It depends...
...on how big your boat is and how far you plan to venture offshore. On my Santana 22 I used to get by on a leatherman, a sparkplug wrench, a box wrench for the keelboats and a shackle key. On my h410 I carry five complete toolboxes (mechanical, electrical, woodworking, rigging/sail repar, fiberglass/gelcoat repair), plus a large bolt cutter, hacksaw, finishing saw, dremmel tool, electric coping saw, cordless drill. In addition, I carry a huge box of assorted fasteners, a semi-huge box of glues and calks (plus other items that come in tubes, such as locktite), and a medium size box of tie-wraps, hose clamps, shackles, rigging tape, et cetera. I'm guessing my total tool weight is between three and four hundred pounds. I pretty much gauge the scope of a boat project by the number of toolboxes I have to pull out to finish it. (and/or the number of trips to the hardware store and chandlery to finish it.) The bottom line is that the hardware stores are few and far between once you get offshore.