I think you’ll probably be fine, of course it will depend upon exactly where your dock is situated, but most of the lagoons in that area are of a depth greater than the waters they come in from…
I live on a lagoon off of Kettle Creek, just north of Silver Bay, and my boat draws a bit over 5 feet. Charted depths for much of Barnegat Bay tend to be a bit conservative in many areas, especially the side bays and coves. For example, most of Kettle Creek is shown on the chart as 4 feet, but in reality is closer to 5 1/2 to 6 feet… I rarely take my boat into Silver Bay, there is a bar that obstructs part of the entrance as charted, but it still shows an overall greater depth than my own cove at Kettle Creek, so I think you’ll have no problem… On summer weekends, Silver Bay is a very popular anchorage, mostly powerboats, but I still see rafts of sailboats that surely draw at least 4 feet and more…
No tides to speak of in that part of the bay, 6 inches at most. The water height is more wind-driven, and throughout most of the summer with the prevailing southerlies and sea breezes, the water tends to be higher up in that part of the bay… Later in the fall is when we can see problems with depths, the NW breeze behind a cold front will blow the water out of that area, that’s when I can sometimes get stuck, if the water gets about a foot or more below an average water level, I can have a real problem getting out of my lagoon…
You’ll go aground in Barnegat Bay from time to time, guaranteed… but it’s all soft bottom, never a problem. Bottom line, if I had only 4 feet of draft, I’d feel like I could pretty much go anywhere, at almost any time...