We've been experiencing a vibration primarily between 3000-4000 rpm that people that ride on our boat notice as well (it's not just in our head!). At 600 rpm's as the motor is engaged in gear there's significant vibration too; it's smooth at the other speeds. The dealer has switched out props to try to alleviate the vibration as well as hit the optimal rpm's at WOT. Three difference props attempted. Came with four blade... two three blade props since then. With each, the vibration continues.
We think highly of the Yamaha 150 motor as it gets good fuel economy and seems to have plenty of power. Our experiences out in PWS have been phenomenal... great scenic beauty, fishing, great family times... but the only negative being the nagging vibration.
Anybody experience something like this? Any ideas?
Thanks for your responses.
The vibration at idle is not to uncommon....especially with an alunimum hull makes it noticeable. It generally comes from a low idle rpm in gear. Your idle rpms should be about 700 to 725.
Also look at this topic of another forum
or this one
Hope it helps
Today the dealer put on extra rubber washers between the motor mounts and the transom. With a sea trial, the F150 still had what I thought was very noticeable vibration at about 3500-3900 rpm's. The explanation from the technicians was that "it's an aluminum boat that's going to have some vibrations occur from the motor." I informed the technicians that a friend's boat (which is pretty much identical to mine) does not have any vibration issues.
The second thing attempted was running a Yamaha OEM 15 1/4 by 15 pitch aluminum prop. With this prop the vibration was significantly less. The dealer is out of the same size stainless steel version so I'll run the boat with this aluminum prop for the time being.
Overall, I'm slightly satisfied that the vibration is less. It is still a little disheartening to know that the rpm range that evidences vibration is what I'd like to run oftentimes out on the ocean.
While at the dealer, I met another new owner of a Hewescraft that said he's had some vibration issues with one of his F150's on his 26' PC. The prop size/pitch change seemed to help alleviate his vibration.
maybe check the prop shaft - turn the prop while watching the little divit at the end from the rear. Also- check the spacing between the prop and the housing on the side while spinning. If there is any flucuation, double check the lower gearcase oil. Sometimes just a little bit will make a big difference over any prop change. With a new gearcase oil change, it may be good for 50 hours or so depending on how out of alignment it could be. I never had any good luck with restraightening the prop shafts- even down the a few thousands of an inch. It could be something else, like loose bolts on the transom holding the motor...... Good luck.