ACFT PENETRATED CLASS C AIRSPACE WITHOUT ESTABLISHING 2- WAY COMS. ATCT INTERVENED.

Narrative

BEFORE TKOF FROM RWY 28L AT HAYWARD; CA; ARPT; I REVIEWED MY SECTIONAL CHART FOR THE AIRSPACE REQUIREMENTS FOR A DOWNWIND DEP. IT APPEARED THE ONLY CONFLICTING AIRSPACE FOR THE CLBOUT WOULD BE THE SFO CLASS B; SHOWING A SECTION BTWN 3000-8000 FT. I DETERMINED A CLB TO 2900 FT WOULD WORK UNTIL REACHING THE 15 NM RADIUS FROM SFO. AFTER TKOF ON THE DOWNWIND; WHILE CLBING OUT OF 2200 FT; HAYWARD TWR ASKED IF I WAS FAMILIAR WITH THEIR AIRSPACE. I TOLD THEM I WAS GOING TO LEVEL AT 2900 FT. THEY REPLIED THAT I HAD INTRUDED INTO OAK CLASS C. I QUICKLY CALLED BAY APCH ; AND THE PROB WAS SOLVED (OAK CLASS C STARTS AT 1500 FT). I ONLY FLY TO THE BAY AREA ABOUT ONCE EVERY YR. SO I FEEL MY SECTIONAL CHART SHOULD SUFFICE. BUT A CLOSE LOOK AT OAK CLASS C DEPICTIONS REVEALS MANY GAPS IN THE MAGENTA RINGS. IT WAS SUCH A GAP THAT LED ME TO MISS SEEING CLASS C AIRSPACE. I SUGGEST CONSIDERATION BE GIVEN TO SHOWING COMPLETE CLASS C AND B DEPICTIONS ON ALL SECTIONAL CHARTS. (I MADE A STRAIGHT-IN APCH TO RWY 28R AT HAYWARD 30 MINS PRIOR TO THIS INCIDENT. NO MENTION MADE BY TWR AT THAT TIME REGARDING CLASS C WHICH I WAS INSIDE AT 1800 FT AS WELL!)