You can say that again. On my friends boat he has every piece of fishing gear that he ever collected on his boat. It must add about 500 pounds of weight to his boat plus it's all cluttered and you never can find anything
Like Simon, I always have the following on my boat and bring additional trays out when I'm targeting something specific:
Tray of bass goodies (swim baits and lead heads)
Tray of lead (12oz down to 1/4oz sliders)
Tray of hooks
Tray of iron
Tray of misc. casting spoons/buck tails
Flouro from 20-60 lb
Sabikis and tool to remove bait from hooks.
Pliers, bolt cutters, fillet knives, sharpening stone, game shears (safer to cut bait on pitching deck), buckets, ziplocks, paper towels and too much other stuff that has been rat holed in every crevice on the boat by family and friends over the years
I like Scott's list, with two modifications: I don't have a flying gaff, and have never needed one; and I lost a bunch of hooks to rust when I put them in a nice tray, thinking it would be convenient. Hooks are kept in their little plastic packs inside the closed tackle box that I bring aboard, and after it is taken out of the pack on the boat it NEVER goes back inside, whether it catches a fish or not. And like Joe, when I had a boat I would unload damn near everything, every time.
Oh, and unless the boat is a Boston Whaler or similar absolutely unsinkable design, a nice big white cooler to cling to while everything else sinks. I think more fishermen have been rescued clinging to white coolers over the decades than all of the rafts and life preservers put together.
I leave all the tools (gaffs, pliers, gloves, etc.) on the boat all the time.
Then I load the basics, terminal tackle, leaders, weights, hooks, small selection of iron, small selection of lead, bait making stuff, 20-40# rods etc. on the boat all the time.
As the season progresses I slowly add more crap as needed. Iron, tuna lures, rod riggers, squid gear, marlin stuff, flying gaff, swordy gear, spear gun, etc.. Most of the big stuff I take home after I'm doing with that fish or season.
By the end of the year the boat is loaded with a ton of crap. When spring comes, I go through every hatch and hold and take out all non essential crap.
Then the cycle repeats....
Also, these things aren't cheap but if you have the room they are AWESOME.