2024.3.29

JMU and NYK Formulating Method for Evaluating Ship
Performance in Actual Seas
JMU and Nippon Yusen Kaisha ("NYK"; head office: Tokyo; president:Takaya Soga) are mutually formulating a method for estimating a ship’s
performance in actual seas before construction is completed andrecently completed verification of a vessel’s propulsive performance inwind and wave conditions in actual seas.*
The two companies aim to know a vessel's performance in actual seas
before the conclusion of a shipbuilding contract and aid in the reductionof GHG emissions by procuring highly fuel-efficient vessels.
Background and Issues
In conventional shipbuilding contracts, the guaranteed speed is set andagreed based on the relationship between the ship's speed andhorsepower in calm waters (i.e., ship performance in calm seas*), andthe shipyard and shipping company mutually confirm the guaranteed
speed during sea trials in the final phase of construction. However, sinceactual voyages are strongly affected by waves and winds, theguaranteed performance in calm seas deviates significantly from theperformance in actual seas.
JMU and NYK introduced a clause guaranteeing ship performance in
actual seas in a shipbuilding contract in September 2020 and have beenworking to verify performance in actual seas.
Overview of Verification
1. JMU and NYK selected two new VLCCs designed and built at JMU
as target vessels and collected data on vessel speed, main engine
horsepower, wind direction, wind speed, etc., for one year from thedelivery of the vessels in 2022.

2. In actual seas, the two companies mutually verified the degree ofachievement against the guaranteed speed/power curve** formulated in2020. The evaluation determined the difference between the guaranteedspeed/power curve and the vessel's data for each wind direction(headwind, crosswind, and tailwind) and calculated the average value.
3. JMU and NYK confirmed that the guaranteed speed/power curve forthe ship performance in actual seas was highly accurate. Bothcompanies agreed to establish an analysis and evaluation method toevaluate ship performance in actual seas technically and objectively forspecific routes.
4. One of the two new VLCCs was built using JMU technology toimprove the shape of the vessel’s hull for better performance in actualseas, and the two companies confirmed a significant difference in thisship’s performance in actual seas, as expected.

The Two Target VLCCs

Future
JMU and NYK will utilize a new method of developing new hull forms tofurther improve performance in actual seas. The two companies will also
evaluate the performance of other vessel types in actual seas.
JMU will continue to develop the vessels with an emphasis on ship
performance in actual seas and introduce new technologies to promote
the building of highly fuel-efficient vessels.

* Ship performance in calm seas and actual seas
Ship performance in calm seas: Propulsive performance when moving
straight ahead in calm weather conditions. Each shipyard has longstanding knowledge of this performance and can estimate it with a highdegree of accuracy at the time of contract conclusion. Ship performancein calm seas is greatly affected by the hull's shape below the water.
Ship performance in actual seas: Performance in weather and sea
conditions similar to those prevalent in the oceans. When drawing up
contracts, shipyards often have difficulty making precise estimates
because the navigation route and weather and sea conditions areunknown. The hull shape above the water significantly affects actual sea
performance.
** Guaranteed speed/power curve
A graphical curve representing the relationship between a vessel's
speed and horsepower.