Chris, 7 & 8, during my time, I would say around 74-76 were re-engined....sign for the future?
with Detroit Diesel engines by the Penske company in the US. Pathetic.....I suspect they put undersized props on them. If you went by engine noise the boats should have been towing water skiers but instead they would be puttering along at around 4kts! After the rengining they were seldom used. Also at that time manpower in the deck dept was cut back and boats would frequently be crewed by Cadets, Officers and Cruise staff.
Shoreside tenders were also used to a fairly large extent. Until Alpha and Beta came along we got frequent complaints about tender service.