Through-Hull Fittings

[Randall Schmidt]

I have a 1984 O’Day 28. When I got her about 8 years ago I replaced the 3 frozen thru-hull fittings along with associated hoses. Alas I have been negligent in exercising the valves on a regular basis. I replaced the brass fittings with mareLon ones. They are once again frozen. I’m planning to haul her out in March to do the bottom. While she is out I can try to exert more force to get them open. If they break I’ll be sure to have replacements on hand to install. I assume if I order the replacements close to my haul-out schedule I can return them if unused. What are my chance that I can force the Marelon fittings open without breaking them? Will I know they are broken or is there a chance I think they are good and only discover the failure with a leak when I splash her? Finally do I go brass or Marlon this time?

 

[dlochner]

You definitely don't want to go with brass. What you are thinking is brass is probably bronze a more suitable alloy for marine use underwater.

What are the through hulls connected to? It could be something simple like growth in the thru hull that has caused them to seize. Unless you're under a real time constraint when the boat is hauled, I'd wait on ordering replacements.

 

[Randall Schmidt]

You definitely don't want to go with brass. What you are thinking is brass is probably bronze a more suitable alloy for marine use underwater.

What are the through hulls connected to? It could be something simple like growth in the thru hull that has caused them to seize. Unless you're under a real time constraint when the boat is hauled, I'd wait on ordering replacements.

I’m sure you are right it would be bronze. Is that better than marelon? One is connected to galley sink, one is sea water input to the diesel motor and one is output from the head when at sea. Only thinking ordering in advance to minimize costs of on-the-hard storage. Do you think there is a chance I get get the fittings to open and close w/o breaking them?

 

[Randall Schmidt]

You definitely don't want to go with brass. What you are thinking is brass is probably bronze a more suitable alloy for marine use underwater.

What are the through hulls connected to? It could be something simple like growth in the thru hull that has caused them to seize. Unless you're under a real time constraint when the boat is hauled, I'd wait on ordering replacements.

I do have the hull cleaned of growth regularly by a diver.

 

[dlochner]

If you have been using the overboard discharge for the head, the problem may well be calcium build up. That can be removed by removing the build up. I had the same problem, it was cured by removing the vent cap on the vented loop and injecting some acid based hose cleaner (Amazon link) and waiting several weeks. It dissolved the crud and the valve worked.

I do have the hull cleaned of growth regularly by a diver.

critters can get up into the valve and seize it.

If they are stuck closed, you could remove hose and inspect them. Seee if there is something on the inside that is causing them to freeze. If the motor intake is frozen, that's a big problem because the engine won't be cooled and the exhaust system will over heat the hoses.

 

[JoeWhite]

Do not order unless you need them. I would remove the hose and pour 1 ounce olive oil into the through hull then try to move the handle back and forth until it moves through its range. Do not use excessive force.
I regularly exercise the through hulls every 3 months. The sea water intake is closed when I leave the vessel and open when engine running.
All my through hulks are Marelon and closed when i leave the vessle. The only bronze 3 way valve is used on the holding tank between pumpout and macerator setting.

 

[Ralph Johnstone]

I would have thought that Marelon would spell the end of all problems regarding thru-hull valves. The only reason I don't have them is the lack of money to travel in such elevated circles.

I've had my bronze valves in place for 26 years now and have never had a problem with them. They will all get exercised for 6 months during the sailing season but no movement during the winter.

For your Marelon valves, try applying heat from a hair dryer when you try to free them. Maybe about 110° F max. to see if they'll move. Once they do move, try some non-pertoleum grease to keep they free.

 

[colemj]

Which Marelon valves do you have? If Forespar brand, then only the 93-series are good. Their other less-expensive ones are notorious for seizing up and handles breaking. Those should not even be sold, and I don't know why they still do. The two look different. The 93-series looks like the first picture, while the regular ones look like the second picture.

If you replace, Trudesign makes better reinforced nylon valves with teflon ball and housing, and I've never had one stick.

Personally, I only use reinforced composite valves/thruhulls (Marelon is a trade name for it). But it is important to use only specific ones. Brass is a no-go, and bronze is more expensive than necessary and a potential galvanic issue.

Mark

 

[Randall Schmidt]

If you have been using the overboard discharge for the head, the problem may well be calcium build up. That can be removed by removing the build up. I had the same problem, it was cured by removing the vent cap on the vented loop and injecting some acid based hose cleaner (Amazon link) and waiting several weeks. It dissolved the crud and the valve worked.



critters can get up into the valve and seize it.

If they are stuck closed, you could remove hose and inspect them. Seee if there is something on the inside that is causing them to freeze. If the motor intake is frozen, that's a big problem because the engine won't be cooled and the exhaust system will over heat the hoses.

I haven't used the discharge for the head. So is the acid based cleaner still worth a shot?

