No predictions loaded for 1998. This site serves NOAA predictions from its own store, and this period has not been fetched for Point Helen yet. Nothing is estimated or interpolated in its place. NOAA's own page for the station has the official table: tidesandcurrents.noaa.gov.
tidealmanac.site/us/ak/point-helen-9454671/1998
Point Helen, AK tide table 1998 (printable) · Tide Almanac