How can I strengthen my boat ??

New Site Yellowcat · Feb 4, 2015

I bought a used 16 ft. flat bottom recently... Boat has had a rough life..
What I would like to know is a way to beef-up the sides.. All the seats except the middle one w/ LW are gone..
Which is good for me, as I can't get around good. The boat is an old Duracraft..
The boat flexes in rough water.. I want to add a piece of metal or aluminum to the sides by rivets or small bolts.

Would 10 or 11 gauge metal be heavy enough to stiffen it up ??? Yet flexible enuf to pull down tight against the sides ??
I need some ideas as to what will be the best.. I'm going to repaint when it's all fixed up

Also I've been told that I can paint the bottom with a paint like used in truck beds.. As long as it's put on with a brush,
it will lay down smooth, so it doesn't have a rough texture..
I fish in some very rocky places.. And it's going to hit rocks..
I have a 20 Hp. Yamaha on it, so I'm not a speed demon..

THANKS FOR ANY AND ALL the input ya'll give.. Going to post pics when I get started..

huntinfool · Feb 5, 2015

If it were my boat, I'd get some aluminum square tubing and place it across the ribs near the top. (Depending on where the flex is)
Since you are saying it is flexing, I wouldn't use pop rivets, I would through bolt it. You could drill a larger hole on the outside and a smaller hole inside. That way you could get a deep socket inside to hold the bolt head.
I have some 1x1 aluminum square tubing that I have built many projects from. Including some floors, and its very strong and durable.

That's just my humble opinion.

As for the bottom, search steelflex on this forum. There is a ton of info about using this product. I did the bottom of my boat with the new formula with Teflon in it. All I'll say is don't unhook the strap, until you're in the water ready to unload! Oh and watch out for the handle when you release your strap......its gonna move fast!!!!!

bobberboy · Feb 5, 2015

There have been several threads here and some debate about taking out the seats in a boat. Some say it doesn't matter. Some say it does. I'm with the latter group. All you have to do is compare the ribs in a boat designed to be open (that is, without seats) with one that has seats. The ribs in the boat designed to be open are considerably heavier duty than those in a boat with seats. There's a reason for that.

If you think about the problem as if it were a building it might help to illustrate the point - a building made with rafters and stringers versus a building with trusses: the rafter and stringer building relies on the stringers to keep the walls from spreading apart at the top. Remove the stringers and the pressure from the weight of the roof and any loading on it such as snow will inevitably force the walls apart at the top. The walls are held in place at the bottom by being anchored to the foundation so the pressure acts on the weakest point, where the roof and walls connect. Even though your boat doesn't have a roof to create pressure to spread the sides out, the water pressure will do the opposite and want to push the sides in. Plus the pounding a boat can get in rough water will cause the sides to flex.

The other thing the seats do is create a rigid box that in addition to enclosing the floatation foam, helps to prevent lateral movement as well. The older fashioned open bench seat does help with the structure but the newer types that are essentially welded boxes add a lot of structure to the boat. Like a cardboard box with the top and bottom open, the four sides can flex all over the place. Once you close the top and bottom the thing becomes a rigid structure.

Adding a piece of flat stock to the side of the boat isn't going to add much to the structure of the boat. If the gunnels are fairly straight you can add a square tube as huntinfool suggests but if they curve it will be hard to make that work. Lots of guys remove seats and replace the structure with a deck that keeps the sides tied together. If you want the boat to be open you have to deal with the strength of the ribs. One way is to have gussets welded on the ribs but that will also provide lots of opportunity for tripping on them as well as effectively narrow the width of the bottom. If you used gussets and then covered the insides of the boat with some kind of sheeting it could work. Doing this wouldn't be cheap though unless you can weld aluminum.

Attwanl · Feb 6, 2015

Very good illustration. Was going to take out my middle seat, going to rethink this now.
Thanks Bobberboy

New Site Yellowcat · Feb 18, 2015

THANKS Ya'll

JMichael · Feb 18, 2015

Another option would be to do like Bobberboy suggest but without the welding. My boat was built without benches by the factory. The way they kept the strength was to add braces that work similar to gussets and they installed them with sheet metal screws. I have reinstalled them with rivets during my build because some of the screws were so near the edge of the metal that they tore through and the other screws would tend to loosen up or back out from vibrations.

In this pic you can see the braces on each side.

Here is a closeup of one where I have replaced the screws with rivets.

And here is what the final flooring/bracing looks like. Yes they do take away a little clearance but they aren't a trip hazard or any trouble in that sense because I don't walk that close to the sides of my boat when I'm moving from front to back.