Seacock Question

[jpendoley]

I am am removing and rebedding all through hulls on my Pearson 365 as part of a gel peel/barrier coat project. None below the waterline were through bolted-most were bedded in 5200 and had to be ground off. They all had good solid backing plates and the hull is at least 1/2 thick wherever they were installed-but I would have thought they would have through bolts. One is a newer Groco ball valve with a flange with bolt holes-but the preious owner did not through bolt. Two cockpit drains in particular are beautiful wilcox crittendon bronze 1 1/2 " monsters with big flanges, but no provisioon for bolts (picture attached). When I look at the flange on the WC units I see enough material and room for drilling bolt holes-good idea? Bad idea? Trying to do this the correct way.
Jim

[BAD ORCA]

Did they glass over the bases of them?

I have the same monsters on my two cockpit drains and smaller ones throughout my boat (different boat). I havn't actually removed any yet but will be removing a couple in two weeks. They very heavily glassed over the tops of the basses on all of them so im assuming mine are not thru bolted either.

On my boat there is approx 1/2" thickness of heavy roving glassed over them. I think im going to just do the same and not thru bolt them. I would think enough heavy glass over the bases would suffice the ABYC 500lb? load standard or even exceed it but im not an engineer. I know the thru bolting is preferred but its just another potential spot for a leak.

[vpbarkley]

The idea is to through bolt into a backing plate but not through the hull itself. I do not plan to bolt seacocks in place.

[Manateeman]

Go to marine how to web pages. Would someone please post the link.
Take the seacock apart, clean, new plug for where the zerk fitting goes. You take out the plug. Tef Gel, put in the zerk and grease.
The flange ought to take three or four bolts no problem. Tap but it’s probably solid. Bronze can be TIG welded easily and will last longer than you.
Very much worth repairing.
The manatee crew

[sanibel sailor]

Nigel Calder thinks bolts thru Hull and backing block. Just thru backing block makes no sense to me.
BTW, none of mine are thru bolted.

[BAD ORCA]

Originally Posted by sanibel sailor

Nigel Calder thinks bolts thru Hull and backing block. Just thru backing block makes no sense to me.
BTW, none of mine are thru bolted.

Isn't there a recommended minimum hull thiuckness for thru bolting? I thought i remember reading it was approx 3/4" minimum for GRP but I might be wrong. Is 1/2" hull thickness maybe slightly too thin for thru bolting or did they just not do it because the seacocks came with no holes i wonder?

[deblen]

https://www.pbase.com/mainecruising/replacing_thruhulls

[Pete7]

I think the bolt through thing is an idea American's continue stick with. Europeans tend to use just a mushroom fitting now.

However, what sort of load do you foresee a seacock being subjected to?

The ballistic plates in my flak jacket were about 3/8ths of some sort of laminated GRP. I didn't test them, but a couple of the lads did with good results.

Pete

[jpendoley]

Well then-its unanimous-there is no consensus on through bolting. Hull is 1/2 thick at this location and they were not glassed in. Held in place by the external mushroom and bedded in silcone of all things. As far as what could impose a 500 pound load, i think a lot of things in the vicinity of that seacock. Scuba tanks get loose, engine goes astray, batteries get moving. All unlikely as hell, but if you can easily do it right, why not have the peace of mind?
I'm inclined to do a little more research. Bolting to the backing plate only seems counterintuitive to me.
Jim

[deblen]

https://marinehowto.com/seacock-thru-hull-primer/

[deblen]

Originally Posted by Pete7

I think the bolt through thing is an idea American's continue stick with. Europeans tend to use just a mushroom fitting now.

However, what sort of load do you foresee a seacock being subjected to?

The ballistic plates in my flak jacket were about 3/8ths of some sort of laminated GRP. I didn't test them, but a couple of the lads did with good results.

Pete

Mushroom head thru hulls have straight(non tapered) parallel pipe threads.
In UK,you can buy bronze or DZR bronzr marine grade ball valves with parallel BSPP threads & these will work fine on a BSPP strait parallel thru hull.

In NA,all marine grade bronze ball valves are NPT tapered pipe thread(similar to your BSPtaper). Strait (parallel) threaded marine valves are not generally available.
It is poor practice(very weak) to screw a NPT valve onto a straight parallel Thru hull fitting.
The result is only 3-4 threads contacting & the valve will screw on no further as pictured in Maine Sail/Marine How To.
Hope this explains why the difference in NA-UK practices.
Cheers/ Len


https://marinehowto.com/

[deblen]

Mis matched threads pic.

[C420sailor]

Groco now makes mushroom thru-hulls with NPT threads at the top. I have them, and they mate beautifully.

[Cheechako]

Originally Posted by jpendoley

I am am removing and rebedding all through hulls on my Pearson 365 as part of a gel peel/barrier coat project. None below the waterline were through bolted-most were bedded in 5200 and had to be ground off. They all had good solid backing plates and the hull is at least 1/2 thick wherever they were installed-but I would have thought they would have through bolts. One is a newer Groco ball valve with a flange with bolt holes-but the preious owner did not through bolt. Two cockpit drains in particular are beautiful wilcox crittendon bronze 1 1/2 " monsters with big flanges, but no provisioon for bolts (picture attached). When I look at the flange on the WC units I see enough material and room for drilling bolt holes-good idea? Bad idea? Trying to do this the correct way.
Jim

I have not used bolts but once. I dislike make a hole in a hull and then adding 3 or four surrounding it. I always used good seacocks and 5200.
Bolts are not bad though probably. I disfigured a finger trying to drill holes in a bronze seacock, so be careful, it grabs drill bits very nicely! then spirals through with the seacock climbing up the drill bit.

So you are concerned that 40 years without bolts is not long enough?
Flanged seacocks without bolts is far far better than a mushroom with a ball valve attached. Think about it... a reluctant valve puts all the force on the threads at the base and there is no support like a flange. That mushroom's threads leave a maximum of 1/16" of material at the thread root with a sharp crevice which may be crack prone..... A good gate valve may be better as there is no leverage to worry about...

[Orion Jim]

There are seacocks designed to be bolted in place. Mine were installed 37 years ago and are still in fine shape.
https://www.spartanmarine.com/all-pr...artan-seacocks