Tried and True method for Removing Old Seacocks / Thru-Hulls

[sgharford]

I have to replace the 2.5” CNC tri-flange thru-hull on port engine raw water intake. It closes all the way but leaks like a siv. While I’m at it thought I would replace starboard engine and two smaller thru hulls (1” and 1.5”) where bonding wires corroded and as result, look suspicious. Was going to replace with Groco SBV for engines and BV series for smaller ones that don’t require winterizing.

I talked to Groco about my fear of originals not coming out easily. They said heat the valve body for about 30 seconds with a propane torch from below (outside of boat) to liquefy any bedding on threads and should come out easy (I have yet to experience anything easy on this boat).

The ‘mushroom’ sections that need to be unscrewed have many coats of bottom paint over them. Assume I should use paint stripper to free up where they contact with hull, or is heating with heat gun sufficient to soften up? What do you do when it just won’t budge? On previous boat, I used dremel with cut off wheel and cut around inside of mushroom section to free, but maybe a better way (didn’t know you guys then)? Any suggestions appreciated.

 

[MikeP]

Most seacocks can be reconditioned to work like new. Removal of the unit itself is almost never required. If you disassemble the valve portion you can re-work it with engine valve-grinding compound, clean it thoroughly and then re-grease it. It should then seal as good as new. There is almost never a reason to actually remove an old seacock unless it has actually rotted away.

Also, the tightness of most seacock valves can be adjusted as well which may eliminate the leak. The valves are commonly a taper fit and tightening the bolt/nut will pull the taper tighter into the bore. Of course if the taper or bore is pitted, tightening may not stop the leak and that's where the valve grinding compound comes in.

Here's a good article that might help: http://www.practical-sailor.com/marine/seacocks.pdf

 

[sgharford]

Well - That is great news for the 2.5" monsters! Thanks Mike. I will try rebuilding them in this case as I have nothing to lose. I still need to replace the smaller ones as one will not close and both are as green as the grinch.

 

[MikeP]

If they won't close they can still be reconditioned if they are the taper-fit kind. Just knock out the taper as shown in the article and clean 'em up!

 

[sgharford]

Their ball type -but pretty sure from looks of it I can unscrew top and get at ball. I have to get water strainer off so will be in there with big wrench anyway - will take a look.

 

[REBrueckner]

Mike P has exactly the right advice....the taper fit types last forever....maybe grease them every five or eight years and may never have to do anything else...

Regarding bonding wires: It makes almost no difference whatsoever if a quality all silicon bronze Amercian made seacock is NOT bonded. I prefer them to be unbonded to reduce them being blown apart in a lightning strike.

But most surveyors want bonding because that's the standard and I have yetto meet one who really understands the pros and cons except the guys who are wood boat experts.... and have seen the damage that can result.

Whack any suspect seacock with a regular hammer...not a sledge.... and if its still in place, you are good to go another 20 or 30 years.

I'm not personally familiar with the stainless steel ball type seacocks; do they fit tight against the bronze bronze or do they have synthetic gaskets between??

Marelon is another option...no corrosion

 

[sgharford]

God knows I don't want to turn this into a bond or not to bond thread - however I must say that the only two thru-hulls that are not bonded on the boat look like crap. Since the one is frozen (handle cracked from prevoius owner) seems good reason to replace to me.

Regarding the 2.5" ball type (not taper), they close full 90 degrees, but do not seal tight. I rebuilt sea-strainers last year and found this out on Port side when I didn't have gasket set right and couldn't fully shut water off (it really is scary when you can't stop even a small leak). I 'forgot' about this until it came time to winterize and all my pink stuff was coming out the bottom rather then thru the engine. The seal (what kind it is I don't know) on ball must be shot. It is definitely worth opening up while still mounted, but I don't really have problem with cost of replacing since I am doing myself and piece of mind 'new' adds when it comes to seacocks (thank God that's one word and not two! would have changed wording of that last sentence).

 

[Walter P]

I have the ball type seacocks on my 1982, 48 MY. A few years ago, I bought 2 new seacocks for the engines from Sam's. One of them was installed straight away since the Stb one was very stiff and wouldn't close all the way. The other was put away until i got a round tuit. Well that was probably a mistake as it will not shut off all the way and the boat is staying in the water for the winter. My situation is that now I can't winterize that engine so I am forced to provide heat to the engine room to prevent freezing. The weak link as far a safety is concerned is the clear plastic raw water strainer that can rupture quite easily if it freezes.

