We lived aboard Sankaty, a Mariner 36 sloop for nine months, while doing America's Great Loop. South from Wisconsin to Key West via the Illinois, Mississippi, Tennessee, and Mobile Rivers before the start of the new Millenium. Then we went north from Key West via the Intercoastal Water Way (ICW) to Chesapeake Bay, then to the Hudson River to Lake Champlain, visited Montreal, entered the Saint Lawrence Seaway and then the Trent-Severn Canal to Lake Huron.
We looked at Pearson 35, Pearson 365, Morgan 34 with centerboard, Morgan 38, Tartan 33 fractional rig with scheel draft, Tartan 37 with centerboard, Allied Princess Ketch, and a center cockpit Gulfstar 42 before we settled in on the Mariner 36 from New Hampshire. The Mariner 36 insides are a lot like the Tartan 37 insides. Sankaty only needs a 51' of bridge clearance. A nice plus on the rivers and the panhandle of Florida.
We used navigation software and found it to be outright dangerous particularly when batteries were replaced in the GPS that feeds the position information to the IBM Thinkpad. The navigation software goes into a dead reckoning mode, but does not appear unusual on the screen. Several times the GPS ON indicator turned green when batteries were changed, but the software stayed in dead reckoning and would not come out till the Thinkpad was rebooted from cold. The moral of this is do not depend on just one method of getting a position.