Thru-hulls, seacocks, and hoses!

[pmagistro]

Ok, I'm working on overhauling my Bristol 29.9. I'm replacing pretty much all of of the thru-hulls, seacocks, and all of the ancient plumbing. I want to run this by you all and gather some opinions.

For the seacocks, I'm basically planning to do what Compass Marine recommends at Replacing Thru-Hulls and Seacocks Photo Gallery by Compass Marine How To at pbase.com. Groco says to use 316 stainless bolts or lags. I'm not sure whether to bolt through the hull from the outside, lag into backing blocks from the inside, or purchase Groco backing blocks and bolt into the hex nuts. Thoughts?

And hoses...oh hoses. I've been agonizing over the options for hoses and think I have it figured out:

- For the 3/4" freshwater system (non-pressurized), I'm planning on using Trident Marine Reinforced PVC Water Hose, likely from Discount Marine Supplies.

- For the 1 1/2" sewage lines, Trident 101. ~22ft. Any leads on the best place to buy this?

- For the 3/4" holding tank vent line, Trident 148.

- For the 1 1/2" cockpit scuppers drains and sink drains, also Trident 101. ~10ft. I know these don't need to be odor safe, but I can figure out a better (ie cheaper) hose to use that's still adequate for critical below the waterline use.

- For the 1 1/2" potable fill lines and manual bilge pumpout, Trident 148 or 144. ~20ft.

- For the 1 1/8" automatic bilge, Trident 148 or 144.

Looks like it's easy to buy 50' lengths of Trident hose at a good price from Discount Marine. I'm wary of Shields after reading reviews, etc but it's definitely easier to go to WM and buy shorter lengths of the equivalent Shields hoses. Thoughts?

I'll take any thoughts, suggestions, or other ideas!

Thanks!
Phil

[Cthoops]

We're also doing a refit of our Bristol 29.9 that we bought in August. I can't help you with the hoses, but for the seacocks we're using MaineSail's no through bolts method. We like to keep the holes in the hull to a minimum, and we used this method on our Bristol 24 with no issues.

We used a Groco backing block on the Bristol 24 which worked well, and we bought another one for the first seacock that we're replacing on this boat. However, since then we've rebedded our deck hardware with G10 and we have some extra remaining, so we'll use that up for the rest of the seacock backing blocks. If we run out of G10 before we're finished, we'll just get some more Groco blocks.

Good luck!

[model 10]

Spring for nice clamps that don't rust, ever.

[pmagistro]

Cthoops, I think I'm gonna use GPO3 fiberglass from McMaster, 1/2" thickness. Did you have any issues with 1/2" backing material (the groco blocks) conforming to the curvature of the hull?

[transmitterdan]

I don't like GPO3 fiberglass in a bilge because it is not as water resistant as G10. If the budget allows I would use G10 over GP03. Also, GPO3 is not as dimensionally stable as G10. McMaster-Carr has both types of fiberglass I believe.

[HappyMdRSailor]

Originally Posted by Guy

Spring for nice clamps that don't rust, ever.

YES!

Originally Posted by transmitterdan

I don't like GPO3 fiberglass in a bilge because it is not as water resistant as G10. If the budget allows I would use G10 over GP03. Also, GPO3 is not as dimensionally stable as G10. McMaster-Carr has both types of fiberglass I believe.

And Yes!

[Cthoops]

Originally Posted by pmagistro

Cthoops, I think I'm gonna use GPO3 fiberglass from McMaster, 1/2" thickness. Did you have any issues with 1/2" backing material (the groco blocks) conforming to the curvature of the hull?

On the Bristol 24 the hull curve was minimal. We haven't stared at the head sink seacock too closely yet on the 29.9, but it didn't really look very different from the 24. We'll just build up the adhesive if we need to, but I don't think it's going to be a problem. We're going to do a dry fit this weekend so we'll know more then.

[S/V Alchemy]

Originally Posted by Guy

Spring for nice clamps that don't rust, ever.

I prefer AWAB clamps over Tridon, which are typical. You don't get shredded hoses.

[model 10]

Originally Posted by S/V Alchemy

I prefer AWAB clamps over Tridon, which are typical. You don't get shredded hoses.

AWAB clamps are pretty nice, $5 each for a 11/2" clamp.. Rust free too.

[HopCar]

You might consider using the Groco Flanged Adapters with Ball Valves. These allow you to change the valve portion without removing the thru-hull.

Groco Flanged Adapter IBVF


The Groco backing blocks do make this project a lot easier.
Groco Seacock Backing Block


I'd love to quote you on the parts you need for this project. I'm a distributor for both Groco and Trident. Email me a list of what you need and I'll work up a quote for you.

[NahanniV]

Originally Posted by transmitterdan

I don't like GPO3 fiberglass in a bilge because it is not as water resistant as G10. If the budget allows I would use G10 over GP03. Also, GPO3 is not as dimensionally stable as G10. McMaster-Carr has both types of fiberglass I believe.

Really ?

Isn't his hull closer to GPO3 than G10 ?

How about the dimensional stability of the bronze ?

I think this is why we use flexible bedding.

Cheers,
JM.

[transmitterdan]

Take a big sheet of GPO3 and prop it against the wall at about a 30 degree angle. Do the same with a piece of G10. Check back in 6 months and tell me which piece you want keeping the water out of your boat.

[NahanniV]

Originally Posted by transmitterdan

Take a big sheet of GPO3 and prop it against the wall at about a 30 degree angle. Do the same with a piece of G10. Check back in 6 months and tell me which piece you want keeping the water out of your boat.

I don't get your point ?
I'm not going to do that experiment, so what would happen ?

The bedding/sealant keeps the water out (?).

My point is that the GPO3 is close to, but slightly better than most fiberglass hulls.

Cheers,
JM.

[jpstevens]

I used Compass Marine's system and was very happy with the results. Set in thickened epoxy and filleted around the edges, that pad ( I built up my own) is not going to move.

[Lepke]

Interesting. My thru hulls and valves are mostly 1942. I take them apart, clean and inspect when ever the boat is out of the water. Properly zinced and cared for, they should just about last forever.