Anyone else' 37C do this? Is there a fix? Mine pulls HARD at more than about 1/2 throttle.
Pulls to port under power
- Thread starter pbknowles
- Start date
Really isn't pulling, it's being pushed. By any chance have you or the PO replaced the prop.. The prop may be over pitched..
Yep, it is called prop walk. But you know, it does not do it in neutral and it is very predictable which means you can compensate for it and use it to your advantage. If you are trying to back out of a slip you can tie a line to a dock or a pylon on your starboard side and just pull on it to prevent the boat from walking to port until you get some head way and then shift to neutral and drop the line. Sometimes a quick burst of power gets you moving back enough to get some steerage and shift to neutral. You could even have some crew member walk the boat back before you engage reverse. Practice. You know you can use prop walk to turn a boat on its axis? Get a knot of speed going forward and turn the wheel full to starboard, follow by shifting to reverse with a little power and the stern will kick out using centrifugal force, prop walk and slippage. The bow will stay pretty much at where you started your turn while the stern swings around. As the boat approaches the completion of the turn shift to forward and you will be facing 180 degrees from your original course without having moved much in position. Requires a little practice. Prop walk can also serve as a thruster while docking to port. Learn how to use prop walk and spare yourself a lifetime of frustration.
Almost every single inboard engine does that, assuming a fixed blade (i.e., not folding, special) prop. Yes, it's called prop walk. You might want to do a search on this not-unusual phenomenon. Good luck, you can learn to use it to your advantage.
Do you mean in forwards or reverse?
I think of prop walk primarily in slow speed (backing out of my slip).
In forward, motoring hard, my boat will “Crazy Ivan” hard if I let go of the wheel. I guess I never thought about if it turns to STB or to Port...but she turns sharply.
So which issue are you referring to?
Greg
Thank you for the replies. I was not specific enough in my original post. I am familiar with prop walk and prop wash and how to use them when docking/undocking and at low speeds. My oDay 27 which I have been sailing for quite a few years now can be turned in her own length using the techniques described above.
This is not that.
What I really meant to describe was:
At high forward speed (gets worse as speed goes up) and high power if I were to release the wheel the boat will execute a hard turn to port and the wheel would spin to port. You have to be careful not to let go of the wheel when motoring fast, it has a constant force on it which is annoying at best and unsafe at worst.
My experience is that the effects of prop wash seem to be more or less canceled out at higher speeds as the effect is relatively small compared the the large forces generated by the rudder itself once the boat is moving at a good clip.
I think I am familiar with "crazy Ivan" as well. My oDay does that. At high motoring speeds she will track fine as long as the rudder is straight or a few degrees port or stb. More than a few degrees though and the turning moment created by the part of the rudder fwd of the rudder post takes over and she will want to turn hard either way. What I am trying to describe is not that, which i would think of as normal with a balanced rudder optimized for sailing not motoring.
Sailme88 OK, granted it is being pushed as the boat is rotating around its CLR. Also, good point on the prop. I just got the boat, but I did find a receipt on board from a boatyard that simply said "install owner provided prop".
The thing is the Hunter 37C rudder isn't balanced at all. There is no area ahead of the post. So the flow over it at high speeds should only serve to keep it straight.
I guess I could get her going at hull speed on flat water and pop into neutral. If thepull push goes away then it is from the prop. If it does not go away, then it is "something else". My post was also trying to see if it was just a characteristic of the boat or if mine is "special".
Thanks, sorry for the vague initial post
This is not that.
What I really meant to describe was:
At high forward speed (gets worse as speed goes up) and high power if I were to release the wheel the boat will execute a hard turn to port and the wheel would spin to port. You have to be careful not to let go of the wheel when motoring fast, it has a constant force on it which is annoying at best and unsafe at worst.
My experience is that the effects of prop wash seem to be more or less canceled out at higher speeds as the effect is relatively small compared the the large forces generated by the rudder itself once the boat is moving at a good clip.
I think I am familiar with "crazy Ivan" as well. My oDay does that. At high motoring speeds she will track fine as long as the rudder is straight or a few degrees port or stb. More than a few degrees though and the turning moment created by the part of the rudder fwd of the rudder post takes over and she will want to turn hard either way. What I am trying to describe is not that, which i would think of as normal with a balanced rudder optimized for sailing not motoring.
Sailme88 OK, granted it is being pushed as the boat is rotating around its CLR. Also, good point on the prop. I just got the boat, but I did find a receipt on board from a boatyard that simply said "install owner provided prop".
The thing is the Hunter 37C rudder isn't balanced at all. There is no area ahead of the post. So the flow over it at high speeds should only serve to keep it straight.
I guess I could get her going at hull speed on flat water and pop into neutral. If the
Thanks, sorry for the vague initial post
I don't think your OP was vague at all. I think your "experiment" would be very worthwhile, and is a thoughtful idea. I bet what you'll find is once you get going as fast as you can while the boat is pulling to port because of the prop, that once you disengage the prop and continue "coasting" at speed, the pull will disappear. It is NOT your rudder, it is the turning prop.
