I just bought an old jon boat, I was planning to do some work on it. Took it out last Saturday and was fine but felt like it flexed too much or wasn't sturdy. It was like standing up in a one seater kayak.

Anything that you could do to make it sturdier on the water?

how wide is it?

I would say 3 1/2 to 4 ft at the top and 2.5 to 3 ft. at the bottom not quite sure what the exact measurement is at the moment. It's 14 ft. long.

I wouldn't say I'm an expert, but had a few jon boat's, big and small. In the process of overhauling one now. If it is a thin gauge sheetmetal, that wouldn't be too abnormal IMO. Make sure no rib's are loose (broken weld's/loose rivet's. If all is good, that's probably just the way it's going to be. A narrow beam such as that would be a bit unstable in choppy or windy condition's. Seen one of them narrow jon boat's (the ones from Academy) that flipped in the wind with his dog on board. Can't get the dog near the water now. Not trying to scare ya, just be smart with the weather.

Whoop's, forgot to try and answer your question. You could try and cross brace the top with a couple of 2x4's. No need to bolt in yet. Just cut'em to a tight fit and wedge them in where you need them. Then take it out for a try and adjust them around to see if it eliminates the flex some.

growing up, I fished all over the state of Louisiana in those narrow 14' flatbottom jonboats, and one general rule we pretty much always followed was, don't stand up. Unless you really really need to of course. And no sudden movements, or walking around upright. And, don't take it out in whitecaps.

I see now that my jon would not be a good conversion project, but I do want to update it. Here are my ides, suggestions would be appreciated:

1. Replacing the bars running the width of the floor of the boat. Most have come loose and one is broke in half. They also do not run up the side of the boat, if that matters.

2. Going to put in a floor, using marine plywood.

3. Was thinking about removing the bench seats and replacing with cushioned low back seats. Would just attach the seat mounts to the flooring. The bench seats are worn, bent and have holes where someone tried to mount seats. Just figured the new seats would be more comfortable. Would this make it more unstable?

Again, any thoughts or suggestions would be helpful. I feel I don't know what I'm doing, oh well the boat was very cheap.

I can't say for sure, not being any kind of engineer, but the benches very likely provide structural integrity for the hull, and might be where the floatation foam is. Putting seats on the benches ought not to be too tough.

marine plywood is real pricey and hard to find - I used B/C exterior plywood with 2 coats poly resin & on top only, one layer fiberglass. be sure it's marked EXT.

general rule, a 4x8 sheet of plywood weighs about 25lbs per 1/4 of thickness - so go thin as you can. 3/8 will probably do.

i would NOT pull out the bench seats because that is where the floatation foam is. it keeps the boat from sinking if it takes on water. with the foam is you will just be swamped. i have a 74 model 14' flatbottom that is 32" wide at the widest spot. the sides and nose also flex alot. it has the ribs that run on the floor but not on the sides. a person that knows how to weld can make some aluminum brackets out of angle iron and rivit or bolt them to the sides and go across the boat to the other side to sturdy the sides up. the trasome is pretty flimsy also all i put on the boat is just my 46lb trollin motor and the transome will flex pretty good in 5th speed.