> Snemma um vorið bjuggu þeir bræður skip sitt og fóruPerhaps just a typo, but that’s past tense throughout
> austur með landi.
> Early in the spring the brothers prepared their ship and
> went east by land.
> Early in the spring those brothers readied their ship and
> sailed east along the land.
> Early during the-spring those brothers prepared their ship
> and travel east along (the) land (ie by coast).