If you go through the trouble of taking them apart I would replace them. Your contractor is not offering the best advice, and recommending the wrong backing material. Don’t waste your time and money on half measures
Seacock Quality... Replace?—Currently on the hard.
- Thread starter testingthewaters91
- Start date
That marine-how-to article explains why you should not use PVC backing plates. The wood in your pictures looks solid and doesn’t look rotted.
Great. That's exactly why I'm coming here... So replacing might be better. He said it'll take like two hours for each one, but he feels it's a waste of money because what I have is good enough. Replacing them may be a good idea. Doing them right, as is mentioned in the article, with proper flanges, seems to be a high skill level job. I'm not sure this little boat yard is totally up for it. I had to haul out here as the other boat yard had an 8 week wait list.
Alright, what I'm thinking is replace 3 with Marelon direct-threaded installation (unsure about boat hull thickness for securing with flanges for now). Leave the engine intake as is because it was rebuilt two years ago and is probably new (although I'll have to confirm that). Use G10 fiberglass as a backing plate this time because it will grab the epoxy well... And while not perfect, this set up will get me through safely until the next haul out and inspection.
The only thing that’s high skill level in the marine-how-to article is the part about making your own fiberglass backing. you can buy G 10 and cut it to size. But I don’t think you need to do that. You can use wood as I wrote above. If you have the agility to get yourself into that space, and you have basic tools, then everything else is easy you can buy the materials. I suggest Groco bronze ball valves and through hulls so it will be a direct replacement for what you have. You won’t even have to drill. Also, as I wrote prior, the wood looks to be solid. Check me on that by poking it with a screwdriver. The wood might not need replacement.
The author of the article (Rodd) also mentions using a step wrench. Those are handy to have if you’re going to do four of these. https://a.co/d/1o5moFp
PS the reason I suggested you go with bronze is because you won’t have to modify the hull holes. If you use Marelon the hole size will be different. They have thicker walls so the outside diameter has to be a little bigger to give you the same inside diameter. This means making holes larger. It will complicate the job a little more.
Roger that. Bronze seems like the better choice.
So the contractor wants to just service the valves but I'm going to ask him to replace them with new ones. Maybe I can pick them up at West Marine and bring them to the yard.
Get matching thru hulls with them. And ask him to confirm he won’t use 3M 5200 sealant. 3M 4200 is the correct choice.
If you’re going to be a boat owner, you really need to learn how to do maintenance projects such as this. Grind off the mushroom part of the thru hull fitting on the outside of hull, then pull the remains thru hull, valve, & tailpiece from inside the cabin. Fabricate 4 new backing plates from 3/4” oak plywood, you can usually buy small sheets from HD & Lowe’s. Use the old plate for a pattern. Coat them thoroughly with a few coats of epoxy, then roughen the surface with 120 sand paper for better adhesion of the 3M 4200. Install the new bronze fittings using 4200 on the thru hull Part. You can use 4200 or your favorite joint sealer on the other threads. May As well replace the hoses (inspect clamps) while you’re at it. I once had a valve stem that broke off the valve body; no way to close it & it was steadily leaking inside the boat. I had a diver, who lived in the marina, stop the leak with a wooden plug placed from outside the hull until I could swap out the valve. That valve was approximately 15 years old & showed no external signs of deterioration. Your valves are much older & two are malfunctioning……time to address this now. 
W
Why grind off the old Seacocks? Why not just unscrew them from the inside and use the tool to take them out?If you’re going to be a boat owner, you really need to learn how to do maintenance projects such as this. Grind off the mushroom part of the thru hull fitting on the outside of hull, then pull the remains thru hull, valve, & tailpiece from inside the cabin. Fabricate 4 new backing plates from 3/4” oak plywood, you can usually buy small sheets from HD & Lowe’s. Use the old plate for a pattern. Coat them thoroughly with a few coats of epoxy, then roughen the surface with 120 sand paper for better adhesion of the 3M 4200. Install the new bronze fittings using 4200 on the thru hull Part. You can use 4200 or your favorite joint sealer on the other threads. May As well replace the hoses (inspect clamps) while you’re at it. I once had a valve stem that broke off the valve body; no way to close it & it was steadily leaking inside the boat. I had a diver, who lived in the marina, stop the leak with a wooden plug placed from outside the hull until I could swap out the valve. That valve was approximately 15 years old & showed no external signs of deterioration. Your valves are much older & two are malfunctioning……time to address this now.
