Boat is 30 years old tank is a afp 109 gallon aluminum .. I am assuming its no good and has to be removed..any thoughts or tips on cutting up floor??

Why assume it is no good?

The age??

I wouldn't go through all of that work just for age. I parted out a hurricane sandy 1989 Baja salt water boat that is almost 25 years old and the tank had zero corrosion and is in perfect condition. If you are worried about it do a pressure test on it. If you are rebuilding the boat completely and want to get it done now then go for it. What make model and year boat?

Rule of thumb is 20 years on a tank.
I replaced my 2 tanks two years ago boat is a 1988..
Had to cut up the floor, big job.
They did such a great job you would never know the whole cockpit floor was replaced.
Looks the exact same as when the boat was new. Cost was about $ 8,000
105 gallon tank was $1100 & 50 gallon bow tank was $500 + a ton of hrs. labor.

You don't want to be in the boat when a tank lets loose. When in doubt replace it!

It's a 1986 k& k ghost.. Floor is glassed plywood carpets out already and seats are coming out..plan is to bolt up some 200 outboards and make it a bay inlet beater/blaster here on li.. Figured easier to do it now.. Have tank so hoping to reuse existing one ...

its a big job , but if you got the tools and smarts to do it , its not too bad . i replaced my tank in my 25 AT few months ago . every quote i got was 7 - 9k . i did in my buddys garage for about 1700 bucks including the pirrelli flooring , the tank and all glass material . i found the center of the stringers set my saw blade at an angle and the exact depth of the floor and cut right down the middle of the stringers . i ordered the tank from speedy tanks , or atlantic coastal welding in New Jersey [ATTACH=CONFIG]505479[/ATTACH][ATTACH=CONFIG]505480[/ATTACH]

I had an 83 K & K Ghost 23 and had to replace the tank in 1994 or so.

Don't know if yours is the same but mine the tank was sitting directly on the bottom of the boat. Salt water from the bilge managed to get between the tank and bottom corroding it. When I pulled it out there were literally hundreds of pinhole corrosion spots on the tank. One was bad enough that it started leaking. No repairing of the tank, had to buy a new one.

Bad part is I had just made a deal to sell the boat when I noticed gas in the bilge but couldn't find a source. Couldn't sell it that way with a clean conscience so I replaced the tank.

Ripped out the carpets, cut the floor board away, replaced the tank with a new custom made tank, re-glassed the floor board back in and put new carpet in. Couldn't tell anything had been done once the job was completed as the carpet concealed everything.

One thing I did different was I mounted the tank on longitudinal foam strips. This keeps it off the bottom and cushions it. Longitudinal direction still allows bilge water to drain to the rear of the boat. Also put foam strips on top of the tank between the tank and the floor board.

Worked out great and the boat is still running today with no problems.

onetime ..was it foamed in? howd you get that crap out and is that how you put it back?? thanks..

OK so bear in mind this was twenty years ago.

I don't recall it being completely foamed in place. Was relatively easy to get out once the floor board was removed.

Used a closed cell foam for the re-install. They were pre-made and as I recall they were some kind of packaging foam that you could buy. They were 1" X 4" strips. As long as you get closed cell foam it will not absorb water. I would think it would be easier to get something now as shipping foams are a lot more common.

Hope this helps but as I said it was 20 years ago.