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five vessels used for transferring pilots to ships in Dutch ports. It has three bases of operation in the port of Rotterdam, at Waalhaven, Botlek and Europoort/Maasvlakte. KRVE’s mooring vessels are spread across 13 locations in the port of Rotterdam, all ready to provide mooring, unmooring and manoeuvring operations. Its five vessels with polymer fenders have been operational for five years, logging around 5,000 running hours per year with no hull damage or significant downtime recorded. Fendercare said KVRE has seen an average operational cost reduction of €15,000 (US$17,700) per vessel per year since fitting the polymer fender systems. Trelleborg Marine Systems uses high abrasion resistant and low density material to give longer periods between replacements. It supplies four different types of tug fenders, mainly from its main base in Dubai, UAE. Last year, Trelleborg developed what it calls a “new high performance super abrasion resistant compound” for its tug cylindrical fenders, which it claims increases service life significantly. FenderTec, of the Netherlands, specialises in manufacturing all types of rubber tugboat fenders that can be of a standard or customised design. Its rubber marine fenders can be cut to length, drilled or pre-curved as required.
Tug fender types and shapes
Tug owners, builders and designers have a choice of five types of rubber fenders for protecting towboats from ships and harbour infrastructure. The main types of tug fenders are*: • Cylindrical tug fenders • D-shaped fenders • Block fenders • M-shaped fenders • W-shaped fenders Cylindrical fenders form the main fendering installed on a tugboat’s stern and bow. They have a longitudinal support chain running along their centre
and usually have straps and chains fitted into their grooves. These fenders are used for pushing against ship hulls of all types and in all sea conditions. D-shaped fenders are similar to cylindrical fenders, but with one flat surface. They are designed to reduce shear forces on tugs and ships. They can be used on the main deck sheer lines, on the forecastle deck and stern of tugs to provide protection. Block fenders can have better grip than cylindrical fenders because of their shape and grooved surfaces. They have large contact surfaces that reduce contact pressures between ships and tugs, which makes them more suitable than other types for heavy-duty applications. This means block fenders could be particularly practical for tugs that operate in heavy swell and storm conditions. M-shaped fenders are usually fitted to the bow and the aft section of tugs to protect the tug and ship from damage during operation. Their weight is low, which improves tug stability, and a large flexible surface area that reduces the forces on the vessel during pushing and pulling operations. M-shaped fenders can be fitted around tight curves and provide additional grip due to their grooved surfaces and stronger attachments to the vessel, which means they are suitable for heavy duty operations. They are usually used as pushing fenders on tugs manoeuvring bulk carriers and tankers at terminals. W-shaped fenders are designed for tug operations in more extreme weather and sea conditions. They can be installed around the curves of most hull shapes and are an effective buffer between tug hulls, docks and ships. W fenders are increasingly used for ocean-going and large harbour tugs. *Some of this information is based on a blog by Malaysia-based Max Groups Marine, which supplies cylindrical, M- and W-shaped fenders (bit.ly/FenderMax). It provides conventional rubber fenders that are durable and versatile for various tug operations.
Kotug’s RT Evolution has polymer bow fenders supplied by Fendercare and Polymarine
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Arctic tugs fendered for gas carrier operations Three winterised terminal tugs built for an Arctic terminal project have been heavily fendered to protect them and the gas carriers they were designed to escort from extreme weather and sea conditions. Spanish shipbuilder Astilleros Gondán built three escort tugs – Pax, Dux, and Audax – for Østensjø Rederi to provide escort services to LNG carriers entering and leaving Statoil’s Melkøya production terminal in Hammerfest, Norway. These tugs are expected to operate all year round in rough sea and weather conditions, but not in ice. These RAstar 4000-DF design escort tugs have bow fendering consisting of a 1,000mm diameter cylindrical fender extending well aft along with a lower course of 400mm thick W-shaped fender, which was specially designed to limit fender contact pressures to 20t/m2. According to designer, Robert Allan, sheer fendering is from a 400mm x 400mm D-shaped fender and stern fendering is a 400mm thick W-shaped fender. In comparison, Robert Allan-designed RAmparts 3200 class tug Panyi has a mixture of cylindrical, W-shaped and D-shaped fenders. It has ship-handling fendering at the bow that consists of two rows of cylindrical fenders of 800mm and 400mm in diameter. A 500mm x 450mm W-shaped block fender is arranged below the cylindrical fenders. There are also 300mm x 300mm hollow D-shaped fenders to provide protection along the forecastle deck and the main deck sheer lines, and similar D-shaped fenders at the stern. TTB
Tug Technology & Business | 3rd Quarter 2017