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lasallehome 04-20-2009 12:10 PM

atomic 4 shifting in forward-- heavy vibes
just bought my first atomic 4 and it was purchased thru an estate sale. so No previous owner to ask.

My problem is after just starting and engined warmed up, I go to put in forward and engine vibrates very strongly- boat will move slowly but mast shakes violently- i will then her back into neutral and maybe reverse and try again- sometimes she connects ok and other times it may take 5 or 6 times before she catches forward with no vibrations-- works fine in reverse though-
tried adjusting shifter

any suggestions-greatly appreciated

sailingdog 04-20-2009 01:24 PM

Sounds like a transmission problem, not an engine one...

Faster 04-20-2009 01:52 PM

Sounds to me like a folding prop that only opened one blade.....

Keldee 04-20-2009 01:58 PM

Or it could also be the cutlass-bearing.We are assuming the prop is clean?Maybe a good place to ask this question and for great info on the Atomic 4 is at Moyer Marine which has an excellent forum.

CalebD 04-20-2009 02:01 PM

Either of the above explanations could cause excessive vibration.
I will add that your engine/shaft alignment could be out and your cutlass bearing could need replacing as possible causes for vibration.
It seems to me that the transmission is the likely culprit though. There are discussions on how you adjust the A4's transmission over on the Moyer Marine Community forums: Moyer Marine Atomic 4 Community - Powered by vBulletin
Our A4 shifts fairly easily into forward gear with little variation in vibration or sound.
Good luck.

Faster 04-20-2009 02:23 PM

The fact that even the mast shakes violently, and the fact that the problem occasionally disappears really points to the prop not opening. But it would be nice to know what sort of prop it is before committing to that theory.

lasallehome 04-20-2009 02:38 PM

thanks -- all i know is that it is a 2 blade folding brass prop

sailingdog 04-20-2009 02:44 PM

My reason for thinking transmission and not prop is that he doesn't have any issues in reverse. A faulty prop would probably give problems in forward and reverse, would it not???

lasallehome 04-20-2009 03:00 PM

I did take her for a ride on saturday, when i started her at the dock and then put her into gear she vibrated heavily- then put into neutral and reverse and tried a few times more and then she was finally ok- I took her for a ride for about an hour and ran just fine.

Next day , same thing happened after she was warmed up at dock had to shift her back and forth few times before vibrations went away and fine for another ride. went sailing and same thing again- vibrated when started in forward again.

THANKS for all your help

Faster 04-20-2009 03:54 PM


Originally Posted by sailingdog (Post 477776)
My reason for thinking transmission and not prop is that he doesn't have any issues in reverse. A faulty prop would probably give problems in forward and reverse, would it not???

SD - in our experience with our ungeared martec, it always opened equally in reverse, but occasionally failed to do so in forward. We took to spinning the prop briefly in reverse and shifting to forward and rarely had that problem again.

Lasalle: do you or do you not have a folding prop on this boat???

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