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Pontoon Trailer Bunk Brackets
Manufacturers use differing styles of bunk brackets. Some brackets are thick steel formed to shape. Others are pieces of stamped steel. The strength is in the base where the two pieces of steel that support the brackets come together. The reason some companies need to weld “outriggers” to their frames is their frames, and usually axles, are narrow. Often these trailers were designed when pontoons were only 8’ wide. To get the bunk brackets out to 77” they need to weld pieces of steel to extend the frame. Bunk brackets distribute the weight of the boat along the trailer frame. If you have a modern heavy pontoon you really should have 4 or more bunk support brackets on each side of the frame. You can easily spot this, just look at the number of cross members supporting the frame sides. There is a difference in the height of bunk brackets. Most trailers have 4”-5” tall brackets. The boat sits lower on the trailer, launches in shallower water. But some companies have really tall bunk brackets, often as high as 11”. The 7” difference between 5” tall and 11” tall brackets may be the difference in launching in shallow water.
Almost as important as the strength of the bracket is how it’s attached to the trailer frame. Attached to the main trailer frame is the strongest method, but some manufacturers don’t have wide enough frames. Bunk brackets attached directly to the pontoon trailer main frame cross members are the strongest. The weight of the boat is carried on the cross member, not on some piece of steel welded onto the outside of the frame. More brackets distribute the weight of the pontoon boat evenly along the length of the frame. The more brackets the better.
The reason that more companies don’t bolt the bracket to their main frame is because the width of their frame is narrow. To get the bunk brackets out to 77” for the modern pontoons they weld on pieces of steel to extend the width of their frame. Other manufacturers don’t have enough cross braces. They can’t use more bunk supports because they don’t have anything (cross members) to attach them to.
Some Brackets are supported by a piece of steel welded to the frame.
This bracket is attached to 2” x 2” steel that’s welded across the top of the frame.		Welded to the frame is a strong way. But on a trailer with welded bunk brackets, you can only use that trailer for the boat it is built for.
		Only one brand of pontoon trailers uses the weak bracket shown to the left. The benefit (to a marine dealer) is that it’s easily adjusted. It just takes minutes for the dealer to set up and adjust the brackets for any size pontoon. But will it support a modern pontoon with a large outboard or I/O engine? The only place that you’ll see this type of bunk support bracket is on small fishing boat trailers. Their brackets are probably just fine for 600 lb. fishing boats, but I question its use on a modern pontoon boat especially one with a larger engine.
		Here’s another heavier duty adjustable bunk bracket. This has large bolts with serrated lock washers, but the weight of your center tube rides on the friction of the two nuts to the bolt. It makes it easy for the marine dealer to adjust the trailer. Again the benefit is to the marine dealer in adjusting the trailer. There is no benefit to the consumer of having the tube ride on two nuts with serrated edges. You may have to recheck and retighten those every time you travel.
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