A helicopter pilot reported the published holding pattern for RNAV Runway 24 approach to 3N6 enters the N90 Class B airspace. Reporter also reported incorrect depiction of geographic boundaries and omittance of other geographic landmarks.

Narrative

While preparing a VFR simulated instrument instructional flight; I reviewed the approach plate for the RNAV RWY24 at 3N6. After reviewing the plan view it appeared the procedure would remain clear of the NYC Class Bravo. I did not review the procedure while geo-referenced or build the procedure on a moving map. After going under the NYC Class Bravo shelf in the vicinity of BONIE I broadcast the discrete transponder code and began monitoring New York approach as workload and radio availability allowed.After beginning the hold-in-lieu of procedure turn at 1800 MSL the pilot monitoring identified the 4 NM outbound leg would enter the Class Bravo prior to the turn and I initiated a descent to 1200 MSL. I tuned the radio to New York approach; monitored for our call sign throughout the remainder of the approach; and maintained 1200 until out from under the 1500 MSL ceiling before climbing back to 1800 MSL. I maintained the discrete transponder code until termination and shutdown.After reviewing the approach plate during post-flight while geo-referenced I determined the plate does not depict Staten Island in the plan view. The plan view erroneously shows the 'Arthur Kill' waterway as the coastline and omits Staten Island; giving a false sense of clearance from the coastline. With the approach plate geo-referenced or the full procedure loaded onto a sectional or TAC (Terminal Area Chart) map it can be determined that the hold extends approximately 0.5NM into the NYC outer shelf in the vicinity of SPATE. Had the pilot monitoring not observed the edge of the 1500 shelf; I would not have recognized as the pilot flying due to the approach plate covering the relevant information on the moving map.There were multiple factors I determined lead to this incident. The first was my incomplete review of the approach plates. Due to complacency and general familiarity with the area I loaded a route and then checked each IAF for each planned approach; but I did not load each holding pattern or full approach and review them prior to takeoff. Time pressure was also likely a contributing factor as I had planned and reviewed 4 approaches prior to departure at ZZZ; 3N6; ZZZ1 and ZZZ2. Another contributing factor was task saturation performing the holding pattern entry causing a loss of situational awareness. Had I been approaching the shelf of the Class Bravo while in a straight and level cruise I would hope that I would have identified the beginning of the 1500 shelf as it is an area I fly underneath regularly; most recently in the week prior. An additional factor was the relative inexperience of the pilot monitoring in the specific airspace borders of the NYC Class Bravo.The final factor I identified was the inaccurate information presented in the plan view of the RNAV RWY24 at 3N6. This approach plate incorrectly depicts the coastline omitting Staten Island; giving a false sense of separation. I would recommend that this approach plate be reviewed and that the plan view be updated to include Staten Island and the 'Arthur Kill' waterway; as it already depicts the Raritan River; Sandy Hook; and Navesink River.