as shown by fig1 the diving spear 10 of the present invention comprises an elongate shaft 12 which may be constructed in separate sections such as a tip section 13 , mid section 14 and tail section 15 . the shaft 12 is mounted with a spear head 16 comprising a spear point 17 and spear head connection shaft 18 . a stretchable thrust generating means such as rubber surgical tubing loop 20 is mounted at the aft end of the shaft 12 on a holding means such as holder loop 22 . the holder loop 22 may be constructed from 3 / 32 inch brass rod which is looped and soldered at the ends to form loop portion 21 and tail portion 23 . as shown by fig2 , and 7 surgical tubing 20 is retained in the loop by passing the free ends thereof through the loop portion 21 and thereafter inserting expanding means such as a 5 / 16 inch diameter copper plug 24 into the surgical tubing cavity 76 . as illustrated by fig6 and 7 this may be accomplished by use of a ball point pen 78 or similar device inserted into a bore ( not shown ) in the copper plug and thereafter pushed into the tubing cavity 76 . as shown by fig2 a string means 26 such as a four and one - half foot length of 3 / 32 inch diameter nylon rope may be attached to the rubber holder loop 22 by passing one end thereof through the loop portion 21 and tying a knot 27 therein . the string 26 may be provided with stiffening means such as an elongate sleeve 30 which may be a fifteen and three - quarters inch length of nylon tubing of 3 / 16 inch outer diameter and 0 . 138 inch inner diameter . the nylon sleeve 30 frictionally engages the string 26 to provide sufficient structural stiffness to allow the string 26 to be quickly and easily reinserted in an elongate bore 42 in the aft portion of shaft 12 as discussed below . as shown by fig2 a second sleeve 28 such as a one inch length of polyethelene tubing having a 0 . 25 inch outer diameter may be provided to frictionally engage the string 26 , rubber holder loop tail portion 23 , and a portion of the longer sleeve 30 thereby ensuring that the string 26 will not be removed from the loop 21 until the sleeve 28 is removed . it may also be seen from fig2 that each shaft section 13 , 14 , 15 comprises a shaft wall 40 with a cylindrical shaft bore 42 therein . mating ends of forward and mid shaft sections 13 , 14 and mating ends of mid and tail shaft sections 14 , 15 are provided with connection means such as tapped portions 44 adapted to accept mid stud 52 and aft stud 46 . spear head 16 may be mounted as by a female socket adapter piece 70 and forward stud 54 adapted to fit in said female adapter 70 and a threaded portion of the spear head shaft 18 . female adapter 70 may be mounted by conventional means such as crimping 72 or the like . as illustrated by fig2 and 5 , a slide means such as a cylindrical piece of metal 34 with a hole therein for attaching string means 26 by knot 36 is slidably mounted within the shaft bore 42 of tail section 15 . the slide 34 may be a 1 / 2 inch length of 5 / 16 inch diameter copper . a stop 56 produced as by crimping or the like is provided proximate the terminal end of the tail section 15 to limit the travel of the slide 34 . the tail portion end 60 may be provided with a bevel 58 having a bevel thickness exceeding the wall thickness 62 of sleeve 30 and also exceeding the wall thickness of 64 of sleeve 28 to prevent jamming of the sleeves 28 , 30 when the string 26 is reinserted into the cavity 42 . as shown by fig5 the string 26 may be of approximately three times the length of the tail section cavity 42 , the longer nylon sleeve 30 being slightly shorter than the cavity length . as may also be seen from fig5 the tail section 23 of holding loop 22 extends into the bore 42 when the string 26 is retained inside . thus when the surgical tubing loop 20 is stretched forward , the rubber holder loop 22 is urged into the cavity 42 and retains one end of the tubing loop 20 in fixed relationship with the end of the shaft 60 . as shown by fig3 the diving spear 10 is &# 34 ; loaded &# 34 ; by grasping the surgical tubing loop 20 across the palm of the hand and stretching it along the length of the spear shaft 12 to a holding position near the spear head 16 . as shown by fig4 the spear is &# 34 ; fired &# 34 ; by releasing the grip on the spear shaft 12 . thrust from the contracting loop 20 accelerates the spear 10 through the divers hand causing it to fly forward , uncoiling the string 26 and moving the slide 34 to its aft most position before being restrained . thus it may be seen that the effective range of the spear is increased by a distance of approximately its own length through the string and slide mechanism mounted within its interior . a short spear with midsection 14 removed might also be provided when it is desired to carry a more compact unit . when a shortened spear length is used the rubber 20 may be shortened as by looping to provide additional acceleration . it is contemplated that the inventive concepts herein disclosed may be variously otherwise embodied and it is intended that the appended claims be construed to include alternative embodiments of the invention except insofaras limited by the prior art .
a diving spear with increased range capabilities . an elastic loop for generating thrust mounted on a string which is slideably mounted in an elongate cavity at the aft end of the spear is disclosed . an elongate sleeve used to stiffen the string to aid reinsertion in the elongate cavity is described . attachment , removal , and replacement of the surgical tubing and string and the structure and use of various attachment devices are also described .