Water flow. If you’re interested in knowing the size of your propeller is it is best to start with measuring the size of your vessel. Find out how to calculate the propeller size of your boat on the YouTube channel, “How to Determine the Dimensions of a Boat Prop”.
The shaft’s diameter is measured to determine the prop size to fit the boat. The shaft runs through the gear casing of the prop and generally made of aluminum or steel. Its shaft will be oval, though it might possess a slight incline. The diameter can be calculated via a different method, if you do not have a ruler to measure in inches.
First, draw an outline of a circle using a pencil on paper. Following that, draw another circle by using a pencil. The distance is between the marks you made (called “paddles”) at the circle’s diameter. Then, take a measurement between one paddle and one and then multiply that number with 0.33). This will give you an estimation of the prop’s shaft/prop’s diameter ratio.
If you don’t own any other measurement tools such as a tape gauge, it can be used to calculate the ratio. You should measure every end of each tape to be sure that they’re even. The numbers you get may not be adequate enough for calculations if they aren’t.