Shaft Question

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Ima90sJezus

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May 25, 2011
28
Catalina 30 Kent, NY
I had a professional Survey done when I puchased my '84 Catalina 30 last season. In the survey, he stated the following regarding the shaft:

"The propeller is positioned too far aft of the strut. ABYC recommends one shaft diameter of distance between the strut and propeller. The 1" prop shaft is scored about one inch from the transmission coupler. The prop is 2" from the strut. I suspect the prop shaft has been moved 1" aft of it's original position in the transmission coupler. Recommend repositioning the shaft to ensure a 1" distance from the prop to the strut."



Whats envolved with "pushing" the shaft an inch more into the transmission? I'm guess I'll need to re-pack the stuffing box as well? She is on the hard now and its my first boat, so I want to go through it all before she launches next month..

Thanks again....
 
redhead78

redhead78

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Dec 30, 2009
680
jeanneau 38 gin fizz sloop Summer- Keyport Yacht Club, Raritan Bay, NJ, Winter Viking Marina Verplanck, NY
I suspect he is reading right out of a book of general spec he is trained with, and as far as what I have been told by my engine dealer when I repowered, the rule of thumb was same distance as your shaft diameter, as he said. Applying a little common sense to this the farther out the prop is from either the shaft log or the strut there will be more strain on them from, the centrifigual forces with the prop spinning, 2" maybe not so much. Also I would think if u had a small ding or chip in a wheel that might only cause a very minor problem would be exagerrated more as u move the blade away from the strut. I would check wf other opinions on this, because if u are not having vibration problems I would think u would have to back off stuff box or lasdorf, unbolt trans coupling, remove prop slide shaft out,(my boat I would have to remove engine as shaft will not clear rudder post) either cut shaft or have it cut on coupler side, and put it all back together. Seems like a lot of work. How old is the survey, have u been running the boat like this for a while....Red
 
Stu Jackson

Stu Jackson

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Feb 26, 2004
23,101
Catalina 34 224 Maple Bay, BC, Canada
What engine do you have? If it's an M25, there is a wealth of knowledge on our C34 website for you, in addition to the C30 Association website (www.catalina30.com)

http://c34.org/bbs/index.php/topic,5078.0.html

http://www.c34.org/wiki/index.php?title=Diesel_Engine

That said, it appears the PO moved the shaft back because of scoring of the shaft exactly where the stuffing box is located. Most likely because he'd scored his shaft by either running the box dry or tightening it too much with no useable flax inside. This means that the potential scored portion of the shaft is now 1 inch or more aft of the location of the stuffing box. To move the shaft you'd need to open the bolts (three IIRC) on the shaft at the shaft coupling, and slide the shaft forward to see what you've got. You also have the potential for a mismatched shaft/coupling alignment.

Given this is a new boat for you, you could mess around with it yourself, find a handy fellow boatowner on your dock or hire a mechanic. Sometimes I feel like "boat mechanic" is an oxymoronic term, since it's rare to find a good one, so ask around. DIY is a great learning curve, but necessary, 'cuz most of us on this board figure DIY is the only way to get it right.

Our website also has a good writeup on stuffing boxes, including a link to Maine Sail's stuffing box, here: http://www.c34.org/wiki/index.php?title=Stuffing_box
The reason I sent you to our C34 website is that many, if not all, of our boat systems are identical.

Good luck.
 
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Ima90sJezus

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May 25, 2011
28
Catalina 30 Kent, NY
Its the M25, and she is on the hard in my back yard. As far as a "mechanic", its me and my father, so everything will be done by us.... I'll take a look at the C34 website and see whats there. I've only had the boat since September, not much "on-water" time with it. Sounds like I should do the stuffing box, no matter what...
 
redhead78

redhead78

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Dec 30, 2009
680
jeanneau 38 gin fizz sloop Summer- Keyport Yacht Club, Raritan Bay, NJ, Winter Viking Marina Verplanck, NY
Have u got any engine time on the boat ??? Red
 
Bob S

Bob S

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Sep 27, 2007
1,805
Beneteau 393 New Bedford, MA
Stu,

Love the C34 site. It's the best organized Catalina site I've seen. Can anyone join?

Ima, You had her last season. Was there excessive vibration? I would remove the shaft and have it cut to the right length for your boat. I don't think you can move it any closer to the transmission. Also remember reading somewhere you shouldn't use bottom paint on your shaft. Maybe someone can help me here?
 
redhead78

redhead78

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Dec 30, 2009
680
jeanneau 38 gin fizz sloop Summer- Keyport Yacht Club, Raritan Bay, NJ, Winter Viking Marina Verplanck, NY
Sounds like if he removes the shaft,and cuts it he will be on the scored area. So his choices look like change the whole shootin match, shft, coupler, stuff box,cutlass brg, or if its not vibrating go with it like it is. It may very well boil down to his money situation. If I, were him and had the dough, I would change it all..Red
 
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