Sliding weights

[kronckew]

there is something called the 'free surface effect' that has serious influences on stability. basically of you have a wide square shape ship, it can be very stable about it's centre of gravity. a push down on one side and the hull weight on the other side keeps it from tipping. add just a bit of water (or mercury) and the slightest movement can cause the fluid to abruptly and uncontrollably run to the lower side, overbalancing the ship and causing a permanent list. it's why ships have longitudinal as well as transverse bulkheads (partitions) to ameliorate the sloshing. and you can pump from one side to the other to balance the ship if one side has more fluid than another.

fernando, don't have anything european without re-researching, but i did have a asian drawing where chinese soldiers with overly long anti-equine swords were paired up to draw each others sabres more quickly. it did mention the individual could pull the blade out in stages by grasping the blade (carefully) part way each time he pulled out a bit. not the best way if set upon suddenly, but i guess OK for a more controlled and traditional gentlemanly duel, tho in the cases seconds (or servants) were in attendance to assist anyway. i think it's posted here somewhere. asuspect i was thinking about a shakespearian passage where one of the principals called out to his servant to hand him his rapier which was discussed on another forum.

aha! found a small version of the drawing for unscabbarding miao dao.