It usually never works that way. They rarely just come out. @BigEasy is just speaking from experience.
dj
When I decide that it’s time to replace the fittings, I always replace the thru hull,
ball valve, & tail piece. I am not interested in disassembly or salvaging parts because a casual observer really can’t inspect the inside of the fittings. When I finish, I have complete “piece of mind” and a basis for future maintenance. In my hands, it takes about 5 minutes to grind the mushroom with an angle grinder & course abrasive disc vs struggling with pipe wrenches, swearing, & busted knuckles trying to take them apart. As you know, the fittings are almost never located in places of convenient access! I have used this technique over the years on two boats & it works for me. But either way, you can do this job yourself & save significant $$$.
So I’ve confirmed that the "seacocks" on my boat aren’t actual marine-rated seacocks. They’re residential-grade Hammond 8901 brass ball valves threaded onto thru-hulls — totally inappropriate for long-term submersion in a marine environment.
The plan now is to remove them properly — either by unscrewing them from the inside or grinding off the thru-hull mushroom head from the outside.
I’m prepping new backing plates made from ¾" white oak plywood, epoxied and sealed. I’ll be replacing the old fittings with proper Groco bronze inline seacocks, which should drop into the existing hull holes with minimal glass work. I’ll sand and prep the hull, then bed the new fittings with 3M 4200.
This will be done for the three main locations:
Head sink drain
Galley sink drain
Waste discharge (head)
I’m still unsure about the engine intake. That valve operates smoothly and looks like it was installed more recently, possibly during a repower two years ago. However, the labeling is worn off, so I can’t confirm what it is. The yard guy mentioned that he was surprised by how little raw water was coming through, possibly due to undersized hose or partial blockage.
I'll post a few pictures shortly. Curious what others think — especially about evaluating the engine intake and whether low water flow could be due to the valve or hose sizing.
Thanks in advance.
The plan now is to remove them properly — either by unscrewing them from the inside or grinding off the thru-hull mushroom head from the outside.
I’m prepping new backing plates made from ¾" white oak plywood, epoxied and sealed. I’ll be replacing the old fittings with proper Groco bronze inline seacocks, which should drop into the existing hull holes with minimal glass work. I’ll sand and prep the hull, then bed the new fittings with 3M 4200.
This will be done for the three main locations:
Head sink drain
Galley sink drain
Waste discharge (head)
I’m still unsure about the engine intake. That valve operates smoothly and looks like it was installed more recently, possibly during a repower two years ago. However, the labeling is worn off, so I can’t confirm what it is. The yard guy mentioned that he was surprised by how little raw water was coming through, possibly due to undersized hose or partial blockage.
I'll post a few pictures shortly. Curious what others think — especially about evaluating the engine intake and whether low water flow could be due to the valve or hose sizing.
Thanks in advance.
Attachments
After some investigation, it seems that this is an Apollo branded valve. Not sure if that's a good or bad thing.
I like to work entire systems. I don't like a bit here and a bit there. What do I mean? When I changed my halyards, I changed every halyard on the boat. When I changed my sheets, i changed every sheet on the boat.
When I did my thru hulls i did every thru hull on the boat.
I just hate being all set up to do a job and then a couple years later have to go through the same thing because I didn't do some part of the system. Also makes record keeping easier. All halyards and sheets were changed on this date. All thru hulls were changed on this date. And so on. For me it helps me know where my systems are and when I go to sell (if that is in my lifetime) I can just show the maintenance records to a perspective buyer. Helps sell a boat.
