I ASSUME YOU ARE REGISTERING IN MA.....
I just went through this "ordeal" last month.
First, you need to pay the sales tax on the boat. According to MA-DOR, Sales tax is due on the 20th day of the following month from date of purchase. Good news is you can pay it online at
https://wf.dor.state.ma.us/mrv/welcome.asp
Be sure to only list the boat and motor sales price DO NOT INCLUDE THE TRAILER (if you purchased it as a total price with the boat). You pay the trailer sales tax at the registry of motor vehicles. Also be sure to print TWO copies of the ST-6 form. One for when you register the boat and one for your records.
I also purchased from an owner who had an outstanding bank loan. It took about 2 1/2 weeks for the title to be sent to the broker. Once you get the title, fill out the registration and titling form
http://www.mass.gov/dfwele/dle/regis...itlingform.pdf
Take the form, the ST-6 form, the title, bill of sale, and the hull ID tracing (although they didn't even look at mine) to the closest office
http://www.mass.gov/dfwele/dle/regoffices.htm
Be sure to have a check or EXACT CASH - no change can be given.
Fees
Motor Boat Registration (Two years)
Length Fee
Under 16 ft $40
16 to < 26 ft $60
26 to < 40 ft $80
40 ft plus $100
Title $25
It's all at
http://www.mass.gov/dfwele/dle/ELEREG.htm
Hope that helps.
Jim