Would you trust your propeller in Antarctica?
We’ve spent seven posts on propellers: drag, pitch, reverse thrust, cavitation, fuel economy and engine loading. Eventually engineering has to leave the drawing board and go to sea. Few places test it harder than Antarctica.
Xplore is a 67-foot Challenge business-class yacht, displacing 41 tons and powered by a 130 hp Perkins diesel. Skipper and expedition leader Stephen Wilkins takes her somewhere most of us would rather not discover a propulsion problem: the Southern Ocean and the Antarctic pack ice.
With some 300,000 nautical miles behind him, Wilkins needed power, reliability, simplicity, economy and low drag under sail. Xplore was fitted with a 590 mm Bruntons Autoprop H9.
Over 13,500 nautical miles of motoring and motor-sailing, Xplore typically ran her engine between 900 and 1,200 rpm when motor-sailing, and never above 1,600 rpm under power alone.
In pack ice and heavy wind, the self-adjusting blades responded to the load and put thrust where it was needed. Because the leading edge presents correctly in both directions, Wilkins reported equal thrust ahead and astern. That’s rather useful when the water around you contains ice.
Then the other side of the equation. Shut down the engine, lock the shaft and sail: Wilkins measured between three-quarters and nine-tenths of a knot more boat speed. On a schedule of 180 nautical miles a day, that adds up across thousands of ocean miles.
His verdict after Xplore’s first Antarctic season was simple. The Bruntons Autoprop propulsion system had “not missed a beat.”
Most of us aren’t taking our sailboats into the pack ice. But the questions are the same ones every owner should ask: can I trust it, will it give me the thrust I need, how does it behave in reverse, what happens when I motor-sail, and what happens when I shut the engine down and sail?
Tell us where your boat is going. It probably isn’t Antarctica, but we’ll take your propeller question just as seriously.
The show opens tomorrow. Come and see us at the Annapolis Sailboat Show, Booth YB3, City Dock, October 15–18. Tell me your engine model and I’ll size your propeller while you’re there. You’ll walk away with your sizing and show pricing on a postcard. No numbers needed: just know your boat and how you use her.
Thank you for following the series. See you on the dock.
#Autoprop #SailboatPropellers #CruisingSailboat #AnnapolisBoatShow #Antarctica
