Tramp Ships Research Articles

Route, speed, and bunkering optimization for LNG-fueled tramp ship with alternative bunkering ports

To reduce emissions, shipping companies are deploying eco-friendly ships, like those powered by LNG or methanol. Unlike traditional fuels, LNG bunkering is available at a limited number of ports. At the same time, tramp or bulk ships have fewer ports of call on their shipping lines, which may necessitate LNG-fueled ships sailing to alternative bunkering ports for refueling. The selection of bunkering ports impacts the operating costs of shipping lines due to differences in fuel prices and geographical locations. Moreover, it must factor in ship speed limits to meet loading and unloading schedules. To optimize the shipping route, speeds, and bunkering plan for LNG-fueled tramp ships, we develop an arc-based mixed-integer linear programming model with the objective of minimizing total operation costs. Subsequently, we propose a leg-based formulation based on the predetermined port call orders. Finally, case studies are conducted to demonstrate the effectiveness and efficiency of the models. Experimental results indicate that the bunkering mode with alternative bunkering ports effectively reduces total operating costs without altering the total voyage time, particularly with substantial differences in fuel prices between ports.

The effects of waiting times on the bunkering decision for tramp ships

This study explores the influence of uncertain waiting times together with uncertain fuel prices, in the selection of bunker fuel stops for a shipowner engaged in tramp shipping. We analyze the stochastic bunkering waiting times in the bunkering optimization problem using scenarios constructed from vessels' Automatic Information System (AIS) records and test their relevance to the bunkering decision. Our findings highlight the tradeoff between port efficiency, as characterized by waiting times, and the economic advantages of purchasing bunkers from cheaper port options and finishing the voyage in higher-priced bunker regions. Although the absence of waiting time would have produced similar results in our empirical setup, introducing waiting times altered the dynamics, making a price-attractive port like Piraeus not as attractive when risk-aversion is modeled, particularly given the risk of prolonged waiting.

МЕТОДИЧЕСКИЕ ОСНОВЫ ОПРЕДЕЛЕНИЯ ДИАПАЗОНА ФРАХТОВОЙ СТАВКИ В ТРАМПОВОМ СУДОХОДСТВЕ

Trump shipping, despite large quantitative and qualitative changes in the composition of the world fleet, the
 emergence of new forms of organization of maritime transport, continues to be one of the most important elements
 of international trade. The global freight market for tramp tonnage is a market of perfect competition for
 the following reasons: a large number of sellers and buyers of homogeneous products independently operate
 on it; each of them cannot significantly affect the level of freight rates and has fairly complete information
 about prices and costs. Due to the fact that tramp ships are not associated with a specific navigation area and
 go where there is a need, the tramp market is sensitive to changes in supply and demand, it is characterized by
 significant fluctuations in freight rates. In this regard, the research topic is relevant.
 Within the framework of the article, the authors propose a methodical approach to determining the possible
 range of freight rates in tramp shipping, taking into account the input parameters of the upcoming voyage and
 the current state of the freight market. The practical calculations carried out allowed us to conclude that today
 for ships of the size "Handymax" in the geographical section of the Black Sea-Mediterranean Sea, the gap
 between the minimum and maximum possible freight rates for ships of the same age can reach four dollars per
 1 ton of cargo

Branch-And-Price Algorithm for the Tramp Ship Routing and Scheduling Problem Considering Ship Speed and Payload

In recent years, increasing fuel prices, depressed market conditions and air pollution issues have brought huge challenges to the tramp shipping industry. This work investigates the tramp ship routing and scheduling problem considering ship speeds and payloads, aiming at minimizing ship fuel consumption. A mixed integer non-linear programming model with a discretized speed variable and a set partitioning model for this problem is established, and a branch-and-price algorithm is proposed to solve the problem. Through the column generation approach, the problem at each branch-and-bound node is decomposed into a linear programming master problem and a pricing problem of the elementary shortest path with resource constraints. A labeling algorithm is adopted for solving the pricing problem. Multiple groups of instances are generated to test the effectiveness of the proposed model and algorithm and analyze the impacts of ship speed, payload, and speed discretization on the solution. Computational experiments are conducted, which verifies the proposed scheduling routing method for tramp ships and confirms that adopting the proposed model can effectively reduce fuel consumption of tramp ships which can not only deepen the theory of tramp routing and scheduling, but also provide theoretical guidance to tramp ship company. The branch-and-price algorithm can effectively solve large-scale tramp ship routing and scheduling problems. Reasonable number of speed discretization points can bring a desirable trade-off between solution accuracy and algorithm runtime.

