CISMAS

HMS Colossus: debris field survey 2004
Targets Identified

The following are the magnetic anomalies where artefactual material was identified. The target numbers consist of the track number separated from the data point number by a slash.

5/884
Position: 260145.7E 5535814.4N
Seabed: Flat sand
Dive No: DFS12
Anchor and chain : A small iron anchor with folding iron stock, approximately 3m of iron chain still attached to the anchor. Anchor shank 2.76m long, 1.16m from fluke to fluke. The anchor is of the round-crown type and thus is later in date than Colossus. The anchor was located c.3m south of the position indicated by the magnetic anomaly.
Iron object : A concreted iron metal bar, square in section and approximately 2 x 0.01 x 0.01m. Located c.12m NNE of the position indicated by the magnetic anomaly. It seems unlikely that this item derives from Colossus.

8/1419
Position: 260118.3E 5535599.9N
Seabed: Sand
Dive No: DFS20
Iron object : Complex in shape and heavily concreted. C.20 SE of the position indicated by the magnetic anomaly. This object is fairly close to the stern section of Colossus and is therefore probably derived from Colossus.

9/5048
Position: 259827.8E 5535456.7N
Seabed: Rock and kelp
Dive No: DFS10
Iron object : Heavily concreted iron ‘bar’, 1.3m long and c. 0.06 x 0.03m in section, tapering to a point at one end. Found 7m SE of the position indicated by the magnetic anomaly.
Shot : A group of approximately 35 concreted iron shot situated approximately 8m west of the position indicated by the magnetic anomaly. The concreted shot was approximately 0.016m in diameter. Depending on the thickness of the concretion, this could be any weight of shot between 18lb and 32lb. The location of these items fairly close to the area where Roland Morris located Colossus material increases the likelihood that this shot was from Colossus.

10/942
Position 259940.4E 5535405.2N
Seabed: Flat sand with small rock outcrops, some kelp & weed
Dive No: DFS22
Iron gun[Gun 9]: Concreted iron gun lying upside-down on the seabed. Remains of the iron fastenings of the gun carriage are evident beneath the gun. In addition the trunnion straps and parts of the strap bolts also survive. The gun’s muzzle lies 3.9m NE of the position indicated by the magnetic anomaly. The cascabel button of the gun has the loop characteristic of the Blomefield pattern gun. The dimensions (see below) are consistent with a Blomefield 32lb gun.
Length (base ring to muzzle face) 2.89m
Diameter of base ring 0.60m
Diameter of trunnions 0.18m
Base ring to trunnion (centre) 1.22m Diameter of bore 0.17m

11/3447
Position: 260173.8E 5535535.6N
Seabed: Sand with occasional kelp
Iron gun [Gun 8]: This is a 32lb Blomefield gun, previously recorded during the survey work undertaken in 2003 (See Colossus Progress Report 2003).
Length (base ring to muzzle face) 2.90m
Diameter of base ring 0.63m
Diameter of trunnions 0.17m
Base ring to trunnion (centre) 1.25m
Diameter of bore 0.15m

11/5880
Position: 260000.5E 5535275.9N
Seabed: Flat sand
Dive No: DFS1, DFS4 & DFS26
Anchor: Iron anchor with one fluke buried in the seabed, the other standing upright. The shank of the anchor lies flat on the seabed. The anchor ring is still in place but the stock (originally wood) is now missing. This anchor is of the round-crown type (introduced in the early 19th C) and as such is later in date than Colossus. The anchor ring was located some 0.50m from the position indicated by the magnetic anomaly.
Shank length 3.20m
Arm length (crown to fluke tip) 1.20m
Ring diameter 0.30m

12/1788
Position: 260094.4E 5535529.7N
Seabed: Coarse sand with pebbles and broken shell
Dive No: DFS11 & DFS27
Anchor : Iron anchor with one arm missing; the shank and surviving arm are lying flat on the seabed. The anchor ring lies 0.20m SSW from the position indicated by the magnetic anomaly. The anchor is of the angle-crown type and as such is earlier than c.1815. If this were an anchor from Colossus it would have to be the kedge anchor, which was the smallest of the five anchors a 74 would normally have carried. The dimensions of this anchor accord very well with the published dimensions of the kedge anchor of a 746.
Shank length 2.90m
Arm length (crown to fluke tip) 1.15m
Ring diameter 0.45m
It should, however be born in mind that St Mary’s Roads has been an anchorage for many centuries and anchors are to be expected in the area. The record of the loss of Colossus7 tells us that the three bower anchors were deployed but no mention is made of the stream or kedge anchors being used. It is hard therefore to account for the missing arm of this anchor if it was from Colossus.

12/2061
Position: 260128.6E 5535581.6N
Seabed: Sand with small rocks and some weed
Dive No: DFS18
Iron object: Heavily concreted iron object 1.8m long x 0.60m x 0.10m. Found 7m ENE of the position indicated by the magnetic anomaly. This is very close to the edge of the known stern wreckage and is therefore probably material derived from Colossus.

