Engine and Shaft line up.

It is very important to have your engine / shaft line-up as near to100% as possible, if the line-up is even slightly out the best performance from the engine will not be achieved. There is also the possibility that vibration damage to the engine will occur, a cracked bearing housing for instance.
An accurate line-up can be achieved by using a long shaft that will project through a modified engine casing or a gearbox as shown below.


CMB 90

An old CMB 90 engine casing has been modified by fitting 5mm ID alloy inserts in the rear housing and  into the case (after removing the needle roller bearing), this allows the line-up shaft to project from the proptube bearing housing through the engine centres.



With engine mountings fitted, the engine/proptube combination can be positioned in the boat to get the correct propeller to hull clearance and the required gap underneath the engine.


Line-up of Mocom gearbox for CMB 45.

The shaft diameter used in the Mocom gearbox is 7mm, whilst your propshaft will be 5mm, you can either temporary replace the gearbox bearings during the line-up process with 5mm ID ones, or alternatively make a couple of 7mm OD, 5mm ID sleeves to sit on the line-up shaft where it goes through the gearbox bearings during the line-up process.



The line-up in the boat is the same as before, check for the required space under the gear and clearance between propeller and hull.