Classification There was a conspicuous aspect of the classification of the
Medusa class. All Dutch paddle steamers had been classified as 'steamships' (Dutch: Stoomschip), 'steam vessels' (Dutch: stoomvaartuig) or even 'steam boat' (Dutch: stoomboot). To the contrary the Medusa's were called by their sailing equivalent 'corvette', or corvette with auxiliary steam power. A more specific label was 'kuilkorvet', meaning a corvette with a covered gundeck.
Dimensions Medusa had a length of about , a
beam of about and
displaced 1,241 tons. The previous sail corvette
Sumatra of 1848, was long, had a beam and displaced 943 tons. In general the corvette with auxiliary steam power still closely resembled the sailing corvette. In detail, it was about a quarter bigger because its length was increased to mount the steam engine and to store coal.
Propulsion The machines for
Medusa were made by
Fijenoord shipyard in Rotterdam, then often referred to as NSBM. On trials
Medusa achieved , meaning that the maximum speed in service would be about . On a somewhat rough sea it was only . The machines for
Amelia were made by
Van Vlissingen en Dudok van Heel in Amsterdam., later known as Werkspoor.
Armament From the start the
Medusas were planned to mount heavy artillery. At the time this was referred to as guns firing 60 and 30 pound shells. There is a note that the initial armament of
Medusa had to be lightened after sailing trials ended badly. In 1853 the
Medusas were ordered to have on the battery deck: 4 grenade guns of 20 cm No 2 and 12 long 30 pounders No 3. On the upper deck there were to be 3 long 30 pounders No 3 One of them on a pivot on front, and two of them on the sides aft. The armament as given in 1865 was 12 * 30-pounder, 4 * 60-pounder, 1 * 12 pounder and two 12 cm mortars. On board were also a 12 pound howitzer and a 3-pound bronze gun, both for landing purposes, and 100 rifles. In 1869 the armament was reported as: 8 long 30-pounders, 4 20 cm grenade guns and 4 rifled 16 cm guns. The 60-pounders were so impressive for a corvette that one might be tempted to think that they were replaced when the battery was lightened. This was not the case, because at the time the grenade guns were officially designated 'by the weight of the solid shot they fired'. For the 20 cm Grenade gun No 2 this meant that it was designated as a grenade gun of 60-pound. Indeed the 20 cm grenade gun No 2 had a caliber of 20.14 cm, exactly the same as that of the 60 pounder gun. The media of 1852 and
de Casembroot therefore designated the 20 cm grenade gun No 2 by mentioning the weight of the solid shot it fired, i.e. 60 pounds, instead of using the novel designation by the bore of 20 cm. To sum it up: the cannon firing 60 pound bullets is the grenade gun 20 cm No 2. The mounting of a 'lighter battery' then consists of removing the 30-pounder guns from the upper deck. ==Construction==