I find it easiest to shoot water like this with my spot meter - that allows me to fish around the scene with the spot meter, and try to place it just outside the brightest points of light - you want to underexpose a bit, because if you don't, the glint area is so enormously blown out that you don't get sparkles, you just get a big white area...but you can't expose just on the sunlight glints either, otherwise the rest of the scene will be pure darkness. ; The middle ground is where you want to be. ; assuming bright daylight, the smaller the aperture the better for me, as it will help underexpose a bit, and also give you some nice star patterns off the glints in the water from the aperture blades. ; And a normal fast shutter speed should be capable in daylight even with the aperture closed down - 1/250-1/1000 or so should be possible. ; It depends on how much you want to silhouette the background.
Here's an example of a peaceful early morning sun reflecting off the coastal waterway as a kayaker was going by...he was paddling right through that sparkle field on the water, and I wanted that sort of dreamy sparkly feel:
That was with my ultracompact, so I couldn't manually set the camera - but I could use the spot meter and meter off of the edge of his wake trail, which forced up the shutter speed and closed the aperture down (F7.1 on a compact like that is sort of like F11-14 on a DSLR). ; That let me get more of the individual points of light, with some star patterns coming off them from the small aperture.
If in doubt, take a few with slightly different settings - maybe try shutter bracketing with a small aperture, so you'll get 3 different shutter speeds - overexposed, exposed, and underexposed...and see which is closest to what you want to get.
Good luck!