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Shaft Lok

Posted: 31 December 2022

Shaft Lok provides a means to safely lock the propeller from spinning whilst sailing. This ensures noise from a spinning prop and shafting is eliminated. A spinning prop can also build up heat in the transmission and lead to unnecessary wear. Long term freewheeling will wear all drive train components unnecessarily.


 Unit Specification


MOD-2 High Torque


 MOD-3 High Torque

 Disc Diameter
 7"  12 1/4"
12 1/4"
 Shaft Space Required
 2"  3"  3"
 Maximum Shaft Dia
1 1/4"
 2"  3"  3"

0.6 pitch/dia ratio

 26"  30" 30"

0.8 pitch/dia ratio

 24"  30" 30"

1.0 pitch/dia ratio

 22"  26" 26"


While sailing SHAFT LOK locks the propeller in the most efficient position, vertical in the rudder and keel opening (if that is what you desire), for the best boat speed,quiet operation and without transmission or propeller shaft bearing wear.

A spinning propeller will cause more drag due to the propeller windmilling, generating greater drag than when stationary. Hence locking the propeller will eliminate drang and thus facilitate speed. During a manufactures comparison tests it was discovered that a standard 15 inch diameter 3 blade propeller increases the resistance of the hull by 48 pounds, the equivalent of dragging a large bucket behind the boat. Shaft Lok by design holds the propeller stationary regardless of yacht speed. All that is necessary to release the lock is to start the engine and engage the transmission. SHAFT LOK automatically unlocks.

Shaft-Lok fits to the shaft between the shaft half coupling and the gland, so it is necessary that there is enough space for the disc to rotate clear of the bottom.

The unit is engaged by pushing down on the knob directly, or via the remote cable if fitted. This is more easily done if the boat is brought head to wind for a short while or boat is slowed right down by use of reverse gear before shutting the engine off. It automatically unlocks after the engine is re-started and put into reverse gear for a moment.

Maximum cable length is 13 feet. Sometimes longer cables can be provided depending on the routing of the cable itself.


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