i find naval combat too easy. ranged ships are far too powerful. they are like seige weapons except their ranged is 2, they have a million move points, there are no terrain problems, and they have tons more space to maneuver. you can kill cities and land units way too easily.
my suggestion is to only allow melee ships to attack land targets, with a hard limit of 1 range. or, give all ranged ships 1 range. or make shorelines like forests in that it reduces range. or dramatically weaken their damage to land targets.
The frigate is, compared to its peers, by far the best of the naval ranged units; although even then, the numbers would not appear to suggest it's an absolute death machine. When fighting fellow renaissance units at 55
strength, a frigate is in a position that's approx. +5
compared to what a crossbowman would face in the middle ages (loosely str 45 units) and while it has the same bombard strength as a bombard, naval ranged units have a hidden 50% penalty against walls of any type (the blue bar.) The real advantage is they are mobile and can quickly mass fire on a coastal target.
But battleships are actually in a weaker position - while they fight infantry just as effectively as frigates v muskets, artillery has +10 bombard strength over it, and tanks exist, giving cities +10 extra garrison power over infantry, and most importantly: urban defenses. The jump between a frigate shooting a city with ancient walls at near parity garrison strength and a battleship shooting an urban defenses city with much higher garrison strength is enormous. While humans often get battleships before these factors come into play, if you try a late game assault using say, missile cruiser fleets, they barely make a dent in an info era city's defenses.
In my estimation of longing for more relevant naval play and trying to balance the ships myself, the ultimate issue lies in the lack of dedicated counter play for land armies. Either the navy is worthless and at best a nuisance (see the Quadrireme) or it's overtuned and completely curb stomps all land units. Because the only answer to a strong navy is another strong navy, or an air force - assuming you care about sea control in the first place. Siege weapons are clearly intended to be something that can strike back at ships, but they are frail; a bombard hits a frigate just as hard as another frigate, and costs the same 20 niter, only it has a lot of mobility downsides; so why not build yourself a frigate with the niter and garrison that?
I'm not sure naval combat needs a nerf though given how situational and map dependent it can be. also I'd be curious to hear from any history buffs here whether it's realistic for naval bombardment to be so op during its time
Continuing from above, the one thing we are missing is something that represents the fact that a major deterrent to ships for a long time was coastal guns, which could be bigger, better armored, and outrange the naval vessel. (As they say, A Ship's a fool to fight a fort!) If this came in the form of some kind of city center building to boost the ranged attack of that city vs ships, it would be fine. That way, players would have a method to resist some naval assaults
if they invested a little production without having to resort to a huge naval buildup themselves. At the same time, it wouldn't be mobile, so you couldn't use it to counter a defending navy.
From a historical standpoint, at least for the battleship era, naval shore bombardment was really dependent on what they were trying to shoot at. The idea that battleships could level entire cities so soldiers could just walk in never really happened, and as seen in Okinawa, if you can't see the bunkers, you aren't going to hit them. But I can't think of any examples where
any indirect bombardment from ships, artillery, or planes knocked out entrenched defenses by themselves.
However, naval fire could suppress coastal guns from firing at landing ships, like at Normandy, and once the troops got a foothold, they could help the ships correct their fire and guide it inland for much more devastating effect. Once you stop trying to shoot at soldiers protected by giant bunkers, things go much better: against troops in the open, like those counterattacking your beachhead, your giant floating artillery battery might as well be divine intervention (with spotters to correct fire). Keep in mind that field artillery is generally a lot smaller than battleship cannons- compare a classic 155mm field gun to a 16" (410mm) naval cannon. I recall a story of a US destroyer fighting against a dozen german tanks on the shore at Salerno and reducing them to scrap. I don't think there are many examples of "battleships vs cities" except some late pacific war stuff. While they work, they are not an economical choice over ground artillery or bombers.
So, yes, naval gunfire is completely OP against exposed land units in the open, although this is exactly why massive bunker networks were made by japan and to prepare against the Normandy landings - there's no way to hold a coast against naval bombardment without it.