Coordinated approaches for port state control inspection planning

ABSTRACT Port state control (PSC) inspections serve to guard maritime safety and the marine environment. Because port inspection resources are limited, inspection efficiency can be improved if the resources are scheduled more efficiently. Currently, ports worldwide apply a greedy inspection strategy. To improve inspection efficiency, this study proposes two coordinated inspection strategies for both liner and tramp ships, i.e., a self-coordinated port strategy and a fully coordinated central agent strategy. Extensive numerical experiments indicate that on average the self-coordinated port strategy performs 2.48% better than the greedy strategy, and the fully coordinated strategy outperforms the greedy and self-coordinated port strategies by 5.02% and 2.48%, respectively. The superiority of the two coordinated strategies is robust to different ratios of liner to tramp ships visiting the ports from 0/100 to 100/0. Therefore, the feasibility and wide applicability of the proposed coordinated strategies are validated. Specifically, when liner ships outnumber tramp ships, the fully coordinated strategy is more suitable; otherwise, both the self-coordinated port strategy and the fully coordinated strategy can be used.

Justification for the use of methods for managing cargo delivery by tramp ships

Justification for the use of methods for managing cargo delivery by tramp ships

Development of a mechanism forwarding and shipping for tramp ships

Development of a mechanism forwarding and shipping for tramp ships

Sailing speed optimization for tramp ships with fuzzy time window

This paper studies the problem of the sailing speed optimization for tramp ships. The transportation time requirements which are associated with shippers’ satisfaction are considered by a fuzzy membership function. A bi-objective model is proposed in which the minimum operation cost and the maximum shippers’ satisfaction are optimized simultaneously. The optimal speed on each leg of a given ship route is determined. A fast elitist non-dominated sorting genetic algorithm (NSGAII) is improved to solve the problem. To test the performance of the proposed model and algorithm, a numerical experiment is designed. The results show that the proposed algorithm has good convergence property and convergence speed.

Tramp ship routing and scheduling with voyage separation requirements

In this paper we explore tramp ship routing and scheduling. Tramp ships operate much like taxies following the available demand. Tramp operators can determine some of their demand in advance by entering into long-term contracts and then try to maximise profits from optional voyages found in the spot market. Routing and scheduling a tramp fleet to best utilise fleet capacity according to current demand is therefore an ongoing and complicated problem. Here we add further complexity to the routing and scheduling problem by incorporating voyage separation requirements that enforce a minimum time spread between some voyages. The incorporation of these separation requirements helps balance the conflicting objectives of maximising profit for the tramp operator and minimising inventory costs for the charterer, since these costs increase if similar voyages are not performed with some separation in time. We have developed a new and exact branch-and-price procedure for this problem. We use a dynamic programming algorithm to generate columns and describe a time window branching scheme used to enforce the voyage separation requirements which we relax in the master problem. Computational results show that our algorithm in general finds optimal solutions very quickly and performs much faster compared to an earlier a priori path generation method. Finally, we compare our method to an earlier adaptive large neighbourhood search heuristic and find that on similar-sized instances our approach generally uses less time to find the optimal solution than the adaptive large neighbourhood search method uses to find a heuristic solution.

Industrial ship routing problem with split delivery and two types of vessels

This paper introduces an industrial ship routing problem (ISRP) of a steel manufacturing company. Given a set of cargoes with pickup, delivery ports, and time windows, the problem determines how to route a fleet of heterogeneous ships to carry the cargoes. The cargoes can be split to be served by multiple ships if their time window is not violated. In addition, a ship can handle multiple cargoes within a route. The fleet of heterogeneous ships consists of two types of ships: company-owned ships and tramp ships. Each of both types consists of heterogeneous ships with different capacities. A company-owned ship can deliver cargoes from multiple supply ports to multiple delivery ports within a route, whereas a tramp ship can deliver a cargo directly from a supply port to a delivery port within a route. To reduce operation cost, the two types of the ships should be well coordinated and utilized. A mixed integer programming model for the problem is presented, and an adaptive large neighborhood search-based heuristic is proposed. Thirty benchmark problems are generated and categorized into three groups according to the number of vessels and cargoes. Computational experiments demonstrate the effectiveness of the proposed algorithm.

