Tzompanakis Marine Propulsion builds and repairs propeller in Piraeus, Greece and have been meeting the propulsion needs of the marine market in Greece and Cyprus for over 30 years.

A customer building a 16.0 m (52.5 ft) boat in Athens recently approached Tzompanakis Marine Propulsion to supply propellers for their boat. A minimum top speed of 25 kts at a maximum engine RPM of 2600 to 2650 was very important to the customer and one of the reasons they chose Tzompanakis Marine Propulsion to size and build their propellers. Tzompanakis Marine Propulsion choose to use PropExpert to evaluate the propellers for this project. PropExpert is a software tool to select, size, and analyze propellers for work boats, pleasure craft and small ships. Tzompanakis used PropExpert to size the propellers as well as the gearbox for this project. These propellers were to be traditional fixed pitch propellers fitted to an inboard engine. PropExpert is an ideal tool to design fixed pitch propellers for an application like this.

Tzompanakis recommended a suitable gear ratio and provided 4 bladed propellers to the boat builder for installation on their craft. The propeller selection was slightly complicated by a high shaft angle due to employment of a V-drive transmission.

The top speed of the boat during sea trials was 26.5 kts at 2650 RPM. The customer was extremely pleased that the boat exceeded its performance requirement. Tzompanakis Marine Propulsion were pleased that the gear ratio selection resulted in full use of the engine RPM range, and the propellers they designed and built exceeded its expected performance. The accuracy of the PropExpert sizing and analysis calculations is one reason Tzompanakis Marine Propulsion propellers exceed customer expectations.

More recently, the extensive coastlines of Greece and Cyprus became home to a new 11.90 m (39 ft) Greek fishing vessel. The vessel is a 15.5 ton, single-screw ship powered by a 240 kW (320 hp) engine rated for 2000 RPM. Tzompanakis Marine Propulsion was consulted during the selection of the vessel’s propulsion equipment. The vessel’s owner requested a top speed of 16.5 kts (19 mph) and a cruise speed of 12 kts (13.8 mph). The owner also wanted to take full advantage of the available clearance for the propeller diameter. After the preliminary analysis, a suitable propeller for the vessel was selected – a 4-blade, 790mmx800mm propeller with a BAR of 0.70. Using the vessel length and displacement along with the propeller characteristics, Tzompanakis Marine Propulsion used PropExpert to size the appropriate reduction ratio for matching propeller and engine RPM’s. PropExpert’s analysis of propeller cavitation and tip-speed criteria ensured that the propeller would perform as predicted. Additionally, PropExpert’s use of the engine performance data ensured there would be enough power to spin the propeller at all vessel speeds.

The performance of the resulting reduction, a 2.30:1 ratio, was validated recently with the sea-trial of the vessel. The customer was quite satisfied with both the resulting vessel performance and the accuracy of the PropExpert analysis. The vessel was able to make the design speed of 16.5 kts (19 mph) at 1980 RPM and the cruise speed of 12 kts (13.8 mph) at 1500 RPM. PropExpert continues to be a valuable and trusted tool to Tzompanakis Marine Propulsion and their customers.

Tzompanakis Marine Propulsion is a PropExpert user since 2004.
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