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WATERSKI MagazineUnless you're Picasso with a ball peen hammer, pounding dings out of your prop yourself is a bad idea. But you can't let 'em go unfixed. That's why it's important to find a good prop shop to bang out the rough stuff and give you back much-needed performance.
Master prop men Jim Ott and Dave Carlson at McDurmon Distributing near Detroit suggest you ask these five questions of any prospective prop shop.
1) Does the shop have the correct pitch blocks to bring the prop into proper pitch? A pitch block is a mold of one blade of the propeller that the shop uses to work the blade back into shape. If they do not have the correct blocks, will they be able to accurately repair the damage?
2) Does the shop index the propeller blades so they are equally spaced around the prop's center? For example, a three-blade prop should have blades exactly 120 degrees apart from each other. If the shop doesn't index, then all of the blades will not generate the same amount of thrust, resulting in an inefficient prop.
3) After the repair, does the shop static-balance the prop so all blades weigh the same? This is very important when they are welding material on to the prop to repair a blade area that has material missing. A properly balanced prop is essential for smooth performance.
4) If your prop has a cup to the trailing edge, does the repair company have cup gauges to check if the cup rise is correct for each blade? This also affects the performance and smoothness of the propeller. If all cups are the same, then each will perform the same amount of work for the propeller. Also, the trailing edge of the blade should have a square edge so that water flows off smoothly.
5) The prop should be finished correctly. Most aluminum should be painted to match the finish before the repair. Nibral or bronze props should have a brushed finish, while stainless steel is polished to a mirror finish. Will the shop do this? – Jay Watson
