I made a data logger module that takes a standard automotive tach wire for use with a custom mercury 44 ignition. It uses gps and the engine rpm to create a time log so the data can be graphed and analysed.

I'm curious as to what other drivers are running for tachometers/data loggers. Would anyone be interested in a data logger such as this? It helps to take the guesswork out of changes made to the boat.