Highball: the other bouncing bomb
Developed in parallel with the Upkeep dams bomb, the smaller spherical Highball was for use as an anti-ship weapon - particularly for use against the German battleship Tirpitz. The Tirpitz was anchored in the Norwegian fjords, so that it could threaten the convoy route from Britain to Russia round the North Cape. Due to the Norwegian geography, Loch Striven (off the Firth of Clyde) was used as a training area, with an old French battleship Courbet being used as a target. The loch was already a secret area, being the training ground of the X-craft midget submarines who were also after the Tirpitz.
During 1943-44, at least 100 Highballs (probably more) were dropped in the loch, either for weapon testing or aircrew training purposes (these were all inert concrete-filled bombs). A current project being carried out by the Archaeological Divers Association to locate and recover some of the bombs from the loch - no complete examples of Highball exist in any museums at present. Any recovered bombs will be donated to air museums or local museums.
The first phase of the project took place over 5 days in July 2010; several Highballs were found close to a length of anchor chain in around 120ft of water. The second phase of the project, which will perform a detailed survey of the site, is expected to take place in early September.
A report on the first phase, with links to some short video clips, is available on the ForArgyll website