*** AV Plate denotes engine Anti-Ventilation plate and may also be referred to
as the cavitation plate.
Electric drill 1/4' drill bit
101, 4200, 5200 marine sealants (Must
be rated for underwater use. Silicone is not recommended.)
Tools to remove your propeller
Small rags for cleanup and to cover
Sealant Cleaner/Remover safe for
painted surfaces (If needed)
The following install is of a top-mount 001 Permatrim being installed on
a 2004 F75 Yamaha outboard. You will not need to alter the Permatrim to make it
fit. If fitment does not seem correct,
*Smaller outboards use 4 bolts per side. Engines
over 115hp use 5 bolts per side.
Remove propeller and cover prop hub area on gear case with a rag to protect from shavings entering this area. Removing the propeller gives you more room to drill.
Drill the first two holes, one each on either side, aft of the sacrificial anode. A definite measurement on the gear case may be difficult so you will need to eye it up and use your judgment. Make sure all drilled holes are well in from the edge of the ventilation plate.
Place the Permatrim over the top of the AV plate. Make sure the Permatrim is straight. The Permatrim should be mounted as close to the raised section as possible without lifting the Permatrim off the AV plate. (The Permatrim in the picture is being installed on a single engine catamaran style boat and needed to be mounted further aft. This is not the norm. The Permatrim should be against the raised section.)
Starting from the center of your first bolt hole (the temporary bolts), place a piece of masking tape from the center of the bolt towards the front end of the Permatrim. Check the underside of the Permatrim to make sure that the tape line is at least inboard from the edge of the AV plate. On most outboards the tape lines will not be parallel and will angle slightly away from each other following the shape of the AV plate. Using a tape measure mark the remaining bolt holes. Remember, 5 bolts for motors 115hp and above, and 4 bolts on all others.
The very most forward bolt hole should be 1 to 1-1/2 from the most forward part of the Permatrim to make sure you will be catching enough of the AV plate. AV plates come in various shapes so you will need to use your judgment.
One your bolt holes are marked you may drill the Permatrim and the AV plate together. As you go forward, the clearance from drill to the side of the engine will become close. Beware of the drill chuck spinning into the side of the engine. On some engines this may be too close, and it may be best to use the next size drill bit and drill the forward holds in a slight angle. The slightly bigger holes will allow the bolts to sit flat even though they are at an angle.
Once drilling is complete, remove the two temporary bolts and remove the Permatrim. Clean the metal shavings between the Permatrim and the AV plate. Dab a bit of the marine sealant around each bolt hole on top of the AV plate.
Place the Permatrim on top of the AV plate. Install all bolts from the bottom up through the AV plate. Place a flat washer on top of the Permatrim over the bolt followed by the nylock nuts. Slightly tighten all bolts until all bolts are installed. Once all bolts are installed, start tightening the middle bolts and work aft. Then tighten the most forward bolts last. Make sure the Permatrim is laying flat on the AV plate before completely tightening. The torque spec is approximately 10 ft lbs. Be sure not to tighten too much as they can snap.