Aim for the waterline

Tuesday, April 10th, 2018

I always assumed that gun crews in the Age of Sail aimed at the waterline because that was where water could enter the enemy ship, but that’s not the whole story, Tom Ricks explains:

But, I kind of wondered, if that were the case, why not aim slightly lower, where a good shot likely would let even more water in the enemy’s hull, and be more difficult to plug? (I thought the answer was perhaps that at many angles, the cannonball might skip, rather than plunge into the water, but I wasn’t sure.)

Well, now I know better. There is a very specific reason to aim right at the waterline.

I was reading an discussion of wood rot in boats and trees by Richard Jagels, professor emeritus of forest biology at the University of Maine. He offers a much more precise explanation: On wooden ships, the weakest point on the hull is right along the waterline, because that’s where the most rot occurs.

There’s a biological explanation for that, having to do with oxygen and moisture. Fungi need a balance of both to thrive and rot wood. Let him tell you: “Above the waterline, planking is usually below 20 to 25 percent moisture content, which is too dry for fungal activity. Below the waterline, wood becomes progressively saturated until the oxygen requirement is not met; again decay is halted. Near the waterline, conditions are just right for decay to rapidly progress: the Goldilocks solution for rot.”


  1. Lu An Li says:

    Cannon balls heated red hot and then fire to penetrate the inside of the wooden ship. Start a fire.

  2. Albion says:

    Unless you can get behind an enemy ship and rake it. As most sailing ships below deck had little in the way of dividing walls (I believe removed before the battle began) a cannon shot thus aimed would travel the length of the other ship doing tremendous damage.

  3. redan says:

    Lu An Li:

    I’ll be conservative and stipulate ‘red hot’ = 500° C.

    What propellant did you have in mind for this fire mission, and what is the propellant’s temperature of ignition?

    King of Battle (Artillery): We put the balls where the Queen of Battle (Infantry) wants them!

  4. Kirk says:

    As an Engineer, I’m just going to point out the traditional Infantry response to why the Artillery is the King of Battle, while the Infantry is Queen: It’s because the Artillery is constantly doing to the Infantry what the King does to the Queen…

  5. Redan says:


    Essayons, brother! We clear the way.

    12 B / C / N / T here, but I started as an 11B Queen. Retired now on the PDRL.

    Well met.

    SFC redan

Leave a Reply