Sunday, 12 February 2017

A COMPANION (OR TWO?) FOR HMS TERROR

The 1835/1836 modifications to HMS Terror introduced a new fitting to Royal Navy polar exploration vessels– the hatched companionway. Covered companionways began to replace open ladderways on smaller Royal Navy ships in the late 18th century. However, the special type of hatched companionway associated with Erebus and Terror is rare on Royal Navy plans and models until the middle of the 19th century.

The aft companionway of HMS Terror was a simple box-shaped structure, with a large sliding hatch on its roof. To access the ladderway, the crew would slide the hatch back, and then pull open two small starboard-facing doors. They would then descend the ladderway backwards, pausing midway to close the doors, and then the hatch, behind them.

The Companionways on HMS Terror


The 1836/1837 Terror profile plan (1) indicates that this companionway could be removed and replaced with a tall winter deckhouse with a standard-sized door (it was apparently shaped like Terror’s water closet). However, pencil marks on these draughts indicate that this special winter coaming was abandoned sometime after Back’s 1836/1837 Arctic voyage.
Prior to 1839, there was no raised companionway in the forward part of Terror. Instead, an unusual hinged trapdoor system was used to access the forward ladderway. Curiously, this ladderway was located on the starboard side of the vessel, and not on the midline as was typical. This feature was changed in 1839, and a raised companionway identical in design, but somewhat larger, to Terror’s aft companionway was installed (2).
Unlike its aft counterpart, its doors faced port, and it was located just behind the funnel for the ship’s stove.  The ladderway below it descended just aft of the ship’s stove. This must have been somewhat inconvenient, as using it would have introduced terrible drafts to the lower deck mess and sleeping area during the winter months.

Besides the clear labeling on the 1839 Terror and Erebus profile plans (2), evidence for this change in the forward companionway’s position can be found on the 1836 profile plan of Terror (1) which shows that the 1836 trapdoor system was scratched out in pencil. The forward ladderway is scratched out on this plan as well, and a new position, consistent with the 1839 profile plan, has been penciled in.

The companionways on the 1839 builder’s model of HMS Erebus (3) are consistent with the 1839 plans (2). However, the model reveals an additional detail, namely that the companionways had two horizontal tracks which facilitated the sliding of the upper hatch. These rails would have been sheathed in a thin layer of brass or bronze on their upper surfaces, and the hatch itself would have had two grooves cut into its bottom surface (and through its forward edge), permitting it to slide on the tracks.

On both the 1836/1837 and 1839 plans, and crucially, the model, the roof of the companionways and the hatches themselves are flat. This contrasts with most companionways of the era, which had a slight camber (often matching the camber of the upper deck). The reason for this unusual trait is unknown, but plans for HMS Investigator show the same flat-topped companionways, suggesting it may have been specific to polar exploration. Whatever the advantage of this specific trait, the overall design must have been very durable; indeed its efficacy is easily reflected in the fact that the basic design is still used on modern sailing craft.  

References:
(1) National Maritime Museum ZAZ5672
(2) National Maritime Museum ZAZ5673
(3) National Maritime Museum SLR0715


The basic components of the companionway were cut from pear 
wood stock using my local Library’s laser cutter. 

Tracks were added to the roof of the companionway. 

Terror’s companionways were very simple box-like structures.

I had trouble simulating the bronze tracks with brass sheeting, 
so I opted to use a brass foil product here. 

Preparing to cut the grooves in the aft hatch. 
The companionways with hatches and tracks 
completed.  

The completed forward companionway. 

The completed aft companionway. 

Mini-Crozier inspects the workmanship. A coat of Minwax 
Wipe-On Poly provides a protective finish that enhances 
the wood. 

These structures were neither large nor comfortable. Robustness 
seems to have been the primary design feature. 

The 1839 Erebus model indicates that the doors had small knobs, 
which I recreated using brass pins filed to the correct size.  I 
elected to show the doors with hidden door hinges (the doors 
swung outwards), which is common on modern 
companionways of the same design. 

4 comments:

  1. I wonder if the companionway had another sliding door at deck level, inside . Idea is that the other sliding door would help keep cold air out...and more importantly, keep water out should a wave crash upon deck.

    ReplyDelete
  2. Stainless steel fibre is used in reinforce monolithic refractories against thermal and mechanical shock by reducing cracking If anyone looking for stainless steel fibre for concrete then you can contact Precision Drawell. Thanks for sharing.

    ReplyDelete
  3. Your blog is very useful and provides tremendous facts. Keep up the good work. Get More Detail About Stainless Steel Fibre

    ReplyDelete