This should not have been a problem. And in a more connected location it would not have been. First, I had to find someone with a USB to SD card reader. One of my former crew had taken mine with him when he left. "Not a problem", he said. "Buy a new one and send me the bill." After an $80 cab ride I discovered that there were none to be found. Next step, find a cruiser to borrow one. Mission accomplished. Now do the download - 2.5 gb. Use the marina WiFi. No dice. It kept dropping. Unfortunately Garmin (who otherwise I think highly of) does not packetize their downloads. You need to get it all in one shot. Next step. Pay $33 to the alternate provider for 3 gb of downloads. After 3 or 4 tries and about 5 hours I finally got the maps. Then it blew up one more time downloading software updates for my gear. Since I had about 3 copies of the updates I was not concerned that I did not get them. But would the charts work? Did I need to start another 2 hour download? Fortunately no, the charts had downloaded intact. One more item off the checklist.
Fair winds and following seas :)