I have a 1975 30 hunter with bad valves.I want replace them with marelon seacocks.I would like any input anyone has on this issue.
replace all seacock
- Thread starter captrick2013
- Start date
Not a difficult project if you are up on the hard. Think about replacing all your hoses at the same time. Gets a bit expensive but will make the job easier and give you some peace of mind. Pay attention to the sink at head. This plastic fitting almost sank my boat.
Personally I am not a fan of Marelon. Maybe you can find MaineSails test of these valves before you decide.
Go Marelon
Professionally, I am a HUGE fan of Marelon. I would use nothing else for underwater through-hulls.
The first I saw these, they were still being made by RC Marine in New Zealand and our Raider had them from the factory. I hated how the plastic handle sort of felt like it flexed when you turned it (I maintain a policy of shutting off all seacocks whenever I leave the boat-- more on this in a moment). I said, 'What kind of cheap toy is this thing?' I thought it awful, like my Uncle Joe at Raider Yacht was getting too cheap.
Later Forespar bought RC Marine's through-hull technology and now sells them as 'Marelon'. In fitting out a recent Cherubini 44 (which uses Marelon entirely) I asked Forespar about the bendiness. It is fiber-reinforced resin; and they test them by-- wait for it-- sliding a 500-lb weight down the hull to collide with the mounted seacock. The seacock survives. Moreover, the handle bends because it's showing you that you cannot put enough strength against the seacock, properly mounted, before the handle will break off (which is pretty tough to do). (Chain hoists have the same principle.)
Marelon bonds very well with 5200, which is what Forespar recommends. Use nothing else with them. The ones you will buy at WM or Defender are the 'aftermarket' style-- they have triangular plates with holes for through-bolting. This is, technically, overkill, but Forespar do this because, in terms of liability, they can't trust the guy installing them in the field. So they count on the bolts to hold the thing in place and hold it against the hull. Apparently too many people insist on putting these down with butyl tape or silicone, neither of which would hold up to that 500-lb weight sliding down the hull. I have 'advised' people that, using 5200 properly, the through-bolts are not necessary. Forespar will tentatively support me on this. But it is crucial that you do the installation in strict accordance with industry-standard use of 5200. Otherwise, get nice silicon-bronze (not stainless) bolts from Bolt Depot and do it that way.
The OEM-style Marelon seacocks, which you can't buy (but I have! --hah!) have little round feet on the bottom that will support the seacock's body about 1/16" above a perfectly-flush fit with the backing plate. This is intentional-- the space is for the 5200, so they can be cranked down hard in one shot, in the new-build phase, the 5200 doesn't get all squeezed-out, and the production builder doesn't have to return in 3-4 days to perform additional adjustments to it. Again-- just use the 5200 as instructed as you'll be fine.
Pay close attention to the backing plates, their shape, fit to the hull, and construction. For Diana I used fiberglass hull cutouts from my cousin's speedboat production, about the best thing available. In 2012-2013 I installed the C48 schooner Light Reign's Marelon through-hulls like this too. The Marelon threads are very good; but there is no tolerance for out-of-parallel inner and outer surfaces. Spend all your time making sure the backing plate fits well, dry-fit the seacock and through-hull, and cut off the through-hull's stem about 1/8" or 3/16" shorter than the bottoming-out mark. Then take the 5 minutes to install and you're good.
Once installed, Marelon fittings like being exercised. Turning them every day is the best policy. This isn't so much for safety-- though this is just prudent yachtsmanship, the seacocks are not going to snap off (unlike old bronze)-- but to keep them free from miniscule gunk. Even during the winter, visit the boat every 2-3 weeks at least and turn them all one way or the other. Apply Marelube as directed (even once a month is plenty). I recommend keeping a conical wedge next to each one, in case of emergency, but it's way more likely the hose clamp or hose will fail than the seacock, which means the same problem.
Compared to nylon, there is no comparison. I would not use nylon through-hulls on even a cheap outboard center-console (as opposed to most of those boats' makers!). They break down in UV and crack at a minute's notice-- or just crack when you tighten the hose clamp too far. And brass ball valves are NOT for boats; don't even look at them.
In short, benefits to Marelon:
1. Compatible with off-the-shelf boating materials (5200);
2. Simple and easy to fit, install, use;
3. No electrolytic corrosion, so no need for electrical bonding;
4. Paintable-- they take any paint with only minor prep;
5. Adequately strong and durable (yielding decades of use);
6. No staining or discoloration, if above the waterline; but they should be painted as they will begin to look chalky from UV (and the cream color of the through-hull flanges looks kind of cheap).
