hole in the bottom of my boat, can't plug it

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scrambledegg

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Sorry if my title's a bit melodramatic. The humdrum truth is I've taken off the stern seal and can't find a replacement. Boat is on the hard, no imminent danger of sinking.

My dripless Volvo seal on my boat's 1" shaft gave up the ghost at the end of last season, not at all surprising as it was more than 15 years old. Problem is I can't find a replacement dripless seal that fits a 1" shaft and a 48mm (~1&7/8") o.d. stern tube, except ones that require a pressure water feed inlet and (in one case) outlet (such as PSS, DeepSeaSeal). Non-water-fed shaft seal offerings from Volvo and Radiche match a 1" shaft to 42 or 43mm o.d. tubes.

I just can't be the only one to hit this problem. I am boggled that Volvo etc make seals that fits just one diameter of stern tube. The original volvo seal on the boat has a part number that doesn't exist any more (888738) . I don't know if that seal actually fitted, or whether the original fitter just got very creative about fitting it.

Anyone out there found a good work-around for this?
Must I bite the bullet and arrange for a pressure water feed (how is that done)?

Thanks for any suggestion
 
When I had a Sadler with a 1" shaft I'm fairly sure that I fitted a 2.5cm seal following advice at the time. This functioned for many years until I sold the boat.
 
Graham_Wright said:
Mine is just a bleed from the exhaust outlet. Simple - 8mm tube.
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ok, that would certainly be simplest, as the exhaust passes close to the stern seal. But I'm curious: I'd expect the water in there to be at lower pressure and full of bubbles of exhaust gas. Does that actually work, and would that actually push exhaust water through the seal, or suck external water up through the seal?
 
scrambledegg said:
ok, that would certainly be simplest, as the exhaust passes close to the stern seal. But I'm curious: I'd expect the water in there to be at lower pressure and full of bubbles of exhaust gas. Does that actually work, and would that actually push exhaust water through the seal, or suck external water up through the seal?
Click to expand...

I don't think I'd do that.
 
scrambledegg said:
ok, that would certainly be simplest, as the exhaust passes close to the stern seal. But I'm curious: I'd expect the water in there to be at lower pressure and full of bubbles of exhaust gas. Does that actually work, and would that actually push exhaust water through the seal, or suck external water up through the seal?
Click to expand...

It's before the exhaust inlet, just after leaving the heat exchanger.
 
Graham_Wright said:
It's before the exhaust inlet, just after leaving the heat exchanger.
Click to expand...

Taking water from there would reduce the cooling of the exhaust system. And I'd want to put a vacuum valve high up in the pipe to make sure seawater from the shaft tube doesn't flow back into the engine.
 
pvb said:
Taking water from there would reduce the cooling of the exhaust system. And I'd want to put a vacuum valve high up in the pipe to make sure seawater from the shaft tube doesn't flow back into the engine.
Click to expand...

The water output from my exhaust is "impressive"! I don't think an 8mm bore tube is going to reduce that much! The function of the feed to the seal is just to lubricate it in case insufficient goes back up the stern tube.

There is a vacuum break.
 
Graham_Wright said:
The water output from my exhaust is "impressive"! I don't think an 8mm bore tube is going to reduce that much! The function of the feed to the seal is just to lubricate it in case insufficient goes back up the stern tube.

There is a vacuum break.
Click to expand...

I meant a vacuum valve on the pipe to the stern seal.
 
pvb said:
Taking water from there would reduce the cooling of the exhaust system. And I'd want to put a vacuum valve high up in the pipe to make sure seawater from the shaft tube doesn't flow back into the engine.
Click to expand...

Could you explain that? why would it be a problem if water from the shaft tube enters the engine (presume you mean raw-water side of the cooling circuit) ?
 
I don't have the measurements to hand but I had a a similar problem. I just happened to have a PSS seal at the time that would not fit and noted that it had a removable insert to step down the diameter of the stern tube fitting. This insert was a perfect adapter for the Volvo fitting too, just stuck into place with some sikaflex. Aquafax are the suppliers of PSS as I recall and they will sell the adapters separately but it will need a telephone conversation with them to confirm sizes. As has already been flagged, I would imagine that sillette can offer something similar.
 
RivalRedwing said:
I don't have the measurements to hand but I had a a similar problem. I just happened to have a PSS seal at the time that would not fit and noted that it had a removable insert to step down the diameter of the stern tube fitting. This insert was a perfect adapter for the Volvo fitting too, just stuck into place with some sikaflex. Aquafax are the suppliers of PSS as I recall and they will sell the adapters separately but it will need a telephone conversation with them to confirm sizes. As has already been flagged, I would imagine that sillette can offer something similar.
Click to expand...

Aha! Could this be what you mean:
vetus plastic hose adapter.jpg
(hope that displays)
Vetus plastic hose adapter
 
vyv_cox said:
You don't need a pressurised feed for a PSS unless the boat is a lot faster than a yacht auxiliary. 12 knots is what the instructions say http://www.shaftseal.com/pss-installation-instructions.html I have a vent tube running from the seal to just below the companionway top step, well above the water level.
Click to expand...

That's very good to know, thanks.
I may have to go with the PSS, provided it fits into the limited gap I have between gearbox coupling and stern tube.
 
Have you asked Volvo Penta through their own web site? I needed a part that was no longer available so I asked and a few days later got an email saying what the replacement part was.
 
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