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Putting a bimini on your jon boat means you won't have to endure the sun when you go boating. It also means that, if you have an aluminum jon boat, you won't burn your hands on the hot metal when you wrestle your boat out of the water. You can build a bimini on your jon boat if you're willing to invest in some fabric, aluminum or stainless steel tubing and a few fittings.
Material for the Top
There are four basic choices of material for the top to your bimini. Cotton canvas is the least expensive option, but it won't last and tends to leak. A high quality vinyl is waterproof and easy to clean. Like canvas, vinyl can become brittle after extended exposure to the sun. Polyester, particularly the form called "solution dyed" polyester, holds its color well, stands up to sun longer without becoming brittle, doesn't leak and stands up well to abrasion. Acrylic tops stand up to the sun well, but tend to stretch, meaning they will eventually sag.
Frames and Fittings
Whether you make it yourself or buy it, pick your frame based on where you boat. Frames come in stainless steel, the best choice for a saltwater environment, and aluminum for freshwater boating.
Stainless steel won't corrode and is stronger, preventing your bimini's frame from collapsing at high speeds the way a lighter aluminum frame will. The aluminum frame tubing should be anodized rather than plated to resist deterioration.
Fittings to hold the frame to the boat come in nylon, which is weather resistant. Stainless steel fittings are strong but expensive. Nylon fittings are strong and have an advantage over the stainless steel fittings. With stainless fittings, the frame will tear up before the fittings will break. The nylon fittings will break before the tubing that makes up the frame, meaning you can turn your boat around and recover the frame. Brass fittings are inexpensive.
Fittings are available in nylon and stainless steel. Nylon is relatively strong and weather resistant. In addition, nylon fittings, which are less expensive to replace, will break before the tubing bends in stressful situations. Stainless steel fittings are more expensive, but are the strongest and most durable. Coated brass fittings are inexpensive but have a tendency to corrode and peel.
Sizing the Top
Use a measuring tape to measure the length of the area you want to cover with the bimini. Stock tops come in 6- and 8-foot lengths, a thought to keep in mind when looking at frames because standard frames are built to accommodate standard tops.
Measure the width of the area to be covered. This measurement should be taken from where the frame is attached to the port--left--side to the starboard--right--side of the boat. Because the mounting bracket will be atop the gunwale, or top of the boat's side, this isn't the same as the width of the boat, the beam.
Decide how high you want the top to be and take a look at your boat. If you have antennas sticking up, you'll either need to relocate those antennas or change your top configuration. If you have rod holders along one side, those will affect how your top is configured and how high it is. If your rods only stick up 5 feet, you'll be safe with a bimini that's 6 or 7 feet high.
Squaring the Frame.
Attach the mountings to the gunwales after you make a decision about the fittings and frame. You need to be sure that the frame is perpendicular to the gunwales and both ends of the frame are parallel; if it isn't the ends will twist and the top will sag. The fittings will give just a bit but, if you measure from the front corner on the starboard side to the back corner on the port side, it should equal a measurement from the front corner on the port to the back corner on the starboard. If these measurements don't match, move the frame around until it does. When the measurements are equal, the frame is square and perpendicular to the boat.
Will Charpentier is a writer who specializes in boating and maritime subjects. A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. He is also a certified marine technician and the author of a popular text on writing local history.