Measuring Acceleration/Speed for Small Vehicles?

stampfli_brit asks: "I am the captain of rowing at my local club, and was looking for a way to improve training. We have an NK SpeedCoach. However, I was looking for something that could measure the speed of the shell several times a second, more like this [pdf]. Any ideas on a cheap system using IC accelerometers or GPS, that could get this kind of information, log it for an hour or two, then dump it to an Apple Mac for analysis?"