It sounds to make as though you want to zoom your chart out so that when your chart first loads your 5 annotations are in view. You can initialise your chart's X & Y axes with a range object using the initWithRange: constructor. If you initialise your Y axis with a larger range, the chart be zoomed out & your annotations should be visible.
// Initialise a number axis with a visible range of between 0 and 50.
chart.yAxis = [[SChartNumberAxis alloc] initWithRange:[[SChartNumberRange alloc] initWithMinimum:@0 andMaximum:@50]];