I have a lowrance 3600c igps linked to a navman vhf 7100 but for some reason it has stoped giving information on my position to the radio. I have cheked all the wires are ok it was fine last week when i was out in my boat but i cant find the problem can you help.

If your GPS was sending NMEA data and now is not, your NMEA configuration may have been inadvertently changed, either due to a user error, or possibly a software glitch.

You can configure the unit to use specific NMEA sentences.
1. Press MENU|MENU| then scroll down to SYSTEM SETUP and press |ENT.
2. Scroll down to COMMUNICATIONS PORT, then press ENT then scroll down to CONFIGURE NMEA and press ENT.
3. A menu appears showing the prefixes of the available NMEA sentences.
A check mark next to a prefix means the prefix is in use. Use the arrow keys (on the track pad) like a mouse to select a prefix, then press ENT to turn off the prefix. (Press
ENT again to check the box and turn a prefix on.)
I'm not exactly sure how the data is labeled on that model but you looking for a sentence that looks like an abbreviation for GPS Lat Lon (it may be something like GPLL). If you're not sure, turn them all on, the VHF will only use the sentences it recognizes.
4. When the desired prefixes are checked or unchecked, press
EXIT|EXIT|EXIT|EXIT to return to the previous page.

let me know if this worked for you, or if I may be of further assistance.