What's this?

[Arien]

What's this and where is it used for?
Somebody know?

2121921220

[moombadaze]

that is your speedo needle adjustment knob.

[kaneboats]

Yup, just turn it and makes your boat go a lot faster. Kind of like drilling out the hole in the pitot tube like we used to do in the old days. Made the boat go over 60. ;)