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boat propeller shaft

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boat propeller shaft boat propeller shaft - EMSS


  • Application domain:

    for boats


The Evolution Marine Shaft System (EMSS) is a complete shaft system from engine to propeller. It's comprised of two major components: 1) the "oil-lubricated section" containing a '22' alloy stainless steel shaft enclosed in a 316L stainless steel shaft log tube with aft bearing housing and forward thrust bearing housing, and 2) the internal connecting shaft with a splined slip joint and flexible joints at each end.

Other system components include the engine adapter, mounting flanges, and monitor tank with its fittings and hoses.

The oil-lubricated section penetrates the hull. Essentially, it's the shaft enclosed in a non-turning shaft log tube. Generally, this tube is 316L stainless steel with an approximate wall thickness of 3/8 inch. It is extremely strong approaching the tensile and yield strengths of the shaft itself.

At the aft end, near the propeller, this shaft log tube mechanically mates with an aft bronze bearing housing consisting of a bearing cap that bolts directly to a mating bronze flange. This mating flange can be of various designs depending on whether the installation involves a sternpost/keel or strut configuration. For sternpost/keel configurations, the flange can have two or four bolts. This flange might only be a three-piece collar machined to accept the bearing cap and machined to bolt directly to fiberglass stern tubes or the aft face of the strut barrels.

Within the aft bearing cap are two double lip seals plus a needle bearing. These operate on their own hardened races. At the aft end of the shaft log tube, there is a plain, "free-floating"bearing.