It's up to you how you wish to run your boat.
dj
When I did my thru hulls i did every thru hull on the boat.
I just hate being all set up to do a job and then a couple years later have to go through the same thing because I didn't do some part of the system. Also makes record keeping easier. All halyards and sheets were changed on this date. All thru hulls were changed on this date. And so on. For me it helps me know where my systems are and when I go to sell (if that is in my lifetime) I can just show the maintenance records to a perspective buyer. Helps sell a boat.
It's up to you how you wish to run your boat.
dj
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 23,070
Just Do It.... In for a penny, in for a pound...
Simple phrases from an old generation. They provide interesting guidance.
If you choose to keep the old part, that will be the one on your mind as you go forward. It'll eventually give you a sleepless night, wondering not if but when it'll be the first to fail; then you'll have to think about all this again.
Then there is the eventual, I am going to sell this boat. I have enjoyed it. The new buyer or surveyor will examine the valves and wonder why this one is older than the others. What other deferred maintenance has gone on? I had better lower my offer just in case.
Either way, it is your boat and your choice. Choose wisely.
Simple phrases from an old generation. They provide interesting guidance.
If you choose to keep the old part, that will be the one on your mind as you go forward. It'll eventually give you a sleepless night, wondering not if but when it'll be the first to fail; then you'll have to think about all this again.
Then there is the eventual, I am going to sell this boat. I have enjoyed it. The new buyer or surveyor will examine the valves and wonder why this one is older than the others. What other deferred maintenance has gone on? I had better lower my offer just in case.
Either way, it is your boat and your choice. Choose wisely.
Thanks for all the input. The contractor has asked me to compile a list of parts to order. I'm going to go into the blocked boat and try to check out the sizes (I'm just guessing below). So far I've got:
1.5” bronze seacock and hose barb for head discharge
1” bronze seacock and hose barb for head sink
3/4” bronze seacock and hose barb for galley sink
Backing plates for all three (G10 or epoxy-sealed plywood)
3M 4200 sealant
316 stainless double hose clamps
Marine-grade hose (sanitation and drain type as ne
eded)
1.5” bronze seacock and hose barb for head discharge
1” bronze seacock and hose barb for head sink
3/4” bronze seacock and hose barb for galley sink
Backing plates for all three (G10 or epoxy-sealed plywood)
3M 4200 sealant
316 stainless double hose clamps
Marine-grade hose (sanitation and drain type as ne
eded)
My rational is that I believe the Seacock was replaced when the engine was rebuilt two years ago, but will require further investigation.
How much water should be flowing into the YANMAR 2GM20F? The contractor seems to think there wasn't much.
How much water should be flowing into the YANMAR 2GM20F? The contractor seems to think there wasn't much.
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 23,070
I chose to match the through-hull, strainer, and hose diameter to the pump intake diameter.
That way, I know there is adequate flow to the pump. There are engineers who will determine the pump's specific demands and calculate the flow constraints from various hose diameters and strainers to arrive at the optimal combination of through-hole size and system.
That way, I know there is adequate flow to the pump. There are engineers who will determine the pump's specific demands and calculate the flow constraints from various hose diameters and strainers to arrive at the optimal combination of through-hole size and system.
As a general rule, head discharge, head sink drain, & galley sink should be 1.25 to 1.5“ and water intake lines for engine & head intake should be .75 ”. That strainer shown on the engine intake appears to be quite restrictive. I had a similar one on a marine air conditioner that repeatedly clogged with algae during summer months. Groco has a strainer that is suitable for engine intakes. The idea is for the strainer is to catch blades of grass, sea weed, plastic bags etc….rather large items. Also, be aware that the engine raw water intake should be double clamped at each hose end all the way from the thru hull tailpiece to the raw water pump. You can check out Groco’s catalog for bronze fittings & part numbers & check prices at your favorite marine chandleries.. For the large diameter hoses, Trident or Raritan saniflex hoses are good choices. Don’t be tempted to use clear or braided hose from the big box stores, it is not rated for below water use.