Some of you may know that I purchased and installed a Flex-O-Fold two blade prop this year replacing my three blade Campbell Sailor...
Well, unfortunately, $$$$$$$$
, the prop is coming off and the Campbell Sailor is going back on. The boost in sailing speed in low winds was able to be felt but in higher winds the performance difference was not noticeable as we were already up against hull speed with either prop.. Net gain in sailing speed = negligible.
My observations:
The Likes List:
*Speed under sail in light winds improved. (not nearly as much as I had hoped)
*When folded she would not catch pot buoys
*Very well engineered and manufactured a true work of art.
*Flex-O-Fold nailed the sizing and the boat could attain max rated RPM.
The Dislikes List:
*Speed gains under light wind sailing of about 0.1 - 0.2 knots, but not worth the drastic increases in vibration
*Slower than 3 blade under power at same RPM
*No matter what could not attain same max under power speed with two blade
*Powering into chop or current lacked any sort of "drive", anemic best describes it
*Bad vibration right at my ideal cruise RPM throttle, had to be backed down
*Reverse about as weak as Richard Simmons. Took blasts of full throttle in reverse to even begin to slow our boat, she's pretty heavy
*Did not fold & continued to spin unless you remembered to lock gear box in reverse
*Vibration was not tolerable AT ALL
*Similar prop walk to Campbell Sailor
*Considerably less power to drive into a tidal current or chop
*Crash stops non-exxistent
Honestly the Flex-O-Fold is a work of art and a very well designed and engineered prop. The forward thrust is surprisingly "OK" for a two blade, in-line with most of the reviews, but nowhere even close to the Campbell Sailor three blade. Not surprising, but as you read some of the FOF reviews it would have you believe otherwise, sadly I did.
Reverse is pretty much non-existent compared to the CS 3 blade, though it is leaps and bounds better than our old Martec two blade folder, which had basically no reverse at all. Our boat is pretty heavy, about 19,000 + pounds, so stopping it is no small feat for any 16" prop let alone a folding two blade. Crash stops.....??? Forget it she just keeps rolling like a freight train....
Where the prop really failed us is in vibration. My wife never really knew I had installed a new prop, I mentioned it, but she tuned me out as; yadda, yadda, boat stuff, boat stuff, yadda, yadda, yadda.
This past weekend she came up to the cockpit to say "something is wrong everything is shaking and rattling". When I went below later I found paper towels & rags stuffed into the stove to keep it from rattling. We have not stuffed paper towels in stoves since we owned our two blade Martec folding prop on the Catalina 30....
Our boat has NEVER EVER had any vibration issues. It has always been about as smooth as glass. She is driven by a 4 cylinder Mitsubishi/Westerbeke on factory Westerbeke mounts. Due to the engine being set up as a v-drive the prop shaft is about 65" long and that is likely where the issues come into play, and got exacerbated..
All folders move the blades further away from the cutlass bearing than fixed props do. The further away from the bearing you are the more likely you'll be to cause "shaft whip". This is a jump rope like effect between the bearing and the gear box flange. I suspect this is what is happened on our boat. The prop was tested for balance and was found to be well within specifications. Two blade props just have more vibration than three, that's accepted knowledge, just how much was always the question? I now know that, for our boat.....:neutral: When you move the blades 6 3/8" from the cutlass bearing, on an already long shaft, these issues are likely unavoidable.
Most sailors would think nothing of this level of vibration as most sail boats I am on are actually worse, and most sailors assume it is just normal. Despite the wide acceptance by many sailors of this level of vibration, it is not normal and my concern is always the level of damage months or years of this type of vibration can cause to the vessel, strut, gear box and other associated items.
If I only ever had to sail, and never used the motor, this prop would be great. Sadly for us we live in the land of summer winds that don't wake up until 1:00 PM most days. The motor gets run and that is just the reality of "sailing" (or power boating with a spar) in Maine.....
So sadly, after all the trouble & expense, I will schedule to have her put in the slings so I can swap out the Flex-O-Fold for our slightly higher drag but SMOOTH Campbell Sailor....
Besides the fact that it is only a two blade prop this is where I feel the problem stems from:
And this is the CS prop and an image depicting a very exaggerated illustration of shaft whip... When I change it out I will measure the actual offset differences...If our boat had a shorter shaft the vibration might have been tolerable...
