Catalina 30 TRBS #2889 "Northern Light"

5411 diesel engine mounts

The rest of the modifications.

Stock engine mount. Very non-compliant!

The new engine mounts are Vetus K50 just as other C-30 owners have used. The Vetus mounts make a huge difference in engine noise transmitted to the hull. Being much more mechanically compliant than the stock mounts, they do raise two issues that have already been documented on the list over the years:

  1. the engine shakes prominently and everything rattles if idle speed is a bit too low, and
  2. despite careful engine/shaft alignment the propeller shaft exhibits mechanical resonance at certain RPMs (slow beat frequency (approximately three second period) and possible shaft contact with the narrow shaft tunnel.)

Both issues must be managed.

I did try out the concept of a "PTS-like" disk that I made out of 1/4" polyethelene installed between the transmission flange and shaft flange using nuts as standoffs.

Here's the installed view. But, it didn't really make a difference in the resonance. Perhaps a real PTS coupler would.