would say a 600 Is just a bit too small, especially If the boat Is on the heavy side.
a 700bb would be a much better bet, these are only about A£21 new and will run on standard nicad/nimh packs from 9.6v upwards and wont run as hot
not worth scrimping really! he will get far more enjoyment from his fireboat for about A£10 more

have a shiny new 700bb waiting to go In my 34" 🚤


db