Well as usual, I digress.... My son made me a nifty tool to remove the seacocks without any cutting or cussin. It's very easy to fabricate and requires only a piece of about 1/2" thick steel plate cut like a pie slice but not so great an angle. The small end should enter the thru hull under the boat by about an inch max and the wide end should be about 1/4 " wider so when you drive it into the thru hull with a sledge it should do 2 things, one being to get a good bite on the bronze thru hull, the other should be to break loose the bedding bond on the threads. After the metal wedge is firmly installed, attach a large open end wrench or very heavy duty fits-all (adjustable) with an appropriate length of pipe for leverage and unscrew the thru hull. The seacock itself gets removed by removing three bolts holding it to the hull. I have used this method for a long time and it has never failed me. If you think it feels too tight, apply a little heat to the thru hull from under the boat. Have fun.....

Walt

 

[takefive]

for what its worth, just removed all seacocks in my 1979 46 cnv. They were all looking very green and fuzzy, plus all were weeping seawater thru bedding at hull. Once I removed three bolts securing each seacock, I actually unscrewed seacocks from the mushroom thruhull(had to remove strainers etc.. to allow room to rotate). Thruhull remained fastened to hull, and when seacock was removed, simply drove thruhull out of hull with a 5 lb. mallet and piece of wood. Proceeded to dip all seacocks and thruhulls in a muriatic acid /water bath. Will be reinstalling all thruhulls/seacocks tomorrow.

 

[yachtsmanbill]

Without trying to patch a hole where a thruhull was at, is there anyone, Groco, Perko etc that makes a replacement bronze bung to fill the holes???
I have between 6 and 8 TH's that I would like to move/remove. Most of these are from the GM heads and old genny TH. Several are also weeping at the hull joint and if I gotta pullem, I'd just as soon eliminate them.
If I had my druthers, I could make a stainless or aluminum patch and screw it and bed it with 5200. I really couldnt trust a fiberglass patch at the critical juncture... ws

 

[jim rosenthal]

I went through this a few years ago when we repowered Blue Note (the first time, and save the jokes about the Velcro engine mounts, boys). Because we had to move the main engine seawater intakes, I ended up with two big holes in the hull.

The best way to plug these is with FRP material. In our case, we had to make new holes which were larger, because I went from gas engines to diesel, so we had the cutouts from the new holes to use in the repairs. However, there are three ways to get the plugs you need to do this:

-make a sheet of the material you require: you start with a flat smooth board and a piece of release fabric, and begin laminating pieces of glass cloth and epoxy, using a squeegee and roller. It takes forty or fifty layers of cloth to get to the thickness you need, and it is a sticky messy process, but you end up with the thickness you require. On top you place a second sheet of release fabric (West System calls this stuff "peel ply") and then another sheet of board, and clamp or weight the whole thing- I used bricks, I think, but anything would do. Come back in a day and undo the sandwich. You can then cut the plugs you need out of the laminate piece you've made using a hole saw. It's best to use a slow-setting hardener for your epoxy and cut the plugs as soon as you can, when they are still green hard. If you've done your prep of the holes you are plugging, you can butter everything up with epoxy and tap the plugs into the holes as soon as you cut them out. This way you get a better bond to the old laminate. The prep of the old opening involves cleaning and degreasing the area, going around the inside of the hole with a sanding drum, and also sanding about three inches around the hole inside and out for your reinforcing fabric. It takes more time to describe it than to do it.

-find a boat that is in the boneyard, and cut the plugs you need out of the hull bottom. Just make sure no one minds first Prep is the same.

-Strongwell Inc is a company that makes preformed FRP structural elements. They sell these things in all shapes and sizes, including flat boards. They will have a production piece of what you need, although it may be expensive. However, there are a number of people on this forum who have faced this challenge, and it might be possible to split up the cost of a piece of Strongwell material and for everyone to cut out what they need.

Hope this is helpful. When I did it, I plugged two holes in the keel of Blue Note, with laminate I made up myself. I sanded a fairly wide area around the plugs and epoxied on glass cloth, about three layers. All those repairs are still in her keel, after twelve years, and so far so good. Note that I used epoxy, but vinylester is fine too. Polyester doesn't stick to polyester so well, and you should not use it.

