How to fit a Type SP2 Vane Steering Gear

NOTE

The information below was written over 30 years ago and must therefore only be used as a reference guide.

PUBLICATION V3SP March.1970

1. Please start by studying Publication No V1SP, obtainable free of charge from M.S.Gibb Ltd. Warsash, Southampton SO3 6ZG. England. This gives a general description of the gear and possible methods of fitting it, and must be read in conjunction with these instructions.

2. Your SP Gear will normally leave our works as follows: One cardboard sleeve containing:- Spruce Servo blade 48" long. Wind Vane c/w arms, lead counterbalance and vaneshaft, partially assembled and folded

   One carton containing:- Servo Frame with servo shaft ready mounted on its vertical bearings, with two spare nylon clips. Bumkin Frame c/w baseplates, latch gear on its stubshaft, and remaining small components. Ropes and lines are secured in position as far as possible.

   ASSEMBLY OF GEAR

3. • Remove the Tufnol bearing block, which is loosely secured by bolts from the middle of the cross-tube at the foreword end of the bumkin frame.
   • Hold the servo frame and servo shaft with the drop nose pin upwards, advance it upwards into the bumkin frame whilst guiding the jaws of the servo tiller up so as to contain the vertical tube of the latch gear between them. Move the servo frame aft so that its horizontal bearing pin enters the hole in the Tufnol block at the aft end of the bumkin frame. Holding it thus, replace the Tufnol bearing at the forward end, so that the forward horizontal bearing pin is in its hole, and bolt up securely.

   BEARING ADJUSTMENT

4. Check that there is a detectable amount of fore-and-aft movement in the horizontal bearings, and a detectable mount of vertical movement in the vertical bearings.

   FITTING THE SERVO BLADE

5. Pass the tricing line (spliced to an eye on the after edge of the blade) up through the centreline whole in the Tufnol block on the bumkin frame, then forward through the eye on the starboard side of the bumkin frame and tie a stopper knot in its end. Withdraw the retaining pin in the top of the servo blade about 3/4" only, so that it is clear of the pivot hole.
6. Remove the tripping line form the hook on the tripping lever (on the forward upper face of the sever shaft), and allow it to pull down inside the main tube, on its lanyard, thus allowing the rope loop at the bottom end of the servo shaft to be puled out about 8", towards the after end of the gear.
7. Advance the top of the servo blade upwards through this loop and into the jaws, so that the fixed pivot pin goes fully home into the slot at the top of the blade. Push the retaining pin fully home so as to hold it thus.
8. Arrange the bight of the tripping line to lie straight through the hooks on the plate on the after side of the servo blade. Pull the lanyard up to recover the end of the tripping line, pulling the blade forward against its adjustable stop. Put the upper end of the tripping line over the sheave at the top of the shaft and hook it onto the hook on the tripping lever, and push the lever down into its nylon clip.

   SWEEP

9. Check that the servo blade, when against its stops, is in the correct position of "normal sweep", in which the toe of the leading edge is about 1/4" (6mm) abaft the vertical line formed by the forward edges of the two steel cross-strips carrying the vertical bearings, when the blade is held fore and aft.
10. The best way of judging sweep is with the help of a timber batten measuring about 6ft x 1 3/4" x 3/8" (1.5m x 45mm x 10mm) with one edge planed absolutely straight. (To test the edge, use it to draw a pencil line on a flat surface, then roll the batten so that its other side is upwards and check the same edge against the pencil line). Having set the tripping line correctly, hold this batten with the top of its straight edge pressed against the forward edges of the two steel cross-strips carrying the vertical bearing pins, and compare its bottom with the toe of the blade. The toe of the blade should now be 1/4" (6mm) abaft the straight edge. To take up any slackness in the blade pivot or bearings, the tricing line should be pulled taut while checking sweep.
11. Adjust the screw stop if necessary, then adjust the screw on the tripping lever to achieve a tension on the tripping line that will just hold the blade forward against its stop when a force of 5lbs is applied backwards against the force of the blade. If more force than this is applied the elasticity of the rope will allow the blade to swing very slightly aft, but will pull it forward into the slot again when the force is relieved. The hook of the tripping lever should now be 1/4" and 1 1/2" from the bottom of its travel. If necessary, re-tie the knot in the tripping line (which normally lies inside the main tube) to achieve this, then repeat the tension test.
12. In service, if the blade should strike a heavy floating object the tripping lever will pull out its nylon clip, and so allow the blade to swing clear, but it is not recommended that this action be artificially induced.
13. Note that the sweep of the blade can be varied while under way, by screwing the screw stop in or out and screwing the hook of the tripping lever either up or down correspondingly.

    FITTING THE VANE

14. Assemble the vane, by unfolding its arms, and the vane shaft to the shape shown in Publication No V1SP, and bolting up firmly. Test fit the vane by entering the lower end of the vane shaft into the top of the shaft of the latch gear, and turning it until the slotted end drops over the pin inside the stub shaft. Pass the stainless pin through both shafts just above the upper vane shaft bearing, to secure them. It will be seen that there are two possible positions for the vane shaft slot on its pin, and it does not matter which of these positions is used. The vane and servo blade may now be removed from the gear, but maybe replaced when necessary to check clearances as described below.

