During the 2030s a new type of shuttle craft vehicle was created to deal with stray asteroids near the newly constructed LaGrange point colonies.  A type of shuttle that could intercept and destroy or deflect asteroids that presented a threat to the colony space stations.  These ships were the Type-35 Defense Shuttles.  From this initial type of armed shuttle came a whole family of defense, assault, and attack shuttles that eventually became known as "space boats" by the spacemen that manned these craft. 
After the Great War broke out in 2049 AD, the United States of North America created the Kentucky class Mark-I assault shuttle, that eventually evolved into the Mark-IA during the Earth Federal Republics upgrade program in preparation for what would become the 1st Interplanetary War.  During that war the Mark-IA quickly proved inadequate and the Mark-II (dubbed the Protector class) was designed and put into production in 2072.  The Mark-II gave way to the FTL-capable Mark-III that was fitted with a type-1 intersection drive unit.  The Mark-III served after the war as an anti-piracy patrol ship within the Inner Sphere of Sol.  It served during the Ceres Conflict as a picket ship within the fleets of the EFR, Venus Consortium, and Mars Federal Republic.  The outbreak of the Outer Sphere War in 2085 showed the inadequacy of the Mark-III in terms of FTL-speed, and fusion reactor output.  Thus, the Kentucky Mark-IV, Avenger, was introduced.  The Mark-IV stretched the space boat concept to its limits and proved that the evolutionary life-cycle of such a craft had reached its zenith as the demands of space warfare had surpassed the ability to pack enough weapons, armor, and energy defense systems into such a small space-frame.  
The Mark-V Vengeance was the last ship of the Kentucky family of space boats.  It pushed the spaceframe beyond what the USSN engineers had envisioned for the Kentucky class and stretched the ship's capabilities far beyond what they intended.  The only section of the ship that was still original was the bridge, and that modular component was so heavily modified that it became something of an art to keep the computer systems stable enough for combat.  A more advanced design (the Type-2100) replaced the Vengeance, however it was only loosely based on the Kentucky class, and was essentially an entirely new design using elements of the Kentucky, Type-59/81, Juno, and Saturn class USSN/LaGrange ships.

NOTE: The AS-03 and AS-01 are shown as a size comparison for the space boats.  The UNSC designed assault shuttles were used by most of the non-EFR/Planetary Alliance stellar nations during the mid- to late-21st century.

These craft are from the Nexus Arcana series of science fiction novels.

The first Trilogy is found here:

Shemyaza Awakens

Ruins of the Ancients

Children of Methuselah