boat motor test

Calculations

# small outboat motor and some batteries
# test calcs to see how much power we could generate
# and how much we probably would need

# real motor (under load)
boatW = 60 V * 200 mA
# 18650 x 8 (guessed lower average mAh capacity)
cap = 3.6 V * 2500 mAh * 8 to Wh
runtime = cap / boatW to h



# reverse calculation: 
# which speed would we expect
boat_mass = 40 kg
person_mass = 70 kg
prop_efficiency = 35 %
mechanical_power = boatW * prop_efficiency

k_drag_base = 1.75 N / (m / s) ^ 2

# --- CASE 1: 2 PERSONS ---
mass_2_persons = boat_mass + (2 * person_mass)

# Calculate the actual drag coefficient for this specific mass (returns N / (m/s)^2)
k_drag_2 = k_drag_base * (mass_2_persons / 1 kg) ^ (2 / 3)
speed_2_persons = (mechanical_power / k_drag_2) ^ (1 / 3) to km/h


# --- CASE 2: 4 PERSONS ---
mass_4_persons = boat_mass + (4 * person_mass)
k_drag_4 = k_drag_base * (mass_4_persons / 1 kg) ^ (2 / 3)

speed_4_persons = (mechanical_power / k_drag_4) ^ (1 / 3) to km / h