The most difficult choice in Rc boating is picking the perfect prop! Propellers come in many different materials, listed from softest to hardest are Plastic, Aluminum, Carbon Fiber, Beryllium Copper, and Stainless Steel. The best performance will be from a perfectly balanced and sharpened Beryllium Copper or Stainless Steel prop. You'll notice that the below pictures of the Beryllium Copper & Stainless steel props are very dull, that's because these props come as castings and need to be filed, sharpened & balanced. For the best "bang for the buck" and no work balancing & sharpening, look at the CNC Aluminum props and Graupner Carbon Filler Propellers. They are great for Sport running.
Stainless Steel
When searching for the perfect prop we need to balance three important factors, Top Speed, heat buildup in Batteries, Motor & ESC (electronic speed control), and the ability for the hull to get up on plane. Most Electric kit boats come with props that will work in a wide range of applications. Changing to the right prop with a kit boat will almost always yield a performance increase. Always start out with a smaller prop and work up to the optimum size. Never put too large of a prop an electric boat first. This will lead to burnt-up ESC, Motor, or Batteries. Bigger is not better in every case, this is particularly true in high RPM motors. To run at their best efficiency they need to spin fast. Too large of a prop will not allow the prop to reach its best RPM efficiency range and will cause heat build-up in the ESC, Motor or Batteries. On the first run with the new prop, run it at full speed for twenty to thirty seconds, observe how quickly the boat got on plane and the top speed, pull the boat out of the water and test for heat, and have an adult give the motor the five-second test. Which is, to hold your finger on the motor for five seconds. If it's so hot you can't hold it for five seconds, it's too hot. Allow cooling fully before running again! If everything is cool or warm, keep doing this test until the pack starts to dump. DO NOT RUN THE PACK TO 0% CAPACITY! This will cause lots of heat and ruin your test results. At the end of the run if things are warm but not hot swap to a larger prop. With Nitro, running too small a prop may allow the engine to spin at to high of an RPM and blow the engine!
Things to remember
The following Chart is from Octura's lineup of propellers. There are other companies that offer propellers but Octura seems to have the widest range of sizes for Electrics. Most props are left-hand props, except for the ones labeled with an "R" after the prop Size. To figure out how far a particular prop will travel, we need to know the total pitch, which is the diameter x pitch. If we take into example the first prop listed(930), 1.18"diameter X .9 pitch = 1.062"The total pitch of the 930 prop is 1.062 inches. Every time the prop shaft turns once the boat will move 1.062 inches. This is with no slip in a perfect world. Well, it isn't a perfect world so as a rule of thumb,
This is assuming that the hulls are well balanced and running freeClick here for a Tool to make some top-speed estimates!
Octura Propellers.
Graupner Carbon Fiber Propellers.
Carbon Fiber
Prather Propellers
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