen to sell the right product for use as a seacock..

Are the series 93 a better seacock? They are about $35 more than the MF850.

They are a much better seacock and they actually meet and exceed the minimum ABYC standards. The OEM/93 Series is the only series in their line up that does. It is also the only seacock product from Forespar that I will install.

Is it best to change out the thru hull while changing the seacocks?

Yes absolutely and absolutely mandatory when using the OEM series as the thru-hull is not the same as the standard ones, much, much thicker. Due to this however you'll need to go up a size so the ID remains optimal for the job...

 

[JRT]

Impressive results, I would do the upgrade grade sure.

 

[Benny17441]

All my seacocks are in small compartments; it would be impossible to accidentally impose a lateral load in excess of 50-100 lbs on them valves. I don't have valves out in the open nor hoses where a load could shift into them so I fail to see how these load requirements would apply to my valve selections. If a hose is pulled with a heavy load I probably would have other more serious structural problems beside a broken valve. There might be other applications were the rated side loads are critical but not on all boats; always look through the numbers. Not nocking the test, it was good but questioning the need for replacing an existing fixtured based on test results that may not apply to your particular needs. Like Leslie suggest try lubricants and periodically exercise the valves. If that does not work then replace the thru-hull and the valve and why not go for the top of the line for an extra $35. Good luck.

 

[Ward H]

Ward before you change them out Forespar makes two types of lube specifically for those valves, might save a bunch of work and $$$.

Les,
Thanks for the suggestion.
I followed Forespars instructions for lubing one of the valves, while the boat was in the water. It made the valve worse. I figure it already had too much crud in it.

The one valve that moves somewhat easily is the engine water intake but it's clear that valve is not mounted as securely as it should/can be. On top of the valve is the salt water strainer, then the hose barb. That whole contraption feels like it could snap off very easily. I open that valve very carefully.

So I would like to go ahead and replace the three seacocks and thru hulls I have and end up with a much secure valve.

Especially after seeing those videos!

 

[FastOlson]

We changed out all of our original RC Marine (later purchased by Forespar) valves to the then-new "OEM" Forespar assemblies, and the later are indeed proper seacocks. That was around 15 years ago.
No material is perfect, but it's nice not to have worry about electrolysis.

 

[jibes138]

If you are replacing your ball valves and thru hulls then just get real seacocks and do the job right. Change out the backing plates with G10 and the new installation will be rock solid. You will be happy you did this.

 

[jibes138]

By the way getting an old ball valve off the thru Hull can be a time consuming PITA. Get an oscillating tool and cut it off by cutting thru the thru Hull threads. It will cut like butter in about a minute. Then cut the thru Hull nut in half with the oscillating tool. The thru Hull should then come right out with a light tap with a mallet or a twist with some channel locks. The oscillating tool makes quick work removing the old backing plate and then sanding the surface to prepare it for the new backing plate.

 

[Ward H]

I'm ready to start on replacing my thru hulls. I have three to do.
After seeing the videos of the 93 series and the MF850 Marelon thru hulls and valves I had decided to go with the Series 93 thru hulls and valves.
Enter the dreaded project creep.
The original 3/4" thru hulls are flush fit. I had decided to go with the mushroom head thru hull and series 93 seacock. When changing over to the series 93 you need to go up to 1" to keep the 3/4" id of the thru hull.
Looking at the specs of both the 3/4" flush fit and 1" mushroom head it appeared that the mushroom head wouldn't quite cover the chamfer of the flush fit MF850.
I was a bit confused about this so I called Forespar.
According to the tech I spoke with, the flush fit thru hull of the MF850 cannot be replaced by the 1" Series 93 flush fit as the chamfer is different. The mushroom head also would not work due to the MF850 chamfer.
They said I had to fill the old holes and drill new ones for the MF850.

So, drilling the new holes and installing the Series 93 sounds pretty easy but two of the three existing thru hulls are in areas with little room to move them.
The filling of the three old holes is much more work than I planned for this spring.

The three existing thru hulls are in small compartments where they are well protected, much like in @Benny17441 reports in Post #6 above. I'm now considering replacing them with the same MF850 valves and thru hulls as existing. This greatly simplifies things as I can reuse the holes as they are.
I close my thru hull valves every time I leave the boat for the night so they get well exercised.


I know I won't be improving the integrity of or bring the thru hulls up to ABYC standards but I will have easy to operate valves. They will be much safer than the very hard to operate existing valves which made me cringe every time I opened/closed them.
I also have wooden plugs at each thru hull location.

Thoughts?

PS: all thru hulls currently have fiberglass backing plates about 1/2".

 

[Gunni]

I went looking for the Marelon 93 seacock in the Forespar catalog, can’t find it, looks like they gave it a new name. Then I went looking for dimensional specs. Poorly documented. Limited selection of sizes. Cut bait and size up to GROCO bronze seacocks. Maybe go up a size to be able to reuse your hull perforation.

 

[AaronD]

Cut bait and size up to GROCO bronze seacocks.

@Maine Sail gives great instructions at https://marinehowto.com/category/plumbing/

 

[LeslieTroyer]

Installing Groco involves a whole new set of issues- running and connecting up a bonding system for the newly installed conductive thru hulls. My Marelon valves are in great shape at 36 years old. Side loading is difficult if not impossible for all but one. Take care of them and they will last the life of the boat.

Les

 

[Gunni]

Installing Groco involves a whole new set of issues- running and connecting up a bonding system for the newly installed conductive thru hulls.

Les

That sounds like a sales pitch from the Marelon sales team! Thousands of sailboaters can tell you - no need to bond quality bronze through hulls, in fact you may create a corrosion problem where none existed.

 

[Maine Sail]

You have discovered why they are called the OEM series.........

 

[Pirate Dave]

Impressive results. I question why ABYS standards are calling for a side load of 500 pounds for 30 seconds. Not sure how or why they would load up that way

 

[FastOlson]

Ward, you do not have to use the flush mounting scheme. The yard mounted ours thru backing plates with thickened epoxy. The outside flange on the thru hull was proud, with oozed out epoxy hardened around it.
All of that was then ground off smooth. The FRP (composite) thru hull then became *one with the FRP hull of the boat.
This series of seacock is rebuildable from the inside, BTW.

*Zen moment in boating



Mounted this way the 93 series would likely withstand an attack by a demented sledge hammer.

One is pictured in this blog entry.
http://www.ericsonyachts.org/infoexchange/entry.php?140-Coupler-Shaft-Seal-and-Antifreeze

BTW, that engine intake with hose attachment is a wonderful invention.

 

[Ward H]

Update
I found a solution that will allow me to stay with the original thru hull holes, unmodified, while using the improved Series 93 valves.

I spoke with tech support at Forespar. They have a Series 93 in-line threaded valve that will fit on the original style flush head thru hulls, just like the original MF 850 ball valve fit on the thru hull. (The MF 850 is the valve that failed in Maine Sail's video above and has the weak handle that can easily break.)
The tech explained how the Series 93 valves have a stronger body and much stronger handle to ball connection than the MF 850.

I agree with @FastOlson that the engine intake valve with hose attachment is sweet. That intake seacock is still under consideration.

Edit: I did spin off off one of the MF850 valves that was very hard to operate. I flushed clean water thru it, then lubed it with Super Lube grease. Didn't help a bit.