Cal Boats CAL 27 Mk III Owner's Manual - Alignment of Engine to Shaft

ENGINE OPERATING INSTRUCTIONS  15

ENGINE OPERATING INSTRUCTIONS

The engine installed in your yacht has already been run and all systems tested before leav-

ing the Cal, plant . We are not going to get into a great amount of detail in this area, for we 

believe the manual supplied by the engine manufacturer adequately covers the subject .

Study your engine owner’s manual and get to know your engine . The knowledge could 

be of great assistance to you . Also, some manufacturers have clinics aimed at the customer; 

contact them for details .

It is advisable that you follow the engine manufacturer’s procedures and recommendations 

on run-in and maintenance . On yachts with propeller shafts, please use the following proce-

dure:

Alignment of Engine to Shaft

The engine must be properly and exactly aligned with the propeller shaft . No matter what 

material is used to build a boat, it will be found to be somewhat flexible, and when launched, 

the boat hull will change its shape to a greater extent than is usually realized . It is, therefore, 

very important to check the engine alignment at frequent intervals and to correct any errors 

when they appear .

Misalignment between the engine and the propeller shaft is the source of troubles which 

are often blamed on other causes . It will create excessive bearing wear, rapid shaft wear, or 

leakage of transmission oil through the rear seal . A bent propeller shaft will have exactly the 

same effect, and it is, therefore, necessary that the propeller shaft itself be perfectly straight .

The engine should be moved around on the bed and supported on the screw mounts until 

the two halves of the couplings can be brought together without using force and so that the 

flanges meet evenly all around . Never attempt a final alignment with the boat on land . The 

boat should be in the water and have had an opportunity to assume its final water form . It is 

best to do the alignment with the fuel and water tank about half full and all the usual equip-

ment on board and after the main mast has been stepped and final rigging has been accom-

plished . 

Take plenty of time in making this alignment, and do not be satisfied with anything less 

than perfect results . The alignment is correct when the shaft can be slipped backward and 

forward into the counterbore very easily and when a feeler gauge indicates that the flanges 

come exactly together at all points . The two halves of the coupling should be parallel within 

0 .003 inches . In making the final check for alignment, the engine half coupling should be held 

in one position and the alignment with the propeller coupling checked in each of four posi-

tions, rotated 90° between each position . This test will also check whether the propeller half 

coupling is in exact alignment on its shaft . Then, keeping the propeller coupling in one posi-

tion, the alignment should be checked, rotating the engine coupling as described above .

The engine alignment should be re-checked after the boat has been in service for one to 

three weeks and, if necessary, the alignment remade . It will usually be found that the engine is 

no longer in alignment . This is not because the work was improperly done at first, but because 

the boat has taken some time to take its final shape . It may even be necessary to re-align at a 

further period . The coupling should always be opened up and the bolts removed, whenever 

the boat is hauled out or moved from the land to the water and during storage in a cradle .

The flexibility of the boat often puts a very severe strain on the shaft or the coupling or 

both when it is being moved . During the alignment procedure, check the set screws which