Most boats in this game are really weak and are readily slaughtered, even compared to their BR range. I have been playing coastal for a long time now, primarily focused on Arcade.
I have finished Japanese and French lines, and are at rank IV for Italy and Germany (I researched the boats but I am waiting for SL discount), rank III for the rest of them. I will be talking about coastal spawn boats, not ones like SKR-7 because they are more comparable with destroyers than coastal spawns.
I would classify three things that make a boat.
- Fast and powerful torpedo (Pr 206, PT-810),
- Powerful armament (Pr 206, Pr 204),
- Bluewater DM (Folaga, M802)
What is Bluewater DM and Coastal DM? Blue water DM is when crews are not counted as a part of the hull, but as a part of components.
This is Yamato HE shell against coastal and bluewater DM.
As soon as one steps into 1.3, it is over as you can face Aconit with 102mm, 2x 57mm, 40mm, 2x 20mm, and a bluewater DM to boot.
Other than Soviet armored boats and those with bluewater DM, or those with specficially powerful armament (pr 206) you can expect to die a lot getting only 57 points.
The Thunderbolt premium boat is one such example of unplayable boats. It is perfectly fit against boats of similar weaponry (quality and quantity) but it will face boats that are much more powerful than it, even those with same or lower BR.
The time it takes to destroy one turret of Arras (which takes like 3% of its crew) is equal to the amount of time it takes to destroy one hull component of a coastal boat with such DM.
Even 40mm does too low damage to consistently keep all the turrets disabled for these powerful boats, especially at 3km+ range.