Bronze vs Marelon Thru-hulls

[kloudie1]

You are correct Hermit, but .. I find it much easier to put new zincs on the prop shaft instead of on the strut.. so if ya gonna protect the strut with the prop shaft zincs, probably best to bond the strut to the engine/keel.. Or like you said you can put more zinc on the strut and leave it unbonded.

 

[redhead78]

Hey all, I replaced mine last year, I had a home depot from PO. I did a lot of checking around and went with the Groco, tri-flange base.. I like it because you can replace the valve seperatly..... Red

 

[FastOlson]

Whoa.....

One thing about Marelon: it's hard to tell if it's marelon or cheap plastic - EVERYONE can tell bronze when they look at it.

But then, don't go by ANYTHING I say: the way I install thru-hulls is to epoxy them in - if they need to be replaced I can cut them out and re-glass. I can't STAND bedded thru-hulls that move when you try to tighten the clamps...

druid

Sorry to seem disagreeable, but I have to take issue....
'Marelon" is a registered product and made only by Forespar. It is a reinforced material and is as far from cheap plastic as you can get without a passport. I have never (yet) seen a knockoff off of one of their products.

Epoxy, Yup. Our "OEM Style" Forespar thruhulls were bedded with epoxy and then ground flush on the outside. What with big backing plates on the inside, they are bullet proof.

 

[Maine Sail]

Both Marelon and UL Marine rated bronze seacocks are fine. Marelon certainly has the edge in corrosion resistance but the failure rate of them is quite high in my experience. I have personally had four of them with handles that broke off and I know other forum members who have had similar failures. Marelon has made some changes but I still know of some recent ones that have also experienced the seized ball / broken handle failure.

For me I much prefer a through bolted Groco flanged adapter then a marine UL rated bronze valve. This allows valve replacement at any time even with the baot in the water and the thru-hull, backing plate and flanged adapter stay sealed to the hull. A little pipe dope on the threads and a new valve threaded on is all it takes for a seacock replacement. Also with a through bolted flange you will have ZERO worries about it twisting.

Proper marine bronze, 85-5-5-5, can last nearly indefinitely. This spring I cleaned, lapped and re-built two Spartan Bronze tapered cone seacocks. They were 31 years old and in 100% perfect condition after some cleaning, lapping and greasing. They showed ZERO signs of dezincification and corrosion except for some verdegris ( the harmless green patina). I suspect they could easily last another 30+ years...

This was posted recently on one of the Catalina forums regarding a Marelon valve failure. Pretty scary stuff..

Last night we were closing up the boat after a week long cruise, and I tried to shut off the galley seacock. We are always diligent about closing the seacocks when we leave the boat. But no good deed goes unpunished.

I turned the handle on the Forespar Marelon seacock and it broke off in my hand. Worse, a solid stream of water began to gush from the hole where the handle fit.

This is not what I would call a "fail safe" design. I imediately pulled out the under sink drawer and put the handle back into the hole. This slowed down the water flow to a trickle, but I could not use the handle to turn the ball to the closed position.

I also couldn't sit there all night like holding the handle, so I asked my wife to get the doomsday box, complete with wooden plugs, a variety of tapes, and my new best friend, silicone Rescue Tape. It is expensive but worth every penny.

Anyway, my wife cut off one foot strips and I wrapped them around the valve, and holding the valve handle in place. The Rescue Tape stuck to itself, even under water. Absolutely amazing stuff. In a few minutes, I had the water flow slowed to a trickle, and I could think about what to do next.

I wish we had caught the whole thing on video. The unedited version of events is much more exciting...


Dave

 

[druid]

Sorry to seem disagreeable, but I have to take issue....
'Marelon" is a registered product and made only by Forespar. It is a reinforced material and is as far from cheap plastic as you can get without a passport. I have never (yet) seen a knockoff off of one of there products.

Sorry - I did NOT mean to imply they WERE cheap plastic - in fact from what I've heard they are the best. The problem is, to the untrained eye they LOOK like plastic, so it's hard to ensure that they are indeed Marelon and NOT cheap plastic.

Not a big point, but about the only thing I can see that's a disadvantage for Marelon.

druid

 

[Hermit Scott]

You are correct Hermit, but .. I find it much easier to put new zincs on the prop shaft instead of on the strut.. so if ya gonna protect the strut with the prop shaft zincs, probably best to bond the strut to the engine/keel.. Or like you said you can put more zinc on the strut and leave it unbonded.

Your way seems best to me also. The easier maintenance is to do, the more likely it will get done in a timely way.

When I make decisions for the boat, I usually try to think of what would be the best thing to do if I neglect maintenance or don't get to the boat for an extended period. Because I get lazy and just may do that.

So, if I don't take care of my seacocks and they seize up from neglect or non-use, I can spend $20 unscrew the old one and screw a new one on.

 

[John Nantz]

Ron: re "hot boat" checking

Hi Ron,

Just got back and checked in and saw your post. Unfortunately, I'm not part of the group that is doing the "hot boat" checking. I was involved in the case where the one hot boat caused a number of problems but only because it was in a slip near our boat.

"We have a group who has come up with equipment and a system for checking hot boats."

John ... can you elaborate on your equipment and system for hot boats? Maybe in a new post to keep from hijacking this one??
THANKS!

