Neil and Smulan good suggestions and as you say restricted by Mac. I should have bought the Garmin data card reader but now very rare.

Looks like the only way will be to do away with search function and use GMapTool to split the .img file. The Mac version of GMapTool is a terminal so will wait until I can use a Windows machine could you give me a basic description as to what to split the .img file into? Thanks