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Turn rates and speeds (frigates vs line ships)


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Some heretical thoughts here. We warned you ;)

 

1. Some people are saying that our ships should turn faster for the speed they are going. They say the turning radius is too big and frigate could turn on its length. Videos of modern brigs turning show nice and smooth tacking with almost no backing force. Which is not the case in our game. 

 

But this was not the most important thing

 

what is key is this. 

 

2. We want to challenge the old concept that we believe could be wrong. For many years in computer games developers made Ships of the Line turn slowly like a brick. 

We were doing detailed research on "rasees" some of which had very detailed sailing quality reports to the admiralty Indefatigable (razee from 64 gun) or Saturn (razee from 74).

Basically most of these ship had very good sailing and excellent maneuvering qualities. They sometimes rolled more than needed, were leewardly (wind drift), or had excellent speeds only in strong winds. But none of the reports said they were very slow turning. I wonder if this assumption is wrong (that SOLs had bad turn rates).

 

We wonder.

Why should 74 turn significantly slower than a Constitution for example? At high speed yes. it would be risky due to height (Vasa), but at an average speed, with its sail area and rudder size what would limit its turning? If 74s were bricks why it was mass produced. Lets say I trim my 74 perfectly well, close lower gunports, why should 

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Aren't there mathematical equations that could, given surface area of the rudder, mass, hull shape, etc. tell you at a certain speed, just how fast the ship could rotate?  I'm not sure, it's more of a question of curiosity.  When you look at some of the modern simulation software, it seems to me that this could be calculated fairly accurately given known dimensions.

 

I do agree, however, that some ships, especially the fore/aft rigs, don't tack as easily as they should.

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We wonder.

Why should 74 turn significantly slower than a Constitution for example? At high speed yes. it would be risky due to height (Vasa), but at an average speed, with its sail area and rudder size what would limit its turning? If 74s were bricks why it was mass produced. Lets say I trim my 74 perfectly well, close lower gunports, why should 

 

 

Traverse drag.

 

So basically compare hull longitudinal crossection below water line against sails area, if you want estimate wind-assisted turn rate. I think that hull surface quality can be omitted for now. 

 

Oh, and drag grows in 2nd power with speed, so basically 60*/min is 4x power consuming as 30*/min.

Hmm, seem to me, that more calculations would be needed to achieve higher precision because hull length definitely is important...

 

 

Your assumption may be quite correct. Or, they were just "manageable" and nobody mentioned that because it was quite obvious back then?

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I think it certainly bears looking into, mathematically if need be.

I harbor similar suspicions to admin. After all, a ship of the line is not significantly longer than a frigate.

They say the turning radius is too big and frigate could turn on its length. Videos of modern brigs turning show nice and smooth tacking with almost no backing force.

This is at slow speeds, though. Sails can act like bow or stern thrusters.

As Ryan said, when you are moving slowly you can turn tighter, but never faster.

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I love that you are trying to get it right instead of just going for arcade balance. It really adds to the immersion to think that the ships are handling like they should.

I wonder if any of my books have material on this subject.

 

What I am surprised about though is that the frigate size vs the SOL size is not as different as I expected. Frigates look so tiny when you see those big battle paintings.

 

I agree though that the old SOL reputation for being a slow good for nothing HOG of a sailer may bear looking at.

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as i often mentionned before, as you progress, larger ships turn radius is not getting better, except for the victory, while it gain a small boost compared to the bellona, but lack on top speed ( max i`ve seen was just over 12 kts )

Maneuvering in theses larger ships is often borderline acceptable when the sails and masts are in top conditions, but it become quickly awry in pvp.

 

Peoples often opt to use chain shots and aim for the sails, it doesn`t take much to stop a larger ship maneuvering around, and if you lose your front mast the ship barely turn/move at all and its a tactic that is getting widely used, often followed by some kiting, sadly the pvp have been reduced to this. Using manual sails is an essential step to turn quickly, but in theses scenarios it doesn`t matter how masterfull you are.

