In order to be sure of the accuracy that you are seeking, I presume the
timer woul dhave to have a readout in the order of 1/100's of a second.

Since this sort of accuracy is common in timing many sporting events (eg
swimming, motor racing, running etc) a chat with the local swimming club
etc might give you some leads to sources

David

wrote:

Can I get recomendations for the most accurate electronic timer that I
can buy?

It must to be accurate to within 1/60th of a second over the course of
6 hours.

Is something like this commercially available, or will I have to build
it, or have someone build it?

Any advice would be appreciated.

Thanks a lot.

Darren Harris
Staten Island, New York.