I have one of those props. The purpose of the holes is to force exhaust gasses into the "new water" into which the prop rotates, decreasing the density. A less dense input allows the engine to accelerate faster. Since HP is torque and RPM dependent, the faster you get your RPMs up the faster you develop your HP and HP is what twists the prop shaft causing your prop to produce the thrust to propel your boat. They are popular on things like Bass Boats where there is a good deadrise at the transom, with setback, (to assist the "pad" functioning at high speed), have large live wells full of water....and if lucky fish, 3 large batteries, and large fuel tanks, all bad for planing/Hole Shot.
The ports need to be treated equally otherwise it would be like having one blade bent (damaged) on your propeller.....vibration producer. I bought mine without plugs and bought and decided to try plugs later on....just playing around for the fun of it. On that prop you had none or full blockage with the square ports. I found the rubber inserts to be a farce, unlike the later model Lasers with the round holes and varying diameter of holes in the rubber plugs from none to fully closed.
On other props I bought like the Turning Point Hustler brand, I would run with the standard ports open, then JB weld them shut, then drill them out to varying dimensions (all 3 or 4 holes same diameter) just to get the feel of how they affect my boat's performance....just for the fun of it.....at 80 years young, you need to keep your mind and body busy....staying off the couch and away from the TV. Wink!
I like to get about a 1k RPM increase in the Hole Shot with a ported prop and I like ported props. That gives me a fast plane. If the holes are too large you loose too much thrust, and that delays the hole shot. Other thing for them to work properly, when you are ready to get on plane, you firewall the throttle for maximum effect of the holes functioning. With the later model Lasers that's easy by selecting the right plug opening.
The other thing that I'd do was to set the trim so that the engine is perpendicular to the hull (right angle) with easy planing, lightly loaded hulls I run with me boating alone. I'd blow out a bit...helping to get the RPMs up and when the prop would catch a jolt forward, usually have 3 Porpoising oscillations, and was gone...quickest shot and the most fun. On other hulls/loads a person would have, trial and error on trim setting would be required, seeking the best position other than the normal tucked fully in position lots of folks use when getting on plane.
Edit: The Ranger Bass Boat I bought new back in 1989 was equipped with the original Laser (before the Laser II), a super fine prop and when it locked up...water pressure sealed off the ports at higher speeds, you got a JOLT forward....great sport!
Gee that helped occupy the morning. Good luck!