    POSITIONING OF GEAR ON YACHT’S STERN

15. The gear is normally fitted on the yachts centreline:
    • With the bottom of the base plates either at deck level or slightly above (e.g. on top of a low taffrail, timber pads or stub bumkins), they must lie between 12" and 33" (0.3m) and 0.84m) above the waterline, and
    • as far forward as can be arranged, after checking the clearances detailed in paras 16-21 below. When the yacht is afloat it is essential that the bumkin be horizontal, and hence the vane shaft be vertical.

    CLEARANCES

16. The vane must be able to rotate through 360 degrees with minimum clearances as follows:
    • From the structure or standing rigging: 1/2" (13m). But note that it is possible to cut out a small piece of the trailing edge of the Type 17 Vane, to clear an existing pushpit rail, as in Fig 2SP of Publication No V1SP.
    • From boom or sheets: 2" (50mm)
17. The vane must have the necessary clearances from "Obstructions to Airflow" as laid down in publication NoV2SP.
18. The servo blade, when adjusted to "normal sweep" as described in paragraph 9 above, must clear the yachts fixed structure by at least 1" (25mm), the underwater edge of her rudder blade by at least 3" (75mm), and her propeller (if a fixed installation) by at least 18" (0.46m). These clearances must be maintained while the servo blade swings to port and starboard to its full limits.
19. The upper end of the servo frame (to which the steering ropes are attached) and the servo shaft must clear the yachts fixed structure by at least 1" (25mm), and there must be enough additional clearance for the tripin glever to rip freely in all positions of the pendulum.
20. Any external rudder stock, plus its tiller, must clear the bumkin frame by at least 1/2" (13mm) and clear the upper end of the servo shaft as specified in paragraph 19 above.
21. It must be possible to lead the steering ropes forward on the desired line without fouling the yachts structure.

    MOUNTING THE BASE PLATES

22. The clearance requirements may necessitate mounting the base plates wholly, or partly, abaft the after end of the deck as described in paragraph 25 below, but the following general rule applies to most installations:
23. Ideally, the whole of the base plate should be supported by a strong level surface, but it is permissible for the last 3/4 " of the after edge to be unsupported., provided that adequate fastenings can be fitted. The strength of the mounting should be such that a grown man can put his weight on the after end of the bumkin frame, or pull upwards with his full strength, without causing major distortion.
24. If possible, the base plates should be held down by bolts, but heavy round wood screws maybe substituted when necessary. Ten holes are provided in each plate, nut only four to six well-spaced fastenings need be used. The fitting should be done with the bumkin frame attached to the base plates.

    STUB BUMKINS

25. Where base plates must be mounted wholly or partly abaft the deck, it is possible to support them by specially made metal brackets, but timber supports are preferred. If the after end of the base plates are not much more than 6" (0.15m) abaft the deck, strong timber pads bolted or screwed and glued to the transom may be used. Alternatively, plank stub bumkins fastened down to the deck (as shown in figure 3SP of Publication No V1SP) may be used to achieve any desired position for the base plates. As a guide, hardwood planks of section 4" x 1 1/2" (102mm x 38mm) are considered adequate when the after edge of the base plate is not more than 12" (0.3m) abaft the deck.

    LAYOUT OF THE STEERING ROPES

26. The two steering-ropes are supplied joined together by two interlocking eye splices. The drop-nose pin on top of the servo frame should pass through BOTH eye splices, so that each rope pulls centrally (rather than offset) on the pin.
27. From the drop-nose pin they lead outwards through the after steering blocks, and thence forward in any required direction. The blocks will automatically align themselves correctly.
28. The starboard rope should lead forward along the starboard side of the yacht, and the port rope to port. In normal layout they then pass through the forward steering blocks and turn inwards to join the tiller eyeplate. In the "Low Tiller Layout" a 1:2 purchase is inserted as described in paragraph 41.

    TILLER EYEPLATE

29. The tiller eyeplate maybe fastened to either the top or the bottom of the tiller as convenient, but not to the bottom unless there is at least 3" (76mm) clearance between the eyeplate’s lowest point and the deck at all angles of the helm. The HOLE in the eye should face fore-and-aft along the tiller.
30. The position of the eyeplate along the tiller is determined by the radius of its swing. This is measured from the centre of the eye along a line AT RIGHT ANGLES TO THE AXIS OF THE RUDDER HANGINGS, as shown in Figures 2SP, 3SP and 4SP of publication V1SP. The radius should be as follows:
    • NORMAL LAYOUT (Figs 2SP and 3SP of V1SP) 10" (0.254m)
    • LOW TILLER LAYOUT (Fig 4SP of V1SP) 20" (0.51m)

    LIFTING TILLERS

31. Lifting tillers are normally used at their ordinary steering height, but if the layout would be facilitated by raising the tiller height higher, this may be done provided that the connection to the rudder stock is strong enough, and the tiller is firmly held up at the required working position by some means other than the vane steering ropes. Note particularly that the measurements of radius (paragraph 30