What are the white objects that are on flatbed trucks. They have hole showing to the back and ports on top.?

Question

I have traveled cross country and have seen them traveling both ways. There is only one per flat bed truck and they are wide loads.

These are very large, being about 35 feet long, 11 feet wide and maybe 10 feet tall with what looks like mobile satelite domes on the top. They also have what looks like hatch openings.l They are slightly pointed in front, sloping down and to the back from about a one foot overhang. In the rear there is one LARGE opening, that being about 7 feet in diameter and they are completely empty with only the manufacturing ribs showing. There are no windows or door openings and all the corners are rounded. I first saw them about 15 months ago on a trip from Atlanta to Oregon in a motorhome. My wife and I saw maybe 200 of them, sometimes with them going both east and west, passing in opposite directions. They all apear to be identical and are not covered or sealed. Don't think they are boats or camper bodies and have never seen one in a rest area or truck stop where we stop to fill up our motorhome. Thanx

Answer 1

Hard to say without a picture. A picture says a thousand words. I would submit a guess that they are boat hulls?

Answer 2

Catch one at a rest stop or truck stop and ask the driver