Shortening Drive Shaft

[Frankly]

The centerboard set up on Cbreeze puts a lot of stainless steel in the water. That zinc on the back of the AP probably wouldn't last 2 months. For years I just replaced the shaft zinc about 3/4 times a year. Last haul out I added a medium teardrop to the side of the keel and connected it directly to the pipe housing the SS CB cable. Now the shaft zinc lasts better part of a year and I can replace the teardrop easier and quicker. I also replaced those Mickey Mouse plastic screws with some SS from Millville Hardware that holds the AP zinc on.

As to paint system from scratch. Clean to bare metal (careful blasting), Pettit metal primer, one coat Pettit epoxy, 3 coats of Trinidad SR. The Trinidad SR is replaced/ added to once a year/ 18 months until I have to replace the AP bearings. Then I start over. I have the old H5 model with water lubed bearings. For some reason that AP holds paint better than the factory 3 blade. Don't have any explanation for that other than maybe a different alloy of NIBRAL

[a64pilot]

I can't find it right now, but Fsstbttms gave me a link to islers diving, they make a bronze adapter that fits a standard "B" prop zinc to an autoprop, much cheaper, more effective and more widely available

[boatbod]

If you've checked the alignment, shaft straightness and cutlass, then the vibration might be due to loose bearings on the autoprop blades. Really you need to haul out and inspect everything.

[DivingOtter]

I'm a commercial diver, salvor, underwater welder and the number one rule for any vessel I dive on, whether it's a 190 ft fishing vessel, or a 30 ft sailboat is lockout tagout. Meaning, signs and locks are places around any and all engine startups and controls. Trust me when I say you do NOT want to be near that thing when it's in gear. Small wheel yes, but once the turbulence kicks up you're not gonna be able to hold your hand straight and it's a serious recipe for losing an extremety.

[Sailmonkey]

Originally Posted by DivingOtter

I'm a commercial diver, salvor, underwater welder and the number one rule for any vessel I dive on, whether it's a 190 ft fishing vessel, or a 30 ft sailboat is lockout tagout. Meaning, signs and locks are places around any and all engine startups and controls. Trust me when I say you do NOT want to be near that thing when it's in gear. Small wheel yes, but once the turbulence kicks up you're not gonna be able to hold your hand straight and it's a serious recipe for losing an extremety.

You do know he's talking about cutting the shaft inside the hull?


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[jimbunyard]

Originally Posted by a64pilot

Prop is balanced, it was new. If you have seen an Autoprop, not sure how you could check blade tracking as the things will spin in circles. It's sort of intriguing that the thing even works.
I have been assured that the prop is good, and have been assured lately that the problem is with my excessive shaft length, but I would have thought 2.5" wasn't too bad, but an Autoprop is I believe an excessively heavy thing compared to a normal prop, maybe all that mass makes it worse?


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After seeing the thing in action, I'd say quite intriguing... While the heavy mass and the excessive overhang seems a likely culprit, since I had it off already I'd be hard pressed not to disassemble it, count the bearings (if you have the ball bearing model) and put each blade on an accurate, precise scale. Even then, an individual blades' specific shape is still suspect; for instance, what happens if a blade is dropped after inspection, but before assembly? Does every one get sent back through inspection?

Obviously I can't know the manufacturing procedures and quality control at Brunton, but I've seen too many instances of defective, new-right-out-the-box items to put much faith in newness as a guarantor of accuracy or quality in manufacturing, assembly or shipping...

[a64pilot]

Originally Posted by Sailmonkey

You do know he's talking about cutting the shaft inside the hull?


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My God, can you imagine playing around a turning prop in the water?
Gives me the willies even thinking about it, about like trying to sharpen the blade on a running lawnmower

Talk about Darwin award

[a64pilot]

Originally Posted by jimbunyard

After seeing the thing in action, I'd say quite intriguing... While the heavy mass and the excessive overhang seems a likely culprit, since I had it off already I'd be hard pressed not to disassemble it, count the bearings (if you have the ball bearing model) and put each blade on an accurate, precise scale. Even then, an individual blades' specific shape is still suspect; for instance, what happens if a blade is dropped after inspection, but before assembly? Does every one get sent back through inspection?

Obviously I can't know the manufacturing procedures and quality control at Brunton, but I've seen too many instances of defective, new-right-out-the-box items to put much faith in newness as a guarantor of accuracy or quality in manufacturing, assembly or shipping...

Diving the boat to clean the prop, you rotate each blade and can feel any looseness or roughness in the bearings, there is no detectable play at all, must be some pre-load on the bearings, or roughness.
If I still have the vibe after shortening the shaft I'm going back to who sold me the prop, we have been working together on this. I assume at that point you replace the prop, but have to exhaust all other possibilities first, and my shaft overhang is outside of acceptable limits.

[DivingOtter]

Originally Posted by Sailmonkey

You do know he's talking about cutting the shaft inside the hull?


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I did not. Then again, I've encountered a lot of hokey things in my career. Like the guy who hired a diver that could get the wheel off, so he used DetCord around the shaft to blow the wheel off. Needless to say, I got it off the bottom. Also, the VA has me on some pain killers at the moment.

[DsquareD]

I know a guy who pulled his prop shaft while his boat was still in the water. He just made a wooden plug and as soon as he pulled the shaft he inserted the plug. Very little water went into the bilge.


Dennis

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[rwidman]

Originally Posted by a64pilot

Diving the boat to clean the prop, you rotate each blade and can feel any looseness or roughness in the bearings, there is no detectable play at all, must be some pre-load on the bearings, or roughness.
If I still have the vibe after shortening the shaft I'm going back to who sold me the prop, we have been working together on this. I assume at that point you replace the prop, but have to exhaust all other possibilities first, and my shaft overhang is outside of acceptable limits.

I think I would replace the prop first. Or just remove it and run the engine to see if the vibration is still there.

[DivingOtter]

Originally Posted by DsquareD

I know a guy who pulled his prop shaft while his boat was still in the water. He just made a wooden plug and as soon as he pulled the shaft he inserted the plug. Very little water went into the bilge.


Dennis

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That's my method of removing them while they're wet. A cedar plug tapped in will expand rapidly and seal it tight.