In most states...
They are likely telling you it is the difference between it being an overweight load or not. Over weight loads require permits and often have special routing requirements and may require escorts and signage.
Once they load the boat it is their load and their
license and livelihood are on the line.
The simple way would be for them to quote you for a permitted haul to the nearest certified scale. The local one day
permit will legally get you to find out which of the quotes CooksFraming suggested you get from them is correct.
It would cost a few dollars, but avoid major problems. If they catch an unpermitted overweight load, they will order the truck parked wherever they pulled it over, until permits are obtained and huge fines are paid.
Pretty sure you can check permits for all states on their DOT websites.
Keep in mind, if this is a long haul through lots of states, it can a big difference in cost.
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