Wespe-class gunboat

The Wespe-class gunboats were a class of 11 armored gunboats of the Imperial German Navy. They were meant for the defence of the North Sea coast. AG Weser in Bremen built them between 1874 and 1881. The boats were often in reserve or used for training purposes.

Technical developments
In Germany, the first plans for coastal defense centered on the use of monitors, e.g. SMS Arminius of about 1,800 t. When the torpedo was developed, the use of such big warships seemed unnecessary. Smaller vessels to defend the torpedo barriers seemed enough.

Local circumstances
The German Baltic Sea coast did not require gunboats. Here, all but two of the harbors had parallel moles. These stretched into the sea on both sides of the fairway. With torpedo barriers and heavy coastal batteries to protect these, it was thought unnecessary to have gunboats to keep the enemy at bay. (Later on, the actual stations of the Wespe class seemed to contradict these ideas.)

On the German North Sea coast and the east coast of Schleswig-Holstein the situation was quite different. Here the Eider, Elbe, Weser, Jade, and Ems exited into shallow waters with many shoals and islands. If the enemy could pass the outer limits of these shallow waters, he could safely anchor and prepare an attack or landing. Vessels defending these areas therefore needed a shallow draught. They also had to defend the local torpedo barriers. Here, these had to be so far from the coast that they could not to be defended by coastal artillery.

Armored or unarmored
After concluding that on the North Sea coast, monitors of about 2,000 t could be replaced by much smaller vessels, the next question was whether these small vessels should be armored or not. England, Denmark, the Netherlands, Sweden and Russia opted for unarmored gunboats. Germany opted for bigger, armored gunboats.

The 'unarmored' school of thought proposed small unarmored gunboats with a single heavy gun. It noted that in these circumstances, these boats offered a small target, while their guns could penetrate up to 20 cm of armor at medium distances. Due to their very shallow draught, these small gunboats could also evade ram attacks. A further advantage was the limited cost of these boats. Which of course also meant that one could buy more of these. This led to the Ant-class gunboats of about 250 t and the Ever-class gunboats of 200 t.

The German Navy school of thought said that an unarmored vessel could only be useful when it was covered by natural heights or a mole. In all other circumstances, it risked swift destruction. The threat by enemy capital ships was of course obvious. A less obvious threat was that posed by steam launches (Dampfbeibooten). These of course had much smaller guns, but these light guns were sufficient to destroy unarmored ships. These light guns were also much more in line with the size of the vessel on which they were mounted. This caused that the launches were way more stable at sea, relating in a far higher chance to hit the target.

Development
After the German Navy opted for armored gunboats, it could issue some specifications for new gunboats. The navy required the use of a gun that could penetrate 20 cm of armor, even at long distances. In turn, the boats should themselves also be protected 20 cm of armor. The gunboats should furthermore be seaworthy and have a shallow draught. The navy required only a limited speed for the vessels.

The Wespe-class gunboats were built by AG Weser in Bremen. Wespe, Viper, and Biene were launched in 1876. Mücke and Skorpion were launched in 1877. Basilisk and Chamäleon were launched in 1878. Krokodil was launched in 1879 and Salamander in 1880.

Hull and armor
The Wespe-class gunboats' hulls were made of iron. They were 43.50 m long with a beam of 10.65 m, a depth of hold of 4.10 m, and a draught of 3.10 m. They displaced 1,109 t. They had no rigging, only a signals mast.

The armor belt was 203 mm thick. It continued at that same thickness along the whole bow section, but tapered to 102 mm at the stern. This was because the Wespes were planned to engage the enemy with their bow forward, instead of with the broadside. The deck of the Wespes was protected by a 50 mm thick deck armor. The class also had watertight compartments and a double hull on the bottom side.

On top of the armored deck, there was a light iron superstructure that served to make the boats more seaworthy. The section before the gun emplacement served as accommodation for the crew. The aft section served as quarters for the officers and non-commissioned officers. Behind the gun, there was a deckhouse, which gave a dry access to the machinery and the officer's quarters.

Armament
The Wespes were armed with a 30.5 cm MRK L/22 on pivot carriage which put its trunnions 3.7 m above the water. The gun was placed behind a circular armored barbette of 203 mm thickness. The class also had a ram.

Later, the Wespes got two 8.8 cm SK guns and two revolver guns. Below the waterline they got two torpedo tubes.

At the time, the Wespe class combined the heaviest gun in the German navy with an armor protection that was comparable to that of many battleships. It was thought this would allow the boats to engage most enemy capital ships on distances at which most of the enemy's guns could not penetrate the boat's armor. In the coastal area, the shallow draught boats could then evade again in spite of their low speed.

Propulsion
The Wespes had two separate steam engines which each drove their own propeller and were separated from each other by a watertight bulkhead. Together, they produced 700 ihp and gave the vessel a speed of 9 kn. For war, there was enough coal on board for steaming at full speed for 40 hours. More coal could be loaded for expeditions that did not require shallow draught.

Cost
The total cost of a Wespe, including machinery and artillery ranged from about 1,034,018 to 1,210,316 Mark.

Use
In 1881, the North Sea station had: Viper, Mücke, Skorpion, Salamander, Natter, and Wespe. The Baltic Sea station had: Basilisk, Kamäleon, Krokodil, Hummel, and Biene.