I’ve noticed the skilltree is a bit different than the skills, it has only 18 skills while there are 19….
Also the lowest middle skill, is the ‘Banquet of frenzy’. It has a different picture.

Coloured Skill Tree Thanks to Rieny:

Shell strengthening
Request: Lv1
Classification: Loading
Installing weapon: All weapon
Consumption MP: 10
Cooldown time: 6 seconds
Skill book price: 20 gelt
Explanation: Shell speed increases and attack power raises, attacks the object.

Restraint shooting
Request: Lv1
Classification: Active
Installing weapon: All weapon
Consumption MP: 20
Cooldown time: 12 seconds
Skill book price: 20 gelt
Explanation: Drift speed of the object within a radius of 100 M is made to a decrease for a fixed time, damage is given to the object.

Maximum speed
Request: Lv1
Classification: Active
Installing weapon: All weapon
Consumption MP : 10
Cooldown time: 30 seconds
Skill book price: 20 gelt
Explanation: Navigation speed increases for a fixed time.

Menace shelling
Request: Lv10
Classification: loading
Installing weapon: All weapon
Consumption MP : 15
Cooldown time: 4 seconds
Skill book price: 50 gelt
Explanation: The object which is inside the designated range is provoked.

Shelling strategy
Request: Lv10
Classification: Passive
Installing weapon: All weapon
Consumption MP: 0
Cooldown time: –
Skill book price: 50 gelt
Explanation: Naval guns attack power increases.

Approach strategy
Request : Lv10
Classification: Passive
Installing weapon: All weapon
Consumption MP : 0
Cooldown time: –
Skill book price: 50 gelt
Explanation: Shooting attack power increases.

Ram strategy
Request: Lv10
Classification: Passive
Installing weapon: All weapon
Consumption MP: 0
Cooldown time: –
Skill book price: 50 gelt
Explanation: Physical defense power increases.

Blessing the tide
Request: Lv10
Classification: Loading
Installing weapon: All weapon
Consumption MP: 50
Cooldown time: 20 seconds
Skill book price: 50 gelt
Explanation: The physical strength of the object inside the designated range is recovered. (in short: Heal)

Smoke of darkness
Request: Lv20
Classification: Loading
Installing weapon: All weapon
Consumption MP : 20
Cooldown time: 20 seconds
Skill book price: 1200 gelt
Explanation: Bullet range of the object in the designated range is made to decrease for a fixed time.

Simultaneous strafing
Request: Lv20
Classification: Active
Installing weapon: All weapon
Consumption MP : 20
Cooldown time: 6 seconds
Skill book price: 1200 gelt
Explanation: Swing speed of the object around is made to decrease for a fixed time, damage is given to the object.

Command of aimed fire
Request: Lv20
Classification: Active
Installing weapon: All weapon
Consumption MP: 15
Cooldown time: 1 second
Skill book price: 1200 gelt
Explanation: Shelling range decreases, critical ratio increases for a fixed time.

Command of spread shooting
Request: lv20
Classification: Active
Installing weapon: All weapon
Consumption MP : 15
Cooldown time: 1 second
Skill book price: 1200 gelt
Explanation: Shelling range increases, critical ratio decreases for a fixed time.

Battlefield
Request: Lv25
Classification: Active
Installing weapon: All weapon
Consumption MP: 100
Cooldown time: 6 seconds
Skill book price: 2500 gelt
Explanation: Attack power of the vessels around increases for a fixed time.

Unity
Request: Lv25
Classification: Active
Installing weapon: All weapon
Consumption MP: 60
Cooldown time: 6 seconds
Skill book price: 2500 gelt
Explanation: Defensive power of the vessels around increases for a fixed time.

Shocking bullet loading
Request: Lv30
Classification: Loading
Installing weapon: All weapon
Consumption MP : 30
Cooldown time: 12 seconds
Skill book price: 4000 gelt
Explanation: It gives enormous impact to the object, makes incapacitation for a fixed time.

Explosion bullet loading
Request: Lv30
Classification: Loading
Installing weapon: All weapon
Consumption MP : 30
Cooldown time: 12 seconds
Skill book price: 4000 gelt
Explanation: Fixed time continuing in the object, it gives damage.

Penetration bullet loading
Request: Lv30
Classification: Loading
Installing weapon: All weapon
Consumption MP: 30
Reuse time: 12 seconds
Skill book price: 4000 gelt
Explanation: Defensive power of the object is ignored, damage is given.

Destruction bullet loading
Request: Lv30
Classification: Loading
Installing weapon: All weapon
Consumption MP: 30
Cooldown time: 12 seconds
Skill book price: 4000 gelt
Explanation: Navigation speed of the object is made to decrease for a fixed time, damage is given.

Banquet of frenzy
Request: Lv30
Classification: Active
Installing weapon: All weapon
Consumption MP : 40
Cooldown time: 1 minute
Skill book price: 4000 gelt
Explanation: Attack power and drift speed increase substantially, but defensive power decreases substantially for a fixed time.

Mostly Finalized. Will edit more in the future.
PS: English is not my mother language and I’m not that old o.o, so the English is not perfect =x