The last I heard was that the marina (our yacht club) was going to write an Operating Manual, or what ever they will call it, and I'm certain this will be one of the elements.

The problem is, with any facility, there are people who know the why and where for, but as they leave, or as their memory fades, the local knowledge gets lost. By putting information about the facility and it's operation into a manual it is hoped valuable information can be captured.

Our problem is that we haven't been involved in boating enough in the past couple years and I've been out of the loop on a lot of stuff that I used to be up on. Next season will be different! (At least it'd better be!)

 

[John Nantz]

Speaking of failed valves

One of the reasons I prefer Marelon is due to an experience I had.

One of my co-workers in an engineering office, a Mehanical Engineer, and past President of the Northwest PHRF, had a C&C 36 that I used to crew on. One of the boats to beat in the West Sound. His foredeck crew (one guy) wound up marrying his daughter and they borrowed his boat for their honeymoon cruise in the San Juans.

Well, as luck would have it, on one of their legs it was noticed that there was water on the cabin sole - and it was getting deeper. Tracing down where the water was coming from they found a through hull had broken off. Fortunately there were plugs tied to each valve and they were able to stop the flow.

When he got the call in the office he told me about the emergency and asked me if I could fly him up to Friday Harbor where the boat was. I volunteered and we took the afternoon off (summer), swung by his house to pick up tools and parts, drove to the airport, and and in less than an hour we were in Friday Harbor (probably 4 to 6 hours via car and two ferries, one way). A short walk from the airport to the marina and we started work on the boat.

The problem valve was in a hard-to-get-at area in the engine compartment. Brave sole that he was, we removed the plug and he screwed on the new valve, taking on only a couple more gallons.

Afterwards we all had a nice dinner and we flew back, arriving about dusk, and the honeymooners got to enjoy the rest of their trip.

The valve failure was due to corrosion which was visible on the INSIDE, and NOT on the outside. Was it properly maintained? I don't know, but probably not. Do we all maintain everything on the boat according to the manufacturers requirements, or to best management practices? Probably most of us don't.

Can I afford to pay someone to do all my maintenance? No. Can I do all the maintenance myself? Uh... that depends. Life has trade-offs.

About 23 years on my five original Marlons now with absolutely minimal maintenance - an ocasional lube job and that's about it. It's as close to a no-brainer as one can get and believe me, I've got a lot other stuff to deal with.

Life is also about choices.

 

[Chuckbear]

With years of experience with both Marlon and Bronze valves, we will never have Marlon valves on board. In 50 years of boating I have never seen a bronze valve fail unless electrolysis was involved. Our current boat still has a couple of 30 year old bronze valves working just fine and trying to remove one is a major PITA. Marlon valves that are not exercised on almost a weekly basis will fail at some point. The valve will stick either open or closed and the handle will break just inside the valve where you can't get to it and it can't be fixed. This means you will constantly need to crawl all over the boat working these thru-hull valves. I have replaced hundreds of Marlon valves because of this. I have never met a bronze valve that was stuck, that could not be made to work again without removing the boat from the water or removing the valve. IMO, Plastic valves by any name have no place on a boat. Chuck

 

[John Nantz]

Thanks for the warning Chuckbear....

.... after all these years, and since the Marelon valves I have are probably close to the very first ones made - 23 years old, do you think I need to start exercising them weekly now?

And to make matters worse, the boat pretty much sits in salt water unused for about six months out of the year so I'm sure they're living on borrowed time, and, they have never been exercised during that time.

 

[Maine Sail]

.... after all these years, and since the Marelon valves I have are probably close to the very first ones made - 23 years old, do you think I need to start exercising them weekly now?

And to make matters worse, the boat pretty much sits in salt water unused for about six months out of the year so I'm sure they're living on borrowed time, and, they have never been exercised during that time.

John,

Your experience has been quite good. Like Chuck I have seen lots of failed Marelon valves, four on my own boats. Here's one of mine that broke and I did both exercise them and lube them..

 

[Chuckbear]

MS, Yep thats pretty much what I have seen more times than I can remember. Including on our new to us boat. Chuck

 

[Maine Sail]

MS, Yep thats pretty much what I have seen more times than I can remember. Including on our new to us boat. Chuck

Chuck,

I used to actually rep a couple of valve lines and have been to plants where they make them. One inherent problem with plastic valves, and not just Marelon/DuPont Zytel/Xytel, but PVC also, is the difficulty in making a perfectly round ball. Many industrial Zytel valves have adjustable seats or use special o-rings in combination with the valve seats. Add to that the issue that many plastics can swell slightly after they come out of the mold and now add some sea life growth and you can see a decent rate of failure.

I know Forespar has worked very, very hard to reduce these problems and I do believe the new valves are significantly less prone to failure, not heard of many of the "OEM" series failures, but I have just seen to many failures and worked selling valves for long enough to not go back to Marelon/Zytel at this point. The material they are made of, DuPont Zytel, is great stuff, and strong, but the balls need to rotate and some times they just don't do this reliably.

They DO have some solid benefits but I am still not yet personally comfortable with the high rate of failures I've seen, have had and read about.

I am NOT, not recommending them, just advising the use of caution. If one starts to get hard to turn you will want to.....REPLACE IT ASAP....