NAMBA October 2021 Web.pub

PROPWASH 9 Jet Boats By Lohring Miller NAMBA Safety Chairman I’ve been fascinated by water jet propulsion. We once considered it for our gas SAW record boats. However, a little research showed that at our speeds a surface piercing propeller is more efficient. The fact that all really fast boats use surface piercing propellers confirms this. There are still some applications where jets are preferred. Who cares about efficiency when you have serious power? The other application is jet sprint racing where boats run on winding courses that are only a few feet deep. October 2021 Jet Sprint Engine In my area river racers run jet boats. Water depth is the main reason, but maneuverability is also important. These boats are highly developed with big engines and front wings for pitch control; see the pictures. River Racer River racing in rapids Jet Sprint Course And you think NAMBA worries about safety. Beside the spectators, there are real people in those boats. As in our racing, the boats don’t go far out of the water. Shallow water and roll cages help protect the drivers. The lack of spinning propellers is also a safety plus. I got interested in building a jet boat after seeing a series of videos by Štěpán Müller. I bought his very well-designed water jet model from CG Trader, printed it, and put it in a 3.5 size Calcraft I had. I used a standard P limited power setup with a UL-1 motor and 2-2S packs in series. (Continued on page 10) Jet Sprint Boat Racing