Issue locking up – real tides gps Review

We were in Grizzely Bay (San Francsico Bay Area - near the mothball fleet). The program was working great until we did GPSreal Time for an Intrpolated reading. The iPhone locked up with the little bar that said "Calculating Tide at this lcoation". I could get information from the predetermined points, but for some reason the "interpolated" points lock up the iPhone and it had to be re-booted. Today it's working fine in my office with no problem. I like the displays and the information, but locking up the iPhone is a problem. I can't figure out why it works now but on the water we had problems. I'll try again next week
Review by Fun Fishing TV on real tides gps.