HUMA Maritime archaeology Gotland
Cannons at sea in 16th century Scandinavia
Until the middle of the 16th century the battles at sea started with a shooting duel between the ships, during which the combatants tried to immobilize the enemy ships by damaging rigging, sails and rudder. The battles culminated in the entry and capture of the enemy vessels.
As the artillery got increasingly more effective the damages inflicted on enemy ships were so large, that many of the vessels sank during the battles. The tactics of battle therefore changed as the artillery became the most important and the ships were thereafter constructed to accommodate an increasing number of guns/cannons. Cannons were high prized and therefore not discarded until absolutely necessary. Furthermore different cannon types served different purposes.
For these reasons many different types and sizes of cannons coexisted on board Scandinavian navy vessels and artillery on board 16th century navy vessels was not standardized. Both wrought iron cannon, cast iron cannons and cast bronze cannons were used side by side on navy vessels. The ordnance on the navy vessels thus reflected preferences and availability of cannons at the time the vessels were equipped.
The gun deck of the Golden Hinde, which is a replica of a vessel that sailed the world in the period 1577-1580. Courtesy of www.goldenhinde.org
The cannon to be recovered from a wreck site outside Visby is a wrought iron cannon.
Construction method of wrought iron cannons:
Wrought iron cannons were constructed either from staves or by bending iron plates into a barrel shape. In either case the barrel was strenghtened by a varying number of bands and hoops. A rough rule of thumb is that the higher calibre wrought iron cannon were constructed from staves, whereas the smaller calibre cannons were made from plates. The muzzle and breech of the barrels were always reinforced.
Firing and projectiles for wrought iron cannons:
Wrought iron cannons were weaker in construction compared to cast cannons of either bronze or iron. The connection between chamber and barrel was not completely gas tight either. The wrought iron cannons were therefore normally used for lighter projectiles such as cannon balls of stone or wooden grenades filled with flint pieces or iron shrapnel instead of solid iron cannon balls. Only the smaller calibre wrought iron guns used solid metal projectiles.
The lack in range and power of the wrought iron cannons was however compensated by the fact that wrought iron cannons had a higher firing frequency, as they did not have to be pulled inboard for cleaning and reloading. Reloading was simply done by replacing the chamber and wedging it tight. The wrought iron cannons were also lighter than the cast cannons and therefore made it possible to fit more cannons on board the ships.
If you want to read more:
Smith, R.D. (1988): Towards a new typology for wrought iron ordnance in The International Journal of Nautical Archaeology and Underwater Exploration 17.1: 5-16
Frantzen, O.L., Mortensen, M.H., Probst, N.M. and Thiede, S.E. (1999): Dansk Søartilleri 1400-2000. Tøjhusmuseet, Copenhagen.
Mortensen, M.H. (1999): Dansk artilleri indtil 1600. Tøjhusmuseet, Copenhagen.
Barfod, J.H. (1995): Christian 3.s flåde. Marinehistoriske skrifter, Gyldendal, Copenhagen.