Bertram 54 Sport fish, good, bad ugly??

Rotted decks will be your main concern. Check foredeck, FB deck, cockpit decks for structural integrity and no water. Rotted fuel tanks is another, especially the cockpit tank. Bad wiring at that age. 12v92's another issue. They did good on a head sea, roll on a beam sea, and ungodly on a beam sea on the troll. I managed one for a while, never loved them. Always have to step on one piece of machinery to access another..........never really cared for them. But IMO a 1988 54' Bertram will be a huge money pit....... your best bet would be to go to a late 1990's, early 2000's Post 50' with 820 MAN's and never look back......much more efficient and a better boat ALL of the way around.

The tanks are aluminum on a 1988 54' Bertram. 2 in the front of the engine room in a good location (high above bilge water and not near ER vents). The aft tank usually goes bad on them because it's under the cockpit sole and close to the bilge water. Bottom line is there are a ton of systems that should be replaced on most 1988 sportfish. Old galleymaid toilets that are constant headaches, does it make sense to buy a rebuilt pump at a $1000 or a complete new raritan toilet (but takes more labor and parts to install), old wiring, old gauges, old electronics, a/c's, decks that are prone to water intrustion and rot, deck hatches, and the biggest are 12v92's.......it'll take you 4 months just to get all of the rebuild parts to rebuild one and then you're dealing with rebuilt liners......and engines that'll need to be rebuilt 900-1000 hours later........Then you want to burn 90 gph to do 21 maybe 22 knots......or 60 gph to do 26 knots in a 50' post that doesn't half half these issues to deal with and motors you'll get 7,000 hours out of before needing a reman. and aren't leaking oil all over your bilge or noisy and stinky. If it's a towered boat, that thing will roll like crazy on the troll.

Don't know, but this sounds a bit out of the blue for a sportfish which was an unreachable bench mark for sea keeping in its size and beyond for two decades (80s-90s).
Beamy seas rolling in trolling is true but that is for full towered units. The Napier hulled Bertram's onward from the seventies are really a good all rounder in all kind of seas.
The machinery thing is correct, but in rough seas (any direction) a Bertram 54/570/60 would still eat most sportfish's in its size today.
Probably a boat which came close to the B54 was the mid noughties realeased (2006-) Hatteras 54 but then not as good in following for its flatter deadrise, and slower in heads seas, and better in beamy seas.

I think before the advent of Gyro stabs, full towers where particularly tough on anything sub sixty feet in beamy seas.

The mid 90's-2006 54' Hatteras is an animal. It is an excellent riding sea boat and build quality and fast. I ran one (a 2004) with a tower a lot, and it rode incredibly well and was a much better boat all of the way around. I ran that boat at 32 knots in 6' seas on the bow coming out of the inlet and then on he beam for 150nm one day and it never once pounded.

The Bertram has a very deep V all of the way back, on the troll or running with a beam sea they rolled very well. The 57' Bertram I also ran 1000's of miles, it was a better riding boat especially on the troll, than the 54' but the COG was too far forward (at least the one I ran with single generator, hard top boat), especially since it had a single 1700 gallon fuel tank at the front bulkhead of the engine room, anything more than 1/2 fuel and it ran like a submarine. Never ran a 63', but would never touch a 57' or 63' due to dozens of them structurally coming apart, including the new at the time 57' that I was running around, owner got rid of it after a year and bertram doing fiberglass work on it twice.

The hull in the 54 and 570 is the same seventeen degrees deadrise aft.
The 630 has a slightly more modified hull, closing at sixteen.
The lower COG and centre tank is what improved the rolling I guess.

The Hatt 54 series 2 was introduced in 2002 and produced till about 2011 (becoming the GT54 in that year), and then replaced by the GT59 in 2017.
Deadrise is a flat two degrees on the 54 if I remember well, and that will surely give you less roll in trolling.
I do agree that the 54 Series II is a better all rounder then the Bertram 54, but it took them like twenty years to make a better boat, and the help of the luxury tax which practically

I'd love to scoop me up a 50 Post!

Yeah, the center tank screwed up the COG on the Bertram 57' and with 1/2 fuel or more the boat is a complete submarine, extremely wet. I did well over 1500 NM's on one I managed. Boat still rolled pretty good on the troll, but not at cruise due to it's 31+ knot cruise speed giving it more stability at cruise, however you'd get a 5 gallon bucket of water on the enclosure every 2 minutes in a 3' sea.

The GT59' did NOT replace the 54' GT. The 59' GT replaced the 60' GT. The 54' GT they still made a year or two after the debut of the 59' GT. The earlier 54's were a better boat than the Bertram 54'.