Billydoo

My 2004 Challenger 1800 has an engine beep after i take a run. When i come back to idle and am changing tubers/skiiers it will beep. I though it was a low oil signal and added oil. It still beeps?

I pulled the boat out of storage and droppped in the water. The speedometer doesn't work. It is stuck a 7mph. I took it out and looked at the spinner/sensor at the back and it is spinning fine. I've had it out 3 times now and no change...

Tips?