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Propeller Chart &
Recommendations
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 the the bellow 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. See
How
to Balance and Sharpen Article for more
information. For the best "bang for the buck" and no work balancing &
sharpening, look at the Graupner Carbon Filler Propellers. They are great for Sport running.
|
 |
 |
 |
 |
|
Plastic |
Carbon Fiber |
Beryllium Copper |
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 to
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,
the pull the boat out of the water and to test for heat, have an adult give
the motor the 5 second test. Which is, hold your finger on the motor for 5
seconds. If its so hot you can't hold it for 5 seconds, its too hot. Allow
to cool 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
- First move the COG (center of gravity)
forward or backward to get on plane quicker. For most monos and catamarans
30% forward of the transom is a good place to start. To check the COG put
your left and right finger 1/3 of the hull length forward of the transom
and have the boat balance in your fingers.
- If the boat will not come on plane,
and the motor seems to be at full RPM the prop is cavitating. You
may need a larger prop with more thrust to get on plane.
- A well balanced and sharpened prop
will always spin at higher RPM allowing a higher top speed!
- Always monitor motor or engine heat!
Cooler is better. To much heat kills!
- Different water conditions will
achieve different results. When comparing test results from a different
day make sure the water and wind conditions where similar!
The following Chart is from Octura's line up 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"
So 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,
- A Mono hull will slip 25%
- A Catamaran of scale Hydro 20%
- A Rigger about 15%
This is assuming that the hulls are well balanced and running free.
Click here for a
Tool to make some top speed estimates!
|
Octura Propellers. |
|
Prop# |
Diameter |
Pitch |
Fits shaft size |
Plastic |
Al |
BC |
|
930 |
30mm (1.18") |
0.9 x 1.18 =1.062" |
1/8" |
|
x |
x |
|
937/3 |
37mm (1.48") |
0.9 x 1.48 =1.332" |
1/8" |
|
x |
x |
|
955/3 |
55mm (2.17") |
0.9 x 2.17 =1.953" |
3/16" |
|
|
x |
|
0955/3R |
55mm (2.17") |
0.9 x 2.17 =1.953" |
3/16" |
|
|
x |
|
977 |
77mm (3.03") |
0.9 x 3.03 =2.727" |
1/4" |
|
|
x |
|
1240 |
40mm (1.57") |
1.2 x 1.57 =1.884" |
3/16" |
x |
|
|
|
1240/3 |
40mm (1.57") |
1.2 x 1.57 =1.884" |
3/16" |
|
|
x |
|
1245 |
45mm (1.77") |
1.2 x 1.77 =2.124" |
3/16" |
x |
|
|
|
1250 |
50mm (1.97") |
1.2 x 1.97 =2.364" |
3/16" |
x |
|
|
|
1250R |
50mm (1.97") |
1.2 x 1.97 =2.364" |
