I have a "84" commander 410 that has a vibration at cruising speed, about 2200 rpm. Its not a bad vibration but one that I think I should look into. Can anyone give me advice on pulling the props and replacing strut bushings. I will check the shafts for being bent with a dial indicator. Last year when the boat was pulled the props looked great.

Rick,

I would be willing to bet it's an alignment problem. What will not cause vibration at lower speeds, may find it's harmonic point and vibrate heavily, only to diminish as rpm changes higher or lower. Look at your shafts while under way, do you see any movement out of axis at all? Is the shaft wiggling back and forth a bit as it penetrates the hull and as it meets up with the hub. If so, you may have found the problem. Naturally, a bent shaft can CAUSE the movement, but unless you struck a darn heavy object, those shafts are probably going to be fine, and the movement could well be caused by having the motor/transmission output shaft in perfect alignment with the prop shaft.






Here are some sections of the long post about my own haul out and shaft/bearing/prop replacement. The whole thread can be found here
http://www.network54.com/Forum/424840/message/1152328119 but the ones noted below are specific to the issues you noted. On my boat, the original shafts were actually fine, the props were too, only needing a scan and repair as needed. Instead, I purchased the latest and greatest new 4-blade jobs, got the pitch too high for the boat, bought new shafts too, probably wasted money on those too, and now I can tell everyone about it (so they don't do the same thing).


Day-6 Got the port shaft out, a little patching, looked over the strut bearings.
http://www.network54.com/Forum/424840/message/1152803302

Day-7 Strut Bearings Came Out
http://www.network54.com/Forum/424840/message/1152849283

Day-8 Paint touch up at lunch, strut bearing installation, ready for shafts and props
http://www.network54.com/Forum/424840/message/1152934344

Day-9 All cosmetic work done !
http://www.network54.com/Forum/424840/message/1153016597

Day-10 shafts, hubs, packing, and ready to launch
http://www.network54.com/Forum/424840/message/1153179235

When you haul your boat, be ready to send the props and shafts off for inspection, the props can be fixed, the shafts are not really able to be tested unless they're on a lathe, it's not realistic for the average guy to do this themselves without a lathe. I don't know about fixing a bent shaft, I understand it's possible, but would much rather have one that does not need any work.

By the way, I'm having my old 23 x 25 3-blades repaired, and will put them back on the boat next time it is out of the water, and then the 4-blade units are off for a repitching job. They are supposed to run with less vibration, but it's hard to tell actually, whether they do or not.

Hope some of this helps,

Regards,

Paul

Paul,
Thanks, this is a lot of help and the pictures were great. I'm hoping to not have to change the shafts. We are ready to pull the boat for this season but will inspect the shafts next season when its in the water again.

Actually, if you're in the water, it won't take but a short run of a hundred yards to see if the shafts are moving left and right due to a misalignment. That at LEAST tell you something, and then once the boat is hauled out, you can remove the shafts and sen them in for a testing.

That would be out of sync to do that in the spring when you want to go in the water, so it's best to test the shafts as soon as the boat comes out, if you think you have a problem there. I can tell you, they are often a real PAIN to get the hub off the shaft, ouch, that was some tough work on our 38.

Good luck,

Send photos when you haul the boat!

Regards,

Paul

Paul,
I already waited to long, the boat is winterized and ready to pull. I will examine it when they pull it and send some picures of the props and struts. I thought that I would put a dial indicator on the shafts to see if they weren't running true and make a visual inspection of the props and cutlass bearings.
Thanks,
Rick

Good luck with the dial indicator, unless you have the shaft on a lathe. If you have a misalignment at the hub, and you rotate the shaft, it can potentially give you a false reading. You'll get data, but whether or not its really worth anything remains to be seen. Naturally, if you have a badly bent shaft and it's wobbling in the center, and good at the hub and strut bearing, that will show.

Props can be pulled and checked, not a bad idea if you have vibration. Bearings can also be checked pretty well with a visual. I am surprised that some bearing manufacturers have a tight fit when new and others don't. Just depends on the brand you select.

Here is a nice article by David Pascoe on alignment, and it is well worth reading!
http://www.yachtsurvey.com/alignment.htm

Morse


Johnson Duramax Cutless



Prop and strut bearing puller
http://www.mindermanmarine.com/prop_puller.htm

Everyone ought to have two or three of these things in their tool chest, lol.

http://www.strutpro.com/

regards,

Paul

Paul,
Were you able to remove the props and shafts without removing the rudders?

Thankfully that would be a "yes". Just about all boats are set up with offset rudders for this very purpose

It was a real bear getting the shaft out of one of the hubs.

When you are ready to reassemble the shafts, if they are new ones, be darn sure you fit them up to your hubs FIRST, before you get everything in the boat. If they won't fit togethere nicely in the shop, they darn well won't fit in the boat when you are standing on your head.

Regards,

Paul