"Most cruisers and runabouts have a draft of 2.5 feet to 3 feet or more, etc.. Smaller boats like skiffs and bay boats, have a draft of a few inches to a foot and a half. Pontoon boats and boats with a flat hull tend to have less of a draft, whereas boats with a v-shaped hull will sit deeply in the water".
Draft varies with load in boat and motor trim/tilt and other variables. Look at the back of most pontoons and you will see that the waterline is about half way up the 25 inch tube. Halfway would reflect a 13 inch draft of the hull. In a pinch with propeller and water intake lifted partially out of the water the max boat draft is the draft of the hull. If you want a number specific to your boat (and gear) put it on a trailer and measure up from level ground to your waterline and then up to hull bottom and motor. Use those measurements to determine your draft. Consider that the waterline was created with a empty boat. Add a couple inches for people on the boat.