Prop question I should have asked first

Jun 17, 2012
201
C&C 35 MKIII Manitowoc, WI
I have a 2002 Hunter 356. I have convinced myself upgrading the 2 blade prop to a 3 blade would help reversing and maybe making headway into the wind and waves. If anybody has experience of before and after a prop change on a like boat that would be great. Of course my power plant is a Yanmar 3GM30F. Thanks
 
Feb 17, 2013
53
Hunter 380 Port Clinton, Ohio
I have no problems stopping the boat with the flex-o-fold prop. The Max prop I removed would walk to port when backing out of my slip. The Max prop has flat blades, not good. The max prop vibrated and my flex-o-fold runs much smoother.
 
Oct 29, 2005
2,355
Hunter Marine 326 303 Singapore
I've gone through 4 prop types, stock 2blades, 3blades Campbell Sailor Prop, 2bkade Flex-O-Fold and 3blades KiwiProp.
All has prop walk. Both 3blades are the smoothest. Both fixed blades drags some.
KiwiProp has best reverse speed and control. FoF is great for sailing.
I love both KiwiProp and FoF so switch between them in 2 years cycle (when haulout for antifoul). Can't afford a 3blade Flex-O-Fold. I'm sure it will be smooth to run, great reverse control and speed and super slick when sailing :)
 
Jan 4, 2006
6,444
Hunter 310 West Vancouver, B.C.
The biggest change I noticed was the reduction in vibration. Thought I'd dropped the new prop it was so smooth compared to the original two blade.

Can't say there was any change in prop walk.
 
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
Changing props to reduce prop walk. Well guys the aeronautical engineers have determined that the prop is not the main contributor to prop walk. Yes you have to have one to have prop walk but just having one does not guarantee that you will get prop walk. Another way of saying this is if your boat has a specific geometry between the flow of water and the angle that the prop (and shaft) move through that water you don't get prop walk. Google "p-factor" for more info. So if your prop and shaft are at an angle to the water flowing over them (i.e. they are not parallel with the water surface) then you WILL have prop walk. If they are parallel to the water flowing over them then you will NOT have prop walk. The ascending blade and the descending blade have different angles of attack and so produce different levels of thrust. more thrust on one side than the other creates a turning (prop walk) force. Also the faster you move through the water the more pronounced the effect. Conclusion: if you have prop walk changing the prop will not eliminate it (though it may mitigate it some but that mitigation comes at a cost to general thrust production) and going slower during docking will reduce the effect. The most extreme example of this is a helicopter that has the "prop" at almost 90 degrees to the fluid flow. It is so bad they had to articulate the blades during each revolution to reduce that angle of attack on the side going forward and increasing it on the side going backward.
 
Mar 17, 2013
11
Hunter 36 Toronto
My Hunter 36 came with a feather Variprop. Like many have pointed out it does not eliminate the prop walk but it has reduced it. We stern into our dock so reverse performance it very important to us. The 3 bladed Variprop works well with predictable prop walk combined with good forward performance. When switching into reverse I found if I run the RPMs up to 2000 for 5-10 seconds and then throttle back to 1000 rpms the boats get through the prop walk stage, moves in reverse and the boat response very well to the helm making reverse docking easy. I also found that when going from reverse to forward the Variprop bites quickly and the boat transitions from reverse to easily. All in all I have been pleased with the general performance of the prop. Vibration is very very little and the 3 cylinder motor combined with this prop is smooth
 
Nov 30, 2010
20
hunter 410 nsw
Hi just changed for a two blade fixed to a kiwi. Researched all the options and kiwi whilst not perfect ticked most boxes. Almost went for a two blade flex
But after watching a guy install two kiwis to his cat 45ft that had suffered a lot of cavitation and prop issue. They worked a treat problem solved.
I installed mine yesterday so easy and the service from the company was fantastic. Took it h410 for a long run yesterday against an outgoing tide worked well chalk and cheese compaired to old prop. Prop walk was minimal.
 
Jan 1, 2006
7,039
Slickcraft 26 Sailfish
Forgive me but what is so bad about prop walk? My H356, with a fixed 3 blade, had it and it was an integral part of boat handling. Single screw power boaters have used prop walk to maneuver their boats in tight quarters for generations.
Go to Payne's dock at Block Island to be schooled in the art of using prop walk to maneuver your boat. Firing up a bow thruster, or not following instructions, might get you reprimanded.
 
Jun 8, 2004
10,024
-na -NA Anywhere USA
Shemandr hit it on the head. In layman's terms, when reversing by position of the blades your boat will move toward the left or port because you do not have steerage or water flow for steerage over the rudder until you do. I taught my customers start way out to eventually back in straight but in tight quarters for example in a marina, start reversing say 20-25 degrees before backing in on a straight line. Then prop walk will work to your advantage. Jim Seamons on JAVA learned that trick on me and eventually his wife was the best of the two backing in. Jim is sailing in the Heavens now
 

JohnSn

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Feb 19, 2011
18
Hunter 356 51111 Dana Point,CA
prop_compare.jpg
My 356 had a 2 blade fixed prop. Wimpy top speed motoring. In close quarters, it felt like I was trying to move my vessel with a handheld mixer. Prop walk, but not horrible. Motoring into a headwind was not happening.
Put a 3 blade on her. Huge difference. Nice top speed motoring. No problem pushing to windward. In close quarters, feels like I have tires on the road. Sails a hair slower- not a big deal. A little less prop walk.
I wont go back. Its a 16x12 3 blade. Basic low speed prop. But we had to adjust the pitch down to a little less than 11”.

If I chose to cross an ocean, I might buy a folding prop as it can be helpful in the miles per day reached over a long haul. But I’d put the 3 blade back on right away. Or maybe I’d use the 2 blade for a passage...
From the engineering side, in my opinion, there’s not enough gain in a folding prop to outweigh the risk. Unless you have some important value to warrant it. Like racing. Or crossing an ocean.
 
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Dec 19, 2006
5,809
Hunter 36 Punta Gorda
I added a 3 blade Flex o Fold a year after getting my new 2007 H-36 and was like night and day
and big improvement in reverse and sailing light wind and great backing in to a slip.
What I like is nothing to do is keep clean just like any prop and no greasing or adjusting and just get proper pitch and never have had a problem.
It always opens and always folds.
Nick