Most sailors wouldn’t dream of tying a bucket to the stern before setting sail. And yet, in hydrodynamic terms, that’s roughly what many of us do every time we leave the dock.
The culprit? The fixed pitch propeller!
Fixed pitch propellers have plenty going for them. They’re simple, relatively inexpensive and provide good thrust; that’s why they’re still standard equipment on many production sailboats. But once you shut down the engine and start sailing, that propeller doesn’t disappear. It’s still down there in the water creating drag. And drag is something sailors spend enormous amounts of time and money trying to eliminate. Sailors fair bottoms, worry about dirty hulls, trim sails by the inch and if they race, obsess over appendages. All the while, there’s a substantial piece of metal hanging underneath the boat disturbing the water flow.
Modern folding, feathering and self-pitching sailboat propellers attack that problem by dramatically reducing the propeller’s resistance when you’re sailing. The potential difference isn’t trivial; sailors can gain as much as three quarters of a knot by reducing propeller drag. On a cruising passage, that’s worth thinking about.
Of course, there is no free lunch in Marine Engineering. Reduce drag one way and you may introduce compromises somewhere else. What will you trade? Power in reverse, efficiency under power, propeller noise, maneuverability? That’s where the subject gets interesting!
Over the next six posts, we’re going to look below the waterline and examine what your propeller is actually doing – both when you’re sailing and when you’re motoring.
And if you’re coming to the Annapolis show, stop by Bruntons Propeller / King Propulsion booth #YB3 (next to Latitudes and Attitudes magazine). Tell us what boat you sail and what propeller is currently underneath it.
If you need help now, call King Propulsion on (757) 739-2050 for a chat. You may be surprised by how much there is to talk about.
Next: Four propellers. Four very different personalities.
#Sailing #Sailboat #AnnapolisSailboatShow #SailboatPropellers
