HydroSim Setup Guide

By Eddie Kanfoush


What does changing the prop pitch do?

[PROP PITCH VALUES - 24.00 inches to 26.00 inches]

The pitch of a propeller is how much the propeller pushes the boat forward in one revolution. If you have a pitch of 25 inches, that means that one rotation of the prop moves the boat forward 25 inches. Having a larger pitch will create a higher top speed, and having a lower pitch will create more acceleration. Finding the balance is essential for both the course you are running and the lane you’re running. On the inside lane or on a shorter course, you want a smaller pitch.

Aside from changing the acceleration to top speed ratio, having a larger pitch will also create more lift at the back of the hull, pushing the transom out of the water more, changing the way the boat rides across the water.

What does changing the prop diameter do?

[PROP DIAMETER VALUES - 15.50 inches to 16.00 inches]

The diameter of the propeller is the size of the propeller from the tip of the blade all the way across. Just like with prop pitch, having a larger diameter leads to a higher top speed and more transom lift, while a smaller diameter leads to more acceleration and less transom lift. Again, finding the balance here is very important, and it depends entirely on what course and what lane you’re running. Try to find a good mix between pitch and diameter to get the most performance out of the boat.

What does changing the shaft angle do?

[SHAFT ANGLE VALUES - 5.50° to 6.50°]

The angle of the propshaft changes how the boat rides. Typically, you want the boat to ride as flat and above the water as possible. With a lower shaft angle, the transom of the boat does not lift as much, which creates more lift at the front of the boat. With a higher shaft angle, the transom lifts more, creating less lift at the front. Generally speaking, you want a lower shaft angle in smoother water, and a higher shaft angle in the rough. This is all dependent on personal preference though, so play around with what feels comfortable for you to drive.


What does changing the gear ratio do?

[GEAR RATIO VALUES - 1/0.49 to 1/0.55]

Gear ratio is important for acceleration and top end ratio. With a lower gear ratio, the boat will accelerate more but will top out very quickly. With a higher gear ratio, the boat won’t accelerate well but it will reach much higher top speeds. Find a good gearbox for the course and lane you are running. Typically the smaller gear ratios are better for inner lanes and shorter courses.


What does changing the skidfin angle do?

[SKIDFIN ANGLE VALUES - 21.0° to 26.0°]

The skidfin is the reason the boat turns at such high speeds. Having a higher angle on the skidfin will allow the boat to corner tighter, but will scrub off more speed in the turn. A lower angle will create more speed through the corner, but leaves the boat susceptible to coming “unhooked,” where the boat rides up on the fin and nearly stops turning, skipping you out several lanes and scrubbing speed until the fin grabs the water again. Play around to find the balance of speed and maneuverability that’s right for you on the course that you are racing on.

What does changing the skidfin toe do?

[TOE IN/OUT VALUES = -2.0° to 2.0°]

Just like the tires on a car, the skidfin can be angled with the leading edge in/towards the boat (TOE IN) or with the leading edge out/away from the hull (TOE OUT). Naturally, the boat wants to pull to the left, largely due to the massive metal fin on the side. Moving the leading edge in (TOE IN, positive angle values) will help the boat straighten out and track better down the straightaway. Moving the leading edge out (TOE OUT, negative angle values) will cause the boat to pull left slightly more down the straightaway, but it may corner better once you reach the turn. Mess with the toe values to find the most comfortable handling of the boat.

What does changing the skidfin position do?

[POSITION FORE & AFT VALUES = -3 inches to +3 inches]

The skidfin is mounted to a bracket on the side of the boat, and can be moved forward (fore) or backwards (aft) on said bracket. Moving the skidfin backwards will create less maneuverability in the corners, but it will be much more stable, or less likely to hook when you encounter a large wave. Moving the skidfin forwards will allow you to turn tighter, but will make the boat much less stable throughout the corner. Find the spot that is most comfortable for you and allows you to hold a lane the best on the course you’re running on.


What does changing the “runner angles'' do?


The runners, also called primaries, are the main running surfaces on the bottom of each sponson. Changing the runners changes the angle of attack on the sponson. By increasing the runner angle, you increase that sponson’s angle of attack, which creates more lift at the front of the boat. On the shorter courses, you typically want a larger angle of attack to lift the boat out of the water more at lower speeds. More lift, less drag, better acceleration. Be careful with this at larger courses though, because you reach higher speeds on those courses, and a higher runner angle could make the boat too light down the straightaways. This part of the setup comes down mostly to personal preference, much like the shaft angle, so play around with it to find your comfort zone.