 

Ships generally have  larger sails as you progress, it should help in some way to ease the turning while using manual sailing, maybe some adjustments are needed here? 

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Wouldn't it make sense gameplay-wise for these ships to have some sort of a weakness or a counter against them? Without maneuverability weakness it would make things more linear with the end-game sol's being the final destination for everyone who want's to compete and lessen the variety and make other ship types obsolete.

Besides isn't the point of the sol to stay in line, hence - Ship of the Line. If it get's isolated from line (it's support and main defence to neutralize the lack of maneuverability) due to unfortunate circumstances or the incompetence of the captain then it should deserve to sink but without maneuverability weakness it wouldn't have the penalty in brawling mode so why even line up with it? My mind draws a picture of generic yolobrawl metagame with these universal SoL's where the battle is forced into a chaotic brawl and the individual skill of each captain takes it from there to decide the outcome.

I know it's not the right topic for it but I would throw it in anyway - Serious endgame SoL should be a group project and have an upkeep. It has to be earned instead of grinded and it would preferably need a group of people to work on it's upkeep. It could be kind of a representative of specific nation/society/group whatever you will call it. An idea to courage people to bring it into the battles would be the seriously lessened upkeep for example.

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Yes, some line ships handled very well, others terribly. Now, the problem there is that historical anecdotes on handling may have nothing to do with speed and radius of turn. They may have been much more focused on other factors of handling, especially safety at sea. "Maneuverability" in the sense we are talking about in game was probably a lesser factor in day to day operations and most confrontations between fleets.

I don't really know enough about the technical aspects of design to comment on whether there was anything about the design of line ships that would make them less maneuverable. However, I would imagine that height of hull above the water would have a big effect with all that surface area to catch wind. Many of the very large line ships were made excessively tall in order to pack in as many guns as possible (and possible purely to be visually imposing) and suffered accordingly in their handling characteristics. Possibly this is partly why razees where remarked to have very good sailing qualities. Also, 74s were noted to have a very good balance of firepower and handling, which suggests to me that larger designs must have often sacrificed something for their firepower.

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Also being heavier, with the same height rigging as frigates? as well as bigger they may have been good handlers but against a smaller frigate I doubt better handlers.

They may have come close to handling well against a 44 if they ever caught one due to the 44's long hull making it a less than ideal turner I would think.

 

74s especially were such good handlers that the fastest were made into flying columns and patrol squadrons. 

They would have caught frigates in the right conditions, but out turning the smaller ones - which I don't think are in game yet. Surprise would be considered medium to large? Trinco and Constitutions were really pocket battleships or super heavy frigates.

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Yes, but catching frigates was about speed, not handling / maneuverability so much. There is no doubt that larger ships could out run smaller ships, especially in high seas.

Surprise was a small frigate in her day. There is a whole class (or several classes) of frigates between Surprise and Trincomallee that is not in the game. Trincomallee is a heavy frigate. Constitution could be described as a super-frigate.

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Firstly, I love how the devs are asking the community to brainstorm with them.

 

Second, a lot of good replies in here already.

 

Third, I'd just weigh in with the idea that it matters a lot what kind of SoL would be involved. Like others pointed out, the 74 became the mainstay of many navies because of its excellent blend between power and practicality. I would wager that any three gundeck ship would be rather more unwieldy than a two gundeck (weight above waterline). So if we're talking about ships of line, then a well-built 74 was probably a decent handler for its size, whereas a really big ship would stray into the 'handle like a bus' territory. The whole thing about the Santisima being only fit for static defence is most likely a little bit exxagerated by now, but there is a definite historical basis for it. 

 

I don't think a smart 74 would be easily outmanoeuvred by a frigate. And even if its possible, the large amount of gun barrels looking at the frigate turns any mistake or hesitation on the part of the frigate captain into a painful affair. So the smart move is always to just stay away from the thing. Could a small or medium frigate 'sterncamp' a very large three-deck battleship given the right circumstances in real life? Probably. For a while at least. But what's the point? One mistake and you're going swimming. 

