Don't have a boat and haven't had to manage GPS data. Based off of a quick 10 minute search I think the program below should work. The help file on the programs look useful but can't test it without data.
You have to download
GPS Utility Standard first and import all of your data.
http://www.gpsu.co.uk/download.html#gpsubfc
You want to use GPSU Batch File Converter Utility to convert it to raymarine format.
This was recommended from
http://www.thehulltruth.com/marine-e...er-import.html
Hope this helps
