Alberto Sabella Class V Deep Space Tug

Mk II from StarDrive Magazine, Volume 1 – Issue 1 (1987), Design by J.M. Kuzee and Pete Rogan

 
NOTES:
Space tugs are, by definition, unglamorous vehicles doing an unglamorous job: hauling cumbersome or disabled spacecraft around a planetary system, into and out of orbit. However, the powerful Starfleet deep-space tugs are a special breed and the Alberto Sabella class is their proudest exponent. Unlike normal space tugs, which operate close to a starport or space station, deep-space tugs are equipped for operations far from any base, to tow starships at warp speeds back to repair yards or salvage depots. They are one of the few ways a disabled ship or captured prize of war can be recovered or towed out of the reach of the enemy.

The Sabellas were designed in the wake of two significant events in Federation history: the Four Years War, with its heavy toll in ship losses and the development of commercial supertugs like the Muletrain, built for pulling massive cargo containers from asteroid mines to industrial worlds. During the War, the Federation was forced to press great numbers of small tugs, commercial and Starfleet, into service in the front lines and many of them and their crews- ill-equipped as they were for long duration duty- suffered greatly. Military Operations and Materiel Command agreed that a new class of deep-space tugs was necessary for service in all frontline bases to provide rescue and recovery capability near potential trouble zones.

Space tugs are normally all engine and command pod, but Chandley Works drew up the Sabella with lines very much like those of other Starfleet vessels, complete with a disk-shaped primary hull and a broad secondary hull to which the warp engines are attached. This simplified the design process for the external configuration and the warp stress calculations in particular. A very simple algorithm is used to determine the stresses any size of load will place on the ship, whether in tractor or presser mode. The use of the two-hulled design also permitted the placement of roomy and comfortable crew quarters apart from the sizable deck space allocated to the tugs vital engineering functions. Though it is not equipped for long-duration missions like an Enterprise class vessel, a Sabella can be away from its source of resupply for up to a standard solar year without hardship to the crew.

The heart of the Sabella is its immense tractor/presser beam arrays, one fore and one aft, that allow it to grapple, tow, or push any vessel up to Class VIII at warp speeds. Both these systems are located on the main pylon connecting the two hulls, close to both the center of mass and the point of main warp stability. Activation of either system affects the tug’s trim and handling very little as a result, making the Sabella a particularly “forgiving” workhorse.

In addition, each Sabella carries four two-man workpods equipped with robotic arms to attach towlines and cables, life-support or power connections to a vessel as needed. These workpods have a normal endurance of eight hours outside the tug’s hull; they are not equipped for atmospheric flight.

The normal mission of a Sabella is the recovery of vessels stranded in interstellar space. The tug secures relatively intact vessels or hulks, activates its powerful tractors and hauls it away at warp speed. Because of the careful design of the ship, it can tow vessels of up to Class III size with no warp factor reduction in speed- that is, its maximum safe speed remains Warp 8 and its emergency speed Warp 9. Each weight class above Class III it tows reduces its speed by only one warp factor each, until it reaches Class VIII. Larger vessels, of course, may be towed by two Sabellas, which lose only one warp factor between them above a towed weight of Class VIII, making their upper weight limit a respectable Class XIV. Of course, such a mass could only be propelled at a maximum speed of Warp 1, but there are few vessels, even among the giant robotic freighters, that even approach such titanic mass. Starfleet considers this more than ample towing capacity.

Sabellas are not salvage vessels; they do not carry either the tools or the life support to sustain a crew for such tasks. A tow from interstellar space is a lengthy process and unless the crew aboard any towed vessel already has inherent life support, the tug cannot keep them alive. Though armed, Sabellas are not warships and if they must operate in contested space an escort is required. Depending on the amount of damage done to a ship or hulk, setting up for a tow can take as long as a day or as little as twenty minutes- the standing record. They must be protected during that time when their crews are completely occupied and the vessels are stationary in space.

The Sabella have proven time and again their worth by rescuing vessels that would otherwise have been abandoned in deep space. The entire class of vessels was justified when the Horense Milabar pulled the pirate-stricken Sunshine class liner Emperor Ankhan from its doomed course into a star, saving the lives of over 900 passengers and crew in 2273. A more invaluable auxiliary starship would be difficult to conceive.

