Much of the novel takes place around and aboard ships and river vessels. The techniques Runolf employs to build Brymsteda are as authentic as I could ascertain. While researching I was surprised to learn that new, unseasoned wood was commonly used and even preferred for the strakes. It also surprised me that sails were made from wool. It didn’t immediately strike me as a textile suited to holding the wind and not becoming waterlogged. However, remnants of Viking sails have been found and they were indeed made from wool. Sheep and wool were a major commodity in the early medieval period, with it being estimated that the wool from four hundred sheep would be needed to manufacture all the textiles required to fit out a typical Viking ship, including the sail and all the clothes and blankets. Making the sail was a laborious process, with rooing (basically pulling the fleece out by hand), separating the under coat wool from the outer coat, carding, spinning, weaving the two types of yarn together, fulling and drying, stretching, and finally coating with oil or fat to act as a sealant and waterproofing layer. The whole process from collecting the wool to finished sailcloth took about two years, so you can see why Runolf would be pleased to find a sail and rope he could reuse following the destruction of the raiders’ ships after their failed attack on the monasteries of Jarrow and Monkwearmouth.

Lots of the details about sailing a Viking longship came from a wonderful documentary I found about the Sea Stallion of Glendalough, a reconstruction of the great longship Skuldelev 2, built by the Viking Ship Museum in Roskilde, Denmark, and then sailed to Ireland and later back again in 2007/2008. There are several other such practical archaeology projects, with reconstructions of traditionally made Viking Age craft, and as a novelist, I get a lot more out of seeing and hearing how people interact with the real thing than just reading about it in a dry archaeological report.

I have not stuck to the tradition of referring to ships and boats as females. It is not clear where this tradition comes from, but there is no evidence that ships were referred to as feminine in the early medieval period. In fact there are documented instances of Vikings referring to their ships as masculine. In the end I decided to refer to ships as neutral objects, despite the powerful spiritual connection their owners had with them.

Orkney became part of Norway in 875 when Harold Hårfagre (“Fair Hair”) annexed the islands along with Shetland. In 794 the islands were still part of Pictland, and it is unlikely, though not impossible, that the Vikings would have had a permanent base there. The name, Tannskári, comes from the possible derivation of the place name Tankerness. A ness is a promontory.