I sent that Video to a friend who had owned a Grover 26. His had a 120 hp Ford Lehman diesel--and would cruise in the 12 to 15 knot range.
The outboard (3 engines) had the whole cockpit full of gasoline! His older son left the boat at the Azores, and would not continue the voyage. His younger son finished the last bit to Portugal.
" they logged nearly 3,000 miles over 33 days, 26 of them at sea. The voyage was entirely free of mechanical problems, with two thirds of the trip being powered solely by the 9.9 kicker. "