Thursday, 22 July 2010

Driving a Sailboat Astern/Reversing Technique for Sailors

Sailboats and yachts are built to go forward on the wind. However, from time to time we need to go astern, so every sailor needs to learn the technique of driving his vessel in reverse and become proficient at it, particularly when crossing stretches of water with a current and also winds. This is one of the most difficult things to achieve in the early days of sailing when there is so much of eveything else to learn. not only do you have to contend with current and wind, but a phenomenon known as prop walk.

When looking forward at the stern of your boat and say the prop spins clockwise (right hand prop), then the action of it through the water will tend to kick the stern to starboard.

When in reverse your prop is rotating anti clockwise, so then its energy will try to kick the stern to port. When you are in forward gear it is never a problem as a minute adjustment on the helm controls it. If the propeller is a left hand prop, then the action is the opposite.

However, in reverse going astern this whole process can be very difficult to manage at the best of times and even more difficult when you are contending with the wind and possibly current as well. Some sailboats are much worse than others! When you are buying yours have the owner or broker drive the boat astern to see how they manage it.

The video below gives you some idea of the problem and how to overcome it. It has been produced by Tom Cunliffe, a well known sailor and instructor of all things sailing.

In my experience, the most simple solution and best way to overcome this problem is to fit a good quality feathering propeller -not to be confused with a folding prop.

A feathering propeller has several major advantages and they are:

The blades follow the flow of water so drag is far less and boat speed increases.

Because the drag is less, improved fuel economy is the result when motoring.

And the real killer is that any good quality feathering prop will give 85% or better driving power when going astern and therefore eliminate prop walk.

This enables you to steer the boat in reverse quite easily even in a strong breeze.

I fitted one to my yacht prior to crossing the Pacific and it was a dream to use when going astern and in addition gave on average 1.5 knots greater boatspeed when under sail. This is a major increase in boatspeed and means an extra thirty to forty nautical miles per twenty four hour period. This is huge when you consider that that extrapolates to four hundred or so nautical miles on a ten day passage, possibly shortening the passage by two to three days.

Video courtesy Tom Cunliffe and Yachting Monthly and images courtesy Google images.

You can read more about fitting and the performance of feathering propellers in my ebook 'Voyage of the Little Ship Tere Moana' downloadable from my website

1 comment:

Unknown said...

Hi there is stern drive props The below propeller brands will fit on your selected MerCruiser engine. However, to ensure proper loading of your engine, please choose the propeller size that most correctly matches your existing propeller. Please use the engine filter above to narrow your MerCruiser propeller options to your specific engine.
The large motor was then bolted to the inside of the boat, usually in a motor house, with the propeller advancing through the stern, driving the vessel forward.