Canadian Yachting May 2016 - (Page 26)

Perfect Prop for your Purpose Part 2 By Rob MacLeod Figure 1: Components of the Marine Drive System A propeller is only as effective as the rest of the drive system. This is a bold statement; but the two experts I talked with while researching this article agree. Robert Huber of Wiggers Marine in Bowmanville, ON and Jamie Fuderer of Kawartha Prop Repair in Buckhorn, ON confirmed that, although it is critical to have the right size, pitch and type of propeller for your boat to gain maximum power from your marine engine, there are a number of inhibitors in the rest of the system that can rob your engine and prop of their ability to propel your boat at maximum speed. Those other parts of the system include the motor mounts, coupling, stuffing box, shaft log, strut (sometimes referred to as a P-bracket) and the cutlass bearing. In addition, if the sacrificial anode attached to the propeller shaft is installed too close forward of the cutlass bearing it can restrict the flow of water over the bearing resulting in increased friction, loss of power and pre-mature failure of the cutlass bearing. Water is the lubricant for the cutlass bearing. Let's define each of the drive train 26 components and some of their variables. For the sake of this article, we are assuming the engine and transmission are operating at peak efficiency. THE MARINE DRIVE SYSTEM In an excellent article on Drive System Alignement in YachtSurvey.com (www.yachtsurvey.com/Alignment2.htm), David Pascoe explains that although the connection of the shaft coupling to the transmission coupling can be aligned to within a few thousands of an inch, the rest of the system "is essentially a freefloating, semi-self-aligning system". How does he explain that? Rubber. Starting with the rubber in the engine mounts the propeller shaft floats - and flexes - on a combination of flexible mounts through the stuffing box, the shaft log and the cutlass bearing in the strut. Engine (Motor) Mounts - play the vital role of holding the engine off the hull of the boat, absorbing vibration from the engine and having the capacity to adjust C a n a d i a n Y a c h t i n g MAY 2016 http://www.yachtsurvey.com/Alignment2.htm http://www.YachtSurvey.com http://www.yachtsurvey.com/Alignment2.htm

Table of Contents for the Digital Edition of Canadian Yachting May 2016

Vantage Point: Wood you ever go back?
Waterfront: Marine News
Club Profile: Midland Bay Sailing Club
Boat Handling: Embarrassment-free Docking Tips - Docking your boat is not rocket science but it also can be intimidating. Follow these clearly outlined techniques to improve your docking performance. By Brenda and Doug Dawson
Shafts and Propellers: Props Part 2 - Part 2 focusses on the other parts of your drive system that can be critical to either maximizing your propellor’s effectives, or robbing it of the ability to perfom its best. By Rob MacLeod
Destination: Azores - The Shards take sabbatical in the Portuguese islands of the Azores in the middle of their transatlantic crossing. Offering stunning landscapes steeped in history, this traditional provisioning waypoint for pilots and sailors is now a blossoming charter destination. By Sheryl Shard, Photos by Paul and Sheryl Shard
Behind the Scenes: MJM Yachts - Made exclusively by Boston BoatWorks, learn how MJM combines old principles of boat design with modern techniques to produce, light, stable and extremely fuel-efficient yachts. By Kate Fincham
Sail Review: Marlow-Hunter 31
Power Review: Jeanneau Leader 46
Power Review: Everglades 230 CC
Crossing the Line: The 180-second Workout

Canadian Yachting May 2016