The image of a Viking sent out to sea in a burning ship is not what the evidence shows. It is a nineteenth century picture, and the excavated graves say something more interesting.
The great Norwegian ship burials were static. At Oseberg, buried in 834, a seagoing vessel was dragged up from the water, set in a trench, filled with a burial chamber, and covered by a mound of turf and clay that sealed it well enough to preserve the wood, the textiles and a carved cart. Gokstad was much the same. These ships went nowhere; they were furnished, occupied and buried in the ground, and the mound over them was a landmark visible from a distance.
Other forms existed alongside. Ships were burnt with their dead in some places. In others, particularly on Gotland and in parts of southern Scandinavia, the dead were laid in a setting of standing stones arranged in the outline of a hull, a ship shape with no ship, which shows that the meaning could be carried by the form alone.
What all of them have in common is expense. A ship was among the most costly objects a Norse community could make, and putting one in the ground took it permanently out of use. Ship burials are a fraction of a percent of excavated Viking Age graves. Most people were cremated and the ashes placed in a small mound or a flat grave, with modest goods or none, and any account of Norse funerary religion that starts from Oseberg has started at the far end of the scale.