13/4708
Position: 259877.0E 5535455.5N
Seabed: Rock, boulders and thick kelp
Dive No: DFS2
Iron shot : An area approximately 2m x 3m of concreted cannon balls – at least 14 were counted. They were situated 3m south of the position indicated by the magnetic anomaly. It was not possible to get a meaningful measurement of the shot due to the irregular nature of the concretion but the divers felt these were probably 32lb shot.8

15/4448
Position 259941.5E 5535407.3N
Seabed: Flat sand with small rock outcrops, some kelp & weed
Dive No: DFS22
Iron gun [Gun 9]: The muzzle of gun 9 lies 2m WNW of the position indicated by the magnetic anomaly. See 10/942 above.

16/2035
Position: 260209.3E 5535554.3N
Seabed: Flat sand
Dive No: DFS9 & DFS19
Iron gun [Gun 10]: Concreted iron gun lying upside-down on the seabed. This is probably the same gun located by the archaeological diving contractors in their work earlier this year9.The muzzle of the gun was 1m south of the position indicated by the magnetic anomaly. The gun has a small pile of lightweight, heavily concreted chain lying on the seabed on its south side. This chain is also evident lying over the top of the gun in the region of the trunnions (three strands). The chain is not continuous but appears to be wrapped around the trunnions rather than around the gun barrel. The cascabel button of the gun has the loop characteristic of the Blomefield pattern gun. The dimensions (see below) are consistent with a Blomefield 32lb gun. Length (base ring to muzzle face) 2.88m
Diameter of base ring 0.68m
Diameter of trunnions 0.18m
Base ring to trunnion (centre) 1.25m

B3/2790
Position: 259893.4E 5535436.6N
Seabed: Rock, large boulders and kelp
Dive No: DFS5
Shot : Heavily concreted cannonballs lying 6m SSW of the position indicated by the magnetic anomaly. Five complete and several broken shot were observed. There was evidence that shot had been removed from the seabed. Copper sheet : A rectangular piece of copper alloy sheeting 0.48m x 0.22m with two nail holes – possibly copper sheathing. This area is very close to the supposed ‘galley’ area and the SW end of the ‘Morris gulley’, so these objects are likely to be from Colossus.

B6/2097
Position 259941.4E 5535405.3N
Seabed: Flat sand with small rock outcrops, some kelp & weed
Dive No: DFS22
Iron gun [Gun 9]: The muzzle of gun 9 lies 3.2m NE of the position indicated by the magnetic anomaly. See 10/942 and 15/4448 above.

B7/216
Position 260207.7E 5535547.5N
Seabed: Flat sand
Dive No: DFS9 & DFS19
Iron gun [Gun 10]: The muzzle of gun 10 lies 5.8m SSW of the position indicated by the magnetic anomaly. See 16/2035 above.

B7/414
Position 260184.5E 5535531.3N
Iron gun [Gun 8] : The muzzle of gun 8 lies 12.55m WNW of the position indicated by the magnetic anomaly. See 11/3447 above.

B9/3296
Position: 259736.9E 5535364.3N
Seabed: Large boulders and thick kelp
Dive No: DFS23
Iron object : Concreted iron object, roughly cylindrical in shape 1m long by 0.05m diameter. This object was 3m SSE of the position indicated by the magnetic anomaly.
Copper alloy strip : small piece of copper alloy 0.20m x 0.04m x 0.005m found 2m north of the position indicated by the magnetic anomaly.
Copper sheathing : A small piece of copper sheathing (with nail holes) 0.01m x 0.05m x 0.001m situated 4m east of the position indicated by the magnetic anomaly.

Gun 7
Position: 260191.26E 5535576.91N
Seabed: Sand and small stones, some kelp
Dive No: DFS29
Gun 7 cascabel formed the centre of the search area.
Copper alloy object: Square in shape 0.058m x 0.058m x 0.007m with 0.02m hole in the centre (see photo). Found 12m ENE of gun 7 cascabel. Iron objects: Two heavily concreted iron objects a) 0.55m x 0.20m b) 0.35m x 0.20m. Found 3.5m NW of gun 7 cascabel.

6 Lavery The Arming and fitting of English ships of War 1600-1815.
The kedge anchor of a 74
Shank 9’ 6” (2.89m)
Arm 3’ 2” (0.96m)
Ring 1’ 3” (0.38m)
Weight 8cwt (406kg)

7 Captain Murray’s account of the loss of Colossus ADM 1/5348 and letter from Murray to Napean ADM 1/2136

8 This estimate should be treated with caution as the difference in diameter between 18lb and 32lb shot is only just over 1”, it is very difficult to estimate the size of heavily concreted shot.

9 The position given to me by the diving contractor is some 10m south of where the gun actually lies – a search of the surrounding area failed to locate any other gun. The contractor told me that their position was only approximate (personal correspondence with Graham Scott).




Introduction
Project outline
ADU magnetometer survey
Wessex Archaeology survey
Project methodology
The targets
Targets investigated
Targets identified
Plan of the targets identified
Summary of anomalies investigated
Anomalies yet to be investigated
The photographs
Conclusions
Acknowledgements
Appendix 1 -Magnetic anomaly graphs
Appendix 11 -Colossus debris field survey - diver record sheet
CISMAS