TWIN-SPOOL WINCH 



CABLE 



ARTICULATED 

 CRANEWAYS 



PONTOON 



Fig. 12.17 Stern crane-ways concept. (AMF) 



appears to be the critical operation in this 

 concept and would likely involve use of di- 

 vers. 



Drawbridge (Fig. 12.18): Also designed by 

 A. P. lanuzzi, the drawbridge system has 

 advantages and disadvantages similar to the 

 AMF and U-frame concepts. 



Stiff-Leg Boom (Fig. 12.19): One of the 

 most readily available and simple concepts 

 for lifting objects at sea, the stiff-leg boom 

 suffers from all the problems associated with 

 such activities: Pendulum effect, handling 

 when the vehicle is in the air and differential 

 motion between lift device and submersible. 



Constant Tension System (Fig. 12.20): This 

 was designed by J. T. Leiby (10) to eliminate 

 shock loading on both submersible and lift 

 device, while at the same time controlling 

 pendulum motion. The constant tension de- 

 vice limits the load on the hook to 1.5 times 

 the rated load. A motion restraining device 

 permits vertical heave but restrains horizon- 

 tal motion. A light "tag" line (nylon) is 

 hooked to the submersible from the ship and 

 the main hook-up (lift) connection is made 

 under constant tension using the tag line as 

 a guide. When lift is started, the constant 

 tension feature is locked in payout mode but 

 still provides pay-in (overhauling) if the vehi- 

 cle should rise faster than hoisting speed. 



Design of the pendulum motion restraining 

 device was not discussed by Leiby. 



Telescoping Boom (Fig. 12.21): The disad- 

 vantages of this approach are as follows: In- 

 haul lines are required to guide the vehicle 

 into hook-in position and, in addition, modifi- 

 cation of the lifting points is required. A 

 shock absorber on the grapple is designed to 

 overcome differences in vertical motion be- 

 tween vehicle and crane tip. 



Hinged Ramp (Fig. 12.22): Proposed by R. 

 Gaul and R. Bradley (Westinghouse), the 

 hinged ramp system seeks to mate the sub- 

 mersible to a submerged, slanting platform 

 which heaves and plunges in concert with 

 the surfaced submersible. Once the submers- 

 ible is on the ramp, it is winched aboard; 

 during the course of recovery, the roll, heave 

 and mass force of the submersible are gradu- 

 ally transferred to the ship. The ball-in- 

 socket joint de-couples roll between ship and 

 ramp, and hydraulic ramps act first as shock 

 absorbers and subsequently as vertical sup- 

 port when the submersible is drawn out of 

 the water. Movement up the ramp may be 

 over skids or rollers on the submersible (re- 

 quiring attachment of the heaving cable by 

 divers) or on a specially designed mobile 

 platform to which the submersible mates. 



The following launch/retrieval concepts 



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