Right here is my two penneth (prob spelt incorrect).
but i have a brakengarth and have for some years now , it's one of Brian's prototypes , a one off and has a 90mm prop in a steerable kort .
When i built mine Brian was still supplying the old motors , big black thing's which i believe were also used to power compressors in refrigeration units when running of batterys ,
I may have it wrong but that's what i believe . Now this thing is powered by 2 12v 12ah batterys through an electronize FR30 esc .
So that's my setup in the brakengarth , if you can get hold of one of these motors then do so the run time is , well i have never flattened mine.
But as an alternative i have made a tug with a 90mm prop and kort set-up running on 24v with an ACtion esc and one of those 6-36v motors , the ones from kids scooters.
I have a pic showing the motor fitted but as it's in the bottom of the hull it's not that clear.
I ran this motor off two 12v 7ah batterys and whilst doing a bollard pull i managed to rip the coupling from the motor /shaft , now this was made from fuel pipe the braided type .
Yes there are better motors out there , but for the price these are up there for value as i paid a tenner for mine