Ritchie Howell recently completed a 61 sportfisher and the result was a beautiful vessel that is currently fishing out of Los Sueños. There is, however, an interesting story to how the vessel came about. I was building the boat for a customer from Venezuela. He was willing to take a chance with me. We wanted to design something exciting, something ultra-modern, says builder Ritchie Howell.
I noticed some guys up north were achieving some great performance numbers and had always wanted to try it. This buyer gave me the opportunity. We set out to engineer a stepped bottom. We had the opportunity to perform some CFD analysis a computerized tank test, Howell describes. CFD is computational fluid dynamics analysis. CFD is a pretty complicated deal, but simply stated it is the use of applied mathematics, physics and computational software to view how a gas or liquid flows.
Howell interest in CFD analysis lay in determining the optimal position of the step to minimize friction between the boat hull and the surface of the water. We ran four computerized tank tests. These are pretty expensive. Wed run it and tweak the bottom. The goal was to reduce friction we go to the point that we achieved 50-knots, Howell describes.
The step introduces a break in the suction of the water to the hull. It not as much about introducing air as it is to bend the suction of the water, Ritchie relates, scientifically. The faster you run, the more water wants to suck the hull down to the water. The steps in the bottom allows you to break the attraction, freeing up the hull. With reduced suction and decreased friction comes greater speed.
Hull render courtesy Ritchie Howell / Ocean Designs
SPECIFICATIONS
LOA:61’8″ Beam: 18′ Draft: 4′ 6″ Weight: 64,000 lbs Fuel:1350 gallons Water: 250 gallons Engines: Caterpillar C-18As, 1150 HP each Gears: ZF 1.75:1 Generators: (2) Caterpillar 21 KWs with sound enclosures Speed: WOT 38.5 knots faster with 4 blade wheels
