prop shaft length on 367

[SV Alfresco]

I have a question about the proper length of the prop shaft. I have been told that the proper distance between the strut and the prop should be no more than 1.5 x the diameter of the shaft, or less than 2" in this case. When I bought the boat, there were 2 zincs between the strut and the prop so this is about 5-6". The boat has a new Yanmar diesel and v-drive, put in by the previous owner, and the shaft is SS. There is some vibration while running under power. Having nothing to gauge this, I don't know what is acceptable. I had the stuffing box replaced with a PSS seal last winter and it seems that the vibration has increased since then. The only thing that was removed was the prop shaft, which was disconnected from the V-drive and slid back. I also removed the old zincs and put two new ones on the shaft between the strut and shaft log. There doesn't seen to be any play in the cutless bearing. I will check flange connection when we pull the boat in the fall. Any ideas on the proper shaft length?

Mike

[SailingSeaDragon]

Mike,

5-6 inches is far more than what I have with Sea Dragon... I just looked at some old pictures of Sea Dragon on the hard and the distance between the strut and the prop is about an inch, maybe a tad more.

Garner

[PeteW]

The prop shaft flange alignment at the V-drive needs to be checked while the boat is in the water. You will be able check the shaft with a dial indicator to see if its straight, turning it by hand. Cutless bearing has a way of disappearing over time. This can make for a wobbly shaft. It will also score the shaft making it unusable. My 365 has a drive shaft with universals on both ends from motor to v drive. No alignment needed there.

I had a marine machine shop make me a new shaft. They will need the coupler off the v-drive to fit. Figure on $500.

[Jim S]

The shaft length on Phantom is 83" exactly.  There is 1.5" between the aft end of the strut and the propeller.  Zincs are placed on the shaft forward of the strut or on the prop retaining nut.  The zincs should not restrict the flow of water through the cutlass bearing.

[SV Alfresco]

Thanks everyone for the great replies. Looks like I'm going to need a new shaft or have this one cut down if it's straight. This is going to be a big off-season; having the stick pulled to check and replace  all necessary rigging, new sheeves, halyards, and lighting. An osprey landed on top of the mast last weekend and bent the wind indicator. Sat there with its wings spread for a while. No other presents though. ;-)  Also, I did get the old Benmar autopilot working, sort of. Ran for a while till it blew a fuse. May be an overdraw from the motor or gears binding. It hasn't been used for many years.

Mike

[INCOMMUNICADO]

Mike, I have a ketch but I think they are all the same.The distance between the strut and prop is one and three quaters inch shaft is 82 3/4 x 1 1/8.Aqualoy stainless single taper.I ordered it from Deep Blue Yacht Supply online with shipping and tax total was 435.48. I hope this will help. Allen

[SV Alfresco]

Thank you Allen. I just came across Dale Tanski's amazing detective work on this problem on this forum from 2009.  A too long key in the flange could be part of the problem since it seemed worse after the shaft was disconnected and put back in.

Mike