Tailored for the Tropics

by | 13th February 2019 | News

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The Naval Architect: February 2019Tropics

Much like there only ever seems to be bad news in the papers, it can seem like the only vessels that get coverage in the maritime media are either the leviathans, those that are particularly green, or so-called ‘autonomous’ ships. While the interest and importance of such vessels is clear, their domination of the column inches means that vessels without such features – which may in fact be very interesting for other reasons – receive little fanfare.


Where these seemingly ordinary vessels stand out tends to be how well their design responds to their intended operational profile. Rather than multipurpose, such vessels are designed and built to serve a specific route carrying particular cargoes (or people), doing so in the most efficient manner whilst meeting local and national regulations.


Ultimately, these workhorses are the most valuable vessels in their owner’s / charterer’s fleet because they perform their intended role reliably and economically, often enabling the fulfilment of long-term contracts. They are therefore less affected by commercial trends, helping to secure the bottom line when other vessels are out of action due to a lack of demand or overcapacity.


A significant ship
For these reasons, RINA’s Significant Ships series attempts to highlight some of these vessels alongside the big names readers will likely already be familiar with. One such example from the 2018 edition, publishing this month, is Tropic Hope, a 159m, 1,148teu feeder container ship designed by the Shanghai Merchant Ship Design & Research Institute of CSSC (SDARI), built at Guangzhou Wenchong Shipyard in China, and owned/operated by Florida-headquartered Tropical Shipping. It is the first of four in the company’s new Carib class, giving a clue as to its intended deployment connecting Halifax, Palm Beach, Fla., Puerto Rico, the Eastern Caribbean and the Virgin Islands.


Although relatively small by modern standards, Tropic Hope is larger than Tropical Shipping’s oldest vessels dating from the late 70s and early 80s, which fall between 79 and 90m; moreover, despite being similar in length to 2001’s Tropic Carib and Tropic Unity, the vessel has over 100 extra teu capacity. The size perfectly suits the requirements of a regional container line operation, allowing access to smaller but crucial ports.


Specifically, Tropic Hope (like other Tropical Shipping vessels) is a ‘reefer carrier,’ meaning that it can accommodate refrigerated containers for cargoes requiring temperature control – especially pertinent in the hot climate of the Caribbean. To enable this, the vessel is fitted with a total of 260 ‘reefer plugs,’ which provide power to the containers’ cooling systems both at sea and in harbour. The plugs are sited on deck and in the holds, allowing reefer stowing in up to two tiers on deck and four tiers underneath.


Adapted to the Americas
The design of the vessel also responds to the non-standard container sizes used in the Americas, which include 45’ and 49’ units. The former can be carried on the lift-away pontoon hatch covers from the third tier, whilst both can be carried on deck. Another anomaly in the Americas is the use of 40’ (and more rarely 45’) ‘high-cube’ containers that are 9’6” tall as opposed to the usual 8’6”, which can be accommodated in the cargo hold. Moreover, Tropic Hope is fitted on the port side with two MacGregor 45-tonne cranes of the electro-hydraulic cylinder luffing type, to enable container transfer at some of the less well-equipped ports of call on the vessel’s route.


When it comes to power and propulsion, Tropic Hope runs on HGO or MGO burned by a single-acting two- stroke low-speed MAN B&W 6S60ME-C8.5 engine. This delivers a high service speed of 20knots which, according to designers SDARI, ‘is quite unique against the background of the growing requirements of the energy efficiency design index.’ A further notable feature is that the shaft generator, with a power take in arrangement, also acts as an emergency take home system.


The vessel also has both a bow and stern thruster manufactured by Brunvoli, providing the high level of manoeuvrability needed in more diminutive ports such as Saint Kitts and Saint Thomas in the US Virgin Islands. A controllable pitch propeller and Becker twisted trailing edge rudder further enhance this quality.


Critically important too is the meeting of Tier III NOx levels, given that Tropic Hope operates within both US Emission Control Areas: the North American and the US Caribbean Sea ECAs. In order to remain compliant, the vessel has a high-pressure selective catalytic reduction (SCR) system installed, bringing emissions within acceptable levels. Operating in waters under the jurisdiction of the US Coast Guard also mandates the installation of a USCG-approved ballast water treatment system, represented by a Headway OceanGuard system.


Hot or cold
A look at the vessel’s classification, provided by Bureau Veritas, further illuminates aspects of Tropic Hope’s design. For instance, in contrast with the features described above that lend themselves to operation in the Caribbean, Tropic Hope has been awarded ‘Ice Class IC’ notation. Although at the lower end of the ice class scale (the vessel does not have icebreaking capacity) the notation nonetheless responds to conditions at the northernmost port on the vessel’s route: Halifax in Nova Scotia, Canada. One significant feature that contributes to the achievement of this notation is the vessel’s double-skin hull, providing extra strength in ice-infested waters.


In sum, Tropic Hope is a well-designed vessel with regard to its operational profile. Whilst it may lack the glamour of a ‘smart ship’ replete with complex systems and technology, the pragmatic vessel is nonetheless innovative in meeting its owner’s needs, and clearly reflects the skill of ‘everyday’ naval architecture.

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