Editing 3013: Kedging Cannon

{{comic
| number    = 3013
| date      = November 18, 2024
| title     = Kedging Cannon
| image     = kedging_cannon_2x.png
| imagesize = 740x259px
| noexpand  = true
| titletext = The real key was inventing the windmill-powered winch.
}}

==Explanation==
{{incomplete|Created by a HEADCANNON. Do NOT delete this tag too soon.}}

Prior to the invention of powered ships, oceangoing vessels moved primarily by means of wind power, which meant that they were restricted by the direction and power of the winds. If a sailing vessel needs to travel upwind (against the wind), they typically make use of a technique called {{w|Tacking_(sailing)|tacking}} (or "tacking against the wind") which involves zigzagging across the wind's direction. This method is significantly slower and more difficult than traveling downwind, but it makes upwind navigation possible.

This comic portrays a fictional scenario where a ship's captain, apparently unfamiliar with tacking, has developed an alternative method based on {{w|kedging}} (also known as warping). 

The basics of kedging are not dissimilar to the comic: a boat affixes a rope or chain to an anchor point (such as a literal anchor) and winches itself closer. Traditionally, kedging involves deploying an anchor from the vessel, either manually or via a smaller boat, and then {{w|winch|winching}} the ship toward the anchor point using ropes or chains. This is a real method, but is clearly very slow and labor intensive. Generally kedging is only effective in shallow waters and employed when tacking is not an option, as for example in harbors or narrow channels where space is tightly constricted. The captain in this strip appears to be using it for long-distance travel, which would be highly impractical. What's more, he deploys his anchor with a cannon, wasting large amounts of gunpowder (although with the setup as depicted, wasting gunpowder would be the least of a ship's concerns, as firing something the weight of an anchor any meaningful distance would require so much force it would outright rupture just about any age of sail artillery piece{{acn}}), all while a confused Cueball looks on, wondering why the Captain isn't trying to use tacking instead.

This approach to transportation has been used in war when the wind halts{{acn}}, with ongoing gunfire. This may be where the concept of using a cannon to deploy the anchor came from, as such a situation may involve an excess supply of gunpowder.

Where the water is too deep for the anchor to reach the bottom, a so-called {{w|sea anchor}} could theoretically be used, but would be even less practical. Kedging with a sea anchor would effectively be a very slow and inefficient version of rowing, which is an alternative (albeit labor-intensive) method to travel against the wind. 

The title text indicates that the captain's system has evolved to incorporate a windmill mechanism that harnesses wind power to draw in the kedging rope. This implies that there is indeed sufficient wind that could be used for tacking, as otherwise the windmill would be ineffective. Likely this is a ridiculously inefficient {{w|Rube Goldberg machine|Rube-Goldberg-like}} solution to wind propulsion, if tacking has been discovered, and an ingenious energy saver (if heavy and expensive) if not. An analysis of the efficiency is below.

==In real life==
On some rivers, {{w|chain boat}}s were used for about a century. A chain would be laid the length of the river, and the boat used a winch to pull itself along the chain. Rudders and booms could replace the chain in the center of the river even around bends. It turned out to be very difficult to drive the chain with enough force - several techniques were attempted. Many ferries still exist that {{w|Cable ferry|use a chain}} (or cable) laid ''across'' a river, tethered at each bank.

{{cot|Speed and economic analysis of dual wind-winched kedging cannons compared to tacking}}
A dual-anchor kedging cannon system for sailing upwind, consisting of:
* Two kedging cannons firing 16 kg anchors
* 6-meter diameter windmill powering winch system
* Dual-winch setup for continuous operation
* Operating in 15 knot headwind conditions

Vessel specifications:
* Length: 30 feet (9.1 meters)
* Displacement: 10,000 lbs (4536 kg)
* Sail area: 600 sq ft (55.7 m²)
* Wetted surface: 40 m²
* Frontal area: 8 m²

;Wind power generation
Available wind power is given by:
''P'' = ½''ρAv''³''η''
where:
* ''ρ'' = 1.225 kg/m³ (air density)
* ''A'' = ''π''(''D''/2)² = 28.3 m² (windmill area)
* ''v'' = 7.72 m/s (wind speed)
* ''η'' = 0.245 (combined efficiency)

This yields 1.95 kW of usable power.

