I am considering a change to a veriable pitch propeller. I have a problem when reversing, the boat "walks" to starboard. Full rudder to port seems to make little difference. I bought my craft in aug. of '06, I found if I pulled the boat half way out of the slip then engaged reverse I could take advantage starboard torque. That's ok in my home port, but I plan to sail on the great lakes. I would like more control in new and unknown ports. Can anyone give me an opinion on different types of props, solid w/ a different pitch, veriable pitch, collapsing or any way to counteract the "walking" to starboard when in reverse. Thanks to all responses and remember SPRING is almost here in Michigan. Time to sail. Dennis
Propeller for H-27, '78
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Moe Horenfeldt
How to take advantage of "Prop walk".
My boat came (used) with a CDI 2 blade prop. It is very efficient and works very well forward or reverse. The boat is slightly underpowered with a Yanmanr 2GM, (I would have preferred a 3 cyl. or even an Atomic 4) as it is only 15 HP. Leaving the dock (my slip has the walkway to starboard) I retain one spring line looped around a cleat, holding the boat to the dock, from the cockpit. This keeps my stern from moving to port and hitting my neighbour. As the boat begins to move backward and we get some way on, I allow that line to be tossed up on the dock. By now the rudder has some purchase, and I can motor straight back with no prop walk. In a tight manouvering spot, I can literally, turn the boat in its own length, by taking advantage of the prop walk to turn the stern to port, regardless of the rudder position, as you have mentioned, and by shifting from forward, (where the rudder does have an effect), and keeping it turning the boat to starbord, the boat becomes very manouverable. If you decide to back into a slip, a little practice in an opoen channel, will give you more confidence ion your "driving" ability.
My boat came (used) with a CDI 2 blade prop. It is very efficient and works very well forward or reverse. The boat is slightly underpowered with a Yanmanr 2GM, (I would have preferred a 3 cyl. or even an Atomic 4) as it is only 15 HP. Leaving the dock (my slip has the walkway to starboard) I retain one spring line looped around a cleat, holding the boat to the dock, from the cockpit. This keeps my stern from moving to port and hitting my neighbour. As the boat begins to move backward and we get some way on, I allow that line to be tossed up on the dock. By now the rudder has some purchase, and I can motor straight back with no prop walk. In a tight manouvering spot, I can literally, turn the boat in its own length, by taking advantage of the prop walk to turn the stern to port, regardless of the rudder position, as you have mentioned, and by shifting from forward, (where the rudder does have an effect), and keeping it turning the boat to starbord, the boat becomes very manouverable. If you decide to back into a slip, a little practice in an opoen channel, will give you more confidence ion your "driving" ability.
No cure for prop walk
A new prop can increase acceleration, reduce drag, provide a better match with your engine, and/or improve reverse power, depending on the design you choose. But prop walk - the tendency of the prop to push the boat consistently to one side or another - is caused by the angle of the propshaft, and the physics of increasing pressure with depth. So a new prop will not help much. Instead, continue the thinking that has you taking advantage of propwalk. Thinking through docking and getting underway will always suggest a solution that has you under control by using and taking account of the predictable effects of propwalk. We cruise the Great Lakes (all but Lake Michigan, so far) and I can tell you that this approach works well for us and others. Search the archives for lot's of discussion of this topic, and ideas for using this "feature" to your advantage. David Lady Lillie '77 h27
A new prop can increase acceleration, reduce drag, provide a better match with your engine, and/or improve reverse power, depending on the design you choose. But prop walk - the tendency of the prop to push the boat consistently to one side or another - is caused by the angle of the propshaft, and the physics of increasing pressure with depth. So a new prop will not help much. Instead, continue the thinking that has you taking advantage of propwalk. Thinking through docking and getting underway will always suggest a solution that has you under control by using and taking account of the predictable effects of propwalk. We cruise the Great Lakes (all but Lake Michigan, so far) and I can tell you that this approach works well for us and others. Search the archives for lot's of discussion of this topic, and ideas for using this "feature" to your advantage. David Lady Lillie '77 h27
A
A.J. Wortelboer
Walk the talk
Yes, it is a fact that all single screw boats walk from "prop walk" one way or the other. My Cheribini Hunter walks the same way to Starboard. What is strange is when you play captain on a boat that has the oposite engine rotation and it goes the other way. I do like the other post said, hold the boat to the dock with a spring line till I get a flow of water across the rudder then let go when I have motion. With the helm all the way over it will usually back straight. If I need a little more control put in netural and let your "way on" give control back to the helm. With practice as the other post claimed you will get use to it and the "walk" can somtimes get you out of hairy pridicuments.
