The Moidart was an armed freighter but was originally built as a schooner rigged steamship 243 ft long. She was built by James Gardiner & Company. 
In 1888 he formed the Western Steam Ship Company Ltd, with James Gardiner & Company as managers, and embarked on a programme of new buildings at the yard of Charles Connell & Company at Glasgow.
The company initially began tramping operations because, at the time, about fifty percent of the world cargoes were carried by any available ship at the lowest freight rates. The company’s first service was between Rio de Janeiro and Cape Town carrying coffee. 
By 1912 the Gardiner fleet consisted of twelve ships operated by four companies, 
Western Steam Ship Company Ltd with 4 ships, 
Indian Steam Ship Company Ltd. with 4 ships, 
S.S. Gairloch Company Ltd with two ships and 
S.S. Kincraig Company Ltd. with two ships. 
At a later date one ship was owned by the Caledonia Steam Ship Company. Their firsh ship was the “Moidart”

The following is an extract from book by Kendal McDonald
They had put a gun on her stern, and given her crew two extra Royal Navy gunners to man it, but it was never fired in anger. Moidart’s last voyage was up-Channel, from Cardiff for Le Havre, a wartime supply run with a cargo of 1550 tons of Welsh coal and another 80 tons of steel plates. 
At 2am on 9 June, 1918, her captain George Skea was in the chartroom plotting out where he would turn away from the English coast and head for the French port. He was 14 miles north-west of Portland Bill, and it was nearly time to start turning.
On watch on the bridge was the first mate, William Drever. The sea was calm, the moon out and visibility was good, but Drever got a sudden shock. A large submarine appeared on his starboard side, only 400m away. The look-outs apparently hadn’t seen it. 
Drever ordered the helm hard over, to put the submarine directly astern. He then raced to the chartroom to alert the captain.
But in less than a minute a torpedo struck the Moidart to starboard near the stern gun, and she began to settle. Another minute, and she sank by the stern. No boats could be launched, and most of the 21 crew found themselves either in or under the water. 
At the height of the struggle to find something that would float, the German submarine glided into the middle of the struggling men and, ignoring their cries for help, demanded to know the name of their ship.
Some of the crew finally found one of the boats floating upside-down, and six men clung to it for six hours until they were picked up by a passing Glasgow steamer, the Clifton Grove. They were the sole survivors.
The U-boat that sank the Moidart was UC77, commanded by Oberleutnant Johannes Ries. He and his crew were all killed just one month later on 10 July, when they were depth-charged by two Royal Navy trawlers in the Dover Straits.
Both the Moidart’s gun and bell have been raised by divers.

Today the wreck stands 6m off of the 35m seabed and is broken into two parts as shown in Callum’s sketch

Submarine UC-77

Type                      UC II

Shipyard              Vulcan, Hamburg (Werk 82)

Ordered               12 Jan 1916

Launched            2 Dec 1916

Commissioned  29 Dec 1916

Commanders    

29 Dec 1916 – 29 Jan 1918             Kptlt. Reinhard von Rabenau (Royal House Order of Hohenzollern)

30 Jan 1918 – 14 Jul 1918               Oblt. Johannes Ries

Career  13 patrols

5 Mar 1917          – 4 Jul 1917          I Flotilla

4 Jul 1917             – 14 Jul 1918        Flandern/Flandern II Flotilla

Successes            34 ships sunk with a total of 50,743 tons.

7 ships damaged with a total of 23,734 tons. (View ships hit by UC 77)

Fate       14 Jul 1918 – Mined off the Flanders coast in late July 1918.. 30 dead (all hands lost).