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Opinions on Replacing Thru Hulls

markvone

Sustaining Member
All the thru hulls on my 1981 E36RH are original flush Forespar Marelon.

When is it time to replace these 30 year thru-hulls?

Thanks!
Mark

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mherrcat

Contributing Partner
I have the same fittings except they are not flush. Are the ball valves just screwed on to the actual through hull fitting? Mine are, but at least there are backing blocks on all of them. In the last survey that was done on this boat the surveyor pointed that out and recommended replacing. When I had to re-insure the boat after buying out my partner, Boat U.S. initially said the through hulls would have to be replaced before they would insure. I was able to talk them out of that.

I would love to replace with true seacocks made of bronze, but right now that is prohibitively expensive. All of my current valves still operate with the exception of one on one of the cockpit drain lines which is very hard to turn. That one usually stays open anyway, but I am afraid if I try to turn it I might break it. When the boat is out of the water again I plan to remove the hose and try to lubricate the valve. (All of them actually.)

If it is a monetary issue, I would say if they still turn easily leave them alone. If you can afford to replace them then do so. I would if money was not an issue.
 
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toddster

Curator of Broken Parts
Blogs Author
Wait... is the issue lack of backing blocks on the through-hulls or obsolete seacocks? I just pulled off all of my seacocks but wasn't planning to replace the through-hulls...

edit: One reason not to open up this can of worms - the one through-hull that I must replace is the derelict speed sensor. The new one has a larger diameter but a smaller and completely different countersink. I may have to completely patch the old hole then re-drill. Quite a PITA unless you can get new fittings with the exact same countersink.
 
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Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
You can make the insurer happy and have new thru hulls if you replace 'em with Marelon thru hulls. (These are a valve body attached directly to the backing plate and Not just ball valves screwed onto a threaded thru hull fitting.)
Get the so-called OEM series. Strong as all get out - probably out live the rest of the hull.
http://www.forespar.com/pdf/techTips/ball-valve-93-series-sail-boat.pdf
Boatyards and anyone in the industry can buy them.
We replaced all the old 80's stuff with these a decade ago.
(FWIW, bronze is just as good.)

Also do some searches here, as thru hulls have been discussed extensively over the last decade.

Just a few threads:
http://www.ericsonyachts.org/infoex...k-Install-quot-Traditional-quot&referrerid=28
http://www.ericsonyachts.org/infoexchange/showthread.php?551-New-Strainer-amp-Thruhull&referrerid=28


Loren
 
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SurabyaKid

Member III
I went through this this spring with the major refit of Pronto. I replaced all with bronze. It appeared to me that the labor was the same and the cost difference per through hull averaged about $35. I decided to go with bronze to never have to worry about them again.Pat
 

toddster

Curator of Broken Parts
Blogs Author
I just read through Nigel Calder's chapter on this since I was placing an order. (Yet another kilobuck poured into the boat without yet procuring new sails...) On the issue of Marelon vs Bronze, he gives them equal marks. He notes that other plastic fittings have been found to fail but says of Marelon only "Forespar has been selling these fittings for many years without experiencing problems with the material." But he does not go so far as to say they will last forever.

Regarding the flanged sea-cocks attached to the backing plate, he says "At one time the ABYC required seacocks to have flanges that could be securely (i.e., independently) fastened to the hull. This is no longer part of any standard, although many bronze seacocks are still installed in this manner." Plastic ones too apparently. He goes on to explain that this is because it's possible to pass the UL load-bearing tests without such a flange.

It's a good thing too, because I don't think I could install such a thing in my head without major surgery to the liner. I posted a blog entry on this a couple of days ago, but I guess it's still in limbo.
 

kari

Member III
Let's not forget the great tutorials by Maine sail at his compassmarine website . . . :nerd:
 

mherrcat

Contributing Partner
Definitely check out Maine Sail's excellent writeup on making backing blocks with threaded stud inserts for mounting flanged seacocks. In my opinion this is the ideal way to do it, with bronze or Marelon seacocks.
 

toddster

Curator of Broken Parts
Blogs Author
OK, you have me convinced. The macerator through-hull was spinning freely with only hand pressure. And still fused to the old valve body! The good news is that it must have excellent sealant in there!

Four flanged sea-cocks and new through hulls now on order. Though I may have to take a sawzall to the head platform.
 

markvone

Sustaining Member
Let's refine the question.

How long do we think the Marelon thru-hull fittings will last?

When do I consider systematic replacement due to age?

I have the 30 year old Forespar Marelon thru-hull pipe fitting, plywood backing blocks and Marelon ball valves threaded on. Double hose clamps and softwood plugs at each valve. My only issues are a broken valve handle in the 'open' position for the galley sink (which I did recently) and a VERY slow weep from the engine cooling intake thru-hull, valve or hose when the engine is running. This leak has delaminated the plywood backing block over the years due to not being fixed by the previous owner.

If I have to replace any of the thru-hulls I will use the Forespar Marelon Series 93 "seacocks" as Loren has done here:

http://www.ericsonyachts.org/infoexchange/showthread.php?551-New-Strainer-amp-Thruhull&referrerid=28

I'll use g-10 backing plates. I don't need bronze or traditional seacocks.



