Quote:
| Originally Posted by SAB The design lends itself well to waterjet propulsion. |
Initially, this was my first thought as well. But...
Shafted propulsion in the monohull section would not be favorable due to trim and CG considerations. However, waterjet propulsion in the sponsons may have their own challenges as well...
If the sponsons are running in a turbulated flow, induced by the bow wave, the intake gullets of the pumps may be prone to ventilation. This may be further compounded by the recessed (raised) position of the sponsons.
Typically, jet pumps are most efficient when placed at keel level, or the deepest section of the hull. They are prone to loosing vacuum when placed outboard, generally because this is a more aerated section AND because any lateral hull oscillation can break intake vacuum on one side, or the other. With a tri-hull configuration, this will most likely result in constant course variations while operating in rougher water. (On a more positive note, this might be the first hull ever developed that would allow jet pumps to work effectively in reverse, as there is no hull interference for backwash.)
I'm leaning toward traditional shaft propulsion in the sponsons for several reasons...
1. The depth of the shaft (and ultimately props) will offset the raised position of the sponsons, placing the props deeper than a jet pump. Aeration considerations would be minimized, as would course variation.
2. The angle at which the shaft exits the sponsons, which ultimately induces negative trim into the bow, is compensated by the extended length of the sponsons. In other words... the longer the boat, the less trim is induced by shafted propulsion.
3. As a planing hull, surface drives might be an option. Typically, surface drives sacrifice low-speed maneuverability, but the width of drive placement with outboard sponsons, coupled with no reverse-backwash resistance, might prove to be a favorable platform for these drives.
These are just some random thoughts. It's not my intent to "critique" your work. It's the first new hull design to capture my imagination in years and I enjoy exploring the possibilities.
