why small ships

Here are some justifications:

1) Large hull requires large shipyard. I do not believe shipyard slippage
construction costs increase linearly, more likely as a power. Hence large
shipywards cost WAY much money, only exist in certain places, etc. and this
tends to limit large constructions. Plus, someone observed the labour issues
about keeping shipyard workers employed, for which smaller vessels are better.
Also from a political perspective, spreading the military budget around is
better too. More political capitol to be made if everyone's riding gets a
small shipyard.

2) Large ship maintenance costs may not scale linearly either. Though I'm not
positive.

3) If I have X large ships, or X*5 small ships, and I have Y worlds to patrol,
if X is far smaller than Y, then there are a lot of places I can't be and even
crappy little enemy ships can do much damage with raids, bombardments, and
troop drops. If I have 5*X small ships, I can probably thwart this type of
attack by distributing them around. They show the flag. They take on commerce
raiders ( the real menace to any interstellar economy), they provide eyes and
ears for intelligence agencies in many locations.

4) In a system scale battle, they enhance your
sensor net dramatically by bringing sensors on-
line in wide areas.

5) They are more expendable. Lose one and it isn't the end of the world. Far
better for recce. Lose a CH or CL doing this and there will be heads rolling
at Fleet HQ.

6) They should be more stealthy in a larger scale hide and seek game.

7) They can do swarm tactics.

8) To make them effective, try replacing some of the beam armament with longer
ranged
weapons such as: MTM, SMR-ER, Beam-3, Pulse
Torpedo. I find the P-torp DD (used in
squadrons) can make a nasty suprise - take a
run in, fire about 20 mu out, turn away. You won't take that many casualties
without the enemy focusing a lot of firepower on you, and you will do him some
damage if you roll even okay. And you can keep attacking (superior to
SMR-ER in terms of longevity of threat on the
battlefield - though SMRs give good one off
punch).

9) A Navy is not just called to fight wars. It must transport diplomats, it
must show the flag to resolve local disputes, it must do customs patrols, it
must do search and rescue, it must perform mercy missions. Use big ships to do
this and you incur an awful expense. Use a small vessel suited to the task
(tailoring smaller
vessels is also undoubtedly simpler - larger
ships tend to be generalist in nature).

10) I agree with the advice about trailing or flanking. I don't agree with the
"firebait" advice. If your escorts preceed your force, they usually are 1 RB
closer, unscreened, and can be induced to threshold with very minimal
difficulty. So very light amounts of fire render them combat inoperative. The
same fire would, if directed at larger vessels, need to be far more
concentrated (range, sheilds, long damage rows) to do anything useful. I can
kill a large number of beam 1 armed corvettes before they ever see engagement
range.... and thus I
destroy say 10-15% of your total NPV before
they can be combat effective (if I myself have opted for an all large ship
fleet). So try to get long range weapons for your small guys, park them behind
the fleet (unless using them as scouts, and once they locate the enemy, they
should be beating thrusters to get away to safety having done their job) or
off to one side, thus presenting a threat "for later use". I don't like small
ships as PDS escorts, they tend to attract fighters, SMs, MTs, and lots of
beams thus stripping the formation of PDS. I happen to be a strong proponent
of the light to medium cruiser (or larger) PDS barge (if in the kind of
environment that merits heavy PDS).

Sorry for the long commentary. But there are a number of reasons to have small
ships, but they tend mostly to revolve around detection, dispersed force
capability, and campaign considerations that don't appear in one off battles.
If they are at a one off, they'd better have some long range teeth and stay
out of the enemy gunsites for the early stages.