Years ago I was involved with racing such models and many designs of the day where regularly overpowered. To compensate spray rains where fitted to the shine line along with wedges or trim tabs at the stern. Another feature which helped, especially for improving high speed turns was the dagger plate .This was a sheet of, brass or aluminium shaped not unlike a rudder but fitted to the keel at the centre of gravity of the model. Ballasting was also important. With these added refinements high speed turns could be achieved quite easily.
Dave Wooley