So this afternoon I got short hauled and removed the new Flex-O-fold two blade prop. The vibration was at a level that was 100% unacceptable to my wife and I. I re-installed our Campbell Sailor three blade and the minute she was dropped back into the water the vibration issues were 100% gone. She is as smooth as a Lexus now...
It was rather funny because as I was getting ready to yank the prop off the US Flex-O-Fold distributor walked into the yard. He went through the whole litany of questions. In the end he admitted that everything was spot on and correct, which I already knew, but he wanted to be sure. He admitted they just went through a similar issue on another boat that also had a long shaft.
With the two blade Flex-O-fold I had entire RPM ranges that were literally unusable and were likely due to shaft whip. I had two "usable" ranges of 900-1300 then 1900-2200 that were somewhat tolerable. All other RPM settings were AWFUL. The prop was pitched correctly so FOF got that spot on.
The difernce in vibration between the two blade FOF and the three blade Campbell is about as drastic as it gets, night & day not even close.
With the Campbell back on I now have 100% of my RPM range from 800-3000 RPM fully usable and silk smooth. Not one bad spot or any hint of a vibration. Out of frustration I used every alignment trick in the book when the FOF was on and she's now aligned to .001" which makes the Campbell even smoother than it was last year. .001" is NOT easy to do and is extremely tedious and time consuming.
So if you still have vibrations when all else is SPOT ON consider that a two blade prop, especially one that moves the blades further away from the cutlass bearing, could be the root cause..
Here's where I feel the problem of shaft whip gets greatly compounded. This is the difference between the fixed prop blade centers, beyond the bearing, and the folding prop.. The difference in overhang between the fixed prop and folding, beyond the cutlass bearing, is a full 3 3/4" !![Eek! :eek: :eek:](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
This is the Flex-O-Fold hub. Sorry, but I was hanging in the slings and did not want to tie up the yards lift for long. This was literally a ten minute swap out. Unfortunately before I remembered to snap the shot I had taken the blades off the FOF. Does not really matter though the "pin hole" is where the blades are centered. This is about 6 3/8" beyond the cutlass bearing.
This is the Campbell Sailor which is about 2 5/8" from the bearing to blade centers...:
Having been using the FOF since mid April re-installing the Campbell Sailor was a very happy day except for the lost $$..:cussing: Depsite the very minimal increased drag of the CS three blade, I would much rather have SMOOOOOTH when the engine is on vs. that extra .1-.2 knots (about what I saw).. Vibrations eventually cause damage and that was also a concern that weighed heavily on my decision to yank the FOF..... I will happily give up that 0.1 - 0.2 knots for a prop that won't damage my gear box or vibrate my boat until things start falling off.
Interestingly enough I found it very, very enlightening that this two blade Flex-O-Fold would NOT fold when the engine was shut off and the gear was left in neutral. The split second it was locked into reverse you could hear if "slap" shut.
So, which causes more drag free spinning or locked...
The free spinning did not even create enough drag to fold this prop.... But yeah a locked prop causes less drag... Right.......![Wink ;) ;)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
My wife can now take the rags out of the oven, no more rattles....![Big Grin :D :D](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
This was an expensive lesson I won't repeat, though I actually did, because my last Martec two blade was even worse....Doh', when will I learn...![Doh :doh: :doh:](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
All I can say is the Campbell Sailor is an exceptionally smooth and powerful prop, oh and it actually has reverse...![Wink ;) ;)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
While I dislike the drag I have not yet been willing to bite the bullet for a three blade feathering prop. Maybe someday...
It was rather funny because as I was getting ready to yank the prop off the US Flex-O-Fold distributor walked into the yard. He went through the whole litany of questions. In the end he admitted that everything was spot on and correct, which I already knew, but he wanted to be sure. He admitted they just went through a similar issue on another boat that also had a long shaft.
With the two blade Flex-O-fold I had entire RPM ranges that were literally unusable and were likely due to shaft whip. I had two "usable" ranges of 900-1300 then 1900-2200 that were somewhat tolerable. All other RPM settings were AWFUL. The prop was pitched correctly so FOF got that spot on.
The difernce in vibration between the two blade FOF and the three blade Campbell is about as drastic as it gets, night & day not even close.
With the Campbell back on I now have 100% of my RPM range from 800-3000 RPM fully usable and silk smooth. Not one bad spot or any hint of a vibration. Out of frustration I used every alignment trick in the book when the FOF was on and she's now aligned to .001" which makes the Campbell even smoother than it was last year. .001" is NOT easy to do and is extremely tedious and time consuming.
So if you still have vibrations when all else is SPOT ON consider that a two blade prop, especially one that moves the blades further away from the cutlass bearing, could be the root cause..
Here's where I feel the problem of shaft whip gets greatly compounded. This is the difference between the fixed prop blade centers, beyond the bearing, and the folding prop.. The difference in overhang between the fixed prop and folding, beyond the cutlass bearing, is a full 3 3/4" !
This is the Flex-O-Fold hub. Sorry, but I was hanging in the slings and did not want to tie up the yards lift for long. This was literally a ten minute swap out. Unfortunately before I remembered to snap the shot I had taken the blades off the FOF. Does not really matter though the "pin hole" is where the blades are centered. This is about 6 3/8" beyond the cutlass bearing.
![](/proxy.php?image=http%3A%2F%2Fwww.pbase.com%2Fmainecruising%2Fimage%2F143703460.jpg&hash=1b886be3dc94b4e6cf0ad073bbaf4c80)
This is the Campbell Sailor which is about 2 5/8" from the bearing to blade centers...:
![](/proxy.php?image=http%3A%2F%2Fwww.pbase.com%2Fmainecruising%2Fimage%2F143703461.jpg&hash=78bc2a5f37113e4bb05218b55bca8940)
Having been using the FOF since mid April re-installing the Campbell Sailor was a very happy day except for the lost $$..:cussing: Depsite the very minimal increased drag of the CS three blade, I would much rather have SMOOOOOTH when the engine is on vs. that extra .1-.2 knots (about what I saw).. Vibrations eventually cause damage and that was also a concern that weighed heavily on my decision to yank the FOF..... I will happily give up that 0.1 - 0.2 knots for a prop that won't damage my gear box or vibrate my boat until things start falling off.
Interestingly enough I found it very, very enlightening that this two blade Flex-O-Fold would NOT fold when the engine was shut off and the gear was left in neutral. The split second it was locked into reverse you could hear if "slap" shut.
So, which causes more drag free spinning or locked...
My wife can now take the rags out of the oven, no more rattles....
This was an expensive lesson I won't repeat, though I actually did, because my last Martec two blade was even worse....Doh', when will I learn...
All I can say is the Campbell Sailor is an exceptionally smooth and powerful prop, oh and it actually has reverse...