June 13, 2020 - The Stuffing Box Story along with a pitted drive shaft - Puerto Vallarta, Mexico

June 13, 2020 - The Stuffing Box Story

As best we can, we have determined that not only did we have clunking stabilizers, but also a drive shaft system that has terrible issues.  FORTUNATELY, they were discovered by an able crew who were able to do damage control and get the boat to a port where we have access to a mechanic that is familiar with Selenes and has over 20 years of marine experience.

Since being hauled out on June 12th, there have been a series of discoveries as Ed West and Captain Nikolay Alexandrov continue to dig into our drive shaft.

This is an original (2008) Amartech shaft seal that consist of:

1) Cutlas bearing at the propeller

2) A fiberglass shaft tube from the propeller to the engine

3) A bearing in the fiberglass shaft tube - forward

4) A stuffing box fitted into a larger diameter, metallic, stern tube

As the team disassembled the system we learned that:

1) Propeller cutlas bearing was failing (it was sliding out and the shaft was loose)

2) The fiberglass shaft tube was heat damaged

3) The bearing in the fiberglass tube - forward - was 90% gone

4) The stuffing box was within 1/4" of totally disengaging from the outer metallic sterntube

Oh, and the shaft exhibits wear grooves and corrosion pitting!

It is suspected, due to the extent of the damage, that the offending event occurred well before the beginning of this trip.

I recall the prior Captain describing a learning event where the Get Home drive was used, and there was not a cooling source of water.  Subsequently, an electric pump had been added as part of the Get Home drive system.

Talking with Amartech about a root cause for failure their response follows:

The event seems to have been caused by a lack of water inside the stern tube (rubber bearings running dry or almost dry).

Similar to e.g. a rubber windscreen wiper, dry running causes huge friction and heat build up.

The aft stern tube bearing is near the propeller with lots of water around and in most cases the aft bearing will be hardly be effected by this.

The fwd bearing however will be quiclky destroyed.

The degenerating rubber will fill the bearing flutes and blocks the waterflow through the stern tube.

Because of the tremendous heat, the stuffing box and GRP stern tube will be affected in time as well.

Martijn Jouwsma

Blokland Propulsion BV - Sliedrecht, The Netherlands

It is unclear what event, or combination of events, caused the system to fail.  Another contributing factor could even be related to the haul out survey as I am uncertain if the owners Captain bled the air out of the stern tube.  However, in the survey it was noted that there was excessive water dripping underway as well as at rest.  And we did have the packing serviced and did a temperature check during our fueling run - cool to the touch.  

One other compounding event is that during our May 10 departure, Nikolay realized the stuffing box was over heating - up to 270F!  He disconnected the engine cooling water hose to hose down the exterior of the stuffing box and reconnected the cooling water.  We eased off the pressure on the packing to allow more water to drip at a much greater rate than a few drops per minute.  The box temperature came down and functioned normally with a much greater drip rate.

The root cause, or causes, will remain a mystery - all we know for sure is that the stuffing box over heated and that resulted in the failure.

Ed's plan is to get a new, improved, Amartech shaft seal system along with a new shaft and reassemble.

Could be in Mexico for 3 to 4 weeks!  YIKES!!!

Things not found during survey:

• Pitted drive shaft
• Failing shaft bearings - even though it had been serviced 2015 and 2016
• Bow thruster wiring issue
• Stabilizer system in need of significant maintenance even though reported they had been serviced in September 2019
• Failed Balmar regulator and missing thermal sensor connection

Blue fiberglass shaft tube resting in the stern tube exhibiting damage from prior bearing removal and heat.

Propeller cutlas bearing that has slipped away from shaft tube.

Propeller shaft with pitting and scoring from failed bearings.