Here are common questions we receive about our Max-Props.
If you can't find an answer to your question here please feel free to contact us.

In simple terms greasing the Max-Prop once a year is perfect in most circumstances. The Max-Prop can be greased with the vessel on the hard or by a diver with the boat in the water. The more often you grease it the longer it will last, at a bare minimum it should be regreased every two years.

Anodes (Zinc or Aluminum) last anywhere between two weeks to two years depending on the galvanic activity on your boat and the water around your boat. On a new installation check the Anodes often until you determine how quickly are deteriorating in your slip or mooring. I would replace the Anode with every haul-out whether it is needed or not, it is inexpensive protection for an expensive piece of equipment.

With regards to antifouling on the Max-Prop, there are many stories of how various household products work to keep growth off the propeller. To be honest most of them work well if you don’t use the propeller, as they create a barrier that marine growth can’t adhere to. But, the more you use the propeller the faster these and most any product will wash/wear off. The tips speeds generated by a propeller will wear the paint or coating at the tips of the blade. There is a very good product called Crystal Prop, it works very well on the propeller. It costs about $125.00 for an application. While no product is perfect, it should last a season when applied correctly, but the life ultimately depend on the use the propeller gets.

The Max-Prop can be set for either right or left rotation, it does not matter to the propeller. The rotation of the shaft is determined when viewed from the stern of the vessel looking forward. A shaft that rotates clockwise will have a right rotation propeller and a shaft that rotates Counter-clockwise will have a left hand propeller.

For a 2 blade measure from the tip of one blade to the tip of the other, this is the diameter. For a 3, 4 or 5 blade, measure the radius, from the center of the propeller to the tip of one blade and double that number for the diameter.

In a perfect world, while powering in flat water with a clean hull and propeller, the propeller will allow the engine to attain its maximum rated RPM. If the propeller allows the engine to attain over its maximum rated RPM then it is not creating enough load to the engine and you are not getting efficient thrust for the fuel that is being used. Conversely if the propeller does not allow the engine to attain its maximum RPM then it is overloading it and could be shortening the life of the engine. If you attain too many RPM then you will need to increase the blade angle of the propeller at your next haul-out. If you attain too few RPM then you will need to decrease the blade angle of the propeller.

The grease we recommend is Lubriplate 130AA. As it has been extensively tested and it performs well in all water temperatures. As an expensive alternative Lewmar winch grease performs well especially in warmer waters.

To increase the maximum RPM’s that the engine can attain when powering in flat water you will need to decrease the blade angle setting. Each two degree change in blade angle will increase the maximum attainable RPM’s by about 13%.

To a certain extent more zinc is better. The Max-Prop three blade has a zinc on it as it is often installed within an aperture where there is no room for a shaft zinc, and the propeller requires some protection. If the propeller shaft is supported by a strut it is a good idea to add an additional zinc.

Yes, the Max-Prop can be reconditioned and repaired. Whether that is normal wear, a blade bent in half, or pitting from corrosion, most damage can be repaired. To repair the propeller we will need the entire propeller, including the hub from the shaft sent to PYI Inc. Before sending us your propeller fill out the Max-Prop Service & Repair Form.

If you shut the engine off with the last rotation in reverse, the Max-Prop can not feather and the propeller and shaft will rotate. We can use this feature to drive a shaft alternator or regenerate an electric motor.

Modern transmissions are either mechanical or hydraulic. There are also mechanical and electronic controls for these transmissions. The procedure to feather the Max-Prop depends on the type of transmission and control being used.

NOTE: Water flow over the blades, combined with drag on the propeller shaft enable the Max-Prop to feather automatically. Follow these procedures to feather your Max-Prop:

Mechanical Transmission with mechanical controls:
  • Power at 2 to 3 knots in forward.
  • Kill the engine with the transmission still engaged in forward. The drag of the mechanical transmission should result in sufficient drag on the shaft for the Max-Prop to feather.
  • If your propeller has been greased properly, it will feather in a fraction of a second.
  • If the propeller has not yet feathered (shaft still rotates under sail), more drag can be added to the shaft of a mechanical transmission by engaging the transmission in reverse, with the engine OFF (WARNING: engage reverse only after the engine has stopped completely).
  • After the Max-Prop has feathered, the transmission can be placed back into neutral.
Hydraulic Transmission with mechanical controls:
  • Power in forward at 2 to 3 knots.
  • Kill the engine while still engaged in forward. The remaining hydraulic pressure will result in sufficient drag on the shaft for the Max-Prop to feather.
  • If your propeller has been greased properly, it will feather in a fraction of a second.
  • After the Max-Prop has feathered, the transmission can stay in forward or switched to neutral or reverse.
Electronic Controlled Transmissions:

These type of transmissions are becoming increasingly popular. Because electronically controlled transmissions automatically go to neutral when the engines are shut off, sufficient drag may not be achieved to enable the Max-Prop blades to feather. If you are having problems feathering your Max-Prop with an electronic controlled transmission, you may wish to consider the Max-Prop Boomerang (spring loaded blades snap into the feathered position as soon as torque from shaft is removed). Watch this video of the Max-Prop Boomerang work.

The Max-Prop Easy can be installed with the boat in or out of the water. Installation is similar to that of a fixed propeller. As well the Max-Prop can be maintained by a diver with the boat in the water. Greasing and changing anodes can be done in or out of the water with no problem.

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  • Lynnwood, WA 98087
  • Tel: 425-355-3669
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