Uncharted Waters New Horizons

Well, first of all, the speed of your fleet depends not only on the navigation level of the character. For quick navigation all the navigation of your ships must have high levels of navigation, preferably 16-17 and above. In the snes versions of genis and swimming speed is determined by the indicators to 13, if the score is 11-12, which is good. You can see it in the section of distribution of the ship's crew to navigate, view of the area and the amount for battle.
Next, the Barge is initially slow ship, and frigate - fast, merge them into one fleet will have consequences, causing the overall speed of the fleet will change, will move quickly, then slowly. That is, if you have 5 barges in the fleet, we add, for example, Galleons or full-rigged ships. If we have a few frigate, their a good idea to combine the Carrak or the Nao.

Navigation levels are only a small part of the speed calculation. The most influential part of the ships speed is the power and the SEAMANSHIP of the captain. This is one of the areas that FatRatKnight dug deep into and posted the results on the Gamefaqs board.

The tacking of the ship also affects speed. In my opinion the Frigate is NOT a fast ship. The frigate, and the barge, is outclassed by the Venetian Galeass...not to mention the Tekks. The fastest ships are the Kansen, the La Reale, the light Galley, and the Atakabun but none of those are that great for battle. For battle the Tekk or the Venetian Galeass are the better ships FOR SPEED and durability. I love a used Tekk for the flagship because of the configuration. If you build a new Tekk or reconfigure a used Tekk you can only have 300 crew, but a used Tekk allows 360 crew and 80 guns. Yes, the BIG disadvantage is the location for getting those ships.

Anyway, the fleet speed is only going to be as fast as your SLOWEST ship. Throw a barge into a fleet of La Reales and your speed will be reduced greatly even with your best navigator.

I think the most important part of the speed formula is this:
Final Speed = [[ [[ [[ [[ Base Speed * 4/3 ]] * Seamanship / 100 ]] * Tacking / 100 ]] * 3/2 ]]

Displayed Speed = Final Speed/3

That and Base Speed is capped at 30. Most of the information is in post #8 in the board topic that is titled, "A few detailed game stats, mechanics, and information (map included)".

One of the factors in determining Base Speed is a ShipWindFactor which is likely the number you are talking about.
To expedite the info here is the base speed calculation that is used when determining fleet speed:
Base Speed = [[ [[ [[ [[ Power * ShipWindFactor * Wind / 150 ]] * NavCrew / MinCrew ]] * (150 - CargoPenalty) / 100 ]] * (10 + NavLevel) / 10 ]]
Notice that the ShipWindFactor is part of the calculation used for every ship in the fleet. If you read more in the "Studying..." topic the CargoPenalty can make a significant difference as well.

Anyway, my point is the same...The ships that I mentioned will be the fastest. When I ran a test using a fleet of 10 Full-Rigged ships over a 6 month trading span between Lubeck and Madeira (or was it Santa Cruz...not really important which one) I made a full round trip more with a fleet of 10 Tekks where I reset and used the same captains...The only difference was the ships and the number of crew. At first glance you think that the Full Rigged ships will hold more, but in practice because you need more crew to travel at your fastest you end up with more from the Tekks.

I got off point again, There are a lot of factors in determining how fast your fleet is going to be...and they are all important. In a lot of cases you can tell how fast your fleet will be by dividing the tacking of the ship by 5 and the higher the number the faster your ship will go under good conditions (captain, ship fully repaired, crew in optimal health...etc.).