I don't like maths any more than you do, so let's keep this simple and move on to the buffet. I've had to interpolate in two dimensions, first to guesstimate what the motors will produce at 80% power as a target setting and second to allow for the fact that we've 22.2V batteries whereas this table for reasons best known to T-motor represents 24.0V performance.
Reasons incidentally that I prefer powering boats to drones are principally (a) motors can be run flat out instead of around half throttle (b) in the event of a crash they are more likely to survive along with the props and (c) there are only two of them instead of four, or worse, eight.
Moving on, note the amperage at 80% is precisely that delivered by the larger battery-packs at 22.2A, which would mean that they would provide power literally by the hour.
Our chosen packs however will be usable at 80% power for five times less (3900 mAh as per 22000 mAh) or TEN minutes, and at 100% they will last for around SIX minutes.
There are two things though to bear in mind, firstly that LiPos can't be run down altogether so we'll consider duration as ten minutes at 80% and five at the maximum. Secondly on the plus side should the props pierce the water at slowest speeds then they can be used to recover prototypes at altogether lower power, for in this case they operate as water-screws.
The other takeaways from all of this is that the thrust on paper is around three kilos at 80% and four at 100%, which is around half and two-thirds the weight of the craft respectively. By way of comparison the most sizeable craft I've driven in the shape of the Airbus 321 weighed 205,000 pounds gross and produced a third of that in thrust... so we're in the right ball-park, albeit water is a lot stickier than air.
The last three columns are also worth examining before the bell goes for our break. These are the largest props available to the U7 motor at 22" instead of 18" or 20". In theory the most efficient rotors are the largest (and thus a helicopter is about twenty times more efficient in the hover than was the Harrier jump-jet).
The maximum thrust for this type of motor tends to come driving smaller props at a higher RPM, albeit at the cost of higher energy consumption. Larger props are more efficient at lower power settings, so ramping up the throttle does the same to torque (or work) whilst hammering efficiency. In terms of grams lifted per Watt expended, note that the efficiency halves between 50% and 100% throttle settings.
At the same time we've gone beyond what T-motor themselves have simply described as the motor getting HOT after ten minutes, to what I've called HOTTER and MELTING respectively.
Motors catching fire do though drive YouTube views and that's what most concerns us.