 

I think the game's sailing and damage model will ultimately be enough to force people into making the correct strategical fight-or-flight decisions in the open world, punish their mistakes and reward their skill. 

 

 

As for actual technical aspects of handling, that's way out of most of collective leagues to accurately speculate on. There's probably all sorts of ship technical stuff involved that determines how agile a ship is. Have you guys considered contacting specific historians or ship engineers? There's surely a few out there who would love to help and weigh in (send em a free copy of the game when it's done :D

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Some heretical thoughts here. We warned you ;)

 

1. Some people are saying that our ships should turn faster for the speed they are going. They say the turning radius is too big and frigate could turn on its length. Videos of modern brigs turning show nice and smooth tacking with almost no backing force. Which is not the case in our game. 

 

But this was not the most important thing

 

what is key is this. 

 

2. We want to challenge the old concept that we believe could be wrong. For many years in computer games developers made Ships of the Line turn slowly like a brick. 

We were doing detailed research on "rasees" some of which had very detailed sailing quality reports to the admiralty Indefatigable (razee from 64 gun) or Saturn (razee from 74).

Basically most of these ship had very good sailing and excellent maneuvering qualities. They sometimes rolled more than needed, were leewardly (wind drift), or had excellent speeds only in strong winds. But none of the reports said they were very slow turning. I wonder if this assumption is wrong (that SOLs had bad turn rates).

 

We wonder.

Why should 74 turn significantly slower than a Constitution for example? At high speed yes. it would be risky due to height (Vasa), but at an average speed, with its sail area and rudder size what would limit its turning? If 74s were bricks why it was mass produced. Lets say I trim my 74 perfectly well, close lower gunports, why should 

 

Just because the data does not exist doesn't mean its not true. 

 

The heavier a ship is the more force is has to overcome to turn. Take this as the neutral force, the force that resists movement. If the ship is going 10 knots it will have a forward speed and pseudo force which is basically inertia. To turn the ship a force must be applied that overcomes this inertia as well as any and all friction. Not to mention more of a SOL will be underwater than a frigate increasing drag and the amount of water needing to be displaced to move said boat forward.

 

Basically the bigger it is the slower it will turn or accelerate given the same propulsion method and propulsion force ratio, if the 74 had a modern day side turbine stuck on the side or 10x the amount of sails and a rudder 10x as big  i'm sure it would out turn the constitution. Take a destroyer vs a cruiser vs a battleship, you can tell which is the most agile just by looking at their size and knowing their force to mass ratios are roughly the same.

 

The 74 was mass produced as it was a compromise, a good amount of firepower, a good amount of speed, a balanced cost, less crew than a 1st rate etc etc etc. Why did Germany and Britain build pocket battlecruisers in WW1? To compromise and put big firepower into a more maneuverable and smaller package. Losing a 74 isn't as devastating as losing a 112 but that 74 can sink said 112. You can't look at something and say since they were mass produced they had to be the best at everything, maybe they were good at everything. Take the Russian T-34, was it the best tank in WW2? Did it turn the fastest? Did it hit the hardest? Was it the most armoured? No. Was it the best bang for the buck for the russians? Yes. Hence it was mass produced while Germany pumped out fewer, better tanks, and we know how that went. 

 

TLDR they have the same propulsion ratios and so the forces being scaled up will result in the smaller ships out-turning the large ship. The only argument would be if the small ship was sailed by cats and the large ship by master seamen than maybe it would turn faster ;P

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Just because the data does not exist doesn't mean its not true. 

 

The heavier a ship is the more force is has to overcome to turn. Take this as the neutral force, the force that resists movement. If the ship is going 10 knots it will have a forward speed and pseudo force which is basically inertia. To turn the ship a force must be applied that overcomes this inertia as well as any and all friction.

 

Basically the bigger it is the slower it will turn or accelerate given the same propulsion method and propulsion force ratio, if the 74 had a modern day side turbine stuck on the side or 10x the amount of sails and a rudder 10x as big  i'm sure it would out turn the constitution. Take a destroyer vs a cruiser vs a battleship, you can tell which is the most agile just by looking at their size. 