The Sabella Mk II was manufactured at the shipyards at Sol IV and Sol VI at a peak rate of sixteen per year. A total of 235 Mk II’s were built by 2287, with 211 still active when the Mk III was proposed. 15 Mk II’s were sold to private interests, 6 have been lost in action, and 3 have been captured intact (1 by the Klingons and 2 by Orion forces.)

By 2286, the loss of 9 Mk II’s forced fleet planners to consider increasing the security associated with the primary mission of the Sabella. By late in the appropriations year it was clear that Sabellas were becoming a primary recovery vessel for damaged ships along hostile boarders as well as in the safer areas of space. The decision was made in early 2287 to re-contract Chandley-Works to produce a viable upgrade to the Mk III. By mid-February, five test beds were ready, and the Mk III was officially commissioned in mid-2288. The Mk III incorporated a more efficient shield system that could defend both the Sabella itself and any vessel it was towing. An improved tractor beam system was also installed to increase control of towed vessel and reduce overall stress on the towing vessel during operations where hostile forces were encountered. Although the Mk III was an improvement over the Mk II, it was soon replaced by the Mk IV beginning in 2294. Of the 42 Mk III’s produce, 1 was scrapped after an encounter with Oiron pirates near the Klingon border.

The Mk IV was introduced in early 2294 and was an immediate success. Along with the larger weapon system, several new specialized systems were installed on the Mk IV that would allow it to salvage vessels faster and more efficiently. A system of modified micro-warp generators were designed to allow the Sabella to quickly change the gravitational field of a stricken vessel. These generators could quickly be beamed to location on a damaged vessel and allowed the Sabella to rapidly move an un-powered vessel away from immediate danger. While the fields were not powerful enough to generate a full fledged warp field, they could allow the Sabella to tow vessels of class IV-VIII at full sub-light speed within five minutes of arriving on site should the need arise. This also allowed hulks to be moved almost immediately, rather than waiting for the lengthy warp-field calculations needed for full fledged warp travel. Coupled with the increased weapon load and a significantly improved shield, the Mk IV was quickly approved as a major upgrade to existing design. Changley-Works proposed the construction of 100 new-build hulls even as the contract was being finalized. Designers proved that new builds could be fielded three to five weeks sooner than refits to the older hulls. The original Sabellas had been designed with an overhaul of the tractor system and warp nacelles in mind, but not a rework of the internal volumes of the vessel. Star Fleet Appropriations approved the construction of 80 new hulls and the upgrade of some 150 existing hulls. Of the original 100 new builds proposed, 69 were delivered before the contract was eventually cancelled in favor of upgrading the remainder of the Sabella fleet. The Mk IV was produced at the Sol IV yards, with upgrades of the Mk III preformed at the Sol VI and Andor shipyards. A total of 274 Mk IV’s were eventually fielded. Only one Mk IV was lost due to combat, with 46 older Mk IV eventually sold to civilian concerns.

The Mk V, still in use across the Federation today, was first fielded in 2343. While most Sabellas were well past their original operating life span, Chandley-Work, now an expert in extending and retrofitting older vessels, proposed a major upgrade to the Sabellas to supplement other front line tugs. An improved version of the venerable FWB-2 was fitted to increase efficiency and reduce fuel costs. The primary shield was upgraded to the FSNE, a successful trinary shield generator system. While more powerful shield generators were available, the FNSE could extend its defensive envelope well beyond the Sabellas them selves, providing some protection to both the tug and its intended salvage. This made the Sabella a popular vessel along the major trade routes, where pirates had learned to attack in large numbers. As responding escorts and destroyed tried to chase down fleeing pirate vessels, a single hostile would often return to harass the intended freighter. Although the Sabellas had weapons, there were still not major warships. The ability to shield a stricken vessel often could buy enough time for pursuing forces to turn back and drive off the final leg of an attack. Coupled with a major increase in the Sabellas primary phase system, the Mk V continued to serve well into the 2370’s. A total of 274 hulls were upgraded to the Mk V version. However, the conflict with the Cardassians, Tallarians and other major powers took their toll. Before being officially retired in 2378, 11 Mk IV’s were destroyed in combat, 1 was listed as missing, and 9 were scrapped, mostly after engaging pirates. 45 Mk IV were placed in reserve fleets and 200 were disarmed and sold to civilian concerns with a further 6 being traded to Federation governments. Two are used as training vessels by the merchant marines. Upgrades of the Sabella were preformed at the Andor and Alpha Centauri shipyards.