the use of duct in propeller is one of the breakthrough in the development of the propeller. Ducting not only claimed toincrease the efficiency of the propeller, but also capable to protect the propeller from impact therefore propeller's lifespan is longer. From that idea then RDP is created. RDP propeller blades are designed to be fixed at their housing called Rim, in the other word, the driving force came from its rim. Nowadays, the usage of non-conventional RDP blade is more common in practice. This research will discuss about design analysis of Kaplan Propeller Kaplan Ka-70 that modified on its thickness distribution. This researchusing motorload as variable. The simulation using Open Water Test. The result, highest value of KT and KQ occur on 30% motor load and highest efficiency is 18,338% achieved on 260 Rpm.