I wanted to put a deck and some storage compartments on my jon boat, it is 12 foot long and 38 inches wide. I have read on other forums that because of the narrow width, the deck would make the boat unstable. I was wondering if anyone has done anything like this on a boat this size and how the boat turned out. Thanks.

Is 38" the beam measurement? Meaning the wide part of the boat at the rails?

That is going to be a little tippy but you might be able to have the deck dropped down a little and that will help.

Get some pics and we will be able to figure it out.

Also a great site for rebuilds that will help out is www.tinboats.net

tons of good info on building tin boats!

Yea, its 38" from rail to rail and your saying if i keep the deck fairly low inside the boat in will help on keeping it stable?

It will help.  Keeping the center of gravity lower will reduce the chances of tipping but with a boat that narrow you are still going to run that risk.

With that being said, keep this in mind.  People fish from Kayaks and canoes all of the time and often times standing up if you are good on your feet and can balance well.  

I think you'll be fine. Biggest thing is to try one height and see how it works. You can always change it. That's half the fun in building your own boat.

That is an awfully narrow boat for a deck.  I personally would not put a deck on it.  If you do make sure it is as low as possible.  I created a built in tackle storage box on my 1436 jon a few years ago.  

I ran it parallel to and behind the front seat.  I built it to hold 8 plano 3700 storage containers plus pliers, etc.  I put a lid on it and it worked great.  It gave me plenty of storage and only took up about 14inches of floor space accross the whole lenght of the boat, right behind the front seat.  This would probably be a safer route to give you storage space.  It is also weighs a lot less than a deck and is MUCH safer.

not wide enough for a deck. UNSAFE!!!!!!!!!!!!!!!!!!!!!!!!!!!

I would maybe put a floor in between the seats, but a deck would probably make it too tipsy.