A Remote-sensing Survey of Key West Harbor and Approaches, 2003-2004 Magnetometers Ready to be Deployed, Key West Harbor, December, 2003 Prepared by: Corey Malcom Mel Fisher Maritime Heritage Society 200 Greene St. Key West, Florida In Accordance with FKNMS Permit # 2003-077
Acknowledgements: Phase 1 of the Key West Harbor archaeological survey has been completed only through the efforts of many. Logan Mitchell, John Wray, Craig Jones, Bruce Darby and George Robb, Jr. of the RPM Nautical Foundation conducted the remote sensing-surveys. Jeff Royal and George Robb, Jr. of RPM processed the magnetic data. Howard Phoenix, Craig Jones and John Wray of RPM, and Sara Tinsley of the Mel Fisher Maritime Heritage Society conducted the reconnaissance diving to identify targets. All underwater photographs are by Howard Phoenix.
Phase 1: Archaeological Investigations of the Key West Harbor, 2003-2004 Project Overview: Maintenance dredging of the Key West Harbor is scheduled to begin in early 2004. To identify, and alleviate any potential impact on archaeological resources, a preliminary archaeological survey of the areas to be affected was conducted. The initial phase of this assessment was a magnetic remote-sensing survey. A number of man-made objects have been identified through this effort, including some of significance. The results of this survey will be used to guide any further archaeological research within the Harbor. Purpose: Key West Harbor was used intermittently in historic times from 1513, when the first European explorers passed through the area, until the early 1800 s. Since 1822, with the island s permanent settlement, it has served continuously as the main point of entry and anchorage for private, commercial and military vessels. As crews and passengers engaged in the course of their daily routines, objects were lost or disposed of overboard. Shore-side activities resulted in similar losses. Over time, many man-made objects have found their way onto the sea floor, and remain there, resulting in an area of concentrated debris. Throughout the recent past, many artifacts from all periods of the islands history, have been collected from the harbor by recreational scuba divers. As large ships enter and exit, they churn the bottom sediments, and objects are constantly being both covered and uncovered. Before beginning this survey, it was expected that many significant artifacts remained, both buried and exposed, within the proposed dredge areas. The harbor was dredged to a depth of 34 feet in the 1960 s, and the 2004 dredging project is planned as maintenance dredging, designed to return it to its 1960 s level. Significantly, the current dredge plans include a provision to go to 37 feet an extra degree of excavation to ensure the desired controlling depth is achieved, and which may impact in situ archaeological preservation. Beginning November of 2003, at the request of the State of Florida Bureau of Archaeological Research and the Florida Keys National Marine Sanctuary, the Mel Fisher Maritime Heritage Society (MFMHS) and The RPM Nautical Foundation (RPM) began an archaeological survey of the Key West Harbor. This survey was intended to mitigate any impact to submerged archaeological resources that might result from the US Navy dredging project of the area, set to commence in 2004. This work is planned in two phases, with the first being the remote sensing of the proposed area of impact. The second will be the recovery of archaeological resources, both as dictated by the results of Phase 1, and also through a random sampling strategy. With the completion of the magnetic survey of the impact areas, and identification of anomalies, selected cultural resources have been deemed significant, and should be removed before any damage or destruction occurs from the dredging.
A view of Lakota s back deck with magnetometer cables and reels during the Key West Harbor survey December 2003 Survey Methods: The 48-foot, aluminum-hulled R/V Lakota was used to tow an array of three Geometrics model 881 cesium magnetometers. Each magnetometer recorded the magnetic field found within its range. This data was then be interpreted as a gradiometer, utilizing the differences in readings between magnetometers. Each of these towed devices was spaced 5 meters apart. The magnetometers sampled the magnetic field at a rate of 0.3 seconds, while traveling at a speed over ground of between 3 and 6 knots. The survey vessel traveled in lanes spaced at 15 meters (approximately 1/100 th of a nautical mile), oriented with the direction of the proposed dredge channel, ensuring that one magnetic sensor passed over every 5 meters of the survey area. Consistent and accurate lanes were ensured through the use of Trimble s Hydropro Navigator software, and Lakota s combination of bow-thruster forward, and twin propellers aft. As the proposed survey area varies in depth from 40 feet to 30 feet, the towed gear was adjusted accordingly. The collected magnetic data was recorded via Geometrics MagLog Lite software, which allows the information to be merged with that from the Global Positioning System. Data was collected to three sets of CD s on a daily basis, as well as stored in the computers hard drives. The combined magnetic and geographic data provided information relating to the distribution of shipwrecks. The magnetic data was interpreted via Surfer 8.0 software, which produced charts showing magnetic intensity relative to the geographic position, via differential GPS, across the surveyed areas. Additionally, a 600mHz Marine Sonics sidescan sonar fish was towed across selected areas. The sonar was set to image either 25 or 50 meters to each side of the towed fish, depending on water depth. The sidescan sonar data was collected and interpreted through Sea Scan PC software, providing underwater, visual images of the surveyed tracks.
