How to Install a Speed Grate on a Jet Boat

The jet ski is the fastest form of jet boat.

Replacing the standard intake grate on a jet boat of any size depends on replacing the standard grate with a speed grate of the same size. Speed grates, sometimes called loader grates, are grates that fully load both sides of the jet boat’s intake. This additional loading can result in an increase in the thrust developed by the motor, with a resulting increase in the boat's overall speed. Replacement is straightforward, and can be accomplished with the watercraft on its trailer.

Things You'll Need

• Marine silicone caulk
• Torque wrench
• 5/16-inch box-end wrench

Instructions

1. Move to the rear of the watercraft, inside its hull, and locate the intake grate -- the only opening on the bottom of the hull. Apply heat to the screws that hold the intake grate in place, using a heat gun, to break the factory-applied thread locker.

2. Remove the bolts and washers holding the conventional grate in place on the bottom of the hull, using a socket. Retain the bolts and washers for the installation of the speed gate. Note that there are no nuts on the bolts. Lift the grate from the intake opening and set the grate aside.

3. Spread a bead of marine silicone caulk around the grate opening, to seal the loader gate to the hull of the watercraft. Apply a light coating of thread locker to the threads of the bolts that will secure the speed grate to the hull.

4. Lower the speed grate to the intake opening. Insert the bolts through the washers that thread the bolts into their bores, to hold the grate in place.

5. Tighten the bolts to the torque specified in the information provided by the speed grate's manufacturer, using a torque wrench.

Tips & Warnings

• Keep the stock grate you remove from the watercraft as a replacement.

• Note that the original equipment grate does not have a rim, whereas most replacement speed grates do.

• Disconnect the negative cable of your boat's battery before performing any maintenance work on your jet boat to prevent accidental starting. Remove the nut from the negative post, using a 5/16-inch box-end wrench. Lift the cable from your battery, move it outside of the battery box and close the lid of the battery box. After the work is complete, reconnect the negative battery cable.

References

• SeaDoo 2008 Shop Manual, 4-Tec Series, 219 100 313”; Bombardier Recreational Products; 2008