RE: Sherman DD
Yes, but all I need it to do is to move while in the water. The real ones only did 5 or 6 knots in a calm sea. I will be happy as long as it makes some forward progress in the water! On land the propeller motors will have no load on them, while in the water the tracks will have a minor load from the suspension and weight of the tracks, which is minimal. The only time that they both will have a load on them is entering and exiting the water.
Herman