TLDR they have the same propulsion ratios and so the forces being scaled up will result in the smaller ships out-turning the large ship. The only argument would be if the small ship was sailed by cats and the large ship by master seamen than maybe it would turn faster ;P

 

 

With the risk of sounding catty: Of course, that's quite obvious. I think what the devs want to know is how much exactly would this difference be? That's a very interesting and very hard to answer question. Will a 74 turn slightly slower? Just slower? Much slower? Or only slightly slower when running in the wind but the difference becomes more pronounced when close hauled? 

 

 

Maybe there are any math physics geniuses on the forums that could do freaky shit with numbers? 

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With the risk of sounding catty: Of course, that's quite obvious. I think what the devs want to know is how much exactly would this difference be? That's a very interesting and very hard to answer question. Will a 74 turn slightly slower? Just slower? Much slower? Or only slightly slower when running in the wind but the difference becomes more pronounced when close hauled? 

 

 

Maybe there are any math physics geniuses on the forums that could do freaky shit with numbers? 

 

No one really knows. The exact forces and numbers at play are unknown. What if one ship just had its bottom cleaned? Every variant of 74 would act differently as well, and so would every variant of frigate. 

 

Just going off the weight alone you would expect the frigate to handle better. The more of the boat underwater the slower it would be. Hence why the fastest sailing boats have almost nothing underwater so they skim over the surface.

http://www.dailymail.co.uk/sciencetech/article-2314635/Hydroptere-The-worlds-fastest-sailboat-hoping-sail-Pacific-record-time.html

 

Basically anything under water will incur drag and a myriad of other forces.

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Just because the data does not exist doesn't mean its not true. 

 

The heavier a ship is the more force is has to overcome to turn. Take this as the neutral force, the force that resists movement. If the ship is going 10 knots it will have a forward speed and pseudo force which is basically inertia. To turn the ship a force must be applied that overcomes this inertia as well as any and all friction. Not to mention more of a SOL will be underwater than a frigate increasing drag and the amount of water needing to be displaced to move said boat forward.

 

Basically the bigger it is the slower it will turn or accelerate given the same propulsion method and propulsion force ratio, if the 74 had a modern day side turbine stuck on the side or 10x the amount of sails and a rudder 10x as big  i'm sure it would out turn the constitution. Take a destroyer vs a cruiser vs a battleship, you can tell which is the most agile just by looking at their size and knowing their force to mass ratios are roughly the same.

 

The 74 was mass produced as it was a compromise, a good amount of firepower, a good amount of speed, a balanced cost, less crew than a 1st rate etc etc etc. Why did Germany and Britain build pocket battlecruisers in WW1? To compromise and put big firepower into a more maneuverable and smaller package. Losing a 74 isn't as devastating as losing a 112 but that 74 can sink said 112. You can't look at something and say since they were mass produced they had to be the best at everything, maybe they were good at everything. Take the Russian T-34, was it the best tank in WW2? Did it turn the fastest? Did it hit the hardest? Was it the most armoured? No. Was it the best bang for the buck for the russians? Yes. Hence it was mass produced while Germany pumped out fewer, better tanks, and we know how that went. 

 

TLDR they have the same propulsion ratios and so the forces being scaled up will result in the smaller ships out-turning the large ship. The only argument would be if the small ship was sailed by cats and the large ship by master seamen than maybe it would turn faster ;P

 

True as far as it goes, but you also have to count the surface area of the rudder into the equation.  If the Victory has enough rudder to overcome the added mass, drag, etc, she may indeed be able to turn far better than expected.  She'll probably bleed speed like a stuck pig in a hard turn, but she may be able to rotate fairly well.

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That would be an interesting fact to have.

 

Anyone interested in bringing up the draughts of a frigate and a 74 to compare the ratio of rudder area to (two dimensional) overall hull area?