From this evaluation, divers assessed a total of twenty-six magnetic targets for their significance. These were selected by their magnetic intensity, and in some cases, their relationship to other known anomalies. Using GPS data, the boat anchored near each anomaly, and divers with metal detectors worked to pinpointed the hits. Their observations were recorded, and in many cases photographs were taken. In accordance with FKNMS regulations, there was no excavation during this phase of investigation. The survey computer s on-screen display of the magnetic signal as it was being recorded in Key West Harbor.
Boundary coordinates of the three areas - Cut A, Cut B, and the Key West Harbor covered by the remote-sensing survey.
The Survey Area: There are three areas of the Main Ship Channel and Harbor that are to be dredged. They run in approximately a north-south line from just west of the island of Key West, to the reef approximately 7 miles south. The areas to be dredged are bounded as follows: Harbor Entrance: N24º 28.219 W81º 48.062 N24º 28.219 W81º 48.126 End Mid Channel Range: N24º 30.802 W81º 48.305 N24º 30.982 W81º 48.256 CUT A Range: N24º 31.714 W81º 49.000 N24º 31.791 W81º 48.867 R12 (dog leg): N24º 31.972 W81º 48.926 CUT B Range: N24º 32.918 W81º 48.865 N24º 32.918 W81º 48.931 Harbor Perimeter: N24º 33.057 W81º 48.704 N24º 33.227 W81º 48.678 N24º 33.558 W81º 48.491 N24º 33.657 W81º 48.680 N24º 33.514 W81º 48.756 N24º 33.517 W81º 48.899
Results: Based on the magnetic data, divers investigated selected anomalies, recording the details of their findings. The majority of anomalies were recorded in Cuts A and B. Key West harbor itself showed much less activity. The divers searches were conducted with the aid metal detectors. The following observations were made: Cut A Anomalies Investigated Anomaly Location Diver Comments 01 W81.80628354 Buried Object N24.51631906 02 W81.80723063 Multiple small buried readings N24.51626771 03 W81.80723063 Many medium buried readings N24.51935424 04 W81.80731994 2-inch diameter steel cable, same as #5 N24.51989645 05 W81.80766976 2-inch diameter cable, over 300 feet N24.52013908 06 W81.8078588 2-inch diameter cable N24.52070771 07 W81.81142838 Debris field, incl. 4x8-foot iron frame and chain N24.52441572 08 W81.81279971 Buried 4-5 foot diameter reading N24.5240994 09 W81.81404564 Small readings, unidentified N24.52866463 10 W81.81462655 Iron framework, plate, banding N24.52793096 11 W81.81598077 6x14 foot buried hit N24.52865068 12 W81.80840511 2x2 foot metal bands N24.518719
Cut A Magnetic Chart with Investigated Anomalies
Cut B Anomalies Investigated Anomaly Location Diver Comments 01 W81.8160272 Soft silt, small hits, cans, iron rings N24.5286491 02 W81.81503261 Scattered modern wreckage, plates, shrimp-net, tire N24.54109527 03 W81.8151431 Piece of metal 20x1 feet, C-shaped N24.54132681 04 W81.81524939 Buried metal object, Iron Tank N24.5475632 05 W81.81488274 Danforth-style anchor, 15-20 lbs. N24.54765879 06 W81.81474726 6-foot Anchor, Metal chair frames, line N24.54280274 07 W81.8154432 Oil-pan from engine N24.53862017 08 W81.81559152 5-foot iron bar with 20-inch sq. ends N24.53799268 09 W81.815763836 Iron bracket and 24-inch steel bar N24.54207707 10 W81.81542609 22 x 14-inch anchor palm N24.53986944 11 W81.81523784 I-beam, pulley, pipe, bundle of line N24.53206005 12 W81.81591097 4 x 6-foot iron plate, I-beam, netting N24.5344452 13 W81.81587674 Very large anchor in two pieces with 100ft of chain N24.53329792 Misc. metal debris, glass bottles, ceramic dishes 14 W81.81862076 Crank and pole, Iron plate 30 x 15 inches N24.53693165
Cut B Magnetic Chart with investigated anomalies.
