Deck beam 5 is our other curved deck beam. To figure out how much elevation it needs, we lay a short piece of straight wood across deck beams 4 and 6 and measure how high the stick is above the tops of the gunwales at deck beam position 5.
If you have big feet and want extra toe room, lay the stick across deck beams 3 and 6. This will give you even more elevation. You will later add deck stringers to stretch from deck beams 4 to 6 or from 3 to 6 and this is what this stick simulates.