You have an extra comma in the end of the column list in the statement. Instead of
str = "insert into ListOfVessels ([VesselCompanyName], [VesselBuild], [VesselType], [VesselGross], [VesselDW], [VesselFlag], [VesselImoNo], ) values (?, ?, ?, ?, ?, ?, ?)"
try
str = "insert into ListOfVessels ([VesselCompanyName], [VesselBuild], [VesselType], [VesselGross], [VesselDW], [VesselFlag], [VesselImoNo] ) values (?, ?, ?, ?, ?, ?, ?)"