Used to be you could order good NOAA charts for the SVI. Not sure now. Seems to me there's been a change in how they do bidnis. The Blue Charts chip for my Garmin works pretty well. CYOA will want you to have a paper chart. I printed out 'chartlets' on letter-sized paper and put them in clear plastic page holders.

As far as returning from the SVI to the USVI... I've done it twice.

It is very tempting to motor straight from Culebra into the lee of St. Thomas and then shoot SE through the gap between Savanna Island and St. Thomas and then sneak up the coast. This is ok of you're motoring and winds are under 15 knots. It's not as sheltered as you'd like. Perhaps if the wind is north of east, you'll be pretty sheltered, but if it's south of east the strategy ain't that great.

The wind and seas are concentrated in the gap between Savanna and St. T, and it can get pretty steep and snotty through there.

I have heard from CYOA staff that if you are going to sail back (vs. motor) that you should take your lumps and make a big tack out into the ocean towards St. Croix and then tack back in when you think you can make Frenchtown. This will take some time. Suggest you leave Culebra real early!