Ideally, you would use either Boat Trailer Bolts or Boat Trailer U-Bolts to mount these bunk brackets around your boat trailers cross-members. The cross-members are the the pieces of either galvanized channel, tubing, or aluminum tubing that connect one side of the trailer frame to the other, typically in front, and behind the trailers axle or axles. In some cases with a tandem axle trailer, there may be 3 cross-members. When mounting this 12 inch Vertical Galvanized Bunk Bracket, mount the flat side to the face of the cross-member, and the open side will face away from the cross-member.
Important things to consider when replacing Vertical Bunk Brackets.
1. Desired Bunk Board Height- Do you want the same size or would you prefer a shorter, or taller height for your boat. If you are going shorter keep in mind the changing ride height of the boat puts it closer to the trailer fenders and also the motor closer to the ground.
2. Keep Track of Hardware needed to replace the bunks. These bunk brackets will mount with either 1/2 inch bolts or U-Bolts. Determine which is needed, and the appropriate measurement. Most commonly, U-Bolts fastened around the trailers cross-member, and through the slotted holes. Determine the dimension needed to go around the cross-member by measuring the height and width. Keep in mind to add extra length for the nuts and washers.
You may also need a through bolt for the desired bunk board you will be installing in the bunk bracket. The correct size bolt is a 3/8 x 3 inch bolt available in Stainless Steel and Zinc Plated.