More accurate sail use

[SavoryHawk]

Overall, I think y'all have done a good job of modeling how sailing works, better than many games, but I think there a few steps that likely wouldn't be terribly cumbersome that could make it even better.

 

I'll keep my explanation short at the moment and if there is interest, I can go on a greater length. I'm a professional sailor who works on boats of the sort modeled by your game, so I have a good feel for how this all works in reality. I might find it gets better as I move on the bigger ships in game, but so far I've felt some elements of sail handling that have been a bit lacking. In the game I've sailed a Cutter, the Lynx, a Pickle briefly, a Privateer, and a Brig. In reality I've sailed the actual Lynx, brigs, brigantines, and tops'l schooners.

 

The element I'd suggest you add is that of center of effort (CoE). I'll simplify it to how it relates to turning. The CoE is roughly the geometric center of one's sail plan averaged out. It is essentially the point at which the wind is pushing the boat sideways, and as you change your sail plan, the CoE moves forward or aft on the boat (up and down too, but that is a different aspect.) This matters when you compare it to the Center of Lateral Resistance (CLR) which does not move much, and is essentially the pivot point of the boat, generally roughly in the center, though not quite.

 

When the CoE is aft of the CLR, the boat wants to turn towards the wind. When the CoE is forward of the CLR, the boat wants to turn away from the wind. So, by changing your sail plan, you can affect how much the boat wants to turn. For instance, if you want to tack very quickly, you can strike heads'ls and sheet in any fore-and-aft sails at the back of the boat tight. This will make the boat want to turn into the wind (often so much so that you don't need any rudder to make the turn) This is because those acts pull the CoE very far aft. After you pass the eye of the wind, you want to reset heads'ls and let the after sails out, otherwise it is easy to get stuck there. Similarly, if you want to wear ship, you can sheet heads'ls in tight and let the after fore-and-aft sails out very far. This pulls the CoE forward and makes the boat want to turn downwind.

 

There are times when, without taking some of these actions, it is impossible to tack a boat, not just getting through the eye of the wind, but even getting to it. Likewise, it is easy to get stuck in irons if these forces aren't managed. I think that with auto skipper on, things are fine as they are, but it would be great if one could gain advantage in how the boat handles in game by handling sail properly as well. Rate of turn seems to be very uniform once one gets going, aside from small changes as one speeds up or slows down, but with reasonable fore and aft modeling of the CoE, rate of turn would vary considerably. 

 

On a connected note, a cutter that lost its headrig and had a shredded tops'l would almost immediately turn head to weather and stall out since there wouldn't be anything to balance out the far aft CoE from the mains'l. If its tops'l were intact, it could perhaps use that to fall off and balance things out some, but it would be an unwieldy beast to sail and it would be almost impossible to get going downwind without striking the mains'l.

 

Really, on any boat losing the headrig is a critical thing, as it provides a significant amount of the forward support for the masts. Without it, the whole rig is weakened considerably, and simply tacking in a strong breeze would run a risk of dismasting oneself. See the Pride of Baltimore II's misfortune in November of 2005. They lost their bowsprit, and shortly thereafter both masts came down as well. In their case, it was the racking forces of high seas that sheered the masts, but a strong aft push aloft would be a significant strain as well. In game terms, one could take mast hp damage based on sails flown as one maneuvers with missing parts of their rig. One could hold up for a bit, and striking high sails would help decrease the wear, but before long things would start to break even without more gunfire coming in. 

 

There is a nice little simulator made by Peter Davis to model the HMS Surprise, and also a brig, that he has on his website. http://www.pdavis.nl/It is very basic, and it has its own issues, but it is great for looking at the different forces acting on various sails in different directions, as well as seeing how changes in sail plan, sheeting, and point of sail affect the CoE. It also models how the CoE affects the boat in terms of heeling forces as it moves higher and lower in the rig.

 

Hope you find this helpful. I'm happy to answer any questions or explain anything that is unclear, or just elaborate further.

 

[maturin]

Fore/aft rigs have an unfinished sailing model that doesn't take rig balance (or even yard angle, really), into account.

 

Square riggers work pretty much exactly how you describe.

 

 

 

 

On a connected note, a cutter that lost its headrig and had a shredded tops'l would almost immediately turn head to weather and stall out since there wouldn't be anything to balance out the far aft CoE from the mains'l. 

Where is the disconnect here with modern sloops? In moderate winds yachtsmen sail around quite happily with just the mainsail, and no rig control problems at all. Which is, as I understand it, because being shorn of half your sail area is going to reduce heeling moment drastically, and heel was the biggest factor in weather helm to being with. On the traditional shallop I sail sometimes, the big spritsail up forward makes the boat slack in light airs, but as soon as there is any noticeable amount of heel, she duly becomes ardent.

[jodgi]

...On the traditional shallop I sail sometimes...

Show us a picture!

[maturin]

Show us a picture!

 

 

1:30 in the bottom right hand corner.

 

There is jib too, but it doesn't do much...

[jodgi]

Cool!

Are you the one with the light blue or red jacket?

[maturin]

Cool!

Are you the one with the light blue or red jacket?

 

There are actually seven people aboard, which was running up against the nominal weight limit where the designer stopped doing the math. Did fine in the chop outside the breakwater, though, with only one little wave coming aboard. 

 

I'm probably the grey smudge abaft the mainmast.

[AKPyrate]

Fore/aft rigs have an unfinished sailing model that doesn't take rig balance (or even yard angle, really), into account.

 

Square riggers work pretty much exactly how you describe.

 

 

Where is the disconnect here with modern sloops? In moderate winds yachtsmen sail around quite happily with just the mainsail, and no rig control problems at all. Which is, as I understand it, because being shorn of half your sail area is going to reduce heeling moment drastically, and heel was the biggest factor in weather helm to being with. On the traditional shallop I sail sometimes, the big spritsail up forward makes the boat slack in light airs, but as soon as there is any noticeable amount of heel, she duly becomes ardent.

 

In general, modern sloops have their mast farther forward than a cutter would have.  Thus, the tendency for the mainsail to turn the boat head to wind is lessened and the boat can sail fairly well by just easing the sheet a bit to reduce weather helm.  Additionally, the modern hull designs have a larger forefoot cut out of the bow and/or a more balanced keel/rudder position, reducing the forward CLR and allowing the COE to be further back.  Personally, besides tall ships, I have sailed many modern sloops and currently own a cutter.  The cutter is almost impossible to sail with just the mainsail as I might do for a sloop.  I need at least the little cutter stays'l forward for balance, though that doesn't require the bowsprit, it is a relatively (ie 40 years old) design.

[jodgi]

I'm probably the grey smudge abaft the mainmast.

I'll start calling you that when I'm mad at you!