DIY Project

How to Handle Fishing Line Wrapped Around a Propeller

By Thomas P. courtesy of e-Ribbing.com

fishing line around a propeller shaft, fishing line damages propshaft seal

This looks harmless enough, but fishing line wrapped around a propeller shaft can be a major problem.

During a moonless night, we cast a fishing line near the shore. While going around the southern headland of an island, an unexpected rogue wave nearly threw us to the rocks. With the boat on top of the wave, the bow turned toward the land and underneath the boat, a big rock flirted with us. A rapid backwards yank on the throttle level saved us from hitting our bow on the rock but it caused the inevitable. The propeller grabbed many meters of fishing line that wrapped around the propshaft. In 10 minutes, we were on the beach where we made a makeshift camp.

Assessing the Damage

The next morning, we took our rigid-hull inflatable boat (RIB) into shallow water and trimmed out the engine to release the propeller from the fishing line. We removed many of meters line and realized that much of it was around the propeller shaft. We had to take off the propeller and we were surprised with the quantity of the fishing line that was around the shaft tangled like a ball of yarn. We managed to clean the shaft and were ready to place the propeller when we noticed a peculiar mass behind the thrust washer.

It looked like a big, irregularly shaped plastic washer. We took it off carefully and after careful observation, we realized it was melted fishing line that had solidified. We installed the propeller and headed for home. We covered 70 nautical miles in less than three hours and by noon we were back in our home slip.

The Dreaded Vanilla Milkshake

The next week we went down to the boat to prepare it for a family outing. While inspecting the engine, we noticed a thick, white liquid dripping from under the bottom propeller blade. The liquid, which looked like milk, was coming out from the gear case. After we removed the fluid-draining plugs in the lower unit, the dreaded thick white milkshake that is a sign of the propeller shaft seal being damaged, oozed out.

Draining outboard lower unit lube, draining gear lube

This is not what we want to see pouring out of a lower unit.

What Had Happened?

The fishing line wrapped between the washer and the propshaft seal and the temperature increase caused by the friction damaged the seal. When the seal is damaged, water enters the gearcase and mixes with the lubricant resulting in the milky liquid.

lower unit gears, outboard gears

Fortunately, the gears in the lower unit were not damaged.

We were lucky that the damage to the shaft seal was minimal so not all of the lubricant leaked out during our voyage home. If the damage to the seal had been more extensive, the gear lube would have been replaced by water and the gears would have likely seized.

damaged propshaft seal, propshaft seal destroyed by fishing line

It’s hard to believe that fishing line could do this kind of damage to the propshaft seal.

If our propeller ever grabs a fishing line, we should not be content just by removing it from the shaft. Always check the integrity of the shaft seal behind the thrust washer and be careful if any dripping white fluid is seen.

By Thomas P. courtesy of e-Ribbing.com