Inboard Engine Mounts

 

Engine mounts perform important functions such reducing engine vibration noise transferring into the hull, dampening the forward and aft shock movements derived from transiting through the waves, and a convenient method to align the drive train of the vessel, a few functions often overlooked or taken for granted. Equipment mounts aboard vessels differ from land use equipment mounts in many ways because they have to with stand not only the movement of the equipment but also of the vessel.

 

This constantly varying movement will range from the body masses being synchronous to opposing each other. If anyone has had the fortune to experience two people simultaneously jumping on a trampoline or a diving board the effects are very similar. Marine inboard engine mounts are stout, can endure large thrust loads, and will keep equipment in place even in severe weather conditions.

 

Engine Mount Design

 

Engine mounts typically have natural or synthetic rubber pads or mount bushings that absorb the vibration. The rubber is available in various harnesses called shore and is measured with a durometer. Like most measurements it is not just a straightforward 1 to 10 but a little more complicated than that. The importance of understanding the hardness is because the weight of the equipment resting on the mount determines the hardness of the rubber required. The design of engine mounts is determined by the applications.

 

Engine Mount Sizes

 

In a stern drive vessel with a smaller horsepower engine, the inboard engine mounts will experience very little thrust force as compared to inboard engine motor mounts for a midsize fishing trawler with a straight drive. If the fishing trawler propeller shaft does not have a thrust bearing installed, the engine mounts are required to bear all the thrust of propulsion going forward or reverse even under severe load. Generator mounts do not endure the same type of loading but suffer from their own gremlins such as gyroscopic influences. As boat engines get bigger, heavier, and more powerful, such as in a commercial engine, the thrust is removed from the motor or gearbox mounts and is taken up by a thrust bearing installed in the shafting.

 

Motor mounts are either generic meaning they are interchangeable between manufacturers such as P.Y.I marine or Bushings Inc. or specific to a type of engine installation such as Chrysler inboard engine mounts or Mercruiser inboard engine mounts.

 

For generic motor mounts there is guidance available to assist in choosing replacement or new mounts that make the choice and selection easier. If installing engine mounts for the first time, replacing marine motor mounts, or simply performing routine maintenance, contact us if you have any questions regarding marine motor mounts.

 

Determining Engine Mount Weight Capacity (Per R&D Marine)

Below are the formulas to use to determine the required pounds per engine mount.

Technical Specifications

Part #	Stud Size	Capacity Per Mount	Foot Print	Mount Pre-Loaded	Deflection	Minimum Height	Maximum Height
800-003	5/8 UNF