Shaft seal question

DJK · May 14, 2022

Can someone explain the function of the water hose on this type of shaft seal? I understand the “packing” type of seal and its adjustment but don’t understand the reason for the water inlet in the shaft tunnel. The black hose connects to a dedicated through hull.

Comodave · May 14, 2022

Usually the hose is from the engine cooling water and provides lubrication to the packing material.

DJK · May 14, 2022

Would that mean that this type of packing material should not drip?

Comodave · May 14, 2022

Not necessarily. It depends on the type of packing used. We used Duramax packing in our last boat that had traditional stuffing boxes. It didn’t drip after it was adjusted properly. But with other packing materials it would drip. That boat also had a hose from the engine cooling water to lubricate and cool the stuffing box.

psneeld · May 14, 2022

Or there might be another cutlass bearing at the top end of the shaft log needing water.

Arc · May 14, 2022

It’s not unusual to have a water feed drip box. The shaft angle may prevent water from reaching the stuffing while underway or they were concerned with overheating cutlass

MVSeafarer · May 17, 2022

That kind of gland should drip a bit underway. Might not drip while stopped depending on waterline relative to the gland.

eagle419 · May 17, 2022

DJK said:
Can someone explain the function of the water hose on this type of shaft seal? I understand the “packing” type of seal and its adjustment but don’t understand the reason for the water inlet in the shaft tunnel. The black hose connects to a dedicated through hull.

In my setup a similar hose connects to a through-hull to expel shaft-lubricating seawater.

This water is picked up near the prop via a small scoop inlet on either side of the shaft so the forward motion pushes the water up the shaft.

Mine is a very old boat, but your hose may do the same.

Comodave · May 17, 2022

MVSeafarer said:
That kind of gland should drip a bit underway. Might not drip while stopped depending on waterline relative to the gland.

Not necessarily. It depends on what type of packing is in the shaft log. On our last boat we had Duramax packing. It can be adjusted so that it doesn’t drip either sitting or underway.

DNT99611 · May 18, 2022

With a dry exhaust boat a scoop and hose is one way to get water to the stuffing box area. Not sure how you ensure flow or know if it stops.

Shaft seal question

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