Prop-er job
Even today, with so much evidence on the table, production sailing yachts are routinely fitted with fixed-blade propellers. And yet it has been demonstrated repeatedly that a feathering or a folding prop is capable of delivering up 95 per cent less drag than an old-fashioned unit. On the average 40-footer, this amounts to perhaps 30kg less drag at 5 knots, adding upwards of half a knot to your sailing. And yet, these modern propellers are usually considered an ‘extra’ on new boats, while most secondhand boats still have their original fixed propeller.
If you are repowering your boat, it is a golden opportunity to upgrade a propeller that will probably need to be changed in any case. But it’s also a no-brainer for any serious sailors, whether you’re a club racer (think what an extra 0.5 knots would do to your performance) or a bluewater cruiser, where the prospect of 10 per cent faster passage times could save days on an ocean crossing.
What you want in a prop
A good propeller should always be designed as part of the broader drive train of a boat. To supply the right propeller, the manufacturer will need to know the power of the engine and its rpm, the reduction ratio of the gearbox, direction of rotation and the space
