Let’s start. I thinking to purchase ready surf board, this foil and this motor
And build own efoil based on this components. I plan to use 80AH 24v Lithium waterproof battery.
So how to do math? How to know for example if surfer weight let’s say 90kg what can maximum speed can achieve with this board? And how far and how long we can travel with 80Ah battery with max speed? If motor engine is 24V 375W 8200 rpm and max thrust 7kg (weight about 1kg), the board size 330x75x15cm and weight about 10kg plus battery weight also about 10kg, and hydrofoil weight about 7kg (size see in description of item).
And also acceleration time measure? How fast surfer can reach max speed on this board?
Sorry I really new in this topic and don’t know so much. I want to start from understanding how to measure all this parameters and what best components may fit for it.
I would also be interested in some general math and physics here.
But based on my reading here and in dozens of motor datasheets, the motor of the propulsion unit you linked to is massively underpowered. It has 375W, but you should aim at multiple kW, so at least 10 times more power. I also don’t think it really would give 7kg of thrust, but even if it would you probably need more like 10-25kg for 90kg of body weight.
Acceleration is determined by the torque of the motor and your motor spins really fast, I don’t think it has much torque. If my little physics skills are not mistaken it has about 0.44 Nm, which is very little, too little.