Mark H,

Why did your surveyor/Boat/US say to replace the thru-hulls? Was it the age of the material for the fittings and valves or the lack of "proper seacocks"?

Thanks!

Mark
 

SurabyaKid

Member III
On the Lake where I keep Pronto, there is not a yard for maintenance work, so most boats are pulled infrequently (3-4 years) and then trailered down to yards on the coast. I had my boat pulled this spring for bottom maintenance and new standing rigging as well as replacement of the through hulls above the waterline that had cracked. The yard did a pretty thorough inspection of the ones below the waterline and they indicated they thought it was time to replace. (1988 so 24 years).

Although not in my budget, my thought was it would be a shame and poor risk to have the road vibration break or crack one and then have to pull the boat all over again. As it turned out, during the removal process, they found several were brittle.

Pat
 

toddster

Curator of Broken Parts
Blogs Author
I've been getting "up close and personal" with through hull issues over the last few days. I like the marelon, but I've already got bronze, so I'll stick with those. There is one issue I've noticed that I have not seen discussed anywhere. With the flanged bolt-on type of seacock, the backing block, it seems to me, must be made of fiberglass. Not wood. Any swelling or shrinkage of the hull or backing block could cause the fitting to leak. With a conventional through-hull, one can just tighten the backing nut. The flanged type can only be tightened from outside the hull, with a special tool, probably after applying a heat gun to the fitting (i.e. not something a diver could do.)
 

mherrcat

Contributing Partner
I don't have the survey in front of me now, but I believe the issue Boat US had with the through hull fittings was that they were not true "seacocks." The surveyor "recommended" the fittings be replaced because they were just ball valves threaded onto the through hull fittings. I'm sure for insurance purposes Boat US was looking for any way to minimize their exposure to a possible claim for their failure. There are only two ways I could see those fittings failing; a severe side impact that shears the fitting off or excessive force put on the ball valve handle that breaks the ball valve off. A side impact seems unlikely since the valves are in some pretty inacessible places; some you can barely reach your hand in to turn the valve handle. The most likely failure would be in forcing the handle due to a stuck valve; this is indeed a possibility since the older Marelon Forespar valves are known to have issues with the handles breaking off.

One advantage of the bronze seacocks, like the Groco, are that the handles are reversible.
 
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markvone

Sustaining Member
Thanks!

Pat,

Can you determine if any of the below waterline thru-hulls were brittle vs the above? I can see the UV exposed thru-hulls having a much shorter life.

Mark,

I can tell you from personal experience that you will not be able to shear the valve off the thru-hull fitting by yarding on the ball valve handle! You will (fairly easily) shear off the handle first if the valve is jammed or tight. That's how I broke mine.


I will be hauling this Fall to do a full bottom job and add new transducers for speed and depth. I have to do something with the engine intake backing block and I'm trying to determine if I shoulld plan on changing out the other below waterline thru-hulls as well. I'm in the Chesapeake, so the next planned haul out opportunity can be a few years from now.

Thanks!
Mark
 

toddster

Curator of Broken Parts
Blogs Author
I think I read that above-water-line through-hulls are often PVC or some lesser plastic than marelon.
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author

SurabyaKid

Member III
Pat,

Can you determine if any of the below waterline thru-hulls were brittle vs the above? I can see the UV exposed thru-hulls having a much shorter life.

Mark,

Mark,

The above the waterline ones were cracked as you can see in the attached picture. The yard told me that the below the waterline ones were in fact brittle and broke while they were being removed. Whether this was from impact or from disassembly I don't know. The other picture is of the transom through hulls replaced with Bronze. The only one not replaced was the small plastic one for engine cooling water (Siphon break?) as it's location was very difficult behind the propane locker and it appeared to be in pretty good condition.

Pat

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Glyn Judson

Moderator
Moderator
Marelon and bronze.

All, As a point of interest, all through hull fittings on our E31 and virtually all that I've personally been aboard (44 other of them) have had bronze fittings both above and below the water line. I'm sure I missed a few and would have to say that if Marelon, they were probably changed out by subsequent owners after leaving the factory. Glyn Judson, E31 hull #55, Marina del Rey CA
 

mherrcat

Contributing Partner
Interestingly the Forespar website has an installation video that shows what looks like about a 1/2" piece of plywood being used as a backing block. They do recommend that it be marine grade and sealed with epoxy, but that block pretty much looks like what was used on my boat with only a locking ring over the through hull fitting and a ball valve screwed onto the end of the fitting, which they do not recommend.

Those transom through hulls on "Pronto" look like what are on my boat. One of them cracked and I replaced it with Marelon. The others need to be replaced...
 
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markvone

Sustaining Member
All my thru-hulls and valves are Marelon

They are all the same above and below the waterline. They all have plywood backing blocks too.

As you can see in the pictures, they even used the flush version thru-hulls above the waterline on the Ron Holland models.
So while Ericson didn't spring for bronze seacocks, they didn't cheap out above the waterline either.
I can't complain about the 30+ years of sevice too much.

Mark
 
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