Some thru-hull/seacock replacement questions

[FredV]

Close to the top of my project list is to replace all the thru-hulls and seacocks on my 37C. A lot has been written on this topic, and there are several terrific how-to articles as well, so I'm just really looking for any updates and opinions on a couple issues:

Bronze vs. Marelon - I like Marelon because it's a cheaper option and avoids electrolysis issues, but I've read a couple comments about the handles breaking off, which is, of course, a bit disconcerting. Is this a "real" issue, that is, does it happen more often than one would like, or is it a relatively rare occurrence that can be avoided with proper maintenance?

Thru-hull strainers - I can't quite get a handle on this one, as it seems there is a fairly even split between those who prefer the strainers and those who contend they get fouled too easily. Your thoughts?

Manifolds - I like the idea of using a manifold, as this implies fewer holes in my hull. I've seen manifold kits as well as a DIY manifold made with PEX fittings in these forums, but while they may make sense to me, I would be very interested to hear how much sense they make to you.

Thanks!

 

[Ralph Johnstone]

As Far as Thru Hull Strainers Go .................

.................. I think I'd rather leave the thru hull wide open, unobstructed, and pick up the crud in the sea water strainer. You can always see what's in the clear strainer housing and clean when required. Clearing the thru hull strainer on the exterior of the hull can be a daunting job when you're in our freezing northern waters.

BTW, very impressed with your loyalty to old Fred.

 

[rardiH36]

Do I have engineering experience on this topic? ... no ... but I'll opine anyway.

The technical advancement of plastics over the last decade has been amazing. Previously, various plastics would become brittle/weak under heat and UV. Now, the newer formulations are virtually indestructible. Car manufacturers make door handles and components out of plastics instead of of cast Al or Fe. They wouldn't do this if they expected plastics to fail faster than metal. The driver side metal door handles on my 1992 Jaguar car failed after about six years. (I don't own it now, sold about 2004). The plastic handles on my still owned 2001 Prius are still going strong with no hint of weakness.

Another thought ... how long do we expect the rest of our ~1980 built Hunters to last? Good chance it will be less than the life of the Marlon fittings you might decide on. I've got several Marlon seacocks on my boat that were installed by a PO probably many years ago. Not one has given me any problems.

 

[rardiH36]

Re my post a few minutes ago. I should clarify that the Marlon fittings on my boat are the sea cock valves that are threaded to the thru-hulls. All the below waterline thru-hulls themselves are marine grade bronze.

 

[DianaOfBurlington]

When I first saw Marelon seacocks in the late '70s (made by RC Marine then; we had them on our Raider) I was extremely skeptical and called them all sorts of rude names. But having had real experience with them I can assure you that they are far and away the best things that's ever happened for this crucial bit of hardware. I was told by Forespar (who bought RC) that they tested them by sliding a 500-lb weight down the hull into the seacock and they neither broke nor came loose. I would use nothing else.

That said, at Cherubini I specified only bronze for the waterline stripe (which still gets seacocks) and above, as they look better; but only Marelon below.

There isn't that much torque on the handle of a seacock; and Marelon ones are largely self-lubricating. In fact, like bronze, they live longer if turned frequently. Shut them off whenever you leave the boat and turn them on when you return and they won't jam up.

If the handle did break the handle from another one on the boat can be fitted to that seacock to turn it for you; but I have never heard of this being necessary.

By the way-- NEVER confuse Marelon with nylon (in other words don't buy purely on price). Nylon through-hulls have NO business being anywhere near the waterline on any proper yacht. The guy who wrote Seaworthy for BoatUS for years says that nylon through-hulls, cracked by freezing or UV light, are a leading cause of at-the-dock sinkings. This is a product you could damage by merely overtightening with a channel-lock. Leave this junk for center-consoles and ski boats. We sailors ('real' yachties) prefer Marelon.

