Suggest to me, an online signup solution

Our rowing club is growing.
Currently boat sign outs are done at the club on a white board.

It seems to me an online solution would be better. There are a number of out of town members who cannot easily drive to the club to sign out a boat.

The obstacles are:
-older, perhaps less computer savvy membership
-resistant membership and executive
-no power at the boathouse ie. no "point of sale" sign ups when you're done for today, to book your boat for next time, if the solution goes online.
This is the big one. Having to rembember to sign out a boat after you've gone to work or home, is a problem.
-with no power at the boathouse, the current list isn't displayed at the site.

The ideal solution is probably the white board.
A nice online solution would be one that used cell phones, where members could send an email containing key words, and their reservation would be added to the schedule.

Anyone know of similar solutions in place which are cheap and easy to implement on existing or old computer hardware?

Something which might be viable, would be a webcam looking at the sign out whiteboard, but that doesn't make it possible to sign up remotely. This is the kind of simplicity of solution which will be required.

Thanks for ideas.