HMS Penelope was first laid down as one of the many sail frigates that England built to a French model.

In the end the promise that she would be the first of a line of true steam paddle frigates proved false.

In the first decades of the nineteenth century the United Kingdom built many comparatively light sail frigates.

Contemporary steam vessels propelled by paddle wheels could match the speed of heavy frigates in most circumstances, but they lacked a comparable armament.

[6] In 1815 six were ordered to "a modified design that incorporated Sir Robert Seppings's circular stern and "small-timber" form of construction,"[7] hence the name "improved Leda class."

In 1832 Sir Thomas Hardy pointed out that the Hébés could not match foreign frigates that had increased their armament.

[6] In 1838 the assistant-surveyor of the navy, John Edye, submitted a plan to convert these frigates into war-steamers.

The existing sail frigate had to be cut in two, and a 63-foot (19 m) mid-section was to be inserted to house the steam engine.

By the time of her conversion to a steam frigate guns had generally increased in calibre and weight.

In early 1844 Charles Napier ranted about Penelope, stating that "sailors called her the Porpoise, for she was always under water, and only came up once every hour to breathe.

It would put a new frigate 14 inches (360 mm) higher in the water, and raise the ports to 6 feet (1.8 m).

[5] It might have solved the shortcomings of Penelope, but by then the navy was already working on converting HMS Amphion to screw propulsion.

Also that the weight of the machinery and coal, together 1,035 tons, was not in line with the displacement allowed by the added mid-section.

Van Kattendijke concluded that it was clear that the experiment had not been as successful as had been hoped, but applauded the daring of the designers.

After arriving in Cork in mid-October Captain Jones reported very favourably about the ship, and stressed that she was much better than the other war steamers.

[4] Penelope played a significant role as flagship of the newly promoted Commodore Jones when he commanded a British squadron tasked with enforcing the ban on the Atlantic slave trade.

[19] Jones contracted a fatal disease during his time off the coast of Africa, and died at Haslar Hospital, Gosport, in May 1846.