T--I have been in that same situation myself and maybe this could help you. I bought a gps and a really good chart of the western basin. Go to www.waterproofcharts.com. I believe the cost is $24.95 plus shipping. The chart shows all marker bouys, light bouys, reefs, shoals, dumping grounds ect. from south shore to up north of Pelee Is.-- West Sister east of Kellys Island .Water depth,latitude and longitude is provided. Chart is waterproof. The other guys on here may be able to direct you to a less expensive map, however I think this is well worth the money. If you want co-ordinates contact me on e-mail. Good luck