From my testings with sails, each sail adds a flat amount of top speed to your ship. The number of knots ofcourse varies with different wind speed and the % amount of weight you have on the ship (+speed reduction by cargo racks)
For example on an empty Schooner a Large Speed Sail adds around 17 knots, while a Small Speed Sail adds around 3.6 knots together you get around 21 knots (Varies with wind and weight). The math behind this appeared this simple, unlike the math with different weight percentages.
I would like to do a video on this, but atm i have no access to any testservers.
And with the "speed points" (22,46,100) i just mean that Mediums are only 46% of the speed of Large Speed Sails, while Small Sails are around 22% of the speed of Large Speed Sails.
Calculating the speed of Handling and Weight Sails would be like this:
A Brigantine with 2 Large Speed Sails and 1 Large Weight Sail: 100+100+60 (Weight Sail 100x0.6) = 260, the max speed is 300 on a Brigantine therefore you do 260/300=0.867, which means that setup is around 13% slower than Triple Speed Sails, without calculating in the Weight Bonus (which would only cut down the speed slowdown by like 7% if below 50% current weight).
Triple Weightsails would be 60x3=180, means the ship would be limited to 60% of the maximum possible Speed and weight lvl ups or weight bonus would not let you go faster than these 60%, they would only reduce the speed slowdown through weight.
Triple Handlings would be 75x3=225 (100x0.75), means 225/300=0.75 (25٪ slower than max possible speed). Which would mean for example if you get to 14 Knots with Triple Speed Sails, you would achieve only 10.5 knots with Triple common Handling Sails (along the wind).
Just my personal way of calculating this.