Help with VBay / SW Pass / Tiger Shoal

[legallimits]

Made it out on Saturday, 9/6 for a full day of fishing. We were out at Tiger Shoal for 6:20. We fished half a dozen spots out there where we've raked them in in the past, and we couldn't get a single trout in the boat. Had one speck hooked, and my leader snapped. Made it all the way until noon without a single fish in the box. We made it in to the reefs by the pass, and we managed to pull in 8 keeper trout along with some trash fish and smaller trout (over about 2 hours). I've been fishing my whole life, but I'm new to Vbay. Although I love any advice people are willing to give, here's what I'm really interested in. I've made six trips offshore to Tiger Shoal. Two of the times, we came close to limiting out. Two times we had a nice fat mess, which was more than enough to keep me happy. The other two, we got skunked. The first time I chalked it up to wind, since we had 2-3 foot seas. This time, it was like glass and we still weren't catching. By all indications, it should have been a great day for fishing. The tide was moving pretty quick and the water clarity wasn't bad. We fished artificial (of various colors) on bottom, in the middle, and top under a popping cork. I can't figure out why the fish weren't biting offshore. I'd love any advice people can give about when the fishing is good offshore and why it might have been bad this past Saturday. Thanks, folks!