See full version: How do you measure a Johnson outboard shaft
Also, what is outboard shaft length? Shaft length: The shaft length announced by the outboard manufacturer is the vertical distance between the inside of the clamp and the cavitation plate. (We will not argue about names here but the proper name for the cavitation plate is ant ventilation plate). Shaft lengths come in multiples of 5" (127 mm). more
Measure from the bottom of your outboard's engine compartment down to the bottom of the cavitation plate -- the horizontal metal wing above the propeller. If the measurement lies between 19 and 21 inches, it's a short shaft. If it's about five inches longer than that, it's a long shaft.
Similarly, you may ask, how do you measure a lower unit shaft?
If you are measuring for a lower unit replacement and your original lower unit is off of the engine, simply measure from the top of the waterpump to the top of your driveshaft. A shaft length that falls closest to 15 inches is short, closest to 20 inches is long, and so on.
It’s important you know the specifications of your motor because the wrong size could lead to damage and underperformance of the motor.
You’ll know that the shaft length is correct when the cavitation plate is in line with the very bottom of the boat. The cavitation plate is the large plate that extends over the prop of your dinghy. here
Also, there are pros and cons to having both a long and short outboard motor.
This is considered the most optimal placement for your outboard and will ensure the best performance for your motor. here
I made a hard turn going only about 15 mph prop came out of the water ,once again trim all the way down .
24-SSL (2012) Express w/6 strakes, awesome cable steering because I'm cheap, big gouge in pontoon where marina staff sideswiped their dumpster, redneck emergency toilet via bucket with a toilet seat glued to it (hey, its just a toilet), polished toons and a broken ladder strap. Hoping to log my 200th trip out this year (2018).
2012 2275 RL, Matador Red, monochrome interior with palm mocha carpet, Yamaha 115, Bimini lights, underwater LED's, side lighting LED's, SS rubrails [links]
If you own an inflatable boat or are looking to purchase one, getting an outboard motor or trolling motor for your boat has crossed your mind. Gas outboards are ideal for most dinghy owners that are looking for speed and power. Trolling motors are also a great alternative for owners looking for more green solutions with less of a price tag. If you are new to boating, it can be tough to know which one will best fit your inflatable dinghy. Getting the right shaft length is vital to the performance of the inflatable and ensuring your motor doesn’t bottom out. In this article, we will discuss the best sizing options for inflatable boats and how to measure a motor to ensure it will work for your setup. [links]
Shaft Length: 55" more
Water Compatibility: Saltwater & Freshwater
Water Compatibility: Saltwater & Freshwater here
Designed to fit a wide variety of vessel mount locations. here
Shaft Length: 40" here
Gary,
I have a Tohatsu 6HP long shaft (25") on my 1981 H22 and use a Garelick model 71042 engine mount, but the shaft length alone should not be considered in isolation. here
1. How far up the waterline is your engine mount (as Dave stated),
2. What sea conditions (wave height) do you (or anticipate to) sail, AND
3. What is the vertical travel of your engine mount ?? [links]
Have had good performance from our engine. That is until now when the shop could not get it apart because the water tube is fused in place due to salt water. We cannot find a tube of the right length to replace the old one. Probably going to shorten the length of the shaft by five inches. Hopefully this will not affect performance. here
These three factors impact what you would or would not want for an engine shaft length. [links]
I would like to hear from other Hunter 22 owners concerning the length of the shaft on their outboard motors. Short, long, or X-long. My boat is equipped with an outboard bracket which can raise and lower the motor. My old Evinrude Yacht Twin - X-long - has developed some problems and I may need to replace her. Your thoughts please.