It was the first time that two Verado 400R engines were mounted on the transom of the 10 meter Skipper NC 100S and therefore we didn’t know which propellers would fit better to this combination. The only fact we had was that the owner of the boat would like the engines to be mounted high, and that’s why he had chosen their Long version with their Sport Master lower units.
We put the 26" Bravo I FS propellers, the only ones at our disposal. We only wanted to note their performance and, depending on it, we would be able to estimate the pitch and behavior of the candidates Max5 propellers in which the boat’s owner was primarily interested.
As we have already mentioned several times, Bravo I FS is a pro finished propeller which was «born» from special interventions made in the design features of the standard Bravo I, which made it «lighter» for our engine.
The detailed results of our measurements are presented in the PDF below.
We had the opportunity to test the Skipper NC 100S and the 26" Bravo I FS propellers in both rough and calm sea. The general behavior of these propellers was good enough, but it was obvious there was a lot of room for improvement.
- the boat got on plane at 2600 rpm and kept 9 knots constantly, despite the 5bf we had on our starboard bow. This excellent speed at which the boat got on plane was something really unacceptable regarding the particular boat’s setup
- although these propellers are designed to hold up the bow, the Skipper NC 100S showed that more bow lift was required
- the engines reached at 7000 rpm at full throttle
- our cruising speed was approaching 45 knots at 4500 rpm with a fuel consumption almost 2 liters per nautical mile
- the acceleration was good enough, as well as the throttle response through the whole range rpm
- the boat handling was good enough despite the high mounting height of the engines
- the slip numbers were quite high, through the whole range rpm, as almost expected
- the propellers were performing with quite efficiency up to 6000 rpm, but from that point and after till 7000rpm, the slippage increased so much that we gained only 5 knots more. This by itself clearly showed that at high rpm, the Bravo I FS propellers were loosing their grip and could not perform very well.
Definitely, the choice of the mentioned propellers is not absolutely satisfactory at the particular engines’ mounting height.
The specific mounting height of the engines was obviously very high for the Bravo I FS propellers. Instead, with the engines lower, these propellers would give better data, better throttle response, better grip, and of course they would grip better after 6000 rpm. In addition, we would be able to trim the engines more out and therefore to keep the bow higher.
So, for the mounting height we had, we have to focus in 4-blade propellers with larger blade area, taller cup, more rake as well as with larger diameter.
We can also choose 5-blade propellers with short tube like Max5 and Maximus ones. We would prefer the Max5 propellers if we are more interested in the top speed, while Maximus ones if we use to travel carrying heavy loads.
With the above mentioned propellers it is certain that the slip numbers will be greatly reduced, the fuel consumption at 4000 and 4500 rpm will drop below 2 liters per nautical mile, while everything indicates that the 10 meter Skipper will surpass 73 knots at WOT.