At 1800 t0 2200 rpm, my 1987 Catalina 30 veers sharply to the left. I have a standard 3 blade prop which has been inspected and found to have no problems. The pull is is hard that it overrides the auto pilot and obviously makes lonng distance travel under power very tireing. When under sail the boat is well balanced and tracks just fine when close hauled. Is there any thing that can be checked or done to find the souce of this problem and rectify it?
Prop walk
- Thread starter sailngolf20792
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Prop walk is normal
Hi sailngolf - While prop walk is normal on most boats, especially with a fixed 3 bladed prop, it shouldn't be so bad as to over-ride your autpopilot. Some possible remedies: - get a more powerful autopilot - change to a 2 bladed prop - replace prop with feathering prop such as a Max prop. Just some thought. Best of luck! Trevor
Hi sailngolf - While prop walk is normal on most boats, especially with a fixed 3 bladed prop, it shouldn't be so bad as to over-ride your autpopilot. Some possible remedies: - get a more powerful autopilot - change to a 2 bladed prop - replace prop with feathering prop such as a Max prop. Just some thought. Best of luck! Trevor
is a very interesting and well covered topic. Try th link. Sounds like you may also have an autopilot calibration problem. See also: http://archive.sailboatowners.com/archive/archivepview.tpl?SKU=2002241095837.76&forumabr=aao&fno=22&&_ptitle=ptitle%2Brtitle&_psamp=psamp&&model=none&forum=none&andor=ws&keyword=prop%20walk&pr=p,r&ssite=CO&srt=[srt]&start=11&max=100&db=2002 Stu
Prop walk to port
I have an 88 C30 that does exactly the same. It will take the boat hard to port letting the wheel go for a few seconds. I have a friend whose C30 does the same. I am reluctant to let a someone inexperianced take the wheel. My auto pilot does handle it however. I believe it's pretty much due to the "balanced" rudder with no skeg,a three bladed prop, and not much can be done. Altering speed can halp a bit, and a clean rudder helps. I've learned to live with it and enjoy the boat. If you find a remedy let us know. Good sailing Ron B Lighthouse point Fl.
I have an 88 C30 that does exactly the same. It will take the boat hard to port letting the wheel go for a few seconds. I have a friend whose C30 does the same. I am reluctant to let a someone inexperianced take the wheel. My auto pilot does handle it however. I believe it's pretty much due to the "balanced" rudder with no skeg,a three bladed prop, and not much can be done. Altering speed can halp a bit, and a clean rudder helps. I've learned to live with it and enjoy the boat. If you find a remedy let us know. Good sailing Ron B Lighthouse point Fl.
My '77 C-30 Doesn't
Hey Guys, I just want to be sure we're talking about the same thing, here. "Prop walk" is when the boat travels sideways as a result of the propeller's movement when the boat has no headway. The ONLY time this happens is when the boat has 0 speed over water and the engine is in gear. This is common when starting from a dead stop or when shifting from forward to reverse. Once the boat gains some speed the rudder & keel will more than compensate for any prop walk and you should be able to achieve a straight course. When you guys say the boat "steers to port" do mean that your boat can't go straight, or do you mean that you constantly have to have your hands on the wheel to keep it from veering to port? Under no circumstances should the boat go sideways while moving through the water 1 knot or more. It's impossible, as long as the keel & rudder are still attached to the boat. If you're bothered by it veering to port without a steady hand on the helm, then that is not prop walk. It is a pain in the neck, though. I've been at cruising rpm's on a long windless leg, taken my hand off the wheel to grab a water and within 4 seconds we're hard over to port. Oh well. To answer the question...I don't think there's anything you can do about it except maybe get a wheel lock for your steering pedestal and keep it relatively tight when on a long straight course. That helps a little when it's being steered by hand, but it's no help when you have the autopilot running. As for when the autopilot is getting over worked, you definitely have something wrong with the autopilot. It may be too small for your boat, it may be a slipping belt, a worn (weak) motor or bad wiring to the motor or the settings might be off (though I doubt it if the autopilot works well while under sail). How old is it? What brand?? Maybe we can help. Good luck, Allen Schweitzer s/v Falstaff C-30 Hull# 632
