Installing a Hydrofoil

One of the easiest performance boosters is also a snap to install.

When I installed the Stingray StarFire Hydrofoil on my bass boat, I had three goals in mind: faster planing, better performance and less chance of chine walking, by adding more horizontal stabilization. I do my boating in the Kansas City area, and some of my lakes are pretty shallow in spots, so faster planing is a real advantage. While I prefer the no-drill hydrofoil models such as the StarFire, StingRay still makes the Classic, which requires drilling four holes in the cavitation plate to secure it. Stingray had a customer who wanted a Classic, and the company let me install it to show how ridiculously easy it is to accomplish. There should be a model to fit most every outboard or sterndrive’s lower unit, but check with the company if you have any questions. According to Brock at StingRay, there are a couple of models it won’t work on, including Evinrude’s new G2 engines, because of the shape of their cavitation plate.

StarFire Installation

You can install the StarFire with or without drilling holes. If it doesn’t seat tightly, you might want to choose the drilled installation, but I didn’t have that problem; it fit my Mercury OptiMax 250 like a glove, so I went with the no-drill install. Before starting, make sure your engine battery is turned off, to avoid accidental starts while working on it.

Step 1. Check to see if your engine has a torque tab installed; if it does, remove it. Mine had a flat sacrificial anode (1), so I skipped this step.

Step 2. Next, slide the StarFire Hydrofoil onto the cavitation plate as far forward as possible (2). Make sure there is no gap between the end of the cavitation plate and the hydrofoil. It was a tight fit, so I had to tap it into place with a rubber mallet (3).

Step 3. If your engine has a torque tab, reinstall it at this time. According to the directions, some engine models may require you to slip one edge of the torque tab underneath the StarFire’s built-in performance bracket before snapping the torque tab back into place.

Step 4. Insert both stainless steel set screws into the predrilled threads (4), and tighten the set screws using the hex key that came with the kit (5). The directions say to keep turning the screws until your hand becomes uncomfortable. That’s all there is to the install. But to make sure vibration from the engine didn’t loosen the set screws or allow the hydrofoil to slide backward, I hooked the engine up to flush earmuffs and ran it for a while. On your first few trips, check it out to make sure it’s not coming loose.

Optional Drill Installation

My hydrofoil fit so tightly I would have had to use a rubber mallet to back it off, and after a few trips it stayed firmly affixed, but if you feel like the StarFire isn’t on snugly and you want a little extra security, you have the option to drill two holes and screw it into place. To do that, first, locate the two pilot holes on the underside of the hydrofoil and use a quarter-inch bit to drill all the way through the unit. Slide the StarFire onto the cavitation plate and use that as a template to mark the position where you will drill through the cavitation plate. Make a mark by running your drill in reverse and then pull the StarFire off and drill through the cavitation plate, making sure to keep the drill bit perpendicular to the plate. Then follow step 4 above to finish it.

Installing the Classic

For this one you’ll need a drill with a quarter-inch bit and a Phillips screwdriver. The kit will have four stainless steel bolts, four nylon/stainless steel locking nuts and four rubber washers.

Place the Classic on top of the cavitation plate and slide it forward as far as it will go. The directions say to use the hydrofoil as a template to drill the holes, but I marked the holes’ location by, again, running the drill in reverse. I then removed the hydrofoil and drilled the holes (6), making sure to drill straight down.

Next, press the four rubber washers onto the Classic from underneath. Place the hydrofoil on the cavitation plate, lining up the holes, and insert the four bolts from underneath. Place the nuts into the holes on top of the unit with the plastic part facing up and tighten the bolts. Don’t over-tighten the bolts! Again, test it out before heading out and again after the first few trips, to make sure it stays tight.

According to the literature, you may see what looks like cracks around the holes, but they are surface “flow marks,” which are a normal part of the molding process.

I was very happy with the results of the StarFire. My time to plane was cut nearly in half and the boat seems more stable when running. The added lift also allows me to stay on plane at a slower speed.


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