help!! just bought new engine won't plane!! please repy

Okay first off thanks for taking the time to read my post.

Well i just bought a 17ft bowrider w/e a 650 65hp merc. (1964 i think)
when i bought it the guy put muffs on it and started her up for me with ease which sold me pretty quick.

But the next day when I took it out to test drive it i was tragically disappointed!

First off when i turned over the motor it started to move instantly even though it said it was in neutral I figured oh well it works so I put it in forward and putted toward the lake.

When i got there i decided to give her her and see what she could but, to my surprise it would pick up and then before it could even reach plane it would slip im guessing because it would rev really high looked like it was trying but would go no faster.

as well sometimes i would try to slowly give her gas and it would reach a point where itwould just start reving. There is also no reverse and i cant honestly tell you i felt it switch from neutral to forward cause it just started to move when i turned the key

Won't go any faster than say 10 km/h really disappointed and worried its gonna cost me a fortune but I need to know what i should do to get it running as i want to convert it into a fishing boat for next summer.

Hi,It should not start in gear,faulty neutral safety switch. Put shift lever in neutral,switched off,turn prop,it should turn in both directions freely.If it locks in one direction and ratchets in the other,you are in fwd.Move the lever fwd and rev until you find neutral,then adjust shift lever accordingly.Before adjusting lever make sure you have reverse,prop locks both directions.If you can't get neutral with cables,disconnect them and adjust by hand.If it's a merc control you should feel/hear a click as it rolls into the indent,an older one ,you might not feel the shift.
Revving and going nowhere fast,sounds like a spun prop.Mark prop from outside to outside on hub take it for a spin and if the line has split your hub need replacing.
Post the #.It's found on the swivel bracket,if it's '64 it'll be somewhere between these numbers.650 (65,0) 1606282 - 1765043 1964 4 cyl That info is compliments of TMD