I was finally able to get multiple days of testing and made decisions on the prop. In the end 10.7/8″ x 12″ was the best prop. I added a fin on the ventilation plate to get on plane quicker with the boat loaded. We have had 6 adults, two children and two dogs on the boat and it planed easily and was able to cruise at 22-25 mph. I think this kind of power is more important than top end speed with one person onboard.
The big test came when we were in Port Gamble for an extended Father’s Day weekend. This coincided with the largest tidal swing in 20 years. The swing when we went ashore for the Mountain Bike Festival was 12′. We carry an anchor buddy to keep the dinghy in deep water on a falling tide. You drop the anchor (we use a box anchor) with the anchor buddy attached and then stretch it all the way ashore. After taking a line to a beach stake or rock you allow the stretch to take the boat back out to deep water. Needless to say we needed more stretch.
The great thing about this boat is that when you pickup and drop people off on the beach, you can step onto the drop-front without getting your feet wet. Also, because the Whaly is roto-molded plastic we were able to slide it down the beach. We place 3″ rounds of driftwood at the keel to keep it from digging in. Four of us easily slid “On-the-Rox” all the way into the water. Nobody got their feet wet and no Whaly’s were harmed in the process.