Cog

On set, the Scarborough Port-Reeve Cog, "The Crow"

The Cog (or cogges or nefs) is often found on seals of port cities (particularly the southern Cinque Ports) - but is also emblematic of the disruption, civil strife and war that followed in the footsteps of trade in the 13th Century. The Cinque Cog is said to be a development of the nordic Knarr - which was probably the workhorse of traders of this time. While southern Cogs visited Scarborough (the Scarborough was probably required to build warships of this type), the northern ports may have relied on modified, armored Knarr - as perhaps shown on the Borough's seal.  Indeed, some suggest that the cog/nef of the Cinque Ports used the Knarr structure on which to build the distinctive castles that now only survive on seals. The Borough seal of Scarborough looks a bit like a Knarr with a defensive tower on the mast. More northern seals (Robert of Wolverston) also looks a bit like the knarr.

Records of legal disputes from the time suggest that cogs, sometimes travelling in large numbers, visited the Scarborough port ("The merchants of Almaine ... Andrew de Camp and John de Catlonde state that they have twelve cogs with their merchandise in the port of Scarborough, and that the Bailiffs of Scarborough have forced them to unload their goods and are demanding outrageous tolls from them; and they will not cease even for the King's letters..." ). 

1264 is a little early to bring Hanse traders explicitly onto our cinematic set, but their ship of preference, the Cog, had been around for some time (mentioned in 948 AD, in Muiden). In form, the Cog presents a distinct difference from the Knarr, the Nordland (Nordlandsbåt) (which may have been involved in an earlier diplomatic incident between the men of Scarborough and the Norse) and the smaller sand/river boats of Yorkshire. 

As with housing assets, there are few accurate representations of the flat-bottomed early-high medieval trading ships. While cogs could be beached on a seashore, the 'top-heavy' vessel was probably more comfortable tied to a pier.

On set, the Scarborough Port in 1264

Building a Cog

Building a prototype cog proceeded as though it were being constructed in wood by the method described by the wooden model builder Harold A Underhill in his superb book on Plank-on-frame models (Glasgow 1960).  

First, a keel is laid and, then, the frame is built around it, using measurements obtained from cog wrecks/recoveries. In reality, with clinker built boats, the internal frame was added to the hull at a later stage in construction - the approach here is convenient for modelling purposes.

At this stage I wrapped a single sided plane around the frame and then distorted it to meet each part of the frame to simulate the exterior clinker-built planking. (Some 3D modelling tools like Blender allow a form of 'shrink wrapping' to expedite this process.) 

From historical sources, I then created a variety of different superstructures and sizes (in the below completed images, I have simplified the deck structure, removing some deck detail to emphasize the shape of the ship). 

Once we tested the basic model on set, we started working on creating detailed textures for the set. First, the outer skin of the boat is reworked in Photoshop to warp the shape of the hull wood. Adobe Substance was then used to create the associated 3D materials to give the hull shape and depth. Below is an early example of an atlas created for the hull, and a still from a lighting test where that early-production skin has been applied, The goal here was to emphasize the clinker build of the original hull - but the results were sketchy :/

Ultimately, the best way to build a clinker built hull, is to actually lay down the planks over each other.

Using the shape as a template, planks were warped over the structure. As in early-high medieval times, the internal frames were then shrunk and fitted to the new skin.

The new skin is then taken back in to photoshop and detailed. Finally, associated 3D files (normal, roughness, and specular maps) are created to build additional surface detail, and cloth sails crafted (these will see a second-life as drying sails, and nets, on the piers) and the ships differentiated by dirt and color masks.