I'm running a RH 3 blade prop and find the boat really pulls to port under power only. At 1000rpm I do not notice it. At 2000 the pull to port is very strong. If I would let the wheel go free, a sharp turn would ensue. Anyone else experience this? FYI...under sail all is well.
Rudder pull under power
- Thread starter Capt Jerry
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Deflectors intact?
My H37C doesn't have enough power to pull to port with its 2QM20. You must have the 30hp. And with a 3-blade your boat would be a lot different than mine with a 2-blade folder. At 2000 rpm my boat makes 5.+ and I fell no pressure on the helm. But I was wondering if your boat still has those two deflectors on the hull? The ones that overlap the top eighteen inches of the rudder. I was never sure if they worked and a lot of guys and gals have removed them.
My H37C doesn't have enough power to pull to port with its 2QM20. You must have the 30hp. And with a 3-blade your boat would be a lot different than mine with a 2-blade folder. At 2000 rpm my boat makes 5.+ and I fell no pressure on the helm. But I was wondering if your boat still has those two deflectors on the hull? The ones that overlap the top eighteen inches of the rudder. I was never sure if they worked and a lot of guys and gals have removed them.
Torque
My H31 with a two blade prop does the same thing. I always just assumed it was due to the rotation of the prop along with the torgue of engine.It also "prop walks" to the port in reverse.
My H31 with a two blade prop does the same thing. I always just assumed it was due to the rotation of the prop along with the torgue of engine.It also "prop walks" to the port in reverse.
Jerry all is normal
the more thottle the more prop walk. I have run two blade fixed and now two blade folding behind my 4JHE. Above about 3knt or 1200 rpm boat keeps trying to go left. Reversing the prop walks the stern to port. TO back out of slip I hit 1/3 thottle for 1/2 boat length, then go to neutral to get the boat to respond to rudder. An autopilot is a nice feature when motoring, sort of lets you pretend the boat actually want to go where it is pointed. Scott
the more thottle the more prop walk. I have run two blade fixed and now two blade folding behind my 4JHE. Above about 3knt or 1200 rpm boat keeps trying to go left. Reversing the prop walks the stern to port. TO back out of slip I hit 1/3 thottle for 1/2 boat length, then go to neutral to get the boat to respond to rudder. An autopilot is a nice feature when motoring, sort of lets you pretend the boat actually want to go where it is pointed. Scott
the deflectors dont matter,
With or with out it still will pull to the left. As far as I know all 37c hunters have the same problem. I have a 44 hp. engine and a two blade and it will take it out of your hand if your over 2200. It is a real pain in the butt. Ed
With or with out it still will pull to the left. As far as I know all 37c hunters have the same problem. I have a 44 hp. engine and a two blade and it will take it out of your hand if your over 2200. It is a real pain in the butt. Ed
Not on every boat
Well, I dunno exactly why mine is different, but with my 27 hp Yanmar and a three blade prop I do not have any significant pull to port under way when going forward. Hand steering is relatively easy up to speeds of 6 kts... and I can control the helm relatively easily from 1200 rpm to 2800 rpm... Backing up is a different story, and the boat has the expected prop walk to port when in reverse and I use the same technique mentioned by Scott in reverse and it works well. You might try talking with a Yanmar mechanic about the proper pitch on the propeller. It has to be matched perfectly to the boat and engine for optimum performance, I was told. It's a job that can be done at the next haulout. The mechanic told me that bad pitch on the blades also contributes to the soot buildup in the elbow joint. (For what that's worth...) Good luck
Well, I dunno exactly why mine is different, but with my 27 hp Yanmar and a three blade prop I do not have any significant pull to port under way when going forward. Hand steering is relatively easy up to speeds of 6 kts... and I can control the helm relatively easily from 1200 rpm to 2800 rpm... Backing up is a different story, and the boat has the expected prop walk to port when in reverse and I use the same technique mentioned by Scott in reverse and it works well. You might try talking with a Yanmar mechanic about the proper pitch on the propeller. It has to be matched perfectly to the boat and engine for optimum performance, I was told. It's a job that can be done at the next haulout. The mechanic told me that bad pitch on the blades also contributes to the soot buildup in the elbow joint. (For what that's worth...) Good luck
prop-walk
The problem could be licked if: the rudder could be designed with a counter-balance area ahead of the (rudder) post...Given the existing post location in the hull, there is not room for the counter-balance rudder surface.. I would like to change the offending hull area, but shudder at the cost!!
The problem could be licked if: the rudder could be designed with a counter-balance area ahead of the (rudder) post...Given the existing post location in the hull, there is not room for the counter-balance rudder surface.. I would like to change the offending hull area, but shudder at the cost!!
Prop-walk
Further to my comment re rudder design, I can only agree with the previous solution offered which was to reduce the prop pitch to the point where it agrees with the engine torque/rpm curve. I too need an adjustable pitch feathering prop!!
Further to my comment re rudder design, I can only agree with the previous solution offered which was to reduce the prop pitch to the point where it agrees with the engine torque/rpm curve. I too need an adjustable pitch feathering prop!!
prop walk
check the gap between the tip of the prop and the bottom of the boat. It needs to be 1 3/4 inchs to 2 inchs . mine was less than 1/2 inch and was causing me a lot of trouble with prop walk when backing. I lenghtened the drive shaft by 4 inchs and the problem went away
check the gap between the tip of the prop and the bottom of the boat. It needs to be 1 3/4 inchs to 2 inchs . mine was less than 1/2 inch and was causing me a lot of trouble with prop walk when backing. I lenghtened the drive shaft by 4 inchs and the problem went away
Thank you for the replies,
I appreciate being able to count on the support of you fellow owners. The boat just had a new bottom job and Yes, the deflectors are there and in good shape. By the way, over 1000 rpm causes backing to port, but at idle speeds she does back up and actually steer either port or starboard. Thanks again.
I appreciate being able to count on the support of you fellow owners. The boat just had a new bottom job and Yes, the deflectors are there and in good shape. By the way, over 1000 rpm causes backing to port, but at idle speeds she does back up and actually steer either port or starboard. Thanks again.
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