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

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

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 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 ).