## 3 Materials and Methods
### Components  
In the following sub-sections, the specific components referenced in the text are numbered for ease of cross-reference with the associated figures, with yellow capital letters denoting vehicle-specific components for reference, yellow numbers denoting spool and tether assembly components, blue numbers denoting anchor sleeve assembly components, and red numbers denoting anchor assembly components. Note that the RAATM was intended to be integrated within a small, spherical AUV, such as the WIEVLE, but could potentially be implemented on a variety of AUVs. In the WIEVLE, the RAATM would be contained within the space aligned vertically with the central axis, also known as the Central Payload Tube (CPT) [4]. In other underwater vehicles, one or more RAATMs may be incorporated in a similar manner such that the configuration enables the anchor port(s) to directly contact the seabed. The spool and tether assembly components are depicted in Figure 3 and labeled with yellow numbers. Figure 3: RAATM spool and tether assembly components: (**a**) RAATM spool and tether assembly components in the _rooted_ position within the WIEVLE; (**b**) RAATM spool and tether assembly components in the _rooted_ (**left**) and _stowed_ (**right**) positions. Figure 2: The RAATM, installed within the WIEVLE, executing the anchoring sequence from the _stowed_ to the _tethered_ positions. The tether spool (1) is mounted at the top of the mechanism by brackets (2). The tether (3) is connected at one end to the spindle (4), upon which it is wound and through which electromagnetic signals may be sent or received; the tether is connected at the other end to the swivel eyelet (5) at the top of the anchor spike (6). The tether thickness may vary depending on the vehicle's size, but it should be thin yet strong enough to hold the AUV against anticipated currents. Since the tether also serves as an electromagnetic antenna, the tether and spindle should be made of an appropriately conductive material, and the tether, when deployed, should be extended to a suitable length corresponding to the intended wavelength of the electromagnetic signal to allow signal transmission and reception via the vehicle's onboard transceiver. Torque is transmitted to the tether spool via one or more electric actuators (7), rotating the spindle to extend or retract the tether. The anchor sleeve assembly components are depicted in Figure 4 and labeled with blue numbers. The anchor sleeve (8) is a cylindrical tube positioned below the tether spool (1) that contains the deployable anchor assembly. It consists of a fixed cylindrical tube joined to a beveled, notched anchor port (9) at the base of the hull. The anchor port retains the anchor plug by permanent magnetic inserts in the base of the anchor plug and the anchor port walls. The cylinder extends upward, terminating just below the tether spool (1), and it contains vertical slots that enable the interfacing of corresponding vertical spur gears (10), driven by electric actuators (11) adjacent to the anchor plug, extending upward and engaging with the corresponding outer splines of the anchor cap coupler (12)--a vertically-splined, externally cylindrical and internally conical (concave) spur gear. The anchor cap coupler is compressed by the anchor spring (13) onto a corresponding (convex) conical spur gear that serves as the anchor cap. The anchor cap coupler has a small, beveled, central guide hole allowing the swivel eyelet (5) to insert and the tether (3) to pass through. The anchor spring (13) glides smoothly within a groove at the top of the anchor cap coupler (12) to allow the anchor cap coupler to rotate freely inside the anchor sleeve (8). The anchor sleeve cap (14) is fixed at the top of the anchor sleeve (8) and retains the anchor spring (13) to enable compression. The anchor sleeve cap (14) contains a central guide hole (15), reinforced with a Teflon insert, to resist abrasion from the tether and damage to the tether, reduce friction, and center the tether onto the tether spool (1).