I think the sound is a bearing probably the motor, could be the shaft, definitely no need to increase power, sails very well

Mark

Motor has been left insitu, Prop shaft found to be vibrating and has now been fixed. Hull stripped back to bare wood and repainted in camoflage. Spray rails fixed to the hull have made a big difference to stability. Not on the original Aerokits drawings. Can now concentrate on Deans Cossack. Plenty of sheet lead for stability but looks good.