Normally, motor mounts are designed to accept static, vertical loads with various hardness of rubber to attain the desired critical dampening ratio and static deflection. With all the power of propeller thrust pushing on the engine and motor mounts, the rubber part of the motor mount, by itself, has to be hard to withstand these horizontal, shear forces while maintaining the critical alignment between the engine and shaft.
In many instances, there are more pounds of propeller thrust to contend with than the static, vertical pounds of engine and gear weight. Under this condition, the very hard motor mounts afford little isolation of the engine vibration to the hull.
To isolate the engine vibration to the hull with truly soft mounts, either expensive thrust bearing assemblies must be used, or -- Evolution Motor Mount Compensators (EMMC). The EMMC will handle all the forward and reverse thrust on the engine and allow for softness in mounts that have eliminated up to 80 percent of the engine vibration to the hull. This alone has reduced sound levels on board a vessel by as much as 15 decibels. Soft mounts coupled to the EMMC positively change the environment aboard any vessel immediately on starting the engine(s).
With a "free floating" engine on soft mounts, it is recommended that all connections to the engine be flexible, i.e., flexible shaft coupling, exhaust coupling, etc. We would be happy to quote on flexible shaft couplings.