The really "Old School" boating thread

[gn7]

The "thing" looks like a 3 dimensional arrow pointing down at the paragraph as part of the ad. So what is this Paralex bottom and how is it different to the earlier models?

That's exactly what that is. Its also somewhat a play on the word Paralax, which is "mis-spelled" in the ad, I think deliberately. A parallax is a visual miss que. or error or you could call it an optical illusion. A true parallax has to do with viewed angle, like looking at a gauge and seeing one reading, then looking at the gauge from a different angle and seeing a different reading. That's parallax error.

On the original 20 ft bottom, it was really nothing more than the 20 v from the Allison boat with strakes.
Later the bottom was changed, I am guessing 1975, but I thought it was before that.

Heres what I THINK Rudy was playing on.
When you first look at the bottom, 99% of the people still see a V with strakes. Its not. Its 2 distinctly different Vs But its all in the view of the bottom. From the side it looks like a V with 2 strakes per side. From dead on in the front, if you look real close, the 2 inner strakes form a double concave ski effect, and the outer strakes are in actuality a different "layer" on a different V angle than the very outside from the outer strake to the chine. Imagine a standard V with nothing more than strakes. The Rayson bottom is really different layers and different angles, that in effect create the strakes.
Plus, in all of this, there is the double "concave" of the center, and from the outer strake towards the keel there is a slight concave as well.
THEN, if that wasn't enough, it all goes away as it goes under the boat, until its just a standard V somewhere around the dash, except the double concave created by the center strakes. That's why they can ride the keel like you see in my avatar on PB.

Its all hard to explain, but the next time you see a 20 on a trailer, take a hard look at it from dead on from the front, and look hard at what you are seeing.

Very few V bottoms have a bottom as complex as a 20ft GN. In my mind, the bottom of the 20 and 21 are sheer genius, and are amazingly tunable with slight changes to the length of the strakes at the rear for differing HP levels and speed.