Tramp Ships. An Illustrated History

Tramp Ships. An Illustrated History

Tramp ship routing and scheduling with integrated bunker optimization

A tramp ship operator often has contracted cargoes that must be carried and seeks to maximize profit by carrying optional cargoes. Hence, tramp ships operate much like taxies following available cargo and not according to fixed route networks and itineraries as liner ships. Marine fuel is referred to as bunker and bunker costs constitute a significant part of daily operating costs. There can be great variations in bunker prices across bunker ports so it is important to carefully plan bunkering for each ship. As ships operate 24 h a day, they must refuel during operations. Therefore, route and schedule decisions affect the options for bunkering. Current practice is, however, to separate the two planning problems by first constructing fleet schedules and then plan bunkering for these fixed schedules. In this paper we explore the effects of integrating bunker planning in the routing and scheduling phase for a tramp operator sailing full shiploads, i.e. carrying at most one cargo onboard each ship at a time. We present a mixed integer programming formulation for the integrated problem of optimally routing, scheduling and bunkering a tramp fleet carrying full shiploads. Aside from bunker integration, this model also extends standard formulations by using load dependent costs, speed and bunker consumption. We devise a solution method based on column generation with a dynamic programming algorithm to generate columns. The method is heuristic mainly due to discretization of the continuous bunker purchase variables. We show that the integrated planning approach can increase profits and that the decision of which cargoes to carry and on which ships is affected by the bunker integration and by changes in the bunker prices.

The Inter-Relations of Shipping Freights

THE purpose of this paper is to examine the connection between the different rates quoted for the use of tramp ships. In the past the literature of shipping has been content to dismiss this subject by saying that all such rates move together in the same direction except inward and outward rates, which move inversely. Our generation, however, requires more precise information. Until I935 the tramp shipping market was one of the most competitive in the world, and the analysis of its behaviour was of academic rather than practical importance. But when in I935 a price-fixing committee was established it became important to know the precise relations between different rates, and to examine the effects of fixing some rates while leaving others free. In the first' half of this paper we shall analyse the pre-I935 relations, using some'of the index numbers which have been published since the end of the last war. The second half of the paper will examiine the effects -of freight control.

Ocean Trade Routes

HE statement that half of the shipping of the world is engaged regularly in the North Atlantic is received by most people with frank incredulity; yet in truth it is not far from the facts, as is shown by recent studies of the U. S. Department of Commerce. A map showing tracks for full-powered steam vessels is often interpreted as indicating the relative importance of the ocean trade routes of the world, and such maps are nearly always given in commercial geographies and books on shipping. The density of traffic over the main ocean tracks is something usually guessed at. A ship plying regularly between scheduled foreign ports is called a by the general public and by Kipling felicitously a lady. In equally picturesque phraseology the drab general-cargo vessel has come to be known as a tramp. The ocean-borne trade of the world is carried in these two kinds of vessels. Liners ply between terminals almost as regularly as railroad trains. Tramps,. in contrast, have no fixed routes or regular sailing schedules. They go from port to port wherever cargo offers. The demand for ship tonnage varies because of the seasonal nature of crops and the needs of commerce. Steamships in liner trades are operated by their corporate owners; tramp ships are operated by their owners or, most frequently, are offered for hire to anyone who desires to move a shipload of cargo at one time. The distinction between the tramp ship and the liner is chiefly in regularity of employment. Structurally each type merges into the other with respect both to speed and size. The liner furnishes service in times both of prosperity and depression. The tramp ship serves two general public purposes. It acts as a regulator of ocean freight rates at times and places where the demand for transportation exceeds the facilities offered by liners. It is the drudge of the seas, carrying the dirty and cumbersome cargoes which have great weight or bulk in proportion to value. The total weight of the ocean-borne cargoes carried in the world's foreign and colonial trades has never been exactly stated, because so many articles and standards enter into the computation and because the methods and periods, on which the returns of governments are based, vary. A committee of the British Board of Trade in I916-1917, after careful computations, estimated that the total volume of the world's sea-borne commerce in 1912 probably amounted to between