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Take care of your prop and it will take care of you

2009 May 1
Dear Boat Doctor,
In your March column, you provide solace to Richard Riley regarding the use of folding props but you don't really solve his problem. I've used a Martec folding prop on my boat since the early 1990s with no problems. The only "trouble" you can have with a folding prop is if fails to open, and there are a limited number of reasons why this can happen. One is stiffness or corrosion in the pivot, for which disassembly and cleaning is the answer. The other is wear-folding props have moving parts so wear is an issue.

In the case of the Martec, when you pinch the blades closed they should not touch. There should be a minimum gap of quarter inch between them. If the blades touch, or worse, you can wiggle the closed blades back and forth, the stops are worn and the prop needs to be reconditioned.

For a nominal fee Martec will weld new stops on the blades and the prop should work like new. This is a lot better than paying hundreds of dollars for a whole new prop.

Wayne Simpson
Brick Township, New Jersey

Dear Wayne,
Thanks for the tip, I did not realize that Martec (www.martec-props.com, 562-435-4494) offered this service. I spoke to them and got clarification on the service and the costs.
The representative from Martec tells me they expect a prop to last between five and 10 years before needing service, depending on use and conditions. There are essentially two ways the props wear-the open and close stops as you described and the pivot pins themselves get loose and out-of-round.

If the stops wear, the prop will not reliably open. You can tell this wear is happening as you describe, the blades should stay a quarter-inch apart when closed. If the pins wear, the prop will likely develop a vibration. You can detect this wear by excess wiggle in the prop blades.
Martec's rebuild service replaces the pivot pins with an oversized pin, rewelds the stops as needed, balances the prop, and replaces the cotter pins. The cost, depending on size and condition of the prop, is between $100-$220.