Electronic boat equipment maker Raymarine has had a takeover approach from sat nav giant Garmin. Raymarine has been on the hunt for a rescue partner as it struggles against slumping profits and rising debts. The two firms dominate different parts of the navigation-systems markets but are different in size. Raymarine, which is based in Portsmouth, is one of the world’s biggest marine electronics firms, supplying autopilot, GPS and fish-finding systems for leisure boats. Products from the group were used by Ellen MacArthur during her round-the-world voyages.