From CS (S 16° 50' 59.8 E145° 44' 39.0 Mag. Var. 7°E Elevation: 23') to MLY (S 26° 44' 41.3 E152° 45' 41.0 Mag. Var. 11°E Elevation: 0') should be a course of 147°43'39.320", reverse course of 325°06'33.481" without magnetic variation, distance 709.1714331 nm.
Using the IGRF2000 model, the magnetic variation at CS (16.849944 S, 145.744167 E )at an altitude of 0 km on 6/4/1 is 7.18°E.
Using the IGRF2000 model, the magnetic variation at MLY 26.744806 S, 152.761389 E at an altitude of 0 km on 6/4/1 is 10.89°E.
Therefore your OBS out should have been 140°37'39.320", OBS in should be 134°13'09.481" assuming the navaids have the correct magnetic alignments, but more than likely they are 5 years out of date.
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It is possible to fly without motors, but not without knowledge and skill.
— Wilbur Wright