Mission 96 – Destroy the Drug Resupply Boats
The boats aren't much to look at- just two speedboats behind the indicated mansion. Approach along the east wall for access to the dock.
Blow up the gas tanks next to each to destroy them with minimal ammo.
If you're planning to kill all the guards anyway, then you can also use grenades, there are replacements in the sentry shack here.
The second site has only one boat, and more replacements grenades if you need them. Take care of business then, if you've hit your total, you can jog just round the corner to see Big Jim.