DNV GL enhances bulb optimisation service

20 Aug 2015
A new tool explores the effect of alternative operational options for the bulbous bow

A new tool explores the effect of alternative operational options for the bulbous bow

DNV GL is enhancing its ECO retrofit service to support shipowners and operators tailoring retrofit projects for a more energy efficient future fleet.

The service identifies new bulbous bow shapes based on computational fluid dynamics (CFD) calculations, and a new tool explores the effect of alternative operational options. DNV GL says this new approach can help customers save 5-10% on their annual fuel bill.

DNV GL says the biggest issue in many retrofit projects is the definition of the individual operational profile. In the past two years the ECO Retrofit service has already helped to upgrade some 200 vessels, but the industry is looking to the future.

“Even though our new ECO Retrofit tool cannot change the volatility of the market, it quantifies performance for a bandwidth of scenarios from worst-case to best-case scenarios, supporting more informed business decisions,” said Carsten Hahn, senior project engineer, ECO Lines, DNV GL.

The copmany’s new ECO Retrofit service creates 5,000 to 10,000 vessel-specific bow designs and assesses them for a broad range of operational conditions using CFD. An interactive excel-based tool allows for immediate exploration of ‘what-if’ scenarios for changing operational conditions. The input is drawn from the target operational profile and is typically displayed in a matrix of four speeds and three drafts.

Optional constraints, such as reaching design speed at 85% engine power, are also considered before the best bow shape for the operational profile is chosen. The tool can then assess the performance of this bow for alternative operational profiles.

In addition, it displays estimated savings (in USD per year and amount of power in per cent) and payback time of the best bulbous bow option for all specified operational profiles. The payback time calculation takes aspects like fleet size, conversion costs and fuel price into account.

If customers want to change any elements of the analysis, the tool can recalibrate the new input to create more ‘what-if’ scenarios and to ensure that the final design is future-proof.

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