If the rudder to wetted area ratio is equivalent, then I imagine that the major factors are length on the waterline, displacement and draft.

 

But probably I should ask the naval architect in my immediate family about this.

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True as far as it goes, but you also have to count the surface area of the rudder into the equation.  If the Victory has enough rudder to overcome the added mass, drag, etc, she may indeed be able to turn far better than expected.  She'll probably bleed speed like a stuck pig in a hard turn, but she may be able to rotate fairly well.

 

Yes but the surface area of the rudder to the forces (weight, drag, etc) ratio has to be much greater than the frigates to come close to its numbers, and the ratio is probably not. 

 

Unless someone uses a very large stick  :ph34r:

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Wow I love this discussion.  For my 2 cents, I am all for reality when it makes sense.  I am hoping that in in the open world game, getting into these bigger ships should be a monumental group effort.  So if it ends up being an absolute beast that turns well, that is fine as long as they are very rare to see and very scarey to risk in battle for the owners.  I am hoping that a single person operating on their own will not have a practical way of getting into the medium to large frigates and line ships should be totally out of reach.  We will see... I see myself in cutters and brigs for the most part, and I'll be happy with that unless I become a member of a well organized group.

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Wow I love this discussion.  For my 2 cents, I am all for reality when it makes sense.  I am hoping that in in the open world game, getting into these bigger ships should be a monumental group effort.  So if it ends up being an absolute beast that turns well, that is fine as long as they are very rare to see and very scarey to risk in battle for the owners.  I am hoping that a single person operating on their own will not have a practical way of getting into the medium to large frigates and line ships should be totally out of reach.  We will see... I see myself in cutters and brigs for the most part, and I'll be happy with that unless I become a member of a well organized group.

 

 

I believe the devs are going with the method of a nation's proper warships being under control of the admiralty. 

 

 

So yeah, there's no eternal grind until you can just buy a 1st rate off the shelf. 

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Quotes

 

I've been searching for hard data some months ago, but couldn't find any simple but yet detailed enough info. Some sources say:

  • The longer the ship, the slower it turns and the larger its turning radius. A ship half the length is probably about four times as maneuverable. It also helps to have fine ends, and weight concentrated amidships.
  • Long ships were slightly less manoeuvrable , Endymion was considered slightly long in wearing - some of the relatively stumpy British 36 and 32 gun 18lb frigates would have had a tactical advantage against longer French ships for example.
  • There are examples of exceptional ships, such as the Unicorn class of 28-gun frigates from 1747 which were renowned for being able to tack in their own length.
  • Lady Washington always impressed me with her ability to tack in very little wind, you just have to know what your doing.  So yes tacking in your own length is reasonable for some vessels.  Niagara tacked especially quickly, like lightening, I'm pretty sure she was tacking in her own length most of the time.
  • Even the very best ships, such as the Niger class of 32-gun frigates from 1757, would only wear in four times the ship's length.
  • Constitution was very long indeed for a Frigate, and her reputation for speed should not be surprising. Yet she was also famous for being heavily built - if we say these things are all dependent on conditions - Java seemed to both faster and more manoeuvrable early in their battle, but Java's large, heterogeneous and poorly trained crew (not to mention lighter guns and more frail scantlings) were unable to take advantage of the opportunities these brought her.
  • You would have to wonder if the variation in the ability of captains to get the most from their ships, and to objectively give data in the sailing reports is more variable than the sailing performances themselves.

(BTW some good reads for those interested: http://cnrs-scrn.org/northern_mariner/vol14/tnm_14_3_57-68.pdf and http://grantvillegazette.com/wp/article/publish-292/ )

 

 

Physics factors

 

All sources agree that lenght is a determining factor for rotation. Here is a list of other factors on modern cargo ships: http://shipsbusiness.com/turning-circle-external-factors.html . The different resistances on a hull may also be taken into account.

