Knocking in Reverse

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Schomer

Schomer

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Oct 16, 2009
19
Catalina 30 San Francisco
I was pulling out of the slip this weekend and after about five seconds of backing up I started to hear some loud knocking. Taking it out of reverse stopped the knocking. I put it back into forward... no knocking. Back to reverse a couple times to confirm, rev'd it up pretty high to see if it changed... still starts knocking after about five seconds in reverse.

Any ideas as to what I should look into?

Seems like it only happening in reverse is somewhat of a clue... what sorts of things happen in reverse that might cause the knocking? It's so bad that I didn't go out in the boat. Didn't want to risk something coming apart. There was no wind on the bay, so no option to sail it back if I lost power.

Thanks for any ideas,

Todd
 
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 either a trans or a loose strut issue. I just got for x-mas a small camera on a little plastic fish rod with a screen. I saw it in sail mag as a gift, and thought what a stupid looking gadget, 79, or 99$$. Moving on I saw it on amazon later on for 59$, Amazon, was giving 40$ off on gifts, if you opened a no anual fee amazon visa card, so yup, for 20$ I am the proud owner of one of these devices.If nothing else the grandkids can keep amused looking at the fish, I am hoping I can see my prop ect....sorry about the off subject rant......might be good for a look under....Red
 
B

Benny17441

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May 24, 2004
7,134
CC 30 South Florida
Last time that happened to me was a short piece of line wrapped around the prop shaft.
 
M

Mike Turner

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Oct 11, 2009
98
Lazyjack Schooner Fairhope, AL
You might check your motor mounts to see if any have worked loose. Ours occasionally do and the first signs are usually knocking/vibration, followed by the prop shaft binding in reverse and stalling the engine out.
 
RAD

RAD

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Jun 3, 2004
2,330
Catalina 30 Bay Shore, N.Y.
When I bought my boat there was a loud knock like sound at a certain RPM and I knew it wasn't the engine so I thought for sure it was a bearing in the tranny but after a lot of reading I read some where that it was a bent shaft or an alignment issue so I checked the shaft and changed all motor mounts with new and did an alignment and all was good
 
Schomer

Schomer

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Oct 16, 2009
19
Catalina 30 San Francisco
Thanks for the tips! I'll see if I can give things a look. I'm not a mechanic by any means, but I'll check what I can and call for backup if I don't see anything.

Seems like it could be something inside, since it only happens in reverse... prop pushing shaft toward the boat...
 
Squidd

Squidd

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Sep 26, 2011
890
AMF Alcort Paceship PY26 Washburn Wi. Apostle Islands
Coupler or cutlass bearing...? prop pulls back and bearing/shaft gets loose in strut...

Open the hatch and get someone to watch (or operate controls Fore and Back while you watch) for movement of motor, trans, coupler, shaft etc...
 
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