Background:

Within GRIP, ESD (Energy Saving Device(s)) are installed on existing vessels. Installation of an ESD can influence the neighbouring hull outfitting elements.

Objectives:

The influence of ESD installation on the hull outfitting elements have been investigated.

Methods:

The classification rules have been studied to identify all parameters and subjects that could be influenced by installation of an ESD.

A selection of subjects is further investigated to provide an estimation of the magnitude of the impact.

Five example ESD’s have been investigated. The influence on the neighbouring hull outfitting elements has been determined by comparison of results of hydrodynamic calculations without and with an ESD.

For two cases, the effect on propeller cavitation behaviour has been investigated.

Results:

The possible effects of an ESD on the requirements according class rules (overview table).

For selected subjects, the magnitude of influence is defined in relation to the change of a directly influenced parameter.

For the example cases, the influence on the neighbouring hull outfitting elements and on propeller cavitation behaviour has been reported.

Conclusions:

Installation of an ESD affects indeed the neighbouring hull outfitting elements and their compliance with class rules in certain cases. The possible effects of an ESD on the compliance to class rules requirements are summarized in Table 1. Most significant impact can be expected for up-stream installed ESD and ESD directly mounted on the propeller. The addition of an ESD to a propeller has a linear influence on torsional frequency and stress as well as whirling frequency, bearing load and mis-alignment. Adding 10% MOI (of total propeller MOI) results in 3% decrease of torsional frequency, 10% increase of torsional stress, decrease of 2.5% of natural critical whirling speed. Addition of 10% mass results in a decrease of 1.7% of critical whirling speed. The influence of an ESD on alignment are shown in Table 3.

Search results

Influence of ESD on neighbouring hull outfitting

Early assessment of ESD benefit