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 |
MOD-3 High Torque
| Disc Diameter |
| 7" |
| 7" || 12 1/4" |
|12 1/4" |
| Shaft Space Required |
| 2" |
| 2" || 3" || 3" |
| Maximum Shaft Dia |
|1 1/4" |
| 2" || 3" || 3" |
0.6 pitch/dia ratio
| 26" |
| 26" || 30" ||30" |
0.8 pitch/dia ratio
| 24" |
| 24" || 30" ||30" |
1.0 pitch/dia ratio
| 22" |
| 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
diameter 3 blade propeller increases the resistance of the hull by 48
pounds, the equivalent of dragging a large bucket behind the
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.
Click on an image for a larger view.