Although the owners originally wanted a boat capable of just 10 knots, Bill gradually made them see that a semi-displacement hull would better suit the type of coastal cruising they were keen to do. The extra speed could also prove to be a bonus if they needed to get somewhere in a hurry, for example to outrun approaching bad weather.
As a result, Luana boasts a round bilge forward, apart from the spray rail, developing into a hard chine over the aft third of the hull. Hardening the chine in this way prevents the stern from “squatting” and, as the fuel chart illustrates, improves efficiency, especially at displacement and slow planing speeds. An aft pocket allows the shaft to run at a shallow 7 degrees, further improving efficiency.
The design enables the single 500hp Cummins diesel engine to propel the 19.2-tonne craft through the water at comfortable cruising speeds of 10.5 knots (at 1800rpm) or 11.3 knots (at 2000rpm). Should a faster cruise be required, 2200rpm will deliver 13 knots and 2400rpm, 14.9 knots. Flat-out, at 2610rpm, and fully laden with fuel and water, Luana’s top speed is an impressive 17 knots.
|ELITE 15.2m Mid-Pilothouse
|Bill Upfold, Elite Marine Design
|Lloyd Stevenson Boat Builders
|Composite GRP (epoxy)
|Twin Cummins QSC 500hp
*with quoted HP