Use Futaba S3003 standard servo for rudder control, use Futaba S3801 sail servo for sail control.
You may consider to spare a few hundred dollars to buy spary paint for your new sail boat, so your new boat is unique from others. Refer to www.seawind-rc.com for more colorful seawind in USA.
Sorry for in-correct web site, I just type by my memory.
Sail servo can output more torque than standard one, I understand some seawind owner use HS-765HB for sail control, because HS-765HB is cheaper than S3801.
HS-765HB has higher torque output and faster in speed than S3801, please refer data below.