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Simonsays095

guide Wind mechanics, rotation, and, sail types: A comprehensive Guide

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Introduction

For this forum post, I thought I would cover some of the wind mechanics. I think this will conclude my discussion of the wind mechanics (unless anyone can think of something else to test!) that started with ship weight and cargo racks (somewhat related to wind mechanics) and continued to my discussion of the sextant buff. Once you finish reading the guide, you should have a very good idea of how to efficiently travel around the ATLAS, armed with the knowledge of the invisible force in ATLAS that allows ye' scallywags to explore the open ocean - the wind!

To organize the post a bit, I will try to progressively get into more of the details toward the end of the guide, and reserve the beginning as a summary for people who don't really care about the details. I will summarize the main points in the "Big Questions" section, and most of the discussion will be in "The Bulk" section. For those interested in the intricate details with how I did my testing, I will leave most of that to "The Details" section.

Big Questions

  1. How do the different types of sails (speed, handling, and weight) differ?
    • The sails differ in the effective angle and maximum speed that they can give the ship. Speed sails give more maximum speed than the other two sails, and handling sails give a larger effective angle than the other two sails. Weight sails have the same effective angle as a speed sail, but they contribute much less to the maximum speed than speed sails - in return, they will add maximum weight to your ship.
  2. When should I use one type of sail over another?
    • Weight sails should only be used when the ship is very overweight. As a rough estimate, put on the first weight sail around 65%, and add more weight sails every 7% weight you add on from there.  Handling sails are faster than speed sails only when you are sailing against the wind (up to 27 degrees either direction from directly against the wind). The benefit with handling sails is that you will never bottom out on speed, unlike speed and weight sails which bottom out quite easily. However, if you aren't making a ship specifically to sail against the wind, speed sails are more widely applicable, just use them.
  3. How does the wind rotation work?
    • The wind rotates in a large circle at a constant speed. It takes about 5 real-life hours (+/- 5 minutes) for the rotation to complete, and it goes through 2 full-wind/low-wind cycles every time. That means that if you are currently in low wind, wait 75 minutes, and the wind will be strong. Furthermore, the strong winds only point North or South, and the weak winds only point East or West. If you have the luxury to plan multiple bases far apart, this means that it will be easier to get back and forth between them if you put them close to the same column (vertically).
  4. Does sail angle affect ship speed? How about wind angle within the effective angle?
    • Unlike in real life, the angle that your sails make to your ship's body make NO difference to your speed. The only angle that changes your ship speed is the angle between your sails and the wind. As this angle increases, the ship speed steadily decreases, even at small angles within the effective angle. Similarly to how weight effects your ship speed (in-depth discussion here), the speed drops off very quickly as you approach the effective angle. Therefore, it is wise to minimize the angle between your sails and the wind whenever possible.

 

Related questions that I will not be answering in this post:

The Bulk

1. How do the different types of sails differ?

All sails have 5 values that dictate their differences: Maximum weight addition, effective angle, acceleration, maximum speed, and turning effectiveness. I mainly tested what I believe to be the most important values, and I may update this post in the future to discuss the acceleration and turning effectiveness, which only affect the handling sails. The rest of this discussion talks about the maximum weight increase, maximum speed, and effective angle of each type of sail.

Speed Sail: Speed sails have an effective angle of about 82 degrees, and by far have the fastest maximum speed of any sail type. In addition, they don't add any maximum weight to your ship - they are the simplest and most reliable type of sail in the game.

Weight Sail: Like speed sails, weight sails have an effective angle of 82 degrees. However, they produce less maximum speed than speed sails (about 60% speed) in return for increasing the maximum weight of your ship. Small weight sails will increase the maximum weight by 1,000 kg, medium sails will increase it by 2,500 kg, and large sails will increase the maximum weight by 4,000 kg.

Handling Sail: Handling sails have the largest effective angle of any sail in the game, at around 118 degrees. Their speed is between the speed of weight sails and speed sails (around 75% of a speed sail's max speed), but they have the fastest open/close times of any sail, and they also rotate faster than the other sails.

Side note: Since the angle of the sails to the ship body doesn't matter, and the sails can be rotated to +/- 75 degrees, you can always reach a max speed for the first 75 degrees by rotating the sails. After that is when the effective angle starts kicking in, and you will bottom out on speed at 157 (82+75) degrees with a speed sail, and 193 (118+75) degrees with a handling sail. Since 180 degrees is straight behind you, this means that you will never bottom out on handling sail speed unless you purposefully point your sail in the wrong direction. Speed sails, however, have a 46 degree arc toward the rear of the ship where you can bottom out in speed no matter what you do.

2. When should I use one sail type over another?

sail-wind_angle.png?width=400&height=300In typical sailing conditions, speed sails are almost always faster than weight or handling sails. Unless you like the feel of sails opening and closing quickly, I would argue (although this is speculation, I haven't done the math on this) that speed sails are always better than handling sails, when used optimally. As for why I haven't done the math on this, consider the following complication: Handling sails are faster than speed sails only past 153 degrees. That gives you a 54 degree window for which handling sails would be better. However, it might be faster to just adjust the angle you sail at to make the speed sail faster, and then tack back toward your destination when you get closer. It makes your trip longer, but you also go faster.

