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The fuse is there to protect the wiring from burning up, and looking at https://www.westmarine.com/west-advisor/Marine-Wire-Size-And-Ampacity.html I see that the max amperage by gauge (for 12V systems and Marine wire) is:
10 gauge: 60A
12 gauge: 45A
14 gauge: 35A
The OTHER consideration is that thinner wires have more resistance, and cause more voltage drop per foot of wire per amp of current carried, and critical wiring is supposed to keep voltage drop less than 3% (0.36V) for a full run (both to and from the battery).
Here’s a chart (for 12V, AWG– NOT automotive SAE wire): https://www.westmarine.com/west-advisor/Marine-Wire-Size-And-Ampacity.html
Free web calculators:
https://baymarinesupply.com/calculator
https://boathowto.com/electrics/wire-size-calculators/
I calculated amps based on the resistance I measured on my start and choke solenoids, using ohm’s law:
AMPS = VOLTS (12) divided by OHMS resistance
For my choke solenoid I calculated 5.45A (must have been about 2.2 ohms), and 2A for the start solenoid (must have been about 6 ohms). Your resistance may vary!
http://www.omc-boats.org
http://www.aerocraft-boats.org