I'm having an issue with my 97 GTI, I got out on the water and after a couple hours of riding, it started to sputter when I accelerated and it wouldn't go very fast at all I killed it and restarted it once and it was okay for about 30 seconds until it started to do it again i then killed it again and the battery was too low to start it. I went home and charged the battery and then i went back out the next day and same thing happened, after a couple of hours of riding fine it started to sputter and wouldn't accelerate. luckily I was close to the boat ramp and I was able to idle back, while going back it started to run really rough and cut off once. I think there is an issue with the charging system.

Any ideas?

(EDIT: Neither of the gauges on the dash work and I'm only running at about 35mph, not sure if that changes anything but just thought I would mention it)