Cutlass bearing shot, what is max shaft wear allowable ?

[Jd1]

I took out a 2005 Catalina 36 for sea trials today and the poor thing sounded very sick and was awfully slow. The boat was hauled and we found a good crop of barnacles hanging off the bottom of the fin keel (hence the speed issue) and we didn't find a cutlass bearing !!! Well there was a very thin remnant of cutlass bearing left but the shaft had maybe 1/4" of play in the bearing.
The shaft is nice and shiny where the bearing is supposed to be and I suspect it has some wear. The shaft is 1".
I would very much like to know what level of wear is acceptable on the shaft. For obvious reasons the broker is telling me it's just fine and they will just replace the cutlass bearing but I would like to make darn sure this won't haunt me down the line someplace. I do have tools to measure the shaft accurately but will need input about the allowable wear.
I would also like opinions on the likelihood of shaft damage due to the flopping around of the shaft. I assume there won't be any damage (no obvious bend or anything) but thought I would ask the question just to make sure.

Last but not least, cruising rpm for the m35 universal diesel is 2000-2500 rpm. What kind of speed through the water should I see in that range (speed/rpm?)
Thanks in advance for your thoughts!

[roverhi]

If the boat is out of the water, you can put a micrometer on the shaft and measure if it is worn and/or out of round. If there was still rubber in the bearing, there is a good chance the shaft is okay. The problem is why did the bearing wear that much?? Too many hours between bearing replacement or an engine that is way out of alignment??

The Yanmar in my boat was poorly installed and didn't have enough adjustment of the mounts to align it. It would eat cutlass bearings in a 100 hours or less with close to a 1/4" of slop. Had to change the bearing every haulout since it was reengined, at least 4 haulouts. Finally got to the point that the set screws were stripped out and the bearing was spinning in the log. This last haulout, had to build up the log by wrapping with epoxy saturated cloth. Coated the cutlass bearing with wax and used thickened epoxy in the log to take up the slop that the bearing had worn into the log. Retapped the set screws and log/cutlass bearing are fixed. Had to pull the engine and do a complete reinstall with different mounts so the engine could be aligned. The shaft was still good but changed the prop and shortened the shaft by an inch so the wear is in a different location but that was because of the new Sailor Prop.

[sdowney717]

Consider using a vesconite bushing, cheap and long lasting. They can custom make one to your size needs. They really are a lot less expensive, even shipped airmail from South Africa.

Vesconite Manufacturer Home Page: Low maintenance bushes and bearings

[Jd1]

I can not choose anything but the original cutlass bearing since I am not fixing the issue - the broker is. My concern here is strictly with the wear on the shaft.
Peter, thanks re the comment on excessive wear - how did you determine that things were out of alignment ? Is there anything I can do to verify that the current setup is properly installed/aligned ?

[onestepcsy37]

this could be a big one.

first, the broker is probably full of it - he's got a personal stake in the sale so his opinion is next to useless. you need a good engine guy to take a look at the coupling where the shaft mates with the transmission and probably the transmission as well. then there's the packing gland. the vibrating shaft may have put the gland out of round or worse, loosened it, and it will soon become a source of leaks. it is likely damaged by the extreme vibration of the shaft. you need someone to look at the whole drive train.

is the cutlass bearing in a strut or in the hull? if it's in a strut then look for strut damage - you might need to reinforce the hull where the strut is attached. if it's in the hull see if it's loose. if it's loose, than you may have to rebuild the hole that the cutless bearing goes through.

if it's just the cutlass bearing then you're maybe looking at a $300 job. if there is any additional damage, and it's very possible, i think i'd tell the broker you want at least $1000 off the price.....

[CharlesFCook]

Why not walk away from the boat? There has never been more people desperate to sell their boats.

[Jd1]

I just found my answer! Located in this URL:
https://www.abycinc.org/committees/P-06.pdf
as posted by Gord May in 2008 on this site .... Thanks Gord !!!

[Acushla]

Jd1
I checked the abycinc data and you now have the acceptable clearance allowances. However it does not mention the question of shaft ovality. For this it should be zero tolerance, any ovality will progessively destroy the shaft and its bearing. If ovality is present on the bearing area of the shaft then it needs to be replaced.
The earlier post advising the use of Vesconite is a good one and worth doing when you need to change the bearing.