Day 2: Boil lime/water until the fruit is soft.
Day 3: add equal volumes of sugar to fruit and liquid. Add as much ginger as you think would be yummy. I use the sugary ginger chunks, which I add after it has been boiling in sugar for a while.
Boil the marmalade until setting point has been reached (test by dropping a bit of the preserve into a glass of iced water and see if it forms a ball when gently stirred), then bottle into sterilised jars.
I'm always surprised how little the ginger taste remains, so next time may be tempted to put in more. Last time I used 250 grams of preserved ginger for a big pot of marmalade, but more would be good. You could also try thinly-sliced ginger root, adding it with the sugar.
Cut the limes into quarters, then each quarter into thin slices, discarding the far ends where the pith is very thick. Cover the fruit with the water and leave overnight in the pot you are going to use to cook the marmalade.
Cut the ginger root into very fine julienne and add to the limes and water. Bring the fruit to the boil and simmer for an hour.
If you use your oven to sterilize your jars, now is a good time to get that going.
Cut crystalized ginger into fairly small pieces, and add them to the simmering fruit along with the sugar. Bring to the boil and cook vigourously. Test for jelling after about 10 minutes - this sets easily, and only took about 15 minutes.
Skim the marmalade and bottle into sterilized jars - it wil make about 14-15 medium jars.