Cut B Anomaly 2 I-beam fragment Cut B Anomaly 2 Iron Pipe or Outrigger section Cut B Anomaly 2 Netting Cut B Anomaly 2 Tire Cut B Anomaly 2 Scattered Metal Debris Cut B Anomaly 2 Scattered Metal Debris Anomaly B-2 proved to be scattered debris, most likely from a modern commercial fishing vessel. Though none of the hull was found, significant portions such as rigging and netting were, suggesting that this may have been a site where the trawling gear snagged, tearing portions of this equipment away from the vessel.
Cut B Anomaly 3 Flattened Pipe, End View Cut B Anomaly 3 Long View Anomaly B-3 is a roughly 20-foot long iron pipe that has been flattened. It may be part of a commercial fishing vessel s outrigger. Cut B Anomaly 4 Cylindrical Iron Tank Cut B Anomaly 4 Partially buried iron object Anomaly B-4 is an iron tank with mounted valves, and a partially buried object. The blackish appearance of the concretion, with loose rock and shell adhesions suggests the latter is made of modern iron. Cut B Anomaly 6 Anchor Cut B anomaly 6 Chair and Line Anomaly B-6 is an iron-stocked anchor, approximately 6 feet long. Associated is a tangle of line surrounding at least one metal chair frame. The anchor is of an older design.
Cut B Anomaly 7 Oil Pan From Engine Cut B Anomaly 8 Five-foot iron bar with 20-inch square ends Cut B Anomaly 8 View 2 Anomaly B-8 is a large, 5-foot long iron bar with 20-inch square plates fixed to both ends. It is roughly the size of an axle and pair of wheels from a train, but its original function is unknown.
Cut B Anomaly 10 Cut B anomaly 10 Anchor Palm Anchor Palm Anomaly B-10 is a heart-shaped, iron anchor palm. It has been detached from the anchor. Cut B Anomaly 11 Pulley Set Cut B anomaly 11 Tangle of Line A combination of pulleys, I-beam, iron pipe, and a tangle of line at Anomaly B-11, suggests this is snagged trawling gear from a commercial fishing vessel. Cut B Anomaly 13 Detached Anchor fluke View 1 Cut B Anomaly 13 Detached Anchor fluke view 2
Cut B Anomaly 13 Anchor shank, View 1 Cut B Anomaly 13 Anchor shank, View 2 Cut B Anomaly 13 Anchor Chain and Shrimp Net Cut B Anomaly 13 Misc. Iron Debris Cut B Anomaly 13 Dark green glass wine bottle Cut B Anomaly 13 Iron Box Anomaly B-13 is actually a large area with the most prominent feature being a large stockless anchor with over 100 feet of chain attached to the shank, and one detached fluke. It appears the fluke was designed to be removable. A variety of other iron and aluminum objects are nearby. Also associated are a number of glass bottles and ceramic dishes, many of which appear to be 100+ years old. The area looks to be both a dumpsite, and a collection area for items washed out of context by both natural and propeller induced forces.
Key West Harbor Magnetic Chart
Conclusions: The majority of the investigated anomalies were composed of modern debris. Two, Anomaly B-6, and Anomaly B-13 are the locations of iron anchors that are of interest. Anomaly B-6 is an iron-stocked anchor that could be as old as 150 years, judging it as it is found. At Anomaly B-13 there is a large stockless anchor in two pieces with a large amount of chain. It is of undetermined age or origin. The dive-training program at the Florida Keys Community College has expressed an interest in removing these anchors to their underwater research area, adjacent to the Stock Island campus. This same facility houses the wooden hull remains of the 1622 Spanish galleon Nuestra Señora de Atocha, and would be a good place to preserve the anchors, while also allowing them to be available as an educational resource. Throughout both Cuts A and B there were buried magnetic anomalies, but the potential for their significance is diminished by the fact that these areas were previously dredged in the mid-1960 s. If time allows, there might be some interest in excavating a sampling of these. Otherwise, the potential is still strong for non-magnetic items to be found within the proposed dredge area, especially within Key West harbor itself. At Anomaly B-13, there are a number of bottles and ceramic items that appear to be over 100 years old. A sample of these should be collected. A system of sampling areas of the Harbor itself should be employed to gain some understanding of the similar types of materials that can be found there. At selected points within the boundaries of the dredging operation, divers should collect all cultural materials that can be found within a given radius of the point. To ensure proper post-recovery documentation, the Mel Fisher Maritime Heritage Society has agreed to provide conservation and curatorial services for any recovered objects. With such a strategy, enough material can be observed and collected to give a good sense of the cultural materials found at the bottom of one of the oldest harbors in the state of Florida, as they existed at the beginning of the 21 st century.