Woody , didn't you weld at some time in your life? You could take a course at the community college in tig welding and make this your project. I made a couple of tanks like you discribe one portside and one starboard side with fiber glass and thin sheet aluminum riveted for forms that were left in place.
yes i did Ross...i have tig welder now ...i may very well be doing that if i dont work out the issues at hand ...
..i have done a lot of studying on the water tank thing ...and was hopeing to use a plastic tank if at all possible ...a sheet of .090 aluminum will cost me about $120. with tax just sitting on the work bench.....and for $214.00 to $270.00 i can have a plastic tank and be done with it.... but the cost of shipping is really getting under my skin even when i say it real fast ..lol..
so yes i may have to weld one up ...i dont have a problem doing that ...just was thinking that the plastic might serve me better ...never thought the day would come in my life time i would ever say that .....
when i had power boats back in the 70's...they usually came with 18 gallon fuel tanks...and back then i used to go from Augusta Ga to Savannah Ga about 3 to 4 times a year on the Savannah river ...and with a turbo charged 6 cyl mercruser that would run about 41 gallons one way with only one place on that 204 mile trip down stream to get fuel so i would add a built in tank in the ski locker in the sole of the boat...
that worked well in those days @.35cents a gallon ...so to answer your quiry about building one yes i may do that...
a lot of things i am doing on this boat i have found out that if i go slow when making a decesion in regards to what i need to do... usually a light will turn on for me and it will get cast in stone ...so there is still time to figuer out what i am going to do....
and btw thanks for asking ......
regards
woody