Motor quiet when idling yay. But up and running booo. It seems noisy and the vibrations are so far, through the range. Have not done full throttle yet as still only running in.

Yes will look at prop but really this is f in annoying.

Searched for threads not enouh info hence my own post.

At this point it has taken out all the joy out of a new motor.

Would appreciate so good direction .

Use the boat very regularly so know the feeling/sound between my old 2 stroke and now the sound of the 4. Good point though.

And importantly you guys have like me so many experiences and skills that I should be able to gain some excellent info as have so far.

Cheers guys keep it pumping.

It is brand new, 2 hours old. It has vibra pad, the transom designed to suit under surtees instruction.

it had similar vibration issues at certain revs, just happened to be cruising speed... we changed the prop to a smaller pitch in the end and it settled down about 70% better. Funny thing was when I upgraded the motor to the bigger DF150 in 2010 all vibration just disappeared...the old motor was fitted to my neighbors 610 Sportscraft as an upgrade from his old Merc 115 2stroke, he ended up having to fit the original Suzuki prop back on the DF115 to stop the thing from vibrating. All alloy boats resonate to some degree.

I have taken all on board and with my own experience in chassis construction and vibration issues have taken a course to remedy.

Firstly there are as you all have seen a number of areas to take into account and all play there part. It is a matter of eliminating the obvious until you end up with the acceptable compromise in some situations.

My course of action has been to seek your feedback which is real time experience, professional mechanics experience and my own.

I have implemented the next stage which is to drill out the existing mounting bolt points in the transom and replace with tubes to accept a bushing rubber of which there are many grades.

Hard surfaces to hard surfaces, ie; motor bracket, to bolt, to transom is really unacceptable. Think cars early hard suspension or no engine bushing to todays isolated componentry.

Add a vibra pad and collared bushes as mentioned before.

This is stage two.

The next stage if required will be to assess the prop size/pitch, as the range of the prop sizes is very good for this motor and I'm starting with a 20" S/S.

If this all fails then the remaining options will fall into the category of acceptable conditions as the motor can be such that its natural harmonics are just that, and in relation to the the hull or boat construction and its own natural harmonics.

Thanks again for your input and when mods and trials are completed I will inform you of my results.

I can suggest to you all that as consumers of products you should ask since it is not yet standard practice for installation, will your motor be mounted with vibration taken into account and at what cost. This is particularly important with alloy construction. Though a sea trial on a boat and motor formula that is the same as the set up you are going to use/install will be most informative.

The cost for my above re-installation method may not be cheap but for my needs is an important area of my overall boating enjoyment. Just like TAS syndrome, I have BESS ( boat enjoyment satisfaction syndrome ). 

First prop ~ no problems, but rev'd too high.

Changed both style & pitch and the whole boat seemed to "shudder" through the rev range. I described it as "cavitation-like" buy "not cavitation". Your description probably far more accurate.

I am finding that all props seem to have differing characteristics. It's not just a matter of "chucking a propeller of so and so pitch" on the back.

I have solved my problem by going to a 4 blade prop. Completely smooth right through the revs. Just playing with the pitch now. Have you a dealer that will loan you a 4 blade to try ?

I have PMed you but throwing this out to a wider audience.......anyone else come across this problem? Just popped a Suzuki 100hp on a Surtees 5.5 Workmate and resonance + vibration has me very very disappointed with the end result.

Cheers

Bricker

Hopefully our ph conversation was productive for you.

I think the path your about to take will be more than suitable for your needs.

Let us all know how you get on.

M