No need for any foam Bob.
The hull has a sealed cover and will and has run under water.
With full power I could dive the boat when I had to much weight in the bow.
I have taken some of the weight out as the waterline was too high.
So if Mr Nuke boy could out pull me he could drag me around all day and I would not sink. (Famous last words)
On the other hand I would hate to have to remove the paint from the tug formally known and Carol M by dragging it along the sandy bottom of North lake.