You would lose sea battle in one or two rounds.

To open the battle of the formations should be like this
84 flame / 35 steam boats
36 rams
25 submarines / 15 rocket ships
30 pedal bags
6 balloon carriers
42 mortars
Take these units in every round as soon as they enter the battle, but for each next round you are sending a new formation, but you have to be careful to arrive on time. You are rotating the mortars especially because they have ammunition for 5 rounds. You can send an item in combination with rocket ships, especially if the opponent has only steam in the first line.

Regardless of whether your opponent has heffs or not, it is crucially important to insert fresh ships in each round and pull rotations on time. If you do not pull the rotation and insert a new one, you have not done anything, because ships already in combat are bothering new ships and new ones do not enter the battle until the old ones are withdrawn or submerged.

You will not win.

Then I things, that you would win, if only he don't get backup, because fireships have stronger attack and better armors than rams. But more likely you or enemy would run out of moral and ships would spread out of battle before all ships would be destroyed.

There's an answer to any question, don't just go with maybe, perhaps and "do this".

You're saying it would take you 75 ships to fill out the frontline. This is false. I am assuming you are looking at the 8+ sea battleplan in the ingame help tab. The numbers here are incorrect and based on a single unit. The amount varies based on every ship. As far as I remember the number is 7 ships per slot, 5 slots. This means that the maximum amount of flames you could have in at any one time is 35.
Now I don't remember how many rams you can have in one slot but my best guess would be 5. This number is the same for the front as it is for the flank.
So the amount of ships your opponent will have is: 5*5+2*5 = 35 rams. This means that even if you oneshot his entire line you will still need at least 3 rounds to kill all of his ships.

Now who would win.

(I will assume you have 35 flames/a full line)
(I will also assume no upgrades and no forge)

The flank and the ranged line will attack before the front.

Balista ship:
HP: 154
DMG: 28
True DMG vs flames: 20

Ram ship:
HP: 154
DMG: 75
True DMG vs flames: 67

As I said, the flank and ranged line hits first. Reducing the damage you will deal. Let's calculate that first.

Balista dmg:
True DMG * amount of ships
20*10 = 200 true DMG

Flanks:
67*10 = 670 true DMG

DMG to front before allied dmg calculation: 200+670 = 870 dmg


Frontline:
67*25 = 1675 true DMG

Total dmg: 2545


Your dmg:

Flame ship:
HP: 219
DMG: 82
True DMG vs rams: 73

First let's calculate how many (if any) flames you loose before first hit.

Let's start with the balistas. Each balista will hit one ship, equally split amongst your front. So, 200/5 = 40 dmg to one ship in each stack. HP left = 219-40 = 179
Now the flanks. Their damage also will be split evenly. 670/5 = 134 dmg. HP left = 179-134 = 45 HP.

So you won't loose any ships before your damage is calculated. Thus we can calculate your damage.

(Number of flames * true dmg).
35*73 = 2555.

You have 7 ships in each stack doing damage to ships split in 5 stacks. This means the two center stacks gets hit twice by each stack, and the reminder gets hit once.

First the center rams (of his). 73*2*5 = 730 dmg

A ram has 154 HP. 730/154 = 4.74. He will loose 4 ships and take severe damage to the last one in slot 1 and 2.

The remaining 3 stacks: 73*5 = 365 dmg. 365/154 = 2.37. He will loose 2 and take moderate damage to the remaining stack.

This leaves him with a total loss of: 4*2+2*3 = 14 ships.


Now the damage you will be taking. All of his damage is coming from stacks of 5, so it will be evenly split. This means every stack of yours is taking 5 hits. Remember you've already taken damage.

5*67 = 335 dmg to each stack.

(335+174)/219 = 2.32. You will loose 2 ships of each stack, taking moderate damage to the remaining ships.

Total loss: 2*5 = 10 ships.



Based on this we can calculate how many rounds it would take you to wipe his fleet using only flames.
Assuming your line is always full we know your damage will be consistent.

He has 82 rams. It takes him 35 to fill his line completely. Until he goes beyond this point his damage (and thus also yours) will stay consistent.

82-35 = 47. 47/14 = 3.35. This means that for 3 rounds you will see no change in the damage dealt. On the fourth he will have 14*4 = 56-47 = 9 ships too little to fill out his line. This means he will only have 1 ship in the flank. Reducing your damage taken by 603. This damage is split among all of your stack, meaning each stack will take 603/5 = 120.6 less damage. Your last ship had taken: 219*0.32 = 70 dmg. Meaning this would be made up for, with an additional 50 dmg to spare. This means you will loose 1 ship less per stack. This will last for 1 round since you will now reduce his damage even further. I could go on but again, I'm not being paid to do so.

Estimated losses: 10*3+5+3+1 = 39 ships.

Minimum ships required to retain estimated loss: 39+35 = 74 flame ships.

And don't bother sending them in fresh. It makes little to no difference when fighting with the amount of ships you do. You would loose 1-2 ships less but would require enough ships for 3 full front lines. Making the minimum ships required 35*3 = 105. An increase of 31 ships to save, at best, 2 ships. Consider where you spend your time in the earlygame.