I am using Jane's 688i for a Learning Platform...since the manual is so nice to learn from. I have attempted something both in 688i and in DW-688i, and I can't figure it out.
When I am at a couple hundred feet deep... surface contact at 5 NM... I either can't see anything on the Broadband.. or [in the case of Jane's 688i], I get a solid contact for a few minutes.. then gone. I tried being deeper and more shallow.
Any ideas? Of course...

... I am using the Crew Assist [at this point].