 

[Vincentc]

I would also recommend using epoxy rather than a metal plug. I have not plugged a seacock hole but have patched malignant blisters in a Gulfstar and bad spots in a plywood skiff with epoxy.

Based on that experience, and depending on the size of the hole, I would either fill the hole with epoxy thicked with chopped fiberglass fiber and collodial silica or cut out a buch of fiberglass disks the size of the hole and lay up the plug in place with epoxy.

In either case I would also bevel the sides of the hole so the diameter of the hole was larger on the outside of the hull than the diameter on the inside of the hull. After thorough degreasing, cleaing and rough sanding I would paint the surface to be repaired with unfilled epoxy. I've used West System, System 3, Maas and Raka. The first three are available from West Marine, Boatworld, Jamestown etc and Raka direct. Raka costs significantly less. All work well. West System has done a lot of R&D and the cost of that R&D is evident in the price of the epoxy, which seems fair. Whether or not you buy their epoxy resin/hardener and supplies, you should buy their publications. I had "The Gougeon Brothers on Boat Construction", lost it in the storm and felt compelled to buy another. It is that good a reference.

The epoxy can be thickened to the consistency of stiff peanut butter and will stay in place long enough to then put a piece of plastic sheeting (or peel ply) against it backed by a piece of plywood. Depending on the orientation of the repair site, devise something to hold the plywood tightly against the hull until the epoxy cures. For example cut a 2x4 slightly longer than the distance from the hull to the ground. Place one end against the plywood and the other standing on the ground at an angle, then slide the 2x4 to vertical.

Vincent

 

[J's Dream]

I did this last winter. To remove the old ones, I didn't bother with heat or a wrench. I took a Sawzall, cut the fitting flush with the top of the nut, and the went outside and cut the sides of the fitting to hammer it out.

I replaced all the thru hulls on the boat, and the ones that came loose quickly, great...otherwise the Sawzall made quick work of them.

As for filling old holes, I ground down a good area around the hole on the outside, and filled it using glass and vinylester resin. I made it a tapered plug so that water pressure is always pushing on it in the right direction.

Jason

 

[jim rosenthal]

One additional comment: after you have plugged the old seacock holes and fitted new bronze seacocks in the new locations, spray all your new bronze equipment with Corrosion Block. If you keep doing this every year, the bronze will stay fairly bright and not turn green. Once it turns green, there isn't much you can do without huge amounts of headaches and elbow grease.

 

[sgharford]

Curiosity about bedding new thru-hulls. I put 3 out of 5 new thru-hulls on this weekend (would have done all 5 but was pouring rain and my helper/brother was starting to get pretty wet). I was using 5200 for bedding compound on tri-flange Groco's. Was running a bead around the inside pad for thru-hull and then putting valve tri-flange to it and mashing it around some to spread before we put bolts thru and snugged them tight. Then put thru-hull (mushroom) on with good bead on underside and snugged tight, then tightened bolts again, then snugged mushroom all the way, then tightened down bolts for last time. Cleaned up excess 5200 with acetone

On two of three mushrooms, I noticed there was slight lip on one side of mushroom from underneath when I snugged tight first time. For final tightening I really had to crank down hard to get lip to disappear. Thinking maybe I used too much 5200 for bedding and it was having a hard time spreading it out. So now I am wondering before I do the last two (the big 2.5” diameter’s with sea strainers attached) is it possible to use too much bedding compound?

 

[REBrueckner]

For the record...external green surface corrosion on a good quality bronze seacock means NOTHING except that there is enough moisture on the bronze to cause some superficial corrosion....in such cases the inside of the seacock is likely cleaner than the outside....don't think you have to change a BRONZE seacock for such an insignificant item....

On the other hand, the first photo in post # 13 shows a standard gate valve not a marine seacock..if its BRONZE likely its ok, but I'm not recommending this style/design and if brass replacing it is not a bad idea....sometimes the stem is a weak link in such a valve...and often the round handle is a cheap metal that corrodes away or may puncture your hand at an inopportune time...

 

[REBrueckner]

not really...any excess caulk should push out as a standard taper thread exerts tremendous compression pressure when the nut is tightened...it has been argued that such nuts should NOT be tightened too much until the caulk is set..that retains a better bead of caulk between the mating surfaces...but likely that's more an issue with softer hull materials like wood...and especially cored hulls!!!