Gunports were meant to be used while sailing. (Good documentary: the pirates of caribean)
reason according to wikipedia:
> Vasa sank because she had very little initial stability—resistance to heeling under the force of wind or waves acting on the hull. This was due to the distribution of mass in the hull structure, and to the ballast, guns, provisions, and other objects loaded on board placing a lot of weight too high in the ship. This put the centre of gravity very high relative to the centre of buoyancy, thus making the ship readily heel in response to little force, and not providing enough righting moment for her to become upright again.
My memory of vasa museum:
At that time, ship designers not necessarily calculated center of mass and center of buoyancy.
They did, however the vasa was modified mid-build to have higher ceilings in the royal stareroom and therefore a substantially higher centre of mass, as this change had knock-on effects all over the design. They added something like a meter and a half of height, and it was substantially more massive than necessary as it was built into already laid down timbers that had been intended to accommodate a lower topdeck level.
So… there are parallels. A wealthy owner saying “I want this”, and a shipbuilder deviating from a previously established design to meet their whims, resulting in compromised stability.
The way this is told in elementary school in Sweden (source is Swedish) is that the Vasa was too narrrow, given it's height. So then the question is, how much wider should she've been to carry the extra height. Vasa's sister ship, Äpplet (the Apple) had a similar deck layout and was about a meter wider. As a layman, considering the technology at the time, it does not sound so much more wider.
A small amount of beam makes a tremendous difference in hull stability.
Anyone who's had experience with rowing shells will be quite aware of this. Beginner's / open-water vs. flat-water shells differ in width by only a few centimetres, but the difference in handling is profound. Both are unstable to the absolute novice, but even a fairly experienced rower from a wider shell will find the handling of a narrower one much more precarious.
(Both are also inherently unstable with CoG well above midpoint, but the dynamic stabilisation provided by the rower or crew is much more critical for the narrower, and faster, shells.)
>As a layman, considering the technology at the time, it does not sound so much more wider.
Think about the lever arm of that "other half meter" of ship that you're dragging up into the air when you heel the ship over plus the increased displacement of the half meter you're burying into the water.
Remember, ships aren't really subject to huge propulsive forces relative to their mass compared to land vehicles. So something like an extra meter is gonna make a pretty big difference.
That was normal-enough practice. In a good harbor, in good weather...any normal ship would have been okay.
The real problem was the Vasa's design & weight distribution - which were disastrously unstable. Which problem had previously been demonstrated in simple dockside testing. Here's Wikipedia's account:
> In the summer of 1628, the captain responsible for supervising construction of the ship, Söfring Hansson, arranged for the ship's stability to be demonstrated for Vice Admiral Fleming, who had recently arrived in Stockholm from Prussia. Thirty men ran back and forth across the upper deck to start the ship rolling, but the admiral stopped the test after they had made only three trips, as he feared the ship would capsize.
A combination of factors: Excessively narrow beam, additional gun deck, resultant high centre-of-gravity, healing over, and then shipping water through gunports.
Gunports are most usually open when guns are firing, which occurs as a ship is under way. Merely having open gunports should not imperil a ship.
The Bayesian similarly had a high CoG and windage courtesy its tall mast, and was apparently susceptible to shipping water should it heel sharply and/or encounter high seas, as seems to have been the case.
