Delta - star starter of pump


I have an issue on starting the pump with following specs:

Protection: IP68
Isolation class: F
Coolant temp.:40 deg. C(104 deg. F)
Type of start: Direct
Max number of start: 10
Rated power: 95 kW
Rated current: 205 Amp
Rated RPM: 960 1/min
Starting current: 1150 Amp
Max voltage: 420 V
Min voltage: 380 V

My client wants me to give him a power for genset for starting this motor with delta - star starting system, soft start, or frequency converter. The most important type of start would be with delta - star starting system.

If anyone could help me on getting the literature to get a calculation for how much would the current decrease with delta - star, or give me info on how should I proceed in dimensioning the genset.

Based on the info here, with starting current 1150 Amp, I would have to put a genset 3 times power the pump (so that the alternator could withstand the starting current)if I would start the pump directly.

Any info would be good.

Thank you.