Stuck at 600-700watts

Maiden successful voyage yesterday of my first efoil build. Attached the foil mast to the back of a rigid safety boat and pushed that around a lake for a bit.

I am running a 6384, Vx3 pro (UART mode) and a Mini FSESC6.8 supposedly good for 150amp.

Battery wise picked up some from AliExpress, 2x 13S2P 48V 100Ah High Power 18650, 1x 48V 24Ah 2000W 13S6P 48V Lithium, each battery has its own BMS.

Don’t fully believe battery spec’s but supposedly the 13s2p has a rate discharge of 13a and the 13s6p 50a.

Started testing and noted following wattage output on vx3 controller.

Test 1…1 x 13s2p, roughly 430watts
Test 2…2 x 13s2p, roughly 650watts
Test 3…1 x 13s6p, roughly 650watts

What I found strange is the wattage didn’t double from step 1 to 2 and step 3 was similar to step 2 giving reason for me to believe there’s a setting in the vesc that isn’t correct. Anyone got any idea’s ? Do you think I should bypass the individual BMS’s ?

Any help appreciated.

Could be many things, RPM limit, propeller too big or small, current limit,…
Best way to find that out would be to log the data or at least connect vesc app via Bluetooth and screenshot the realtime data page under that condition