ROBOTECH Technical Files
by Pieter Thomassen


Seron Thoun class Border Fleet battlecruiser

Robotech Masters RDF Seal
Seron Thoun
Naval Separator

Name and disposition:

Ship's complement:


Propulsion systems:

Endurance and mobility limits:

Weapon systems:

Air group and mecha complement (typical for Border Fleet, 1995):

Tirolian forces:
Zentraedi forces:


Design notes:

The Seron Thoun class is designed to be the backbone of the Border Fleets of the Tirolian Mercantile Empire. While the large Sian Dereta class carried heavier armament and was in general more capable, it also was an expensive design to produce, and another vessel, cheaper to produce in large numbers, was required to man the borders. The result was the Seron Thoun.

On first sight, the Seron Thoun resembles a cross between half a Sian Dereta and a Nupetiet Vergnitzs flagship. However, the design has no such lineage, and is in fact completely original. The resemblance with the Sian Dereta is caused by the use of a nearly identical Reflex cannon, which accounts for nearly half the length of the ship. The slightly bulging aft section is dominated by a main thruster of the same segmented multi-reaction plate design also used in the Nupetiet Vergnitzs (and, for that matter, in many Invid mecha). Two outrigger bodies and a command citadel reinforce the likeness of the Sian Dereta. As with the larger ship, these are sensor mounts and micronian command centers respectively, and the outrigger sensors (with rudimentary hyperspace scanner arrays and EM sensors) protect the center body from flanking attacks. Two large disc shaped low frequency radar transmitters are mounted on the hangar abaft the ventral cannon boom. Three more large antenna's are mounted in front of the cannon boom.

The Seron Thoun is topped by a micronian command citadel, for like the Sian Dereta the Seron Thoun has a mixed crew. Underneath the command center are the barracks for the micronian crew. The Zentraedi forces are located in the dorsal and ventral bulges of the main cannon boom, and in one large hold in the center hull. The Zentraedi mecha and the lesser craft are placed in a hangar bay in the aft ventral of the cannon boom; the Bioroid forces launch from a hold in the center of the hull, under the Tirolian crew quarters. The engineering spaces were located forward of the engine and aft of the main hangar, flanked by the outriggers.

All Border Fleet ships carried a heavy cannon armament at the cost of torpedo tubes and troop capacity. Apart from the Reflex cannon, the Seron Thouns carried five large anti-ship particle cannons, more than the Thuverl Salan heavy cruiser. They were mounted in a chin mount on the ventral of the cannon boom, in one dorsal cannon boom mount and in an elevating mount in front of the command citadel, and two in, uniquely, the connecting structures with the outrigger bodies. Unlike the Sian Dereta, all these weapons could be brought to bear on the forward arc, where Tirolian tactics placed the heaviest emphasis. Consequently, the Seron Thoun had about the equivalent anti-ship firepower of the larger Sian Dereta class. The ships also carried a complement of particle beam turrets rather large for a ship of their size, and the standard anti-mecha and anti-missile missile turrets. As stated, the torpedo armament was minimal, though this did not really matter with the large cannon armament. The Bioroid and Zentraedi troop contingents were pared to the bone, although the Border Fleets did receive qualitatively superior personnel and mecha.


Fifty years after the first Sian Dereta was commissioned, the first dedicated Border Fleet battlecruisers entered service. The Seron Thoun class ships were designed to complement the Sian Dereta class, one of which was to form the nucleus of a Border Fleet battlegroup, typically comprising five Seron Thoun vessels. As with the Sian Dereta, the Seron Thoun was a qualitatively excellent vessel with heavy firepower and very powerful and sensitive sensor arrays. The lack of a large quantity of troops and torpedo armament made the ships as designed unsuitable for the police and conquest taskings of the regular Zentraedi, but this was not their designed function. Many hundreds of these ships were assigned to Tirolian Special Forces groups rather than to the Border Fleets.

From 1730 through 1969 almost 400,000 Seron Thoun vessels were produced by the Tirolian Mercantile Empire, and production ceased mostly because the Border Fleets were at their authorized strengths (for the shrinking empire), not so much because of any obsolescence of the design. This does not mean that the Seron Thoun was not getting 'long in the teeth', as the saying goes, and a design effort for a succesor was already under way. This new vessel would have been the complement battle group member to the new Sian Macross class, but construction of the Seron Ameg, as the project was named, never reached the prototype stage. The Seron Ameg was in effect a smaller edition of the Sian Macross, and the first non-Tirolian Home Fleet vessel to be equipped with the new Reflex cannon technology, which no longer required a boom design. As with all Tirolian ships, save the core fleet of the Robotech Masters, the Seron Thouns lost power to protoculture depletion in the first decades of this century, stranding the ships in the border regions or making them easy targets for hostile forces such as the Invid and other inamical alien forces.

Like its larger siblings, the Seron Thoun is a design well suited for conversion into a micronian manned capital ship. In place of the Zentraedi and Bioroid troops, a full division of Terran troops can be carried, in addition to expanded naval mecha numbers. Five Seron Thoun lookalikes were contructed by the United Earth Government as the Valivarre class, so that, combined with the SDF-3, the Pioneer fleet would look like a returning Border Fleet battlegroup. The Tirolian Republican Navy has procured several ships based on the Valivarre design (Nairok class). However, there must be thousands of stranded, undamaged Seron Thoun vessels spread in the old fringe regions of the empire, and reconstituting and converting such a vessel should be an economically more viable prospect for the poorer races. No suitable Seron Thoun has been found, so far, and no race has announced any plans for active salvage operations.

See additional design notes.

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