Pull up a sandbag a quick history lesson
Two decades ago Offshore Components the boat building division of Northern Diver asked Ralph and Mike to update the Osprey 18 and came up with the new range of: Merlin 5.0m, sparrowhawk 5.2m, Eagle 5.6m and the rare Sea Harrier at 6.4m.
The Merlin was a disaster and quickly dropped, leaving the Sparrowhawk with a recommended maximum of 75 hp and I think the Eagle at 100 hp. The Sparrowhawk would do 36 mph with 75 hp and the Eagle 44 mph in race trim.
The Sea Harrier was recommended for 135 hp but one with 200 hp Merc V6 broke the boat (The same owner also broke an XR24 replacement by hitting a partially submerged wreck at 50 mph in the middle of the night) whilst pissed
In 1993 a customer asked Offshore Components to build a Sparrowhawk with a Suzi 115 hp. They refused because they knew the customer and also suggested it was far too much power for a little rib. However the customer persisted so eventually a Sparrowhawk was built with dire warnings from the manufacturer. A year later the new owner returned to say fab boat and nothing went wrong so Osprey upped the rating for the Sparrowhawk to 115 hp having been field tested by a customer for a year. The Eagle also got uplift to something like 150 hp.
As with most rib manufacturers of the time a tape measure bore no resemblance to the quoted lengths or widths and weights were a best guess depending on how much a trailer bent under the load.