the release mechanism was connected to it, served as a lift point for 

 the lowering of the double block. The modular add-on block measured 

 4x4x1 feet, and had a 5-inch hole in the middle of it. The lower 

 portion of this hole has the same shape and dimensions as the guide 

 cone skirt. On the top of the hole, a catch was attached for emplace- 

 ment and retrieval. A guide cylinder made of 4-inch pipe was vjelded to 

 the inner wall of the 5-inch tubular hole. A notched lower edge of this 

 guide cylinder fits with the top edge of the guide cylinder on the guide 

 post. During the mating of the add-on block to the guideline anchor, 

 the guide plates force the add-on block to re-orient and match each 

 other (Figure 5) . 



Guide Frame. A versatile guide frame, a rectangular truss fabricated 

 of steel pipes and angles, was designed for use in both single and double 

 guideline systems. Two or more such trusses can be quickly bolted 

 together to make a longer guide frame. For a single guideline system, 

 a guide cone and a lift m.ember are attached on either side of the guide 

 frame.* For a double guideline system, a guide cone is installed on 

 either side of the guide frame, and the lift member is inserted at the 

 middle, between the trusses (Figure 2). 



Guide Cones. The guide cones were made of short sections of standard 

 5-inch steel pipe and steel plates. The plates formed a conical skirt 

 below the pipe section to guide the guide post into the guide cone. A 

 vertical slot cut along the side of the guide cone allowed the quick 

 insertion and release of the guideline. Another function of the skirt 

 was to prevent severe bending of the guideline against the sharp edge 

 of the steel pipe section. Figure 6 shows a guide cone used in the 

 first series of sea tests. The fin-like plate below the guide cone in 

 Figure 6 was one of the supports for the current meter. 



A latch was designed to block the opening and to keep the guideline 

 inside the guide cone. The wing nuts could be loosened and the latches 

 opened to allow passing of a guideline. For later tests, a metal strip 

 was attached to the latches to completely cover the slot, and the open 

 end of the tube was reinforced by a peripheral stiffener. 



Mechanical Release. A mechanical release (Figure 7) was developed 

 for placing or retrieving objects from the seafloor. The release 

 basically consists of three barrel hooks hinged to three flanges. The 

 flanges, spaced 120 degrees apart, are welded on the outside of a sec- 

 tion of steel pipe. Each hook is controlled by a spring with one end 

 fastened to the flange. There are two places that the free end of the 

 spring can be attached. When the spring is attached to the top of the 

 hook, the tip of the hook tends to close into the retrieval position 

 (Figure 7) . When the spring is attached to the hook below the hinge 

 point, the hook is forced to open into the release position (Figure 8). 



*Two guide cones, one above the other, were used in earlier tests; 

 a single guide cone worked better for deck handling. 



