Gate Valve Seal

[rwmiller56]

Hi, all,
The gate valve for my 26M ballast tank broke where the handle rod connects to the gate valve (inside the valve body). Fortunately, this occurred when the boat was on the trailer I will be replacing the entire valve assembly.
My question is, what forms the seal between the valve assembly and the ballast tank opening in the hull? Is there a rubber gasket, or do I use marine sealant? I found plenty of discussions on this forum related to the valve, but not much about the seal.

Another thing. The heads of the 4 screws that attach the valve body to the boat are somewhat corroded (the boat spends about half the year in a slip in salt water). I hope there is no problem loosening these. Any tips?

Thanks,
Roger

[bradhill]

[Phillip]

Are the pictures here of any benefit?
Cheers
Phillip

http://macgregorsailors.com/phpBB/viewt ... 0&start=15

[rwmiller56]

Are the pictures here of any benefit?
Cheers
Phillip

http://macgregorsailors.com/phpBB/viewt ... 0&start=15

Phillip,
Thanks for pointing me to this link. The photos do help, but on the first picture, I'm wondering what is the gray colored part of the unit on the left? I ordered the complete valve assembly from BWY, and the picture on their website showed only the black part of the unit, on the right.

Also, your picture shows nuts on the outside of the unit (black side). On mine, there are Philips head screws on the outside. I don't know what's on the inside, but the discussion seems to indicate that the hole are threaded in the fiberglas. Again, I'm wondering why the difference.

Thanks,
Roger

[Phillip]

This is what i did.
I purchased a complete unit from my Irrigation Company.
On the right hand side, are the parts I replaced, hence that photo shows un-servicable used-old parts (slide valve and vent), which I kept.
The new half (slide valve and vent) is now on the boat.
On the left hand side is the brand new never-used half of the unit.
To use it, I would have had to remove the old half from the hull, and there was no point.
I just put the new piece (right side) over the 4 protruding bolts and did them up.
I really hope this makes sense.
I did note the size of the bolt heads holding the unit together, and thought to myself - don't go over tightening these.
Cheers
Phillip

(I kept what is in the pictures because I am a production nursery, and these fittings are for low pressure water pipes (ours are 90mm dia), and i thought, well - one day I might just need them).

[rwmiller56]

This is what i did.
I purchased a complete unit from my Irrigation Company.
On the right hand side, are the parts I replaced, hence that photo shows un-servicable used-old parts (slide valve and vent), which I kept.
The new half (slide valve and vent) is now on the boat.
On the left hand side is the brand new never-used half of the unit.
To use it, I would have had to remove the old half from the hull, and there was no point.
I just put the new piece (right side) over the 4 protruding bolts and did them up.
I really hope this makes sense.
I did note the size of the bolt heads holding the unit together, and thought to myself - don't go over tightening these.
Cheers
Phillip

(I kept what is in the pictures because I am a production nursery, and these fittings are for low pressure water pipes (ours are 90mm dia), and i thought, well - one day I might just need them).

Phillip,
OK, thanks. That makes more sense to me.

The only difference is, you say the bolts were protruding from the left side piece, through the right side piece.
In my case, the 4 Philps screw heads are visible on the right side piece, so it appears that they screw into the hull (self tapping).

I'll find out when I get it all apart

Thanks,
Roger

[Phillip]

Got me worried Roger, so went out to the shed and checked it out.
Mine are definitely bolts and nuts.
Now what I am questioning is my recollection of events - did the bolts protrude or did they screw in.
Probably not an issue to you now as it will all make sense shortly!!.
Cheers
Phillip

[seahouse]

Hi Roger –

As a side note the gate valves will last a long time and work smoothly if you give them an occasional spritz with a quality silicone spray or other similar lubricant (non-petroleum based) compatible with rubber. And it’ll help keep that new one new.

- Brian.

OK, on edit I will add that there are dedicated O-ring lubricants, which should be used if possible. Silicone sprays will work in a jiffy, but some of the cheaper ones use a solvent carrier which, until evaporated, has a detrimental effect on some rubbers. And, in the case of a gate valve, evaporation might take some time, extending the likelyhood of damage.

[rwmiller56]

Hi Roger –

As a side note the gate valves will last a long time and work smoothly if you give them an occasional spritz with a quality silicone spray or other similar lubricant (non-petroleum based) compatible with rubber. And it’ll help keep that new one new.

- Brian.

Thanks, Brian. My boat is 5 years old, so I have to assume that the gate valve is original equipment, and the 2 PO's never replaced it. It was difficult to operate right from the start. I'll try the silicone spray, I have plenty of that laying around.

I'm also adding an extension to the handle rod, so that hopefully the handle will sit well above the top of the transom, instead of flush with it, which puts sideways torque on the rod and valve.

Roger

[K9Kampers]

I'm also adding an extension to the handle rod, so that hopefully the handle will sit well above the top of the transom, instead of flush with it, which puts sideways torque on the rod and valve.

What do you see causing the sideways torque?
To make the handle sit well above the transom, I'd be concerned about the snag-potential of something bending it or breaking it off!

[rwmiller56]

I'm also adding an extension to the handle rod, so that hopefully the handle will sit well above the top of the transom, instead of flush with it, which puts sideways torque on the rod and valve.

What do you see causing the sideways torque?
To make the handle sit well above the transom, I'd be concerned about the snag-potential of something bending it or breaking it off!

The handle has always been a tight fit against the back of the transom, so there is a little sideways pressure on it.
Good point about snag potential, though. I'll consider that.

[rwmiller56]

OK, I replaced the gate valve today. The good news is that the old valve came off easily, and the new one went on just as easily.





The bad news is that I did manage to strip the thread in the fiberglas for the upper right hand screw. I know there have been many warnings not to tighten the screws too much, but I was a little over zealous when installing it. Me bad! Right now, the screw is held in with some 4200 sealant.

What is the best way to repair it? Should I redrill and retap the hole to a new larger thread size? Or should I just replace the existing machine screw with a self tapping screw of larger size?
Or is it really something I should worry about? The other 3 screws are installed properly, and are not stripped.

Thanks, and any help is appreciated.

Merry Christmas to all!

Roger

[Catigale]

I think it will be below the waterline, so it might prevent you from running empty ballast on the water. Not problem if you are trailering. I think i would want any mac ballasted on SF Bay !!!

Easy fix, remove...drill out hole...epoxy hole...cure.....drill clearance hole....reinstall.

[rwmiller56]

I think it will be below the waterline, so it might prevent you from running empty ballast on the water. Not problem if you are trailering. I think i would want any mac ballasted on SF Bay !!!

Easy fix, remove...drill out hole...epoxy hole...cure.....drill clearance hole....reinstall.

Fixed. I drilled out the hole in the valve body, and used an oversized 5/16" SS self tapping screw. It grabbed onto the fiberglas good, and sealed that corner of the valve body.

Roger

[Catigale]

Take the rest of Sunday off...

Bravo Zulu