;Drag forces
Total drag combines water and air resistance:
''F''<sub>drag</sub> = ''F''<sub>water</sub> + ''F''<sub>wind</sub>
where:
* ''F''<sub>water</sub> = ½''ρ''<sub>w</sub>''C''<sub>d</sub>''A''<sub>w</sub>''v''²
* ''F''<sub>wind</sub> = ½''ρ''<sub>a</sub>''C''<sub>a</sub>''A''<sub>f</sub>''v''²

Using:
* Water density (''ρ''<sub>w</sub>) = 1025 kg/m³
* Hull drag coefficient (''C''<sub>d</sub>) = 0.04
* Wetted area (''A''<sub>w</sub>) = 40 m²
* Air density (''ρ''<sub>a</sub>) = 1.225 kg/m³
* Air drag coefficient (''C''<sub>a</sub>) = 0.8
* Frontal area (''A''<sub>f</sub>) = 8 m²

Total drag force = 1053.4 N

;Anchor ballistics
For 300 m range with 45° launch angle:
* Required velocity = 54.7 m/s
* Launch energy = 23.7 kJ
* Black powder energy per shot = 680.4 kJ
* Launch efficiency = 3.5%

;System performance
* Winch speed = 3.60 knots
* Cycle time = 194.7 seconds
* Effective speed = 3.04 knots
* Compared to tacking speed = 4.95 knots
* Speed ratio (kedging/tacking) = 0.61

;Economic analysis
* Shots needed per nautical mile: 6.1
* Black powder cost per shot: $10 (0.5 lbs @ $20/lb)
* Cost per nautical mile: $60.76
* Powder consumption: 9.2 lbs/hour
* Operating cost: $184.90/hour

Example 100 nmi journey:
* Total powder cost: $6,076.12
* Journey time: 32.9 hours

;Conclusion
The dual-anchor kedging cannon system is both slower and significantly more expensive than traditional tacking:

Speed disadvantage:
* Achieves only 61% of tacking speed
* 100 nmi journey takes 32.9 hours vs 20.2 hours tacking

Economic disadvantage:
* High powder costs ($60.76 per nautical mile)
* Requires significant powder storage (303 lbs for 100 nmi journey)
* Additional wear and tear on mechanical systems

Key limiting factors:
* Limited wind power available (1.95 kW from 6 m windmill)
* High drag forces (1053.4 N total)
* Poor ballistic efficiency (3.5% of powder energy converts to useful launch)
* Long cycle times due to realistic winching speeds

The system could potentially be improved by:
* Larger windmill (though practical size limits on boats)
* More aerodynamic anchor design
* More efficient powder-to-launch energy conversion
* Reduced transfer time between anchors

Therefore, given both the energy constraints and economic factors, traditional tacking remains far more practical for upwind progress. The key insight is that while the kedging cannon seems to "cheat" the wind by going straight upwind, it actually requires converting wind energy to mechanical work less efficiently than a well-designed sail plan, while also consuming expensive gunpowder. The indirect path of tacking makes better use of the available wind force with no consumable costs.
{{cob}}

==Transcript==
:[A two-masted sailing ship with its sails up is floating on a calm sea with tiny waves. Two tiny figures can be seen at the ship's bow. One of them is speaking. In the next panel it becomes clear this is the captain.]
:Captain: I hope someday someone invents a way to sail upwind.  
:Captain: Using the kedging cannon just wastes so much gunpowder.

:[Close-up on the deck of the ship, showing two persons behind the taffrail. Cueball is standing behind the ship's captain and talking to him. The captain is wearing a black bicorne navy hat and aiming a cannon containing an anchor forward. Chains are draped from the cannon.]
:Cueball: The '''''what?''''' 
:Cueball: Wait, do you not know how to sail upwind? Is that why your ship takes forever to--
:Captain: Stand by...'''''Fire!'''''

:[Distant shot showing the anchor and its chain being launched out in front of the ship, towards the right of the panel. Cueball and the Captain can still be seen behind the cannon. The cannon has exhaust fumes coming out in front and the sound it makes is indicated:]
:Cannon: ''Boom''

:[Same setting but the anchor is now under water and the chain has become taut as the ship is dragged forward to the right. Movement lines behind the ship indicated its progress and it is also further into the frame than the previous panel. The movement is caused by pulling the chain back in on the ship. This produces a series of sounds:]
:Dragging chain: ''Click click click''

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Characters with hats]]