In the
USA hourly rates for labor can run 85 to 110 per hour or more. This could take you 3 or more weeks of time and material.
Usually, refinishing an
interior is something that is better handled by the new owner themselves over time. Really, unless your
boat from 1981 has a near perfect
interior you will probably find more pressing needs that will deserve your
money and attention.
IMO - don't factor the refinish into your
buying decision.