David Woodhouse, 65, from Grimsby has been sentenced to 18 years in prison for three rape offences and 12 indecent assaults involving young girls.
He was found guilty at Grimsby Crown Court on Friday, July 8.
The offences occurred in the 1980s over a six year period and were commited against two girls.
Detective Inspector Peter Thorp from the Protecting Vulnerable People Unit said: “David Woodhouse has been convicted following a painstaking investigation by Detective Helen Garrod from the Protecting Vulnerable People Unit.
“His two victims suffered the most unimaginable experiences that no child should ever have to and showed incredible courage and bravery throughout the investigation.
“I sincerely hope the victims will now be able to rebuild their lives again.
“I welcome the verdict today and hope this sends a strong message to those victims who have never come forward but suffered abuse at any point in their lives.
“Humberside police will always listen and do everything we can to ensure your voice is heard and those guilty of such horrendous offences are caught and face justice.”