whats the best way to prevent an alumnium boat from flexing?

[matt88]

I have a 1648 aluminum flat bottom riveted jon boat with the high sides and its an old boat that has been cut up and redone probably more than once. The only bench in the thing is the one in the back a couple feet from the transom. It has a thick alumnium deck welded on the end of it and a livewell/storage compartment in the middle. Also has a thin fiberglass floor. I cannot find any cracks or loose rivets on the bottom of the boat but it does have a minor leak. If your in the boat an hour or so it will build a few inches of water in the very back. Not a real big deal the bilge pumps it out in a few minutes but I would like to attempt to get it right. Im pretty sure I know where the leak is but a bigger problem is that the boat has too much flex in it. Its my first boat so if it isnt supposed to have any just tell me lol. Anyways I had some one inch square aluminum tubes and I have bolted these to the upper part of the ribs on the inside of the boat. It is now a lot stiffer than before but still has a little flex left in it. Before I go any further I was hoping someone who has dealt with this before could tell me the best way to fix it. thanks

 

[Bob_VT]

Re: whats the best way to prevent an alumnium boat from flexing?

You might have some weak points in the boat....

Pictures?

Fiberglass deck??? Pictures please

 

[matt88]

Re: whats the best way to prevent an alumnium boat from flexing?

this is before I added the reinforcements. The fiberglass deck was a new one to me too. It was put in by the previous owner. Its really nothing more than about an 1/8 in of fiberglass run across the length of the bottom of the boat covering the ribs. Initially I had planned on removing it but its strong enough to support weight,theres enough space underneath for water to flow back to the bilge pump so it stays dry and to me its pretty much as good as ply board but lighter so I left it.

 

[matt88]

Re: whats the best way to prevent an alumnium boat from flexing?

wish I had splurged more on the seats,lol.

 

[Bob_VT]

Re: whats the best way to prevent an alumnium boat from flexing?

This is a 1648 layout. That livewell partial seat in the middle is the culprit for the flexing. Until you get braced all the way acreoss.... it will flex.

There are other jon boats that have a pass through center bench but it is a seat on the sides boxed in and the center has a small opening.

 

[matt88]

Re: whats the best way to prevent an alumnium boat from flexing?

Is it possible to add enough structural support to be able to leave the center bench out? I plan to add a console and steering later on and that will be on the other side of the livewell. So it will almost be all the way across. I was hoping that with the addition of the square tube supports and the console to help with bracing it would make it stiff enough. I have seen a lot of jon boat to bass boat conversions on the internet and was curious on how they dealt with this problem. Im guessing there ply wood floor adds enough support where my thin fiberglass floor probably doesnt add any. thanks again.