Please see the diagrams and descriptions below to identify the correct style of propeller shaft for your application

This is the most common design of straight inboard propshaft. The propeller end is tapered, keyed, and threaded to an industry standard. The propeller is secured to the shaft by a full (prop) nut and a half (jam) nut. A cotter pin is installed as a secondary means of security. The transmission coupling end is straight and keyed to the proper size based on shaft diameter. The installation of the propeller full and half nuts is a source of debate. Installing the half nut first or the full nut first is a matter of preference.

This style propshaft is typically found on older boats (Chris Craft, Lyman, etc.) and also on ski boats. The propeller end is tapered, keyed, and threaded to an industry standard. The propeller is secured by a single castle nut and cotter pin. The transmission coupler end is straight and keyed to the proper size based on shaft diameter.

Double taper straight inboard propshafts are most commonly found in ski boats but are becoming more common in all sizes of boats. The propeller end is tapered, keyed, and threaded to an industry standard. The propeller is secured to the shaft by a full (prop) nut and a half (jam) nut. A cotter pin is installed as a secondary means of security. The transmission coupler end is also tapered and keyed along with the coupler. The shaft is secured to the coupler by a nylock nut. The taper on the coupler end is not an industry standard and therefore needs to be matched exactly when replacing the propshaft. The dimensional information of the taper will need to be supplied to provide the proper fit to the existing coupling. If the taper dimensions cannot be supplied accurately a new tapered coupler should be ordered with the replacement propshaft.

Double taper V-Drive propshafts are typically used on newer design V-Drive transmissions where the transmission coupler is located on the forward facing side of the V-Drive. The transmission output shaft is a hollow tube design that allows the propshaft to run through the tube and couple to the transmission flange on the front side. The propeller end is tapered, keyed, and threaded to an industry standard. The propeller is secured to the shaft by a full (prop) nut and a half (jam) nut. A cotter pin is installed as a secondary means of security. The transmission coupler end is also tapered and keyed along with the coupler. The coupler is machined with a reverse taper to match the propshaft taper. The shaft is secured to the coupler by a nylock nut or a castle nut and cotter pin. The taper on the coupler end is not an industry standard and therefore needs to be matched exactly when replacing the propshaft. The dimensional information of the taper will need to be supplied to provide the proper fit to the existing coupling. If the taper dimensions cannot be supplied accurately a new tapered coupler should be ordered with the replacement propshaft.

When replacing a double taper propshaft, the dimensions at the transmission coupler end are needed. The taper at the coupler end is not an industry standard like the propeller end of the shaft. These dimensions need to be exact to the thousandth of an inch. A micrometer or caliper will be required to obtain the dimensions.

The propshaft will be machined based on the dimensions supplied. This site is not responsible for improper fit due to incorrect dimensional information supplied. If there is any doubt regarding the taper dimensions, we suggest ordering the shaft with the proper fitted tapered coupler or reverse taper coupler based on your specific need.

Identifying and measuring propeller shafts requires precise and careful measurements.
If you are unsure about this process, we suggest you refer to a certified marine mechanic.  You can also give us a call for more information.