If you can afford the extra cost, you'll never regret having at least a minimum of 30 feet.

I agree with a bunch of the above. Within reason, no matter how big, you will wish it were bigger. Stuff has a way of accumulating and taking up space you hadn't figured on.

I built mine 24 feet deep at the lake, with the engine trimmed down, detachable tongue , and pushing the front over to one side my 21 footer will fit, barely, probably not going to put it in the garage much, sure wish i would have gone to at least 26 feet.

If you go too big, it will kill resale of your home. Most women do not bass fish and like to buy living square footage in a home, not storage sq footage. Now if you don't ever plan to move, then I'd say build it 40ft.

I just bought a 21' Ranger, with trailer and engine it is right at 30' long.
Don't forget to add extra wide doors too, not only are they long they are wide!
Wish I was into boating and fishing when I built my house. My garage is not even close!

Check the Ranger and Bass Cat web sites. I believe they have overall lengths listed. A swing tongue is a huge help.

If you can swing it do a 30ft deep garage. Mine has more. Behind the boat is a great place for tackle and other boat items.

40' X 30' deep. 20'6" Gambler with a 12" JP. No swing away tongue. With motor toter on, I have a 3 feet of clearance