Well, unfortunately, $$$$$$$$
, the prop is coming off and the Campbell Sailor is going back on. The boost in sailing speed in low winds was able to be felt but in higher winds the performance difference was not noticeable as we were already up against hull speed with either prop.. Net gain in sailing speed = negligible.My observations:
The Likes List:
*Speed under sail in light winds improved. (not nearly as much as I had hoped)
*When folded she would not catch pot buoys
*Very well engineered and manufactured a true work of art.
*Flex-O-Fold nailed the sizing and the boat could attain max rated RPM.
The Dislikes List:
*Speed gains under light wind sailing of about 0.1 - 0.2 knots, but not worth the drastic increases in vibration
*Slower than 3 blade under power at same RPM
*No matter what could not attain same max under power speed with two blade
*Powering into chop or current lacked any sort of "drive", anemic best describes it
*Bad vibration right at my ideal cruise RPM throttle, had to be backed down
*Reverse about as weak as Richard Simmons. Took blasts of full throttle in reverse to even begin to slow our boat, she's pretty heavy
*Did not fold & continued to spin unless you remembered to lock gear box in reverse
*Vibration was not tolerable AT ALL
*Similar prop walk to Campbell Sailor
*Considerably less power to drive into a tidal current or chop
*Crash stops non-exxistent
Honestly the Flex-O-Fold is a work of art and a very well designed and engineered prop. The forward thrust is surprisingly "OK" for a two blade, in-line with most of the reviews, but nowhere even close to the Campbell Sailor three blade. Not surprising, but as you read some of the FOF reviews it would have you believe otherwise, sadly I did.
Reverse is pretty much non-existent compared to the CS 3 blade, though it is leaps and bounds better than our old Martec two blade folder, which had basically no reverse at all. Our boat is pretty heavy, about 19,000 + pounds, so stopping it is no small feat for any 16" prop let alone a folding two blade. Crash stops.....??? Forget it she just keeps rolling like a freight train....
Where the prop really failed us is in vibration. My wife never really knew I had installed a new prop, I mentioned it, but she tuned me out as; yadda, yadda, boat stuff, boat stuff, yadda, yadda, yadda
. This past weekend she came up to the cockpit to say "something is wrong everything is shaking and rattling". When I went below later I found paper towels & rags stuffed into the stove to keep it from rattling. We have not stuffed paper towels in stoves since we owned our two blade Martec folding prop on the Catalina 30....
Our boat has NEVER EVER had any vibration issues. It has always been about as smooth as glass. She is driven by a 4 cylinder Mitsubishi/Westerbeke on factory Westerbeke mounts. Due to the engine being set up as a v-drive the prop shaft is about 65" long and that is likely where the issues come into play, and got exacerbated..
All folders move the blades further away from the cutlass bearing than fixed props do. The further away from the bearing you are the more likely you'll be to cause "shaft whip". This is a jump rope like effect between the bearing and the gear box flange. I suspect this is what is happened on our boat. The prop was tested for balance and was found to be well within specifications. Two blade props just have more vibration than three, that's accepted knowledge, just how much was always the question? I now know that, for our boat.....:neutral: When you move the blades 6 3/8" from the cutlass bearing, on an already long shaft, these issues are likely unavoidable.
Most sailors would think nothing of this level of vibration as most sail boats I am on are actually worse, and most sailors assume it is just normal. Despite the wide acceptance by many sailors of this level of vibration, it is not normal and my concern is always the level of damage months or years of this type of vibration can cause to the vessel, strut, gear box and other associated items.
If I only ever had to sail, and never used the motor, this prop would be great. Sadly for us we live in the land of summer winds that don't wake up until 1:00 PM most days. The motor gets run and that is just the reality of "sailing" (or power boating with a spar
) in Maine.....So sadly, after all the trouble & expense, I will schedule to have her put in the slings so I can swap out the Flex-O-Fold for our slightly higher drag but SMOOTH Campbell Sailor....
Besides the fact that it is only a two blade prop this is where I feel the problem stems from:
And this is the CS prop and an image depicting a very exaggerated illustration of shaft whip... When I change it out I will measure the actual offset differences...If our boat had a shorter shaft the vibration might have been tolerable...
