New CAPELLI Tempest 42 – Twin 450hp XTO Yamahas
MAR.CO R-Evolution 26 – Mercury Racing 450R
New CAPELLI Tempest 42 – Twin 450hp XTO Yamahas
MAR.CO R-Evolution 26 – Mercury Racing 450R
NUOVA JOLLY Nauma-tec – New Suzuki KURO 250hp
At the 63rd Genoa Boat Show we had the opportunity to test the brand new DF250AUN Suzuki mounted on the Nauma-tec Freccia 800.
Naumatec 800 is a fast tender that has exactly the same hull as the 800 racing which can reach 80 knots, while traveling very safely at 50.
Naumatec Freccia 800, the deck of which features a central opening typical of the American 'Bow Riders', is a highly enjoyable and practical tender both during navigation and when relaxing at sea. Despite its very aggressive appearance, once you get on board, you feel like you are in an enjoyable lounge. Her simple, clean yet aggressive lines make it a boat with a strong personality that combines speed with Italian refinement and elegance.
Suzuki "Kuro", which means "deep black" in Japanese, is a new version of the DF250hp that made its debut at the Genoa Boat Show. The 4-liter, 6-cylinder engine block has been upgraded with new electronic mapping, which has increased the rpm range to 6,300. Its lower unit has been redesigned to reduce drag and improve performance, while the asymmetrically designed skeg provides better steering stability. The numerical reduction of the gear ratio to 2.08:1 combined with the powerful gears continue to allow the use of large propellers, while the lower unit is now faster and allows us to use longer propellers, which in combination with smaller diameter ones will give us higher speeds, especially in light or racing boats.
Also, the top of the matte painted cowl has been redesigned and the air intake grills have been modified to better supply and cool the engine.
During our test, the engine wore a 4-blade 14 5/8΄΄x 21΄΄ Revolution propeller making a very good combination of performance and ride quality.
Nauma-tec was getting instantly on plane, was extremely fun and maneuverable but also remarkably stable both in our maneuvers and at high speeds.
At 3000 rpm we were cruising at 20 knots consuming 1.2 liters per nautical mile, while at 3500 rpm we were running at 25 knots with exactly the same fuel consumption.
At 4000 rpm we were running at 30 knots burning 1.4 liters per mile, while at 4500 rpm our speed reached 34.5 knots with a consumption of 1.45 liters per mile.
At 5500 rpm we reached 46 knots with a consumption of 2 liters per mile, while at full throttle, with 60% trim, we reached 6300 rpm and a final speed of 49.3 knots.
We notice that from 5500 rpm to 6300 rpm we got only 3.3 knots, which is evidence of excessive ventilation of our propeller due to the high engine trim. Therefore, the actual revolutions that the engine raises with the Revolution 21" are close to 6000, and not 6300, as the increased slip values at WOT also show.
We are therefore led to the conclusion that under no circumstances should we go for a longer propeller pitch, even if we choose one with a smaller diameter or with one less blade.
There is no doubt that it is worth trying the pro finished Bravo I LT 21 inch of pitch propeller, which will allow us to get another 150 rpm or so allowing our engine to reach closer to its maximum rpm limit, resulting not only in its good operation but also the increase in top speed too.More rpm – higher speed.
Furthermore, since the bow of the boat does not appear to be very light, there is a good chance that we will gain benefit from the gradually increase of the diameter of the ΄΄diffusion ring΄΄ (flare) of the Bravo I LT propeller barrel resulting in greater lift with all that entails.
