i was just thinking - by adding the top deck u move the center of gravity pretty high up in the full loaded boat
are you going to add counter weight balast at the very bottom ?
Although I know we touched upon stability in these modded jons in an earlier post figured I'd do a quick followup to your question.
As for ballast or extra weight, I have never personally added any extra weight to try and increase stability. The whole purpose of the construction of this boat is to increase its "fishablility" while not significantly impacting its portability. Any extra weight, even for stabilities sake cuts down on its ease of transport.
In terms of making the center of gravity higher in the fully loaded boat you may want to think that question through again. The reality is the "load" of the boat, ie all your gear, battery, etc, is still in the same positions they would be without the deck. The only thing you've really raised is your own center of gravity. Hence why I build all my decks below the gunnale, your center of gravity ends up no different than if you add a swivel seat post directly to the seat, a common practice in most jons.
Now I will say this, the real "cheat" here is to spend time with your boat BEFORE you do any conversions!! As I said, I got this boat and did the first round of repair/mods in fall, I ended up taking the boat out 7-8 times before deciding on the deck and layout, plus I wanted to make sure it would catch fish....
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During 2 of these trips I brought along a 2 x 12 that I laid across the seats from bow to stern and 7-8 cinder blocks. Then I spent the first hour or so shifting weight and seat post positions around the boat to help determine the best layout and positions for weight. This also allowed me to determine how the craft would behave dependant on where I positioned the seat post, battery, gas tank, etc. A little time spent on layout and weight balance lends to a much more stabil craft.
This all being said, you have to be realistic about what your gonna use the boat for and be understanding of the limitations of that particular size boat. I have done decks on all size jons, and it is possible to put them on the 10 to 12' jons as long as you realize
that your probably not gonna use much more than a 12" seat post, the option of a "leaning" style post is much harder to get away with unless youve got good balance. And you need to be wary of just how much gear you stow aboard. I personally prefer to mod jons over 12' with the 14' being my favorite with a good balance of size to weight. (I believe Stratos would agree with me on that!! I do hate that tracker deleted the livewells on the 14' for the newer model years thou...)
Like I said never considered adding weight or ballast as I'm a firm believer that you can use the existing weight you have to balance the boat.
Ohh and for those of you that have now said, "what about the weight of the deck?" Bear in mind that the entire deck assembly weighs in at under 40lbs. and we are dealing with an object that measures approx 32" by 44" or 1408"sq this translates to roughly 9.7sqft of deck surface area, soooo the 40lbs that it weighs is distributed at a rate of 4.12lb per sqft and this is EVENLY distributed at a height that is no taller than the existing seat height!! How's that for weight distribution!!!!