Shaft Seal Cooling Hose Barb Ripped Off!

[Jamme]

I can generally tolerate many things; sinking is not on the list for now… Here’s what happened today; pics at the bottom of this post.

I was doing regular commissioning work on my Beneteau 31 for the season (prepping engine, visual checks etc.). Boat is already in the water.

I noticed some rust on the shaft seal hose barb. A more careful inspection revealed that the junction between shaft housing and barb is completely gone — the barb stays “magically” in place (simply because the water pressure is not too strong) but as soon as one touches it, it comes off its housing, springing a dangerous leak into the boat.

So here are a few questions for you:

1. Does a proper repair require another haul out. I don’t want to take shortcuts, so it’s fine if I need to.

2. Has anyone seen this type of hose barb attachment (apparently glassed into the housing as opposed to attached to the shaft seal itself). How is this barb attached to the shaft seal? How does one repair it?

3. I am thinking about replacing the entire seal with a new one. Any suggestions/ recommendations or should I just go with the same model. What model is this?

Thank you in advance, apologies if this is a duplicate, and fair winds to all.

[skipperpete]

Don't panic, it's easily managed with a rubber bung and a hose clamp around the tube for added security until you settle on a repair plan. What is important is to know where the flexible hose goes to, if it's just a vent line to allow air in the stern tube to escape, no problem but if its a water feed from the raw water side of the cooling circuit it will become a source and could cause flooding problems if the engine is running. finally there is the vague possibility that the vent loop (siphon break) has been plumbed into that line,really bad engineering definitely but I've seen it done before (and into the aqua lock).
How many hours has the shaft seal been run for? Have you replaced one of those "volvo" type seals before, they can be a bit tricky first time.

[SY Harmony]

That barb IS NOT part of the shaft seal. It is part of the stern tube. Something Beneteau made. The black rubber shaft seal is Volvo iirc.
I’d just do as above. Clamp a piece of rubber over it, or glass it over. Or a piece of aluminum with life caulk and a couple hose clamps.

The hose is there to let trapped air escape when you splash. So no need to fix it until the next haul out with a good patch in place.

[DUNCANMAC]

That's a new one for me. I replaced my psst dripless seal recently. The mechanic insisted on the vent tube. Old one didn't have it. I actually like the Volvo design better. I agree with the previous poster. Not a big deal but you will want to properly plug that tube when you can. My understanding is the vent allows water to ingress and help cool the friction of the shaft and seal . At the rpm most sailboats run I think it's a mute point.

[Jamme]

Thank you both.
The flex tube comes from the heat exchanger, so I suspect water flow from the heat exchanger is required to lubricate the seal. If I glass it, not sure of the consequences.

Engine (and shaft seal AFAIK) has 500hrs.

[SY Harmony]

Originally Posted by Jamme

Thank you both.
The flex tube comes from the heat exchanger, so I suspect water flow from the heat exchanger is required to lubricate the seal. If I glass it, not sure of the consequences.

Engine (and shaft seal AFAIK) has 500hrs.

Whats the rest of the exhaust system?
Raw water from the heat exchange should go into the exhaust hose to cool and discharge it.
Water is a good coolant but a bad lubricant

That looks to be a small diameter hose, maybe 3/8” does it go up to the radiator cap?

[Scubaseas]

Link below is the Volvo seal install manual. You can seal off the hose fitting. Either tap and install bronxe plug or fiberglass a patch over it. As mentioned a rubber plug and a hose clamp will work as a temporary repair. If you have a couple of toilet bowl wax rings you can seal the boat in the water by stuffing these between the hull and the prop shaft. Then use an underwater applicable epoxy like marine tex but you'll get a better repair with a dry surface by hauling out.

Be mindful to "burp" the air out of the seal when the boat when you relaunch. The seal has to be in water with no air in order to not overheat. You are supposed to grease it once a year or every 200 running hours.

https://www.generalpropeller.com/pdf...structions.pdf

[deblen]

Found this vid on Youtube by searching Volvo Penta shaft seal. There are quite a few more vids for this seal on YT.


Water for lubing this seal runs up the shaft tube,thru the slotted cutless bearing. No hose is required However,when you launch boat,you must "burp" this seal by squeezing it a bit to allow air in the shaft tube to be replaced by water.
Adding the hose & running it above the waterline aways would allow air in the shaft tube to exit via the little hose & save you the "once at launch" squeeze burp.
AFAIK,there is no reason that water should be pumped into that little hose. The VP seal will be sufficiently lubed ,as long as the boat remains afloat,by water running up thru the cutless & stern tube.
Hope this helps you decide whether the minor convenience of "auto burp" is worth the risk of that hose fitting.

https://www.youtube.com/watch?v=2dLDqNw3lns

[Mickeyrouse]

Originally Posted by DUNCANMAC

At the rpm most sailboats run I think it's a mute point.

I can confirm that. I installed a PSS seal during a major re-build in 2008. The yard mechanic convinced me the hose fitting wasn’t needed, so I capped it off. The engine has about 3000 hrs on it in the intervening 15 years, and the seal seems to be sealing just fine. Shaft speed rarely exceeds 1500 RPM.

[Jamme]

Thank you all very much for you input and experience.

I will temporarily seal the barb housing as recommended and test the shaft seal temperature by hand at the dock by running the engine in reverse. If the hose is not needed, as anticipated, the temperature should not raise. Otherwise, I will realize quickly and shut off before it’s too late.

If temperature stays cool as expected, I will permanently seal the barb housing on my next haul out.

Fair winds, and happy boating season (for those that live at my latitudes)! ⛵️

[NYSail]

The hose is needed. Beneteau design with the cutlass on the end of the shaft log limits water flow to cool things down. The hose is used to inject water into the shaft tube. Mine broke last season…… however mine has a separate thru hull fitting rather then the engine water. this is a common issue. I glasses in a stainless steel nut over the hole and bought a matching nipple and was done. Bought from McMaster-carr. Much stronger. Good luck!
Greg

[Bill O]

NYSail has a good repair w/a threaded receiver in the stern tube for the hose barb and would do something similar if I needed to permanently fix it.

It seems intentionally put there w/the Bene stern tube design, so wouldn't just cap it off/remove it.

[SY Harmony]

What’s different about the Bene tube design?
Where does the other end of this hose attach?

[deblen]

Originally Posted by NYSail

The hose is needed. Beneteau design with the cutlass on the end of the shaft log limits water flow to cool things down. The hose is used to inject water into the shaft tube. Mine broke last season…… however mine has a separate thru hull fitting rather then the engine water. this is a common issue. I glasses in a stainless steel nut over the hole and bought a matching nipple and was done. Bought from McMaster-carr. Much stronger. Good luck!
Greg

I stand corrected. Bene needs this cooling hose. Sorry/Len


https://forums.sailboatowners.com/th...nipple.184699/

[SVTatia]

What hasn't been discussed is why the hose barb failed in the first place.
It seems (by the picture) that a brass fitting was used - bad choice.
So as mentioned above, and if the hose is not needed, the OP only needs to find and install an SS plug fitting matching the threads.