Weight weight_sails.png?width=400&height=300sails have a bit more utility for hauling large loads. However, they only add a fixed amount of ship weight (not a percentage), so they are relatively less beneficial as you put points into weight. Additionally, you can split up your haul into 2 trips if you really have to carry a lot, and that may even speed up your haul time. In general, it is beneficial to add your first weight sail at 63% weight, and then add another one every 8% weight you add after that. If you have not read my guide regarding cargo racks, I highly recommend you read that if you have a heavy ship. At any weight that you would consider using weight sails for, you should also be considering cargo racks, unless you have a lot of weight that you cannot put in cargo racks (such as cannons and cannonballs).

This is a section that I can definitely do a bit more testing and mathematics (trigonometry, here I come), so I will be updating this in the future. Until then, much of the notes in this section are speculation based on dozens of hours of testing these mechanics. Trust them or don't, it's up to you.

3. How does the wind rotation work?

unknown.png?width=237&height=301The wind rotation is locked into the cardinal directions - strong winds always go North or South, whereas weak winds always go East or West. Furthermore, the rotation is locked into the clock as well - strong winds always happen at Noon and weak winds always happen at Midnight. There is a day in between strong and low wind, so if you have strong wind (at Noon on some day), the next low wind happens at midnight the following day, 1.5 days later. If you currently have low wind, just wait 1.5 in-game days for the next strong wind period. Since one in-game minute is 2.1 seconds (see my sextant buff post for more details), This means you should wait for 75 minutes to get the opposite strength of wind.

The wind strength does not change consistently over the course of the rotation. From Noon on the day before the weakest wind until Noon on the day after the weakest wind (for a total of 1 in-game day), the wind strength drops to the minimum and then rises very quickly, starting and ending at about 50% wind strength. Therefore, most of the time the wind is above 50% strength, and if you find yourself caught in a low wind period, you only have to wait until the next Noon for the wind to become strong again. Pull over, feed your animals, pay your crew, and you can be on your way again in no time!

The image on the left shows how the wind strength arrow changes over time, with the in-game time overlaid around the image to show you how fast it rotates. You can see in this image why you should wait for the next Noon after a low wind - that is when the wind starts picking up again!

 

4. Does sail angle affect ship speed? How about wind angle within the effective angle?

As long as your sails are pointing with the wind, the angle your sails make with the body of your ship does not affect your speed. Therefore, only the angle between your sails and the wind makes an impact on your speed.This angle makes a big difference in your speed as you get close to the effective angle. For example, if you are 75% of the way to the effective angle, you still have about 61% of your max speed. Once you reach 90% of the way to the effective angle, though, your speed drops to 44% of your max speed. At 95% of the effective angle, you only have 35% of your speed left.

Wind-sail angle effects your ship in a very similar way to weight. The biggest difference is that when you reach the effective angle, you go a minimum speed of 29% of the max speed. However, because of the very fast drop-off of speed as you approach the effective angle, it is generally wise to not get anywhere near it. In-game, this means that you should avoid sailing in a direction that makes your sails turn red in the HUD indicator, and think a bit about your heading if your sails are dark orange. It may be wiser to turn a little more with the wind, and then cut back in the other direction (tack) when you get closer to your destination.

The Details

Testing Details

All numbers in this guide were obtained through testing in single player, and confirmed (somewhat) using the numbers in the devkit. It is hard to convert the numbers in the devkit into actual usable in-game numbers, but I did my best. If anyone is familiar with the devkit and would like to give me a tutorial, I would love to talk to an expert, just message me and I will give you my details.

For the most part, the tests I ran involved getting the sextant buff, then equipping a ship with a specific sail configuration and sailing it across H8 (no islands, so I can stay within a single grid and get about 19k meters of testing space, along a diagonal). Once the knot display reached a stable speed, I recorded the time, latitude, longitude, and speed in knots, given by the sextant buff. I recorded this data again at the opposite end of H8, and computed the total distance traveled and the time in game-minutes it took to travel that distance (in longitude units). I then converted this speed in long/game-minutes into ATLAS knots (see my sextant buff post for details).

For the effective angle calculations, I had to do something slightly different. I aimed my ship as close to true North as I could. This involved setting the wind direction (using setdir 90) to North and the wind speed (using setwind 12) to the maximum strength, and rotating my ship until the wind arrow had no pixels off of the directly vertical line. I verified my (very close to) true North heading by sailing some time and noticing no change in the longitude coordinate. In fact, for much of my testing, my ship could lean left and show one longitude and lean right to show another, 0.01 higher. Because this lasted a long time, I am fairly confident in my heading being essentially true North.

