Certification
The trailer should have a certification from the manufacturer that states the rated carrying capacity of the trailer or the GVWR of the trailer. If it is the GVWR you will need to subtract the weight of the trailer from the GVWR to see if the remaining weight is within the weight of the boat that you want to carry. The one thing that I would be concerned about is the length of the trailer as well as the weight capacity. If the balance is not proper it will sway from side to side on a single axle trailer as it is being towed and the overhang front or rear could cause clearance problems for the tow vehicle or too little tounge weight to safely transport the boat in question.