  • The hull crossection area resistance ("form resistance") equals 1/2 C r S v², with C form coeff r water density S projected surface and v speed - but is only accountable for a % of the total resistance.
  • At low to normal speeds, the main resistance is the "frictional resistance" which equals 1/2 C r S v² with C Reynolds friction coeff r water density S wetted surface and v speed. I'd guess it would have been a bigger % of the total resistance in the 18th century because of the roughness of the hulls (and on modern ships it increases by 15% every year without hull cleaning).
  • There are also the wave resistance and air resistance.

 

Then the final turn rate also depends on the turning power (rudder and/or sails). But at least we can notice that apart from length, the surfaces (projected and wetted) are important factors - and they are related to the ship draft (thus weight). Also the equation used in linear approximations is in the form of [ sum of moments = mass * acceleration ]. Those would explain the maneuverability differences between frigates and SoLs. And it would also corroborate the admiralty reports about razees (ships with the upper deck cut, thus less weight and air resistance).

 

 

Formulas

 

As for hard data, Poyraz linked me a good source some time ago ( http://www.eagle.org/eagleExternalPortalWEB/ShowProperty/BEA%20Repository/Rules&Guides/Current/145_VesselManeuverability/VesselManeuverabilityGuide_June06 ). The full systems of equations are complex for me, but there is an empirical method (p. 88) proposed that could give insights.

  • We find that beam (width), block coeff (underwater hull % of underwater cube) and rudder profile decrease the steady turning diameter. And length, draft and bow profile increase it.
  • And the tactical diameter (lateral distance to turn 180°) is affected by the same parameters as previously, and increased by initial speed. Same for the advance (longitudinal distance to turn 90°), transfer (lateral distance to turn 90°) and turning speed.

The formulas are only true for lengths > 55m and lenght/beam > 5.5, which wasn't the case for 18th century ships. Still the relations feel right. To get an idea of how the different parameters affect the turn, by simplifying we find:

Steady_Turning_Diameter/Length = 9.73 -13 Beam/Length - 5.8 Block_Coefficient - 3.82 Rudder_Profile/Length.Draft + 7.79 Bow_Profile/Length.Draft

 

Also for modern ships, the block coefficient is important (all things being equal) in both advance and steady turning diameter. Block coefficient in the 18th-19th centuries was about 0.6-0.7 for a merchant, 0.5-0.6 for a warship (the more streamlined a ship, the lower its block coefficient).

 

 

turn_a10.jpg

 

But this could only be applied to rudder turns at normal speeds with a balanced rig. For sail turns, the basic ratio used in modern boat design is sail area/displacement (weight), as a comparison of sailing powers.

 

There are many examples of full calculations on the internet for auto-pilots or prediction, but tbh I'm not sure it's worth the time to calculate everything with 18th century constants. I don't think the most modern simulations can be done without model testing in a pool, although approximations could be used. The linear calculations are based on a momentum equation on the yaw plan. The rudder is seen as a moment, thus the sails could be seen as moments as well.

 

 

In game

 

But another thing that could get some tuning in the current game, is the relation between rudder turning and sail turning. I feel sail turning could be more effective especially at low to normal speeds. Also the efficiency of the rear/front stacks could be modified depending on the pivot point, which is closer to the bow when the ship makes headway, and closer to the stern when the ship makes sternway. That would enable us to choose the most effective stack for rotation (when making sternway or wearing), while keeping the other one to maintain speed. The principle of the pivot point is explained and detailed here: http://www.cnrs-scrn.org/northern_mariner/vol09/nm_9_3_53-59.pdf . Also the rudder turning decelerations could be higher, especially at high speeds, once a ship reached its max turning rate.

 

Also the razee ships aren't like all the SoLs. They were re-built to increase their sailing effectiveness at the cost of fire power, to avoid them the prison hulk or the pyre. As for the limitation of the turning, I don't think that the rudder or sail areas could have countered the increase in wetted surface, draft and mass. As a comparison, most ships couldn't reach their hull speed because the drags were too high for the sail forces. But with the use of headsails/spanker, I believe we could imagine a little increase in maneuverability.

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