A question regarding "point of sail"

[Bushbaby]

In my ruleset "Raked Sterns and Balls of Iron" I try to come up with a realistic, yet simple set of rules regarding sailing. I have read a lot about the subject, but information is still hard to come by. Therefore I turn to the expertise here on LAF!

As of now, each ship has a movement allowance. This allowance is divided by a modifier depending on the wind direction (it is also affected by sails but that is another thing).

The modifiers are:

Broad reach x1
Beam reach x2
Running x2
Close reach x4
In irons - no movement

e.g: A ship with an allowance of 50 cm moving in a beam reach would move 25 cm. In a broad reach it would move 50 cm and in a close reach, the ship would only move 12,5 cm.

a) Would you say these modifiers are realistic when it comes to square rigged ships like galleons?

b) Would a lateen rigged ship have different modifiers? 

[Duke Donald]

In case you haven't seen it, this academic paper may contain some answers to your question: Whitewright, J., 2011, “The Potential Performance of Ancient Mediterranean Sailing Rigs”, The International Journal of Nautical Archaeology (2011), 40.1: 2–17.
downloadable here: https://www.academia.edu/490286/The_Potential_Performance_of_Ancient_Mediterranean_Sailing_Rigs

It deals mostly with Ancient and medieval ships and focuses on the Mediterranean, but I feel some of the main conclusion can be extrapolated to later sailing boats. According to this paper the performance of square and lateen rigs was very similar.

[Bushbaby]

This chart from the paper seems to correspond quite well to my approximations. Tacking or going upwind should cost x6 instead of x4. Otherwise the proportions between beam/running and broad reach seems to stand true.