The five blockship used during the Zeebrugge and Ostend Raids on 23rd April 1918 were all drawn from the Apollo-class of 2nd class Protected Cruisers. There were twenty-one ships in the class plus eight of the slightly modified Astrea-class, and they were built between 1889 and 1892.
Their characteristics when built were:
Six of the class were converted into blockships for the Zeebrugge and Ostend raids. These were:
HMS Iphigenia
HMS Thetis
HMS Brilliant
HMS Sirius
HMS Sappho
To prepare them for their use as blockships, the vessels were stripped of most of their armament and many compartments were filled with concrete. The extent of the damage inflicted on the blockships during the raids can be gauged by the following photograph:
Their characteristics when built were:
- Displacement: 3,600 tons
- Dimensions:
- Length: 314' (96m)
- Beam: 43' 6" (13.26m)
- Draught: 17' 6" (5.33m)
- Speed: 19.75 knots
- Complement: 273 to 300 officers and men
- Armament: 2 × 6-inch (152mm) QF Guns; 6 × 4.7-inch (120mm) QF Guns; 8 × 6-pounder QF Guns; 2 or 4 × 14-inch (360mm) Torpedo Tubes
Six of the class were converted into blockships for the Zeebrugge and Ostend raids. These were:
- HMS Intrepid: Expended at Zeebrugge
- HMS Iphigenia: Expended at Zeebrugge
- HMS Thetis: Expended at Zeebrugge
- HMS Brilliant: Expended at Ostend (1st raid)
- HMS Sirius: Expended at Ostend (1st raid)
- HMS Sappho: Intended to be used at Ostend (2nd raid), but broke down on the way and not used
HMS Iphigenia
HMS Thetis
HMS Brilliant
HMS Sirius
HMS Sappho
To prepare them for their use as blockships, the vessels were stripped of most of their armament and many compartments were filled with concrete. The extent of the damage inflicted on the blockships during the raids can be gauged by the following photograph: