This will give you a idea of the size of these. Yep...I went overboard a bit! The smaller motor was in a Piper Cub RC (400 motor I think)
My model is getting heavy. The bulkheads are the larger plywood. The fiberglass and many coats of paint/resin have added a lot of weight. Just as well because I will have to add ballast so she sits in the water correctly. I will use lead shot for ballast.