Wednesday, 29 June 2016

GETTING PUMPED FOR TERROR’S BIRTHDAY

Today marks HMS Terror’s two-hundred and third birthday - the anniversary of her launch in Topsham, Devon on June 29th, 1813. Within a year of her launch, Terror would be harassing American cities along the Eastern Seaboard, and would even have an epic poem written about her exploits by Francis Scott Key. Today, when Americans sing their national anthem, they reference the history of our favorite exploration vessel.

This date also marks the third anniversary of the start of the Building HMS Terror blog, and today we’ll be celebrating our respective anniversaries by discussing Terror’s pumps.

By 1845, Terror had at least five pumping mechanisms installed, though it likely had other moveable “fire pumps” as well. For her size, Terror had a relatively large number of water management devices. Comparing the 1836 upper deck and profile plans of Terror to the 1839 plans shows that an additional two common pumps were installed just behind the forehatch, while the main pumps flanking the main mast were upgraded and replaced. 

These changes were likely a response to the near sinking of Terror during George Back’s arctic expedition of 1836-1837. In the spring of 1837, ice damage to Terror’s sternpost and keel created leaks so severe that five feet of water gushed into her hold every hour. Back ordered his men to work the pumps continuously during Terror’s return voyage across the Atlantic. The crew became so exhausted that they had to beach the vessel at the closest landfall, at Loch Swilly in Ireland.

Rice, the shipwright responsible for Terror’s 1839 refit, responded to this near disaster by upgrading all of Terror’s pumping systems. He also introduced penstocks into the limber board system in the hold, which allowed the crew to manage the flow of bilge water into her well.

Below, I’ll discuss each of Terror’s new pump systems in turn.


Massey’s (Massies) Patent Pumps (Bilge):


Massey’s patent pumps were a reliable flywheel pump system of a type that became very popular on civilian and navy vessels in the latter half of the 19th century. Testing of Massey’s pumps began in 1833 and timed trials on board HMS Thunderer showed clear advantages over traditional chain pumps. Water discharge rates over short durations were similar to the chain pumps, but at greater periods of time, the Massey pumps outpaced the chain pumps significantly (1). The main advantage of the flywheel design seems to be that “it [did] equal work with less fatigue to the men” (1). The trial was so impressive to the Admiralty that they installed Massey’s pumps on HMS Vestal in 1834 (2), and increasingly on Royal Navy vessels thereafter.

Massey’s pumps were a double action “lift and force” pump, consisting of a camshaft driven by two crank handles. The camshaft drove two 18 inch piston rods that powered the pumps. A heavy iron flywheel was mounted on the fore end of the camshaft, and, once in motion, it assisted in maintaining the momentum of rotation (thereby making the crank handles easier to turn). Unlike chain pumps, Massey’s pumps were very difficult to  clog, and could “…discharge a block of wood 9 or 10 inches in diameter”(1).  This was obviously the perfect pump for an arctic expedition vessel.

My plans for the Massey pumps on board Terror are derived from measurements shown on the 1839 plans of Terror and Erebus, with additional information gleaned from the somewhat more detailed HMS Investigator plans. Cross sectional details, especially of the fly wheels and piston rods, were derived from historical images of similar flywheel pumps, as I was unable to locate the patent for Massey’s 1833 pump design.

Plans for Massey's Patent Pumps, as installed on HMS Terror in 1839.



Common Pumps (Bilge):


Terror was fitted with two common, or suction pumps, also known as "elm tree pumps" due to the use of a single bored-out elm trunk as their barrel or tube.  Elm was used because of its general resistance to water, though other water-resistant woods could be employed. The pumps were extremely simple, consisting of a brake (or handle), a spear (or piston) and two valves, and were thus very easy to make and repair. The advantage of placing two common pumps in the fore of the ship was that the fore hold could be pumped out independently of the rest of the ship; which could be critical in a situation such as Back found himself during the 1837 Atlantic crossing.


Plans for HMS Terror's common pumps, as installed on HMS Terror in 1839.


Truscott’s Pump (Fresh Water):


Truscott’s pump was a simple invention that revolutionized the way water was stored and retrieved on Royal Navy vessels. Inspired by a visit to an ale house in 1812 (3), Truscott designed a relatively simple iron pump attached to a small diameter pipe system that led to the hold. Just like in the ale houses, he attached a flexible leather hose to the end of the pipe and fed it into the water casks. This obviated the need to move the casks to retrieve water. This was a major boon on sailing vessels, because moving casks to retrieve water was time consuming, dangerous, and inevitably impacted the ship’s trim, requiring periodic rearrangement of the ship’s casks and ballast. This simple invention eventually led to the use of permanent iron water tanks on sailing vessels, which ultimately resulted in the abandonment of shingle and iron ballast.

A plan of Truscott’s pump (ZAZ6848), dated 18th September 1814, is held by the National Maritime Museum.  The 1839 lower deck plan for Terror and Erebus indicates that one Truscott pump was located at the rear of the ship’s stove, on the starboard side, close to the door to the sickbay.  This pump permitted the crew and the ship’s cook to access fresh water as it was need. Since the water tanks in Terror’s hold surrounded the Sylvester stove/furnace, it is possible that the device could have be used throughout the winter months.  However, it is likely that the fresh water tank above the Fraser stove provided enough for the ship’s needs without using the hold tanks (at least during the winter months when fresh water ice was available).  

Truscott's pump (in red) as installed on HMS Terror in 1839.
The ship's water tanks and Fraser's stove appear in blue. 


References:


1. The Nautical Magazine: A Journal of Papers on Subjects Connected with Maritime Affairs in General. 1833. Page 292.

2. Sharp, James. 1858. Memoirs of the Life and Services of Rear-Admiral Sir William Symonds, Surveyor of the Navy from 1832 to 1847. Longman Brown Green Longmans & Roberts, London. Page 153.


3. Transaction of the Institution of Architects. 1865. Page 191.

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