My 1986 26 footer, of which I am the happy and recent third owner, came equipped with a Martec MKIII folding propeller. It is a 2-blade, measured at 12"x12", mounted on the 3/4" shaft.
The pitch has not been adjusted for a long time and it might now be too powerful for my engine, which maxes out at 2500 rpm or less in gear. If I go to full throttle, black smoke comes out as I get close to 6 kt. But the diesel mechanic said not to worry.
I have no problems with the prop in reverse or forward. It does have some port prop walk, but so would a fixed blade. (And I feel I once read a convincing argument that a folding prop has less prop walk.) The blades open fast in reverse: If I give a short blast when docking, it feels like I applied the brakes.
Gary Beck who now runs Martec Prop Service recommended that I refurbish it. He wrote me:
We can get it in good shape and re-pitch it at the same time. (a full refurbish + re-pitch should run approx. $355.00 or less + S&H)
Typically the propellers should be refurbished after time (approx 4-10 years, depending on the environment the prop lives in, amount/type of use, the size of prop, number of different operators.)
For more information please go to our website
www.martec-props.com, click on Eliptec propeller, and then click on refurbishing a prop.
Sadly, the idea of refurbishing the prop occurred to me only after I’d hauled the boat, painted the bottom, and put it back in the water. My local dive service says the Martec folding prop is the one prop that has to be removed on dry land. It has a lot of tiny parts for a diver to drop. So I might do this next year when I haul the boat, but really, the prop seems to work fine (I typically power out of MDR for about 30 minutes, and on the trip north from Dana Point after buying the boat went about 5.5 kt for 5-6 hours steady under power.)
The former owners raced, which must be why they put in the folding prop, and they marked the shaft so that under way, you can easily twist it to the position in which both blades are swept back. To obtain maximum drag reduction, you must do this. If you just turn off the engine and sail, chances are that one blade will be hanging down and create some drag. Still, this must be less drag than a fixed prop. A few times I have reached down and twisted the shaft to reduce the drag. It’s annoying for a large person with a bad back in the tight confines of a 26 footer, but doable. You have to crawl into the quarter berth and temporarily remove a panel. I can’t tell how much difference it makes since my knotmeter doesn’t work. (I rely on a Garmin Foretrex to see my speed, but it uses satellites, not the paddle wheel below the fo'c'sle.)
Here is Gary's contact information:
Gary Beck
Martec Prop Service, LLC
14520 N Music Trl
Prescott, AZ 86305
Tel: 928-778-2035
Bus. Hrs. 8am - 5pm (MT)