Madprops you are going at this bass-ackwards.
If, as you say, the intention is to 'cruise' to places where
racing is happening, then offload all non-race-related
gear on the
dock prior to the race.
If the race is a longer distance, then carry minimalist 'lightweight backpacking'
gear to suit.
If
racing 'dock to dock' leave the
anchor behind on the first
dock.
If you want to beat the superlightweight modern tris by lightening an older boat, you are essentially wasting your time.
Not only have the
hull materials changed, but hull shape, rig
power and everything else too.
Just removing 50-100kgs from a 37' older tri won't cut it.
Basically any tri that doesn't have either a centreboard or dagger board won't really cut it against more modern 'racing focused' boats that are so fitted.
BUT, having said all that, if it's longer-distance 'cruising racing' - like Trans-Pac, or Brisbane-Gladstone or similar, then using some of the suggested lightening techniques would be of benefit.
On longer distance races, it's as much the luck of the draw, plus good tactics, that wins races - so if the windshifts fall your way, or you
route the boat better to take advantage of
forecast wind, you can still beat 'technically faster' more modern boats.
Based on what I've seen here in Oz, the accepted wisdom is to increase the height of the
mast by 10-20%, increese the size of the sails and rigging to suit, reinforce chainplates etc to suit, utilise synthetic rigging to reduce the even-more weight up top (older boats tend to be more prone to pitching), and so on.
Rebuilding the cabinetry will not help you much much. Especially as trius tend not to have muhc in the first place, and it already tends to be pretty lightweight in the first instance, but sure, sacks will be lighter, netting will be lighter.
As others have suggested, removing a
diesel and replacing it with a lighter two-stroke
outboard will be more sensible.
It's like what super lightweight backpackers, mountaineers and cross-country skiers do - spend loads of money to replace items you can't do without with smaller, lighter ones.
So, for example, a two-burner gas
stove and its
propane cylinder aren't light. But an MSR single-burner backpacker/mountaineering
stove is very light, by comparison. And the
fuel it burns can be gasoline, so with the
outboard, that reduces fuels needed to be carried, and reduces the number of containers. Aim not to
motor much, so you only need
fuel to get off the dock.
Gas cylinders = heavy
steel; gasoline containers = lightweight polypropylene.
Instead of hiking boots, wear Crocs. Instead of jeans, wear thermal tights.
If only two aboard, share a cup, bowl, plate, knife, fork, spoon. It's a few more ounces.
I know that sounds almost ridiculous, but as someone pointed out higher up the thread, 1000oz saved adds up.
Replace the (probably) older Dacron sails with new, lighter weight Mylar or similar. Better cut, lighter weight. Which is heavier,
roller furling or a second lightweight sail with plastic hanks?
Replace stainless blocks and
deck gear with nylon and or
Spectra soft-blocks. Every one replaced saves ounces. Ditch the stainless deckwear like pulpit, pushpit. Ditch the trampolines. It's all weight.
Fitting a hand-operated
Katadyn watermaker saves both the
electric motor to drive it and the
battery capacity needed to run it, and the
solar panels needed to supply them. Fit a smaller, lighter
LIFEPO4 battery. Keep fit by 'making water'!
Make one gallon per person per day. But do it four times a day. So you only ever have one gallon on board. As you use it, replace it.
Ditch all the
instruments except the
compass and a mobile
phone fitted with
Navionics (or whichever). Race tactics
software is available for cellphones. Leave the
laptop at home.
Swap alloy spars for carbon-fibre
replacements. Stronger and lighter.
But, seriously, you might as well buy a modern boat that has all the above already built in. It would probably even be cheaper (assuming you don't already own the 'older trimaran' you are attempting to make lighter.
Whatever you do, 'adding lightness' costs big money.
And if all the
work you do only removes 100kg, sailing solo (ie: no crew) saves that without having to spend a cent.
See where I'm coming from?