7. Inexpensive, especially at larger sizes (1-1/2") as compared to bronze.
Benefits of bronze:
1. Pretty when polished;
2. Strong enough to build bridges out of (but I would keep an eye on fiber-impregnated resin technology there too!).
The aforesaid is NOT a paid advertisement by Forespar Marine.
Professionally, I am a HUGE fan of Marelon. I would use nothing else for underwater through-hulls.
The first I saw these, they were still being made by RC Marine in New Zealand and our Raider had them from the factory. I hated how the plastic handle sort of felt like it flexed when you turned it (I maintain a policy of shutting off all seacocks whenever I leave the boat-- more on this in a moment). I said, 'What kind of cheap toy is this thing?' I thought it awful, like my Uncle Joe at Raider Yacht was getting too cheap.
Later Forespar bought RC Marine's through-hull technology and now sells them as 'Marelon'. In fitting out a recent Cherubini 44 (which uses Marelon entirely) I asked Forespar about the bendiness. It is fiber-reinforced resin; and they test them by-- wait for it-- sliding a 500-lb weight down the hull to collide with the mounted seacock. The seacock survives. Moreover, the handle bends because it's showing you that you cannot put enough strength against the seacock, properly mounted, before the handle will break off (which is pretty tough to do). (Chain hoists have the same principle.)
Marelon bonds very well with 5200, which is what Forespar recommends. Use nothing else with them. The ones you will buy at WM or Defender are the 'aftermarket' style-- they have triangular plates with holes for through-bolting. This is, technically, overkill, but Forespar do this because, in terms of liability, they can't trust the guy installing them in the field. So they count on the bolts to hold the thing in place and hold it against the hull. Apparently too many people insist on putting these down with butyl tape or silicone, neither of which would hold up to that 500-lb weight sliding down the hull. I have 'advised' people that, using 5200 properly, the through-bolts are not necessary. Forespar will tentatively support me on this. But it is crucial that you do the installation in strict accordance with industry-standard use of 5200. Otherwise, get nice silicon-bronze (not stainless) bolts from Bolt Depot and do it that way.
The OEM-style Marelon seacocks, which you can't buy (but I have! --hah!) have little round feet on the bottom that will support the seacock's body about 1/16" above a perfectly-flush fit with the backing plate. This is intentional-- the space is for the 5200, so they can be cranked down hard in one shot, in the new-build phase, the 5200 doesn't get all squeezed-out, and the production builder doesn't have to return in 3-4 days to perform additional adjustments to it. Again-- just use the 5200 as instructed as you'll be fine.
Pay close attention to the backing plates, their shape, fit to the hull, and construction. For Diana I used fiberglass hull cutouts from my cousin's speedboat production, about the best thing available. In 2012-2013 I installed the C48 schooner Light Reign's Marelon through-hulls like this too. The Marelon threads are very good; but there is no tolerance for out-of-parallel inner and outer surfaces. Spend all your time making sure the backing plate fits well, dry-fit the seacock and through-hull, and cut off the through-hull's stem about 1/8" or 3/16" shorter than the bottoming-out mark. Then take the 5 minutes to install and you're good.
Once installed, Marelon fittings like being exercised. Turning them every day is the best policy. This isn't so much for safety-- though this is just prudent yachtsmanship, the seacocks are not going to snap off (unlike old bronze)-- but to keep them free from miniscule gunk. Even during the winter, visit the boat every 2-3 weeks at least and turn them all one way or the other. Apply Marelube as directed (even once a month is plenty). I recommend keeping a conical wedge next to each one, in case of emergency, but it's way more likely the hose clamp or hose will fail than the seacock, which means the same problem.
Compared to nylon, there is no comparison. I would not use nylon through-hulls on even a cheap outboard center-console (as opposed to most of those boats' makers!). They break down in UV and crack at a minute's notice-- or just crack when you tighten the hose clamp too far. And brass ball valves are NOT for boats; don't even look at them.
In short, benefits to Marelon:
1. Compatible with off-the-shelf boating materials (5200);
2. Simple and easy to fit, install, use;
3. No electrolytic corrosion, so no need for electrical bonding;
4. Paintable-- they take any paint with only minor prep;
5. Adequately strong and durable (yielding decades of use);
6. No staining or discoloration, if above the waterline; but they should be painted as they will begin to look chalky from UV (and the cream color of the through-hull flanges looks kind of cheap).
7. Inexpensive, especially at larger sizes (1-1/2") as compared to bronze.
Benefits of bronze:
1. Pretty when polished;
2. Strong enough to build bridges out of (but I would keep an eye on fiber-impregnated resin technology there too!).
The aforesaid is NOT a paid advertisement by Forespar Marine.
John:
Thanks for the great info.
My boat has a mixture of bronze and Marlon on each thru-hull.
I have had no trouble with the Marlon valves themselves except for the very large one for the galley sink drain which I plan to repair at my haul-out next month. When shut, it is water-tight. But when open it leaks a drop every so-often. A new o-ring on the valve stem spindle should fix I've been told. The engine raw water valve is opened and shut several times per week for the past seven years and shows no signs of fatigue. However, I have been thinking to replace it at my haul-out in May ... just for good measure since it is used so much. The huge Marlon valve for head waste is always shut (and capped) since a higher end porta-potty does fine for our day outings and the occasional overnight.
Best I can tell, I believe the actual thru-hull fittings are probably Hunter factory original. Bronze with plywood backing plates. A P.O. at some point replaced all the valves with Marlon by threading into the original thru-hull threads as in the attached picture of my engine raw water thru-hull/valve. At my last haul-out several years ago, from underneath, spot scraping here-and-there revealed only healthy yellow brass. Same on the hull interior part of the fittings. The plywood "backing plates" are never damp and show no evidence of softening. I hope to see again nice yellow brass on the bottom side.
In case you are wondering about the DIY switch contraption mounted on my raw water valve. It's a "forgot to open the seacock" alarm. My Yanmar warning buzzer had an unused input that I utilized for the purpose. I only once forgot to open the seacock. And after I installed the switch to ensure I wouldn't the mistake again. I was fortunate because my engine was a raw water cooled type that was converted to self contained cooling, it still retained the 140 degree thermostat. I was able to shut down the engine before any real damaging heat happened. Might have been a different outcome if I had a normal 170 degree setup.
Thanks for the great info.
My boat has a mixture of bronze and Marlon on each thru-hull.
I have had no trouble with the Marlon valves themselves except for the very large one for the galley sink drain which I plan to repair at my haul-out next month. When shut, it is water-tight. But when open it leaks a drop every so-often. A new o-ring on the valve stem spindle should fix I've been told. The engine raw water valve is opened and shut several times per week for the past seven years and shows no signs of fatigue. However, I have been thinking to replace it at my haul-out in May ... just for good measure since it is used so much. The huge Marlon valve for head waste is always shut (and capped) since a higher end porta-potty does fine for our day outings and the occasional overnight.
Best I can tell, I believe the actual thru-hull fittings are probably Hunter factory original. Bronze with plywood backing plates. A P.O. at some point replaced all the valves with Marlon by threading into the original thru-hull threads as in the attached picture of my engine raw water thru-hull/valve. At my last haul-out several years ago, from underneath, spot scraping here-and-there revealed only healthy yellow brass. Same on the hull interior part of the fittings. The plywood "backing plates" are never damp and show no evidence of softening. I hope to see again nice yellow brass on the bottom side.
In case you are wondering about the DIY switch contraption mounted on my raw water valve. It's a "forgot to open the seacock" alarm. My Yanmar warning buzzer had an unused input that I utilized for the purpose. I only once forgot to open the seacock. And after I installed the switch to ensure I wouldn't the mistake again. I was fortunate because my engine was a raw water cooled type that was converted to self contained cooling, it still retained the 140 degree thermostat. I was able to shut down the engine before any real damaging heat happened. Might have been a different outcome if I had a normal 170 degree setup.
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as i read this in your last post, I want to suggest that you should never be seeing yellow brass on the hull of your boat anywhere, healthy or otherwise...
bronze is good, brass is not.... and they do look different if you have ever seen both side by side.
Centerline ... you are right. I started my post citing "bronze". Than in a moment of inattention, I typed "brass" later on. The fittings are "bronze". I do know that brass is a no-no for most boat applications.as i read this in your last post, I want to suggest that you should never be seeing yellow brass on the hull of your boat anywhere, healthy or otherwise...
bronze is good, brass is not.... and they do look different if you have ever seen both side by side.
I caught that in your post, but for those who may be reading the thread and NOT know the difference, I thought I should make it clear