point of convergence of the diverging arms 17 a rigid lifting arm 19 is fixed onto the articulation hinge formed by interconnecting pin 18 and positioned between the two parallel side arms 6a and 6b of the fork shaped structure the rigid lifting arm 19 is hinged onto the interconnecting pin 18 at the free end of its two diverging arms 19a and 19b as best seen in fig1 and 3 at the converging ends of the rigid arm 19 shown by reference numeral 20 there is supported a group of pulleys 21 about which a cable 22 passes and is wound through transmission pulleys 23 onto a winch 29 operation of the winch 29 and pulley systems 23 and 21 varies the position of the rigid lifting arm 19 about the interconnecting articulation pin 18 a second group of pulleys 24 is supported from the end 20 of the lifting arm 19 and about which passes a cable 25 from which is suspended another group of pulleys 26 carrying a connecting hook 27 during pipe laying operation a pipe 2 is connected to the hook 27 and by operation of a winch 28 supported from one of the diverging arms 17.