My MA came with a 70 gallon tank. Now I know that engines now get better gas mileage but if you have 40 you have 40 gallons to work with. I have 70 now if I only want take on 40 I can. But if I want to go farther I can. I think its better to have more than enough to just having enough. With a bigger tank I can run to bimini I can go to the marquesas I can run far offshore on the west cost and have plenty of gas in reserve

I will probably be going with the largest I can fit as the consensus appears to be 40 gallons at the low end of the spectrum. Don I promise I can count , multiply , and divide.

There are many "rules of thumb" for safe fuel consumption when going off shore. The one I remember most is 25% of your fuel running out, 25% for fishing, 25% running back in and 25% for reserve. I'm with Jorge, ya need to have "plenty of gas in reserve", to me 40 gal capacity would be minimum to safely take the offshore adventures you mentioned.

Math and stuff
 

Leland, Don was just covering his bet that you might have attended the Hillsborough County School System, as did he and be math challenged. You see, if one is really good at math they would just "Charter"!
And don't be "snippy" with your Tampa Bay SeaCraft Bretheran or we'll send Eric to have a "conversation" with you, and he is a very rare "Southern Viking".

Well T-3 since my wife is also from Plant City I figured I would be nice with Leland. Actually Deb is average at counting and multiplication, however she's really, really good at dividing, especially my allowance in to smaller amounts. I was just doing some simple math for fuel burn and range, don't want there to be excessive arithmetic challenges for us edumacated in eastern Hillsborough County. :)

With the closest good offshore reef over ten miles out I would not even think about a 25 gallon tank. The way the weather can turn around here it would not be worth the risk.

There are plenty of productive reefs right in the bay. Check out Apollo Beach Reef and the Skyway areas. No point in becoming a statistic!

the previous owner took the boat from sugarloaf key to Parumph nevada, painted it green to go duck hunting on Lake Mead. I may be from Plant City but I'm not Nevada duck hunt dumb.

Strawberries!
 

Leland, I think the 115 Zuke will net you at least 4 miles to the gallon at 4,000 and probably 18 knots so theoretically you should have a 100 miles range with the 25 gallon tank. If you launch at either beautiful Cockraoch Bay or lovely Bullfrog Creek, you are probably limited to 60' of water off of Egmont. However, then you are faced with running headlong into one of those Avon Park manufactured afternoon thunderstorms in Tampa Bay "trying to get back to the trailer". If you drag it over the Skyway to Ft. DeSoto you are probably good to 90' west of Egmont and maybe get to the pipeline for some A.R.'s for our generous there day season. I have a 32 gallon tank on my 19' Sawzalled bowrider with a 90 E-etc triple and usually burn about 20 gallons a day running to 40' of water off of Bayport which is about a 75 miles day, with maneuvering on spots, when I'm out there. So in summery, if you put the 40 gallon tank in you'll be set for all conditions and situations.
P.S. you are in charge of the Strawberry shortcakes at the next West Coast Gathering and Don likes his with extra whipped cream.

"extra whipped cream"

Oh hell yeah!!! :)

What Terry said.

I have a pair of 20 gallon tanks, but often I fill one and the other is empty. It is nice so that I don't have a 1/3 full tank sucking water out of the marine air and into the tank.

Expect at least 4 MPG.

Sometimes I do one tank and a 5 gallon tank for that reason. You could do 25 plus another small one, like a whaler under-seat tank.

I prefer 2 small tanks to one.