Prop for 1977 18SF with Suzuki 140

[McGillicuddy]

Aha! Suspicions confirmed! No trim tabs.
Next to that sweet motor, trim tabs would be your greatest asset. I understand not wanting to drill any holes in your boat so I'll leave that alone now.

A 4 blade will help lower your minimum planing speed and get the pointy end down much quicker.

As Denny mentioned, for less than $50 you can get a planing foil. SE Sport makes a foil that doesn't require 4 holes in the anti-cavitation plate. http://www.amazon.com/SESport-SPORT-.../dp/B002HW3IJO
If that solves the problem great. If not, they are an easy resale on CL or whatever.

I had one on my Seafari and was pleased with its effect. I took mine off because when I dropped to a 15p stern lifting Black Max, my hole-shot to plane became virtually instantaneous. Of course my motor is a 300 lb Merc 115 and my CG is farther forward.