Update 1/7/18: (Wave Making Resistance - for world travel speeds)
I've almost exhausted the interwebs of free wave making resistance study material. I've incorporated the wave resistance coefficient curves that are found commonly in publications. The net effect for this game is that a particular ship hull design will perform well at certain speeds where the family of hull waves act together to minimize waves (the hollow part of the curve). On the other hand there will be speeds that the hull does not like due to amplification effects of said family of waves (the humps). I've gotten my physics engine to reflect this behavior. The only "drag" (pun intended) about this is that data is not available nor can it be empirically determined. This means these wave coeff curves will have to be "winged" or "makeup" for each major ship hull family and adjusted to reflect any observations logged in the 18th century such as "ship was fast with strong winds but slow under light winds".
Here's a few examples showing ship speeds compared to true wind speeds at wave effect peaks and lows. All of this technical jargon amounts to sea chases playing out differently under light and heavy winds just as they did in real life.
The heading is constant at 136 degrees and the braces were adjusted for each case to maximize sail forward driving force.
Below is an example of light winds where most of the resistance is made up of viscous drag. The ship is capable of obtaining 57% of the true wind speed.
Here the ship is a little over 6 knots and from the curve to the right where the dotted gray line meet, it is at a poor performance spot (wave effects are amplified). The ship is only capable of 40% of the true wind speed.
Here is the opposite case of the ship sailing now at a favorable speed in regards to wave effects. The curve and gray line are meeting at a hollow. At 9.25 knots the ship is making 46% of the true wind speed.
Finally, a top speed test with 30 knot winds. The wave effect is dominating and the ship is only capable of 37% of the true wind speed. Notice how the red curve only rises from that point; the top speed is limited by the bow and stern waves boxing the ship in.
So from a programming standpoint, I feel my sailing engine is now sufficient to produce "realistic" results with the right data input. I'm now moving on to making the world map code that will track the ships sailing about the oceans. Here is another can of worms I'm about to open as I am going to place Trade winds, etc, tidal currents on the map and vary them with the seasons. In net this will encourage ships to use the real routes.
I am getting closer to having a common server that we can all join together. The rest of the pieces just need built first.
Later...
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