Bilge Flood, Dripless Shaft Seal Suspected

[Alan Gomes]

At about the 25 min mark the video really lets the "expert" bloviate. He has opinions mixed with attitudes.

Yup. I don't care much for dripless seals either, but this guy's criticism of them is way over the top and actually bordering on hysterical.

I'm with Ray on this one. I'm using the GFO packing, however. I only rarely have to make an adjustment to it, and when I do it's really easy. (I haven't touched the adjustment in over a year.) I've read that the clay stuff is kind of a pain because it's messy when it comes time to remove it, but I have no first-hand experience with it. I do know that MaineSail really abominates the stuff. But then, he also has some criticism of the GFO packing in terms of potential galvanic damage, especially if one has a bronze shaft. But I've seen no obvious evidence of that on my stainless shaft--so far. Since the GFO works well for me I've seen no reason to look beyond that.

 

[ConchyDug]

Dripless seals are common in the marine industry this isn't new science. Most commercial vessels and high output marine powerplants use a type of dripless shaft seal. There isn't some poor squid packing a gland nut on an Ohio Class sub. A lack of proper installation and continued maintenance causes a lot of systems to fail early. Just assess, mitigate and annotate then move on. Also, I found this in the PSS rebuild kit a friend gave me.


I like how Walter says, "they created a solution for a problem that doesn't exist". Yet if you go to his site he is promoting a hydrofoil lifting effect boat for servicing offshore wind farms... which is a market that's already serviced with O&G crew/supply boats, barges and helicopters.

 

[Kenneth K]

You could still use the engine to charge batteries, just not put it in gear. But we are sailboats.

As Christian says, a failed PSS (like many other engine related issues) may prevent you from motoring, but it shouldn't sink you boat.

Without prior planning or a cache of supplies, I was able to wrap my ruptured PSS with trash bags and zip ties, enough to slow the leak to a rate that a single Rule centrifugal bilge pump could stay ahead of. After a few dives to pack material into the shaft log, the leak was reduced further until the boat was finally hauled and towed 5 days later. I never had more than about 3-4" of water in the bilge.

 

[Kenneth K]

Latex cloth (per Christian Williams) or rubber from an old inner tube would be even better.

 

[Christian Williams]

Today's update:

I proceeded to remove the blue hose. When I turned off the valve on its thruhull valve, water continued to pour out of the hose. Same rate as with the valve open. You gotta be kidding me. No way. Is it possible to misunderstand this simple valve?

Well, I tried misunderstanding it, and failed. So I went to The Boatyard -- that's the name of the fancy MDR yard that installed the dripless --and they didn't understand it, either.

So they're sending somebody to take a look. Hmmm. Been like that for two years?

Valve in open position. Closing it has no effect on flow. Huh?

 

[Nick J]

This plumbing makes absolutely no sense. Valve closed, water comes from the shaft log, valve open, water comes from the thru hull or shaft log. This port is supposed to have water flow through it to avoid air getting trapped in the shaft log. The seal relies on water to lubricate the mating surface so air wouldn't damage the seal. In high speed boats, the water is forcefully
supplied by the raw water cooling system which would displace any trapped air. On our low speed vessels, simply venting this port well above the water line ensures any trapped air is allowed to escape. This typically only happens at launch or maybe a bad broach. The crazy part to me is how much trouble you've had with your yard in figuring this out. The only advantage I can see with this configuration is allowing slightly more room for trapped air to accumulate before it's an issue.

My vent is the large black tub in this picture. It runs up to just under the starboard lazarette lid. This was as high as we could reasonably get it and centered so a hard broach that left us on our ear for a long time wouldn't cause any issues. You should be able to remove the blue hose from the thru hull and hold the open end above the waterline as a proof on concept. Once you're satisfied, you could ether connect it to another piece of hose to get the open end to a comfortable height or replace with a longer section (port will let water in until the new section is placed and secured if done in the water). Other option is to plug the port as noted above and just burp the seal after haul out or when trapped air is suspected.

 

[Christian Williams]

You don't even have to vent it, says Eric Young at PYI.

The real puzzle is a valve on a thruhull that doesn't shut off. They're coming for a look tomorrow morning to straighten out either me or the valve.

 

[Kenneth K]

This plumbing makes absolutely no sense...... simply venting this port well above the water line ensures any trapped air is allowed to escape.

Exactly. Even ignoring the (always open???) valve, the raised loop makes no sense. When the boat was launched, the tube full of air. I see no way for the entrapped air to escape, so it can't "vent" the PSS. It seems all they built was a trapped-air loop, which would still require burping the PSS after launching.

 

[Loren Beach]

For a moment there I thought that photo in reply 46, was from the interior of the Space Shuttle. Wow!

 

[Kenneth K]

The original PSS for sailboats (low speed boats) had no vent. Burping was only required after launch. I asked my yard to put in a new PSS in 2021, but they said the new vents only cause problems: 1) the need for an interior vent or a thru-hull, 2) dissimilar metals corrosion of the vent barb (is it not stainless steel?), and 3) creating another (un-needed) open hole (or two, if you add a thru-hull) in the boat.

My yard just put a rebuild kit on my old PSS and sent me on my way. So I think just plugging the vent hole and burping the PSS after launch is a viable option.