During the moonless night we threw the longline near the shore. While going around the southern headland of the island an unexpected swell of a high wave nearly threw us to the rocks. The bow turned towards the land being on top of the wave and under the boat a big rock "flerting" with us.
The "rapid" push of the throttle level backwards saved us from the unpredictable consequences of the hit of our bow on the rock but it caused the inevitable. The propeller grabbed the longline and many metres of fishing line along with the hooks were wrapped around it. We noticed it immediately and in ten minutes we were at the beach where we set our small makeshift camp.
The next morning, we took the rib in shallow water and trimmed the engine out in order to release the propeller from the fishing line. We removed a lot of metres of fishing line but we realized that there was still plenty of it around the propeller shaft.
Then we had to take off the propeller and honestly we were surprised with the quantity of the fishing line that was around the axis tangled like a ball of yarn. We finally managed to clean the axis completely and I was ready to place the propeller back when I noticed a peculiar mass behind its thrust washer.
It looked like a big, of irregular shape, plastic washer. I took it off carefully and I started observing it. It did not take me a long time to understand that it was a melted fishing line which was solidified and formed into this peculiar shape.
Being relaxed at last, we brought the propeller back to the shaft and we set sail for our base. We covered 70 nm in less than three hours and early at noon we were at the parking space where we leave our boat.
The next week I went again to the boat in order to prepare it for a family trip to the Sporades Islands.
When I finished with the cleaning of the boat I headed to its stern to have a look at the engine.
I was surprised when I noticed that thick, white liquid was slowly dripping from the blade under the propeller. I came close and realized that this liquid, which looked like milk, was coming out from the gear case. No way though did my mind think that it was the fishing line the propeller had grabbed a week ago.I unscrewed the vent screw and removed the drain one from the bottom of gearcase. Instead of valvoline this thick, white liquid was coming out.
Taking off the propeller I realized that the shaft seal was ruined to such a great extend.
So, what had happened?
The big quantity of the fishing line, which was wrapped between the washer and the propshaft seal, and the local increase of temperature that was created due to its friction, caused the alteration of the seal. This had as a result the influx of water inside the gear box which being mingled with the valvoline formed this milky liquid.
We were lucky though, since the deformation of the shaft seal was relatively small in order not the whole amount of valvoline to leak during our three hour cruising a week ago.
What would have happened if the deformation of the seal was extended and the valvoline was replaced completely by the sea water? We would definitely not have the time to cover the 70 nm of our return and the cogwheels of the gear box would break due to the high temperature which would have been created.
Therefore, if our propeller ever grabs a fishing line, we should not be content just by removing it from the shaft but we should always check the integrity of the shaft seal which is behind the thrust washer and to be careful in case there is valvoline leak.