Fox
God im so pants at skiing
- Location
- Isle of Skye, Scotland.
Hey guys, i havn't posted in about 10 jillion years. Can anyone please tell me what do the dimensions of the impellor actually mean? Like 13/16.
Thanks!
Thanks!
Impellor numbers
- Thread starter Fox
- Start date
- Location
- Mount Albert, Ontario
On an impeller like you suggest with a 13/16 pitch, the 13 and 16 are the angle of the blades on the impeller. The first number, in this case 13, designates the angles of the leading edge of the impeller blade. So the leading edge (the part of the blade that would be the furthest forward when installed on the boat) is at an angle of 13*. The second number is always in relevance to the trailing edge of the impeller blade, the part of the blade that is furthest back when installed in the boat. This means that the pitch changes over the length of the blade. It starts off at 13* and progressively steepens to 16* by the end of the blade.
In General: A lower pitch is easier for a motor to turn in the water and generates better acceleration. A taller pitch usually translates to a higher top speed, but only if the motor has enough power to adequately spin the impeller at a good RPM.
However, things like pump diameter, exit nozzle diameter, impeller cone size and pump hub diameter can all effect how any impeller performs. Problems such as cavitation (caused by air in the pump) can also be an issue with lower degree impellers usually. Cavitation causes the impeller to "Slip" in the water.
In General: A lower pitch is easier for a motor to turn in the water and generates better acceleration. A taller pitch usually translates to a higher top speed, but only if the motor has enough power to adequately spin the impeller at a good RPM.
However, things like pump diameter, exit nozzle diameter, impeller cone size and pump hub diameter can all effect how any impeller performs. Problems such as cavitation (caused by air in the pump) can also be an issue with lower degree impellers usually. Cavitation causes the impeller to "Slip" in the water.