How Do You Measure Shaft Length On An Outboard Motor

So, I was out on the lake last weekend, tinkering with my old outboard motor. You know how it is, right? You're out there, the sun's shining, fish are biting, and suddenly, you realize your motor's not quite performing like it used to. I mean, it's not like it's suddenly going to start singing opera or anything, but you know what I mean.

Anyway, I figured it might be a good idea to check the shaft length. Now, I've been around boats for years, but for some reason, I always forget how to measure this thing. I mean, it's not like it's rocket science, but still, it's one of those things that slips my mind. I'm sure I'm not the only one, right?

Why Measure Shaft Length?

Before we dive into the how-to, let's talk about why you'd want to measure your outboard motor's shaft length in the first place. Well, for starters, it can affect your boat's performance. If the shaft's too long, your prop might not be submerged enough, which can lead to cavitation - that's when your prop isn't getting enough water, and it starts to make a nasty, high-pitched sound. Not good.

On the other hand, if the shaft's too short, your prop might be too deep, which can also cause performance issues. Plus, it can lead to damage if you hit a rock or something. So yeah, it's important to get it right.

Alright, Let's Get Measuring

First things first, you'll need a tape measure. I know, I know, groundbreaking stuff here. But seriously, just make sure it's a flexible one, so you can wrap it around the shaft.

Now, here's where it gets a bit tricky. You want to measure from the bottom of the prop hub to the top of the gear case. That's right, not the bottom of the prop, not the top of the gear case, but the hub to the case. If you're looking at it, the hub's the part that the prop bolts onto, and the gear case is the big, heavy bit at the bottom of the motor.

So, you'll want to unbolt your prop (be careful, it can be a bit of a pain if it's been on there a while), then measure from the bottom of the hub to the top of the gear case. Easy, right?

What If It's Not Right?

If your measurement isn't what it should be, don't panic. There are a few things you can do. If it's too long, you might be able to shorten the shaft. If it's too short, you might need to extend it. But remember, this is serious stuff. If you're not sure what you're doing, it's always best to take it to a professional.

And hey, while you're at it, you might want to check the rest of your motor. It's not a bad idea to give it a once-over every now and then. I mean, you want it to last, right?

So, What's the Magic Number?

Alright, so you've measured your shaft. Now what? Well, the ideal shaft length depends on a few things - your boat's size, the prop you're using, the water depth where you usually fish, that sort of thing. But as a general rule, you want your prop to be about 1/8 to 1/4 of an inch below the waterline when the motor's trimmed up.

So, if you've measured your shaft and it's not quite right, don't stress. Just make sure you're doing something about it. Your motor (and your fish) will thank you.

And there you have it. Measuring your outboard motor's shaft length. Not quite as exciting as catching the big one, but still pretty important. Happy boating!