Marine Nozzle Tests


To demonstrate the difference in design efficiencies, tests were conducted using (3) 72 foot trawlers of 375 Hp @ 1800rpm with 6:1 reduction gear each performing the same work. One was fitted with an open propeller, one with a Kort nozzle and a Kaplan propeller, and the third with a Rice Speed Nozzle and Rice Skewed Kaplan.

Test results :-

Open Prop 66" x 44" Bollard Pull: 4708 kg Max Speed: 9.3 knots. Fuel: 1512 lts/day

Kort Nozzle 61" x 56" Bollard Pull: 6646 kg Max Speed: 9.0 knots. Fuel: 1264.5 l/day

Rice Nozzle 61.25x 59 Bollard Pull: 7182 kg Max Speed:10.0 knots. Fuel: 1174.5 l/day

These real test results show significant gains:-

- 90 lts/day less fuel consumption by the Rice Nozzle & Propeller over the Kort.
337.5 lts/day less fuel used by the Rice Nozzle & Propeller over the open prop

- increased bollard pulling ability over the Kort nozzle by more than 1/2 ton and 2.47 tonnes increased bollard pull over the open prop

- increased pitch due to the efficient low drag shape of the Rice Nozzle design means increased running speed with the Rice Speed Nozzle saving time and fuel


In further trials between two sister tug vessels, the Rice Thrust Nozzle System (Rice TN) again outperformed the older Kort 37 nozzle. (see Table below)

Nozzle Vessel
Vessel HP Nozzle ID Free Running
Pull Ahead
Bollard Pull
Rice TN 98 Feet 2 x 1950 106 Inches 13 Knots 61.3 Tons 42 Tons
Kort 37 98 Feet 2 x 2150 103 Inches 12 Knots 54.4 Tons 39 Tons

(Results Certified by Bureau Veritas)

The Rice Thrust Nozzle is based on the Rice Speed Nozzle profile and was especially developed for tug work to maximize efficiency with both forward and astern thrust.

The Patented Rice Nozzle has less drag than the Kort nozzle due to its hydrodynamic design. This means previously lost engine power of about 10% can now be used as extra pitch which increases free running speed approx 10% and trawling thrust by 6% approx.

Rice had made 4800 Kort nozzles (originally designed in 1935) before developing the superior Rice Speed nozzle. Well over 2500 Rice Speed nozzles are now in use world wide since introduction in 1985. The Kort nozzle's biggest draw back is the high drag coefficient which is successfully addressed with the more efficient Rice Speed Nozzle.

Putting it simply the RICE Nozzle gives More Thrust, More Pulling Power, More Speed, from the same power input and uses Less Fuel. The cost of fitting a Rice Nozzle and a Rice KSK propeller are soon recovered through fuel savings and better performance.

Satisfied Rice Speed Nozzle owners in many countries have proven the Rice Nozzle does work better and saves fuel.

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