Sharrow vs Standard Prop on Robalo R302
by Sharrow Marine 28 Aug 2022 03:05 PDT
Sharrow vs Standard Prop on Robalo R302 © Sharrow Marine
The conventional props tested on the Robalo R302 were stainless steel 15.25" x 19" (38.73 cm x 48.26 cm). The Sharrow props were 15.04" x 19" (38.02 cm x 48.26 cm).
One of the most critical aspects of every center console's performance is at what RPM the vessel gets on plane. It is here that the Sharrow Propeller's performance is remarkable. It can be seen clearly in the charts that the boat is nearly on plane at 2500 RPM and 15.4 mph.
At about 2800 RPM, the boat is firmly on plane (typically about 17 mph for these types of boats) with the Sharrow props and 25.4 mph at 3000 RPM. With the conventional stainless steel props, the boat has not yet been able to climb over its bow wave.
At 3500 RPM, where most engines produce their most efficient performance, the R302 equipped with the Sharrow Propeller goes 58% faster than the boat with conventional blades (32.5 mph vs 20.6 mph). This also means that the boat can stay solidly on plane at about 800 RPM less than it can with the standard props.
The Sharrow Propeller gets more miles per gallon (MPG) than the conventional props at all speeds, except at WOT when both prop designs are equal.
Cruising Speed Efficiency: For a boat such as the Robalo R302 center console, cruising speeds are generally considered to be from 20 mph to 35 mph, where the range is maximized and comfort, depending on sea state, is best. Here we see MPG improvements from 15% to 29% for the Sharrow props over the conventional units.
In the Range chart above, we see that at 25.4 MPH, the R302 can travel 109 miles (29%) farther than it can with conventional props.
The actual number of miles of increased range the Sharrow props deliver at cruising speeds is significant. Note that at 33 mph, the Sharrow props have 62 miles greater range.
At the cruising RPMs of 2500, 3000, and 3500, the R302 equipped with Sharrow Propellers will get you to your destination 33%-38% quicker at the same rpm when compared to conventional propellers. This benefit also results in a quieter ride (as much as 80% quieter) due to lower RPM and lower cavitation levels.
True Advance™ is a design feature within all Sharrow Propellers™ that contributes to the incredible efficiency and performance of the Sharrow Propeller™. It allows our propellers to achieve their maximum advance rate and efficiency much earlier on in the RPM and speed range of a boat compared to standard propellers.
The benefits of Sharrow True Advance™ include:
- Unmatched efficiency
- Greater range
- Superior fuel economy
- Increased load capacities
- Faster speeds (up to 10 MPH FASTER) at cruising RPM's
- Enhanced handling and maneuvering
- Up to 50% more reverse thrust for greater stopping power
- Lower emissions / reduced carbon footprint
- Quieter operation
- Less driver and passenger fatigue
- Longer engine life
- Can be utilized on virtually any propeller driven craft
In the charts above, we see that the R302 equipped with a set of Sharrow Propellers is.2 MPH faster on the top end and faster during acceleration to 30 MPH as well.
Galeon 325 GTO / Twin Mercury 400 HP Outboards
Sharrow Marine collected data on a Galeon 325 GTO with twin Mercury 400 hp outboards. The boat has a L.O.A of 32' 9" and a beam of 10' 11" and a deadrise of 21. Dry weight is listed as 14,200 lbs. and the estimated test weight was 15,200 lbs. The customer asked us to develop a propeller that would get the boat on plane at a lower RPM and keep it on plane at lower RPM to allow a greater range of cruising speeds.
Key collected data takeaways
- The Rev4 propellers needed 5000 RPM to maintain a planing configuration. The Sharrow Propellers were able to maintain plane at 4000 RPM, greatly extending and widening the usable on-plane speed range.
- Both sets of propellers achieved similar WOT RPM levels. 6225 RPM for the Revolution 4's and 6325 RPM for the Sharrow Marine props.
- The Advance Rate of the Sharrow props was much higher throughout midrange RPMs and contributed to being able to achieve a wider range of cruising speeds.
- The 0-30 acceleration of the Sharrow Propeller was 10.76 seconds vs 16.53 for the Rev4 propellers