A decision support system (DSS) is being proposed to support cargo planners in how to allocate general cargo transportation orders into platform supply vessels (PSVs). Besides mandatory cargoes which must be embarked, pending transportation orders should be prioritized and many operational constraints must be observed. The available tools found in commercial enterprise resource planning (ERP) allow for creating and editing cargo manifests without any support mechanism. The decision process it is totally dependent upon the planner, who is responsible for cargo selection, for checking consistencies and for solving conflicts without knowing, in advance, the position of each cargo in the deck. The proposed DSS interacts with commercial ERPs and provides an environment for manual cargo allocation through a drag-and-drop mechanism, and a heuristic allocation procedure focused in maximizing deck occupation respecting a broad range of operational constraints.

1. Introduction

An effective response to the demand of drilling rigs and production platforms for supply items is a key issue in offshore logistics. Besides being a strategic segment, the assets present in the exploratory and production phases have extremely high capital and operational costs, reaching as high as $ 650,000 /day (Energy Global, 2013; Offshore Magazine, 2013), and cannot have its operations jeopardized due to supply shortages.

While urban distribution systems often operate under traffic congestion, waterborne distribution operations may be adversely affected by environmental conditions hindering vessels to execute timely schedules. It is not uncommon reports of vessels that were kept from delivering supplies due to critical weather conditions in Campos Basin, Brazil. Irregular demand patterns may cause the distribution problem to become even more complex inasmuch as incoming transportation orders, that should be promptly managed, compete with backlogged ones. Considering that orders must attend a time window frame, late orders may gain an emergency status as their due dates are approached.

Given that the ports serving the offshore system considered in our study are working under high occupation rates and that late deliveries from suppliers often occur, the distribution system demands continuous monitoring and effective support tools in order to get the most out of limited resources.

Differently from the container market where general cargo are unitized into a few types of standardized ISO containers and conveyed in full cellular containerships, in the offshore segment no such standardization exists. Consider, for instance, the following companies that were found by browsing the internet in search of " offshore container": Acorn (2013); BSL (2013); Ferguson (2013). One will realize that each company provides more than a dozen types of containers and baskets for transporting goods. Rather than criticize or defend the use of a restricted set of standardized container types in offshore operations, our intention is to stress that this aspect poses an additional difficulty when planning cargo allocation.

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