Just a thought on the motor setup on the s boats,i've done two in 1/24,but i found to use two motors the turning circle is too big,as the rudders are so small to use one centre motor it tended to rock from side to side but the turning was better,a mixer can slow it down on the turn,the best performing s boats i've seen have two props and two non scale rudders.
I left them on two main motors,one smaller centre motor with a micro switch, and scale rudders,but it means carrying more batteries,i'm thinking of going back and reworking them soon,to get them runnig better,they ran fine but not enough endurance for me.
David5