With my ship and sails pointing due North, I set the wind to many different angles away from North (using setdir X), and recorded long/lat/time like before. However, there is the added complication of crossing server borders. I kept track of the time as I crossed borders (only going North, remember, not East or West), and there was no time gained or lost. The coordinates were a different matter - when you cross a border (at least in Single player), the game puts you at 0.14 longitude units further than you entered. I just had to keep track of how many borders I crossed and subtract 0.14 for each one. This added some error, but I couldn't think of a better way to do the tests without rotating the ship between tests. If I did rotate between tests, the slight variation in the way my ship was pointing would make the effective angle very difficult to compute, since small changes in angle near the effective angle make a large difference in the ship speed.

Any derived numbers (like maximum speed contribution per sail) were obtained using the trendline function in Excel, or the Solver addon for Excel.

Detailed Numbers

I will put detailed information here about the specific numbers I obtained from testing. I will also update this section if I did some math that confuses anyone.

- Since the full wind rotation takes 6 in-game days, the wind rotates around at 60 degrees per in-game day, or 1.19 degrees per real-life minute. Additionally, the strength of the wind changes twice as fast in the "low wind region" from Noon before the lowest wind until Noon after the lowest wind. The graph below shows this region where the wind power changes much more rapidly.

unknown.png?width=400&height=229

- Weight and speed sails have an effective angle of 82.0305 degrees, and handling sails have an effective angle of 117.725 degrees

- The table below shows my current data on maximum speed from each type of sail, for each type of ship. I will be adding to this in the future, as I collect more data.

unknown.png?width=400&height=236

- Handling sails are faster than speed sails once you pass 152.59 degrees. At that point, you should switch all sails over to handling sails (if you can't just rotate a few degrees to make the speed sails worth it).

 

Conclusion

Generally, you will want to use speed sails, and only in rare cases will you want to use handling or weight sails, since their benefits don't outway the massive increase in speed that speed sails give. However, if the wind is just too weak and you are doing everything you can to milk speed out of your ship, you can always just wait for the next Noon, and the wind will be guaranteed to be at 50% and rising in strength. Finally, Avoid sailing in a direction that makes your sail HUD indicator dark orange, since your speed drops off very quickly as you get close to the effective angle, where the sails turn red.

Please leave a comment if you think I missed anything, and let me know if I have not explained something clearly enough. I am happy to answer DMs or regular comments. Finally, I would like to thank @Kummba for encouraging me to look into the wind mechanics, and giving me a jumping off point with the wind rotation mechanics.

See you on the high seas!

Edited by Simonsays095
Added images!
  • Thanks 2

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Thanks so much for this post, you processed and presented the provided information better then i could have.

People that read hte post without the pcitures shell reread when they are in, i saw some amazing ilustrations.

Hope people will understand the "simple wind system" better now, and therefore are able to reduce traveltime.
Thanks again for your hard work <3,

Kummba

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Awesome work and well written. A couple of questions tho,

Is it ever better to add a weight sail rather than a cargo rack.

We know the speed parameter doesn't work on speed sails but what about all the other bonus parameters.

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4 minutes ago, pfg said:

Awesome work and well written. A couple of questions tho,

Is it ever better to add a weight sail rather than a cargo rack.

We know the speed parameter doesn't work on speed sails but what about all the other bonus parameters.

He will show some pictures, it will make the weight sails situation more clear.
I personaly would never use weightsails, racks are way better, and i like to go fast.

Otherwise weight sails should only be used for when the weight can not be put into racks. Like cannon ship and transporting alot of tames.

 

At least the velocity parameter on speedsails is disabled on purpose . I would assume it is the only disabled parameter, the testing and retesting is hard.

 

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14 hours ago, pfg said:

Is it ever better to add a weight sail rather than a cargo rack.

13 hours ago, Kummba said:

Otherwise weight sails should only be used for when the weight can not be put into racks. Like cannon ship and transporting alot of tames.

Just to clarify this point, weight sails and cargo racks are completely independent of each other. When you should add each one depends almost entirely on your ship weight percentage. As @Kummba points out, cargo racks are only useful when you actually have the free weight available to put into a rack, whereas weight sails will increase the speed of your ship by increasing the maximum weight. However, the math behind weight sails does not care about how many cargo racks you put on, and vice-versa for the cargo racks. Therefore, the numbers I put in here for when to add weight sails and the numbers in the cargo rack post are correct no matter the number of weight sails or cargo racks you have on the ship.

Thus, you shouldn't think about this like "weight sails OR cargo racks", but rather "weight sails and cargo racks", which means that you should never substitute a cargo rack for a sail or vice-versa. They should be used together for optimal efficiency.

 

14 hours ago, pfg said:

We know the speed parameter doesn't work on speed sails but what about all the other bonus parameters.

I have not tested this mechanic, but I definitely see myself tackling blueprints in a separate post in the future. Of course, if/when I get around to doing it, I will add a link to this post for people with this question. Thank you for asking!

Edited by Simonsays095
fixed grammatical errors

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