To ensure optimum performance from your propellers please perform the following prior to installation.
1. Check propeller shaft
Fifteen minutes with a dial indicator while the shaft is still installed can save a lot of agony later. If you don't have a dial indicator, you can use the following method. Rest a pointed stick on the rudder, aligning the pointed end with the machined center of the shaft, than rotate the shaft. Any deviation will be apparent indicating the tapered end of the shaft may be bent.
2. Bearing check
Make sure the cutlass bearing is tight. If there is any play of the shaft in the cutlass bearing, the bearing needs to be replaced. Please note that certain types of water lubricated bearings require clearance. If your yacht is fitted with such a bearing, contact the manufacturer and ask them what the maximum allowable clearance is.
3. Check key and keyway
Check that the key fits the keyway. The key should slide easily through the keyway, with no apparent slop. It may be helpful to note the direction of the key in the keyway.
4. Propeller fit
Dry fit the propeller to the shaft, without the key in place. Check that the propeller does not rock on the taper. Mark the shaft at the forward end of the propeller hub.
5. Fit propeller to shaft
It is good practice to "lap" the propeller to the shaft. It only takes a few minutes and will improve the fit. Purchase some coarse valve grinding compound from an automotive supply store. Liberally coat the tapered end of the shaft and the bore of the propeller with the grinding paste. Slide the propeller onto the shaft. Apply gentle pressure and rotate the propeller on the shaft 90䯠the right , then 90䯠the left and repeat this several times. Occasionally remove the propeller from the shaft and wipe out the valve grinding compound and visually inspect the bore. Continue this until a minimum fit of 75% is achieved. Most valve grinding compounds are water soluble and wash off easily with soap and water.
6. Check propeller position
Carefully clean the propeller and the shaft and check the "dry fit" once more. You will probably notice that the propeller goes to a different position on the shaft than before. Mark this new position.
7. Install propeller
Install the propeller with the key fitted to the shaft. Some people prefer to use a lubricant on the shaft, we do not recommend this. Check that the propeller goes up to the mark on the propeller shaft. If it doesnt, the propeller is sitting on the key and you must reduce the height of the key to overcome this problem. Draw the propeller up the taper using the propeller locking nut, then lock this nut with the second nut. Don't forget to fit a new cotter pin.
8. Shaft zinc
One word about shaft zincs. They should be as far forward on the shaft as possible, or as near to the cutlass bearing as practical. You are trying not to disturb the water flow to the propeller.
9. Alignment check
After the boat has been in the water for 24 hrs, the engine alignment should be checked.
10. Vessel performance
You should record your vessels performance after the hull is cleaned and the propeller is tuned. Take note of your top RPM and speeds achieved. This data will be useful the next time you fine tune your propellers.
11. Painting propellers
Painting your propellers will degrade the performance. Barnacles, on the other hand will degrade the performance more than properly applied paint. If you use the boat often painting is not necessary. If you have the bottom regularly cleaned then painting is also not required. On the other hand, if you are like most of us and use the boat not as often as you would like, then painting may be helpful.
Follow the procedure below when painting propellers:
A. The propellers will be clean when you receive them apart from a light coat of oil. Remove this oil film using alcohol or acetone.
B. Choose a good quality Zinc Chromate primer and lightly coat the propellers.
C. The anti-fouling paint to use on the propellers is sold under various trade names as Outdrive Anti-fouling Paint in spray cans. Spray 2-3 light even coats of paint on the propellers taking care not to get any paint into the bore of the hub.
D. Allow at least 48 hours drying time before putting the propellers into service.
E. Dont apply standard anti foul paint with a brush as it tends to "spin off" the propellers quickly and can not be applied as evenly as spray paint.
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