Shaft temp after stern Gland replacement

[skippy2]

Hi everybody,
I have just replaced the old packing gland with a Radice RMTA dripless shaft seal (a reengineering of the Volvo Shaft Seal).

The seal has a hose connector that should be used, as the datasheet says, for lubrication water inlet.

The stern tube and the seal are well under the flotation level and the flow of water, removing the seal, is plentiful.

After reading several advices on this and other forums I connected a hose without connecting it to a pressurized water source, but taking it well over the floating level and leaving it open as a vent because the low speed of a sailboat, I read, should not create issues in water flow.

After going out for a test of 30-40 minutes at cruise revs (2200 RPM, the engine is a Bukh DV20) I returned in port and, after mooring, I checked the seal touching the seal itself and the shaft.

The seal is almost cold (the atmosphere temp was about 18°C)- just warm, the shaft a little more warm, not hot (can be touched without pain).

Is it normal or have I to worry about?

Thanks for your replies

[Roy M]

That's pretty normal. On a conventional wax/flax packing shaft log, I learned from my masters that you want the coupling nut and shaft to be warm at the touch, enough to allow the wax to slightly soften and allow enough water to enter and cool the shaft, about one drop per second, underway. When the shaft stops making turns, you want the wax to cool and shut off all drops within a couple minutes. This is a dynamic process. Over time, with a conventional coupling, you will find that it leaks at rest, therefore requiring you to back off the lock nut, tighten the packing nut just enough to stop the leak, then retighten the lock nut. You keep doing this until the packing no longer stops the leak, then you repack the packing with the new wax/flax packing material. Other materials, such as teflon, work similarly, but with different schedules for tightening/repacking. My personal preference is old school for stuffing boxes, so my coupling is in a convenient location for maintenance. Repairing a dripless in the water is not for the faint of heart.