Overheating packing gland - what should I do ?

[island trader]

arrrg!! looks like you have a problem. you need to get your drive engine slid forward some, packing needs replacement every so often and I can't see any room to get the cap nut far enough back.

[ribbony]

That is a good idea. I will have a dive under the boat to see how much spare shaft protrudes near the prop. I suspect it will be no more than 10mm as the idea was to reduce the extention there. I think the formula was the portrusion should be less than 50% og the shaft diameter (1 & 1/4").

So near, yet so far !

[GordMay]

ABYC Section P-6 Propeller Shafting Systems (6.5.5.4) limits the propeller overhang* to one shaft diameter.

This does not apply where the last bearing is installed aft of the propeller.

* The distance between the forward end of the propeller hub, and the aft end of the last strut bearing

[4HMainer]

Water is the best lubricant for stern gland stuffing, it is also the best conductor of heat.

Stern tubr bearings are often ruined by grease, it blocks the water flow and the bearing heats up, pinches and wears. If you're unlucky it will seize.

Water lubricates and cools very efectively.

[the chunkies]

Originally Posted by ribbony

Finally we have some mobility after two years of restoration. However we ran into a problem. The packing gland / stuffing box gets really hot while motoring about 1 km down the bay from mooring to jetty. The first time it happened it seized up and only turned after it cooled. I loosened it off quite a lot, the shaft turns easily by hand when it is cold. Then the next time we did the run (today) it happened again, not as fast but still it seized. What ended up turning, was the brass stuffing box turning in the rubber hose connecting to the stern tube.

When I assembled the shaft I used a lot of lanotec grease, as a result of that we have not seen any water drip from the shaft to date.

Any ideas on what is happening and just how hot do the stuffing boxes get ?

Hi Friend one of the problems with stuffing box's is how tight and how much water to let in. First normaly you have either 3 or 4 pieces of square stuffing material that looks like square rope these are cut to the circumfrance of the shaft and fitted with the joints at approx 30deg from each other I always use water pump grease and smear a little on them before fitting them. Then fit the front plate you will have either one that has a nut on either side or the type with one big nut which slides over the shaft. you should do these up just tight enough to have the water dripping at about 5-10 drops a minute. With the type that has 2 nuts 1 either side it is very important to make sure that they are pulled up at the same torque and the plate goes into the stuffing box straight. The best type of stuffing gland material is P.T.F.E as it doesnt get hot quickly and lasts a long time. I hope this is of help. Regards Pete new member

[migot1]

Originally Posted by ribbony

Finally we have some mobility after two years of restoration. However we ran into a problem. The packing gland / stuffing box gets really hot while motoring about 1 km down the bay from mooring to jetty. The first time it happened it seized up and only turned after it cooled. I loosened it off quite a lot, the shaft turns easily by hand when it is cold. Then the next time we did the run (today) it happened again, not as fast but still it seized. What ended up turning, was the brass stuffing box turning in the rubber hose connecting to the stern tube.

When I assembled the shaft I used a lot of lanotec grease, as a result of that we have not seen any water drip from the shaft to date.

Any ideas on what is happening and just how hot do the stuffing boxes get ?

THE ENGINE IS NOT INLINE WITH THE SHAFT! GET A PRO AND HAVE THE MOUNTING RE LINED!!!

MIKE

[migot1]

GET THE ENGINE RELINED! THE MOUNTING HAS TO BE RELINED!

[Maine Sail]

Originally Posted by ribbony

Picture did not work. Here is a link to the photo: Project Yacht

If that's all the room you have to work with haul the boat and replace that stuffing box with a Las-Drop or PSS dripless type seal. That stuffing box will be next to impossible to re-pack without moving the engine forward. Even removing the Drive Saver only gains you 3/4 of an inch of your shaft/prop spacing to the strut allows it..

[ribbony]

In the long term we will have to fix up this drive train so it can be more maintainable, a dripless gland or shorter coupling to get more room for repacking.

The coupling was not quite what we had ordered from the supplier, it should have been shorter, the grub screw you see on the brass coupling does not hold the coupling on to the shaft instead it locks in on the nut that holds the coupling on to the tapered end of the shaft. But, all that is a long story and we are stuck with it for the time being.

Once the water clears in the bay (weeks of rain) then we can dive under the boat and have a crack at the problem from both sides. Until then the electrical system is being done & there is a great birds nest of wires around the interior.

Thanks for the tips and tricks, we will keep advising of the progress.

[donradcliffe]

I have a similar tight fit, and just lift up the back of the engine until the transmission flange is above the prop shaft flange, letting me slide the prop shaft forward.

[ribbony]

Ooooh, I like that. After kifting the engine, I may have to remove the flange to get at the packing gland properly but that is a lot better than slipping the vessel. Thanks.