They have been converted to static divers, but I'd leave it as a dynamic diver. If you're running in ponds which are wadeable or where the boat is easy to recover, you can ballast the boat down until it's only just positively buoyant, then you'll only need a whiff of throttle to submerge, and the boat will be much easier to keep at depth, behaving very much like a static diver.
Although you won't be able to hover the boat, it will return to the surface very slowly once the throttle is cut. If you go below a couple of feet, the boats box may deform enough to make the boat slightly negative, which is why you need to be sure the boat can be recovered should it sink and you're unable to power it to the surface.