Good luck, please let us know.
That I think is a common thread on the the 37c. My daughter has a 1984 37c with a 3qm30 and a Campbell sailor three blade prop. It pulls very hard to port under power. But it will turn starboard in almost a boat length when put in reverse. In other words I don’t think there is anything wrong with your boat. Years ago I had a Freeport 41, full keel design. It too pulled hard to port under power. My H466 also pulls to port under power but much less than the other two.
I have a three blade flex-o-fold prop and before that a two blade fixed. Both exhibit wicked thrust to port when in reverse. Both tend to pull the bow to starboard when in forward although the side thrust does not seem as powerful. Unless your engine rotation is opposite, I am not sure why you would pull to port in forward.
propellors create two forces, not just one. the propellor digs into the water and pulls itself ahead, force#1. the propellor also 'paddlewheels' to the side, force #2. force#2 is there at all rpms, forward or reverse.
the thrust in back of the propellor is the byproduct of the propellor digging ahead. directing the thrust, the byproduct, will give you steerage. the thrust is not linear.
twin engine vessels counterrotate to negate force #2
airplanes offset the alignment of the engine to correct for these two forces.
propellor pitch could make some difference, blade shape, bent strut,
distance from prop to rudder.
it is normal the the boat hooks to the left. to what degree could be many of the above factors.
the thrust in back of the propellor is the byproduct of the propellor digging ahead. directing the thrust, the byproduct, will give you steerage. the thrust is not linear.
twin engine vessels counterrotate to negate force #2
airplanes offset the alignment of the engine to correct for these two forces.
propellor pitch could make some difference, blade shape, bent strut,
distance from prop to rudder.
it is normal the the boat hooks to the left. to what degree could be many of the above factors.
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Have owned my 2006 45CC Hunter for about 2 years, previous boats owned were 32' and 27'. I have about 100 hours motoring, so have a baseline of experience on steering under power. Recently, I hauled out and had new bottom paint and thru-hulls replaced. Since then I experience severe pull to port under power at high RPM's. At 3,000 RPM's (about 7.5 knots) the pull is severe. If I let go the helm, the boat completes a 360 circle in less than 8 seconds. If I run up to 7 knots and pull back on throttle then release helm, the boat continues in a straight line. No issues under sail. What could have happened while dry-docked?
* Prop was inspected and cleaned in dry-dock; not a candidate as cause.
* Hull is new paint, free of debris; not a candidate as cause.
* It was a 3 blade prop before haul-out; not a candidate as cause.
* Had diver inspect hull, prop, rudder while in slip; no abnormalities.
Any experiences or solutions would be appreciated.
* Prop was inspected and cleaned in dry-dock; not a candidate as cause.
* Hull is new paint, free of debris; not a candidate as cause.
* It was a 3 blade prop before haul-out; not a candidate as cause.
* Had diver inspect hull, prop, rudder while in slip; no abnormalities.
Any experiences or solutions would be appreciated.
What you are experiencing is prop walk.. Just as in astern the boat will walk to port until the rudder gets bite, so too in motoring ahead you will have the same experience. Archimedes and Newton are teaming up here. This is a classic reason while dual engined boats use counter rotating props. Supposedly prop walk is the reason that Sabre offset their prop and shaft...
A thought: Prop pitch has been cited above. When you are in forward and motoring your engine should be just reaching full throttle, say 3,000 RPM as your boat reaches hull speed. If your boat reaches hull speed at half throttle you have too much pitch or too much prop diameter. That excess prop, if present, may be contributing. I have never noticed the severe turning force on the rudder in forward that you describe but my boat is different.
Sailme88 & RoyS; thank you for your input, but I think I may have not explained my issue well enough. I understand your comments about pitch and prop-walk, I'm quite aware of the effects. I think I need to focus on the significant difference in steering between before and after dry-docking for bottom paint. Before haul-out the steering was normal, typical prop-wash, nothing abnormal. After re-launching, the steering has severe pull to port. This difference in steering is VERY noticeable. To ferret the issue I'm having Charlotte Ann hauled-out again and have the steering system inspected, lubricated, and tightened. Also, I asked for new rudder post bearings only to find out the service technician doesn't know where to locate the parts. My new project; where to buy replacement rudder post bearings since Hunter-Marlow has discontinued these parts.
Cheers!
Cheers!
Have you checked for rudder parts with the good folks on this website. I’m sure they can help. To clarify I mean the SBO staff.
My Catalina 28 MKII is a member of the turn hard to port club. Let go of the wheel at 3/4 throttle and she'll immediately go into a spin. Under sail...goes arrow straight. Yup, gotta be the prop.
I've searched the net, and found a little bit of info that indicates this model is prone to the phenomenon. I've considered getting a new prop, but each season I just put up with it.
I've searched the net, and found a little bit of info that indicates this model is prone to the phenomenon. I've considered getting a new prop, but each season I just put up with it.