Hey Guys, I just want to be sure we're talking about the same thing, here. "Prop walk" is when the boat travels sideways as a result of the propeller's movement when the boat has no headway. The ONLY time this happens is when the boat has 0 speed over water and the engine is in gear. This is common when starting from a dead stop or when shifting from forward to reverse. Once the boat gains some speed the rudder & keel will more than compensate for any prop walk and you should be able to achieve a straight course. When you guys say the boat "steers to port" do mean that your boat can't go straight, or do you mean that you constantly have to have your hands on the wheel to keep it from veering to port? Under no circumstances should the boat go sideways while moving through the water 1 knot or more. It's impossible, as long as the keel & rudder are still attached to the boat. If you're bothered by it veering to port without a steady hand on the helm, then that is not prop walk. It is a pain in the neck, though. I've been at cruising rpm's on a long windless leg, taken my hand off the wheel to grab a water and within 4 seconds we're hard over to port. Oh well. To answer the question...I don't think there's anything you can do about it except maybe get a wheel lock for your steering pedestal and keep it relatively tight when on a long straight course. That helps a little when it's being steered by hand, but it's no help when you have the autopilot running. As for when the autopilot is getting over worked, you definitely have something wrong with the autopilot. It may be too small for your boat, it may be a slipping belt, a worn (weak) motor or bad wiring to the motor or the settings might be off (though I doubt it if the autopilot works well while under sail). How old is it? What brand?? Maybe we can help. Good luck, Allen Schweitzer s/v Falstaff C-30 Hull# 632
I thought "prop walk" only occurred when in
reverse due to the water flow from the prop (prop wash) being interrupted by the keel. Why would there be any going forward?
reverse due to the water flow from the prop (prop wash) being interrupted by the keel. Why would there be any going forward?
Paddle Wheel
Prop walk is caused by the “paddle wheel” effect of the movement of the lower half of the prop through the water. The proximity of the hull, struts, etc breaks up the flow around the upper half of the prop. With a clockwise rotation, prop walk is to starboard. If counter clockwise, the motion is to port. If the prop were suspended inside a tube, there would be no prop walk effect. The effect may be more pronounced in reverse for a couple of reasons; the prop shape is less efficient in that direction and the rudder is designed to take advantage of prop wash. Prop walk is a relatively weak effect. Once forward or reverse motion through the water is achieved, the hydrodynamic shapes of the keel and rudder begin to exert much greater forces that overcome it. Prop walk can be used to advantage in low speed docking maneuvers. Many boats have their fuel and pump-out fixtures on the port side for this reason. When you come into the gas dock, toss out and secure a line to the bow and bring the boat to a halt. Then put the prop in reverse. The counter clockwise motion will slowly bring the stern around to the dock along the port side.
Prop walk is caused by the “paddle wheel” effect of the movement of the lower half of the prop through the water. The proximity of the hull, struts, etc breaks up the flow around the upper half of the prop. With a clockwise rotation, prop walk is to starboard. If counter clockwise, the motion is to port. If the prop were suspended inside a tube, there would be no prop walk effect. The effect may be more pronounced in reverse for a couple of reasons; the prop shape is less efficient in that direction and the rudder is designed to take advantage of prop wash. Prop walk is a relatively weak effect. Once forward or reverse motion through the water is achieved, the hydrodynamic shapes of the keel and rudder begin to exert much greater forces that overcome it. Prop walk can be used to advantage in low speed docking maneuvers. Many boats have their fuel and pump-out fixtures on the port side for this reason. When you come into the gas dock, toss out and secure a line to the bow and bring the boat to a halt. Then put the prop in reverse. The counter clockwise motion will slowly bring the stern around to the dock along the port side.
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