Yes, it is a fact that all single screw boats walk from "prop walk" one way or the other. My Cheribini Hunter walks the same way to Starboard. What is strange is when you play captain on a boat that has the oposite engine rotation and it goes the other way. I do like the other post said, hold the boat to the dock with a spring line till I get a flow of water across the rudder then let go when I have motion. With the helm all the way over it will usually back straight. If I need a little more control put in netural and let your "way on" give control back to the helm. With practice as the other post claimed you will get use to it and the "walk" can somtimes get you out of hairy pridicuments.
B
Benny
You have a challange!
The h27 Cherubini has the worst manners in reverse than any other. Changing of the prop will not solve that so the challenge is to learn to use it to your advantage. Many a times I have backed up of a transient slip with the boat facing in the wrong direction but with the knowledge that by using prop walk I can turn the boat around on its axis. Our 27 has a Yanmar GM1 and walks to port. To back out of a slip utilize a spring line to hold the boat in position until it gains way, if there is little wind or current you can shift to neutral and let the boat just coast out or you can alternate between neutral and reverse. (there is no prop walk in neutral) Under heavier winds or current the procedure is the same but gunning the engine back and forth as opposed to shifting to neutral. To turn the boat on its axis we gain forward motion at a slow speed under 1knot and turn the wheel full to starboard, before reaching the apex of the curve we shift into reverse where prop walk will swing the stern out. Before the boat comes into a stop we shift to forward to maintain forward motion and regain momemtum. After the apex of the curve we shift again into reverse and boat will again swing the stern and the boat will have turned 180 dgrees in a circle with a diameter of approximately the boat's length. Just practice
The h27 Cherubini has the worst manners in reverse than any other. Changing of the prop will not solve that so the challenge is to learn to use it to your advantage. Many a times I have backed up of a transient slip with the boat facing in the wrong direction but with the knowledge that by using prop walk I can turn the boat around on its axis. Our 27 has a Yanmar GM1 and walks to port. To back out of a slip utilize a spring line to hold the boat in position until it gains way, if there is little wind or current you can shift to neutral and let the boat just coast out or you can alternate between neutral and reverse. (there is no prop walk in neutral) Under heavier winds or current the procedure is the same but gunning the engine back and forth as opposed to shifting to neutral. To turn the boat on its axis we gain forward motion at a slow speed under 1knot and turn the wheel full to starboard, before reaching the apex of the curve we shift into reverse where prop walk will swing the stern out. Before the boat comes into a stop we shift to forward to maintain forward motion and regain momemtum. After the apex of the curve we shift again into reverse and boat will again swing the stern and the boat will have turned 180 dgrees in a circle with a diameter of approximately the boat's length. Just practice
J
John Mc
Prop
Our H27 1976! 8Hp. -weighing in at 7000lbs!--- Prop it anyway you choose-but like everyone else, we use it to aid in docking!(prop walk that is) That's the only time we use the motor anyway. (it surely doesn't have the power to motor the boat in any major current.) Good Sailing
Our H27 1976! 8Hp. -weighing in at 7000lbs!--- Prop it anyway you choose-but like everyone else, we use it to aid in docking!(prop walk that is) That's the only time we use the motor anyway. (it surely doesn't have the power to motor the boat in any major current.) Good Sailing
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