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Problem with Prop after I hit small piece of Wood

G

George Cinquegrana

Guest
" I have a 1976 115 horse Evin

" I have a 1976 115 horse Evinrude and I was on the lake tonight and hit a small log with the prop. It sounded like the Prop released like it is supposed to.

When I put the engine back in gear it ran fine at slow speeds. As I advance the throttle, the engine sounds like it is working hard but no speed. I also notice an unusual wave pattern coming from behind.

I took the boat out of the water and the Prop looks fine. Could it be the release mechanism did not re-engage properly?

Thanks in Advance for your help.

George "
 
"George... A prop consists of

"George... A prop consists of a bronze hub, vaulcanized rubber, and the prop itself (rubber between the hub and the prop). The bronze hub is what contacts the prop shaft splines. The vaulcanized rubbers purpose is to absorb shock should you hit a underwater object of considerable resistance to eliminate lower unit damage. There are times when the vaulcanized rubber fails and no longer grips the bronze hub or the prop as it should.... and although the hub is turning as it should with the prop shaft rpm, the water resistance on the prop blades is so great that slippage occurs (the prop doesn't turn except at low rpms). You have a choice of having the prop rehubed, or purchasing a new prop.

Joe
"
 
" Your problem may be with the

" Your problem may be with the prop hub. The hub is pressed into the body of the prop using very high pressure. I have seen props where the hub is "spun out" within the prop causing the hub to spin without turning the prop. The symptoms of a spun prop hub match your symptoms exactly. You may be able to visually inspect the prop hub and see if you can detect any damage from the hub slipping. Often, a prop shop, or some other business that is involved with refurbishing props will need to look at the hub and test the integrity to be sure this is your problem.

Scott
www.marine-outboards.com "
 
" Thanks for the advice, I wil

" Thanks for the advice, I will go out and get a new Prop. To replace the prop, is it as easy an taking out the pin, unscrewing the nut and tkaing the prop off and then doing the reverse to install the new one?

George "
 
"George.... That's all the

"George.... That's all there is to it. If the splined shaft is somewhat lacking of grease, add some to it.... keeps the prop from becoming frozen to the shaft. Also, there's a large thrust washer in back of that prop which usually stays on the shaft, but they have been known to stick in the prop also. Make sure that thrust washer goes where it belongs.

Joe
"
 
" Thanks Joe for the help. On

" Thanks Joe for the help. One more question. I have been looking online for the right prop for the outboard and it is very confusing. It is a 1976 Evinrude 115 outboard, Long Shaft. I have it on a 16 ft V-Hull Fiberglass boat ( it flies!).

Any suggestions on which prop to install. I have a 3 blade on it now but I am not sure the pitch, etc.

Thanks
George "
 
"George.... Sorry, that's

"George.... Sorry, that's not a line of expertise for me. Check with your local dealer to see what the top full throttle rpm rating of your engine is. If for instance, it's rated to hit 5000 rpm, you would want a prop that would allow you to come close to that figure but not to exceed it. A reliable dealer should be able to pinpoint the right prop for you.

Joe
"
 
Are there situations where a

Are there situations where a new prop is not necessary? I have a friend who says he replaces some plastic piece in the prop. I have a 1985 Johnson 175 and I have the same symptoms as the thread above. The only difference is that it did not feel like I hit anything.

John
 
" John.... I recommended above

" John.... I recommended above that it could be "Re-Hubbed" or replaced. It depends on the condition of the prop. If a blade is torn off and another damaged bad, a new prop would be the way to go. If the prop is in fairly good condition, get it rehubbed for much less than the price of a prop. Give us a little history on your engine... when did the prop work satisfactory last, when did you notice this problem, exactly how does it act, etc? "
 
" Joe:

Thanks for the reply

" Joe:

Thanks for the reply. The history on the engine is unclear as this was a "gift." It has run well per my friend with basic engine repairs and maintenance. I have used it sporadically over the Summer. Last week I was running up the river at about 30mph when the engine went to high revs so I backed off the throttle. I was able to putt home though because the prop turned at low rpms. After reading your post, I felt it was the same thing although I didn't feel that I hit anything.

My friend has a 1996 Merc 225. He has been prone to hitting things so he now uses these kits with plastic parts that "break apart" if he hits something. I imagine it works the same way as the vulcanized rubber does. When it happens, he takes the prop off, drops another one of these pieces in and off he goes. Seems pretty cool and much better than blowing through props. Maybe it is a special type of prop he bought. I know he purchased a new one recently that was pretty high end. I don't know which type it is though.

John "
 
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