wretched excess of geekiness
Jul. 29th, 2012 08:38 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
dancing_crowLast night in the middle of the swimming Alice asks "what is hull speed for a human?"
Hull speed is the speed a boat or ship can go before the length of the wake is longer than the boat, and the boat is essentially pushing uphill, and using several times more energy. Vessels can plane well above hull speed, and with enough engine power they can run above hull speed, but for the vessels I generally mess about with, hull speed is very definite limitation.
So tonight, because I'm the one in front of a computer (in a very rare appearance of standard US masculinity Al was watching sports on the couch with a (root)beer this afternoon) I was tasked with calculating hull speed on a human.
There is a hull speed calculator making some of this easier - otherwise you have to calculate the square root of the LWL (length at waterline) on your own and multiply it by 1.34 to get knots:
For a basic 6 ft human, hull speed = 3 knots.
3 knots = 1.5 m/sec
the 200 m world record is 1:42:00 which is 200m/102sec = 1.9 m/sec
so the Olympic level swimmers are working well above hull speed, powering up their own bow wave, which is what it looks like watching them. Awesome.
Hull speed is the speed a boat or ship can go before the length of the wake is longer than the boat, and the boat is essentially pushing uphill, and using several times more energy. Vessels can plane well above hull speed, and with enough engine power they can run above hull speed, but for the vessels I generally mess about with, hull speed is very definite limitation.
So tonight, because I'm the one in front of a computer (in a very rare appearance of standard US masculinity Al was watching sports on the couch with a (root)beer this afternoon) I was tasked with calculating hull speed on a human.
There is a hull speed calculator making some of this easier - otherwise you have to calculate the square root of the LWL (length at waterline) on your own and multiply it by 1.34 to get knots:
For a basic 6 ft human, hull speed = 3 knots.
3 knots = 1.5 m/sec
the 200 m world record is 1:42:00 which is 200m/102sec = 1.9 m/sec
so the Olympic level swimmers are working well above hull speed, powering up their own bow wave, which is what it looks like watching them. Awesome.