October 18 2012

October 18 2012

TOPIC: “Challenges in Vessel Speed Optimization”
Report by Dr. Christos A. Kontovas

On October 18th, 2012 the second technical meeting for the 2012-2013 season took
place in the auditorium of Maran Tankers Management, Inc, in Athens. Mr. Jussi Pyörre,
Vice President of Technology and Co-founder at ENIRAM Ltd., Finland, presented the
titled topic to more then 60 SNAME members and guests.

Mr. Pyörre presented a way to estimate the optimal speed profile through an
optimization algorithm which takes as an input the operating conditions and the fuel
consumption model under some constraints.
The constraints are related to the arrival time based on the contract agreement,
weather conditions, engine capabilities etc. Operation conditions take into account
wind currents, the depth of the water etc. The fuel consumption model estimates fuel
consumption based on various inputs including speed, weather, displacement, currents,
trim etc. This model depends on sub-models such as the Hull model that estimates the
necessary power as a function of speed, the Engine Model that estimates the Specific
Fuel Consumption (SFOC) based on the engine load factor and the Propeller Model that
estimates the propeller efficiency as a function of the Advance Coefficient.

Mr Pyörre further analysed the nature of models based on the white and black box
approaches. Mathematical modeling problems are used often classified into black box or
white box models, according to how much a priori information is available of the system.
According to the presentation, White box is an understandable and rigid model based
on predetermined equations that uses prior information but is not adjusting to changing
conditions. On the other extreme side, black box is a hard to understand model, loosely
predetermined that uses no prior information but is very flexible.
Somewhere in the middle, lies the grey box model, which is easy to understand, partly
predetermined and uses prior information. As a result models that fall into this category
are very flexible and easily adjusted to changes. Two examples of these different
approaches were presented; one regarding ship squatting and another on estimating
wind resistance.
ENIRAM uses a 'Grey Box' approach to their Fuel Consumption Model based on a huge
database of continuously collected operational data and regression analysis thereof to
model the hydrodynamic, aerodynamic, propulsion and engine.

Then, the optimisation algorithm was presented. The algorithm is based on OpenMDAO
(www.openmdao.org), an open-source Multidisciplinary Design Analysis and
Optimization (MDAO) framework written in Python. Mr Pyorre noted that the quality of
inputs is very critical and mentioned the speed through water as a major input.

Concluding his presentation, the author addressed the issue of human factor and
presented the format of various delivered reports (e.g. rate-of-usage, dynamic sea
margin, hull fouling analysis) as well as the outputs of the ENIRAM Fleet Performance

The presentation of this lecture can be found here.
For more information on ENIRAM’s Optimum Speed Assistant please visit the company
website at http://www.eniram.fi

After this presentation of significant current interest, a reception was held at an adjacent
hall at Maran Tankers, Inc.

 Mr. Pyorre, the author from Finland, is receiving from Prof. Papanikolaou, the Section's Chairman, the remembrance gift,
a SNAME bronze silver paperweight .

 from left to right:
C. Kontovas, Papers Com. Chairman; N. Pinkney of ENIRAM;A. Papanikolaou, Chairman; J. Pyorre, Author; P. Lalangas, Secretary / Treasurer.

The presentation can be found below
18.10.2012 Eniram , Mr. Pyorre's Presentation.pdf