It all depends on the type of motor and the Kv rating of the motor. The Kv rating gives the number of revolutions per volt when off load.If they have used low Kv rated motors then they will be low revving and high torque which is what you want to drive a large prop on a scale tug. As long as you keep the battery voltage down then the speed shouldn't be too fast. If necessary then if you are using a modern transmitter you can set the throttle endpoint to less than 100% and reduce the speed like this.If they have fitted a high Kv motor then you might have a problem, these are high revving and suit small props better, using a large prop leads to overloading the motor and high currents. In this case a low battery voltage may be essential to keep down the speed and current.I have the ST Cruiser tug which has a low Kv rated brushless driving quite a large prop. I did find it overpowered as standard using a 3S LiPo pack but used the programming ability of the esc to reduce the maximum revs of the motor making it much more scale like.
Jim