(I confess that I took advantage of my tenure at Cherubini Yacht by ordering for Diana the 'OEM-grade' seacocks, the ones with the wide base-- not triangular-- that sell only to builders, not to retailers and consumers directly. These are built like little Marelon outhouses and the wide base makes them rock-solid against my wide backing plates. Sorry if this option isn't available to everyone; but one could probably purchase them through a nearby boatbuilder. I cannot comment on the final cost-- Forespar uses 'list' prices on these only for basing OEM discounts, but they were still cheaper than the other ones.)

 

[amcmahon]

Hey Fred, please don't make the mistake I made 3 years ago. I had pulled my h27 for its 3 year bottom paint and had bought Marlon to replace the thru hulls and valves. I took the first 1 1/4 thru hull off and looked at the new plastic vs the heavy brass and decided I was not comfortable with the plastic, so I put new brass thru hull and ball valve. Returned Marlon stuff to Defender and took 10% restock hit.
Now 2+ years later I took a good look at brass valve and it is a mess - covered with white electrolysis gunk. I will nervously wait till next haul out in 9 months and I WILL go with Marlon.
Just a short addition - About 6 years ago I was 'winterizing' h27 (she is kept in water 365) on her mooring. Was closing original gate valve for engine cooling and as I turned handle, the valve started to crumble in my hand. Water leaking in, I was able to wrap a piece of twine around valve to hold it together - still leaking. Nearest haul out 3 miles away - called and made arraignment, but had to sail down Brunswick river, then 1 mile on Cape Fear river and into tricky channel to dock and crane. A major nightmare!

 

[Ed Schenck]

If you actually did use brass instead of bronze then you oughta' be haulin' the boat. And soon.

 

[Maine Sail]

If you actually did use brass instead of bronze then you oughta' be haulin' the boat. And soon.

Ditto! I have customers with 40 year old bronze seacocks that when cleaned up are as good as new... You need to use the "right" materials for below water.

For reference Marelon is Dupont Zytel which is glass reinforced NYLON. It is PVC that you don't want to use below water.....

 

[Bill Roosa]

Hey Fred, can't comment on the vertures of bronze over Marelon though both seem to be getting high marks.
I think you will find the breakdown on strainers falls along the lines of the type of water you sail in. Lake sailors are not going to typically need them but if you are sailing in kelp fields then they do help. As for cloging, that is a maintenance item during haul out. All three of the boats I've owned had them and they where all painted over and pretty much on their way to being clogged. Scrape the paint, take off the screen and clean out the inside then bottom paint the inside before reattaching the screen.
manifolds are a matter of cost and what exactly you connect together. You would not, for instance want to connect the waist overboard discharge to the inlet for the sink salt water foot pump. with that said the issue is then one of can the manifold provide sufficient flow for all the devices attached to it and the cost of running more hose to get to the manifold. i think you will find that the cost (and hassel) of running the extra hoses is more than an additional seacock. YMMV as that is clearly dependant on how the boat is layed out.

 

[amcmahon]

If you actually did use brass instead of bronze then you oughta' be haulin' the boat. And soon.

My mistake - was bronze not brass.

 

[DianaOfBurlington]

One of the reasons I specified bronze through-hulls at Cherubini for use above the waterline was because Marelon gets chalky from UV light. The through-hulls in the transom of my H25 look awful and they haven't even been tested in seawater yet. I expect this is the nylon in the Zytel getting eaten by the sun.

I cannot say they are broken down and they certainly aren't yellowed or anywhere close to cracked. I would imagine their inherent flexibility makes them a little more durable than straight nylon.

But under the water there is nothing better than Marelon; and I expect this is due to the fiberglass content that MaineSail mentions.

 

[FredV]

Great - just what I was looking for. As soon as I get our damn house sold, I can finally get the time I need to focus on the boat. I suspect I'll need to replace all the plumbing, so am now thinking all Marelon seacocks and Pex pipe with Watts connectors throughout. I'm sure I'll be asking more questions soon.

Thanks for all the info!