The sea water valve for my inboard diesel is stuck open so I can use the boat. I just cannot shut it off.

 

[dlochner]

I haven't used the discharge for the head. So is the acid based cleaner still worth a shot?

The sea water valve for my inboard diesel is stuck open so I can use the boat. I just cannot shut it off.

I'd say so. You may not have used it, but the prior owner may have. If it doesn't work, be sure to neutralize the acid with some baking soda before removing the fitting.

 

[Randall Schmidt]

Which Marelon valves do you have? If Forespar brand, then only the 93-series are good. Their other less-expensive ones are notorious for seizing up and handles breaking. Those should not even be sold, and I don't know why they still do. The two look different. The 93-series looks like the first picture, while the regular ones look like the second picture.

If you replace, Trudesign makes better reinforced nylon valves with teflon ball and housing, and I've never had one stick.

Personally, I only use reinforced composite valves/thruhulls (Marelon is a trade name for it). But it is important to use only specific ones. Brass is a no-go, and bronze is more expensive than necessary and a potential galvanic issue.

Mark

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Thanks for the education on types of Marelon thru-hulls! I looked back at my 2016 receipt and see the yacht yard that did the work then listed it as Seacock 1.5 M Marelon 1 1/2"for $115.48 each. I got 2 of these. Also got Marelon Elbox 1/2" pipe - 5/8" hose 90 degree elbow, and a Marelon T-pipe 1.5 Forespar tailpipe 1-1/2" ($11.65 each and got 2 of these). Also got M<arelon TH 1.5 thru hull mushroom ($26.72 ea., got 2); and Marelon TH .5 1/2" thru-hull mushroom ($13.04); and a Marelon scoop 3/4" strainer screen for 3/4" thur-hull. I believe mine looks like the 2nd photo but I will go look and take a photo when I venture to the boat again soon. I'm surprised my workorder receipt has so many related parts listed. And I did not include the hoses. If I end up having to replace these how many of the parts will I need and are any compatible with the higher quality model you listed?

 

[Randall Schmidt]

No marelon hits on a search at discount marine!? this is what I see on West Marine. Nothing indicated series 93. Flush Thru-Hull Valves | West Marine. I found it on WM: Mushroom Thru-Hull Valve 1 1/2. Based on the price I must not have the 93 series. You recommend not trying to fix the exisiting fittings and move forward with replacements to the 93 level?

 

[dlochner]

No marelon hits on a search at discount marine!? this is what I see on West Marine. Nothing indicated series 93. Flush Thru-Hull Valves | West Marine. I found it on WM: Mushroom Thru-Hull Valve 1 1/2. Based on the price I must not have the 93 series. You recommend not trying to fix the exisiting fittings and move forward with replacements to the 93 level?

Here's one:

https://defender.com/en_us/forespar-marelon-93-series-ball-valve-mushroom-thru-hull-fitting

 

[jssailem]

You recommend not trying to fix the exisiting fittings and move forward with replacements to the 93 level?

A good idea if you would like to reduce the worry about your thru-hulls. If you are not concerned about the possibility of them leaking/breaking off in your hand, then fixing them is a solution.

 

[colemj]

No marelon hits on a search at discount marine!? this is what I see on West Marine. Nothing indicated series 93. Flush Thru-Hull Valves | West Marine. I found it on WM: Mushroom Thru-Hull Valve 1 1/2. Based on the price I must not have the 93 series. You recommend not trying to fix the exisiting fittings and move forward with replacements to the 93 level?

If you have the one you linked to at West Marine, then that is a 93-series and should be OK. Just find out what is causing it to stick. They are generally easy to operate, but if you have something caught in it, that could prevent it from turning.

If you have one that looks like the second picture above, I'd get rid of it. Either for a 93-series, or even better a TruDesign brand one with collar.

We have both 93-series and TruDesign thruhulls. The TruDesign are better, but the 93-series offers more configurations for special purposes like 3-way valves (which is why we have two of them).

Mark

 

[peterbud]

RAndy check and see what duck Creek wants for the truck Hull. I did one a few months ago and found their price very competitive. Just don't have Tyler do the work.
Peter bud Wicked Good

 

[nramsey]

Just get Trudesign composite thru hulls and be done with it.
I replaced bronze and marlon thru hulls 12 years ago and they NEVER stick.

 

[Ran-Dee9229]

RAndy check and see what duck Creek wants for the truck Hull. I did one a few months ago and found their price very competitive. Just don't have Tyler do the work.
Peter bud Wicked Good

Thanks for the advice Peter.

 

[Ran-Dee9229]

My head discharge valve opens and closes fine. My sea water intake for the head works as well. Here are their photos for what it is worth. They seem to be good quality and are the same age as the water intake for the motor cooling.

 

[Ran-Dee9229]

Here is a photo of the valve that I cannot close.