3/16" |
x |
|
|
|
1255 |
55mm (2.17") |
1.2 x 2.17 =2.604" |
3/16" |
x |
|
|
|
1270 |
70mm (2.76") |
1.2 x 2.76 =3.312" |
3/16" |
x |
|
|
|
1337/3 |
37mm (1.48") |
1.3 x 1.48 =1.924" |
3/16" |
|
|
x |
|
1427 |
27mm (1.07") |
1.4 x 1.07 =1.498" |
1/8" |
|
x |
x |
|
1435 |
35mm (1.38") |
1.4 x 1.38 =1.932" |
3/16" |
x |
|
|
|
1440 |
40mm (1.57") |
1.4 x 1.57 =2.198" |
3/16" |
x |
|
|
|
1445 |
45mm (1.77") |
1.4 x 1.77 =2.478" |
3/16" |
x |
|
|
|
1450 |
50mm (1.97") |
1.4 x 1.97 =2.758" |
3/16" |
x |
|
x |
|
1455 |
55mm (2.17") |
1.4 x 2.17 =3.038" |
3/16" |
x |
|
x |
|
1455/3 |
55mm (2.17") |
1.4 x 2.17 =3.038" |
3/16" |
|
|
x |
|
1457 |
57mm (2.24") |
1.4 x 2.24 =3.136" |
3/16" |
x |
|
x |
|
1457R |
57mm (2.24") |
1.4 x 2.24 =3.136" |
3/16" |
x |
|
|
|
1457/3 |
57mm (2.24") |
1.4 x 2.24 =3.136" |
3/16" |
|
|
x |
|
1460 |
60mm (2.36") |
1.4 x 2.36 =3.304" |
3/16" |
x |
|
x |
|
1462 |
62mm (2.44") |
1.4 x 2.44 =3.416" |
3/16" |
x |
|
x |
|
1462R |
62mm (2.44") |
1.4 x 2.44 =3.416" |
3/16" |
x |
|
|
|
1465 |
65mm (2.56") |
1.4 x 2.56 =3.584" |
3/16" |
x |
|
x |
|
1467 |
67mm (2.64") |
1.4 x 2.64 =3.696" |
1/4" |
|
|
x |
|
1470 |
70mm (2.76") |
1.4 x 2.76 =3.864" |
3/16" |
x |
|
|
|
1470 |
70mm (2.76") |
1.4 x 2.76 =3.864" |
1/4" |
|
|
x |
|
1475 |
75mm (2.95") |
1.4 x 2.95 =4.130" |
1/4" |
|
|
x |
|
1540 |
40mm (1.57") |
1.5 x 1.57 = 2.355" |
3/16" |
|
|
x |
|
1567 |
67mm (2.64") |
1.5 x 2.64 = 3.960" |
1/4" |
|
|
x |
|
1630 |
30mm (1.18") |
1.6 x 1.18 = 1.888" |
1/8" |
|
x |
x |
|
1640 |
40mm (1.57") |
1.6 x 1.57 = 2.512" |
3/16" |
|
|
x |
|
1650 |
50mm (1.97") |
1.6 x 1.97 = 3.152" |
3/16" |
|
|
x |
|
1655 |
55mm (2.17") |
1.6 x 2.17 = 3.472" |
3/16" |
|
|
x |
|
1657 |
57mm (2.24") |
1.6 x 2.24 = 3.584" |
3/16" |
|
|
x |
|
1662 |
62mm (2.44") |
1.6 x 2.44 = 3.904" |
3/16" |
|
|
x |
|
1667 |
67mm (2.64") |
1.6 x 2.64 = 4.224" |
1/4" |
|
|
x |
|
1732 |
32mm (1.26") |
1.7 x 1.26 = 2.142" |
1/8" |
|
x |
x |
|
1735 |
35mm (1.38") |
1.7 x 1.38 = 2.346" |
1/8" |
|
|
x |
|
1740 |
40mm (1.57") |
1.7 x 1.57 = 2.669" |
3/16" |
|
|
x |
|
1740/3 |
40ma (1.57") |
1.7 x 1.57 = 2.669" |
3/16" |
|
|
x |
|
1742/3 |
42mm (1.65") |
1.7 x 1.65 = 2.805" |
3/16" |
|
|
x |
|
1745/3 |
45mm (1.77") |
1.7 x 1.77 = 3.009" |
3/16" |
|
|
x |
|
1747 |
47mm (1.85") |
1.7 x 1.85 = 3.145" |
3/16" |
|
|
x |
|
1750 |
50mm (1.97") |
1.7 x 1.97 = 3.349" |
3/16" |
|
|
x |
|
1752/3 |
52mm (2.05") |
1.7 x 2.05 = 3.485" |
3/16" |
|
|
x |
|
1755 |
55mm (2.17") |
1.7 x 2.17 = 3.689" |
3/16" |
|
|
x |
|
1760 |
60mm (2.36") |
1.7 x 2.36 = 4.012" |
3/16" |
|
|
x |
|
1860 |
60mm (2.36") |
1.8 x 2.36 = 4.248" |
3/16" |
|
|
x |
|
1930 |
30mm (1.18") |
1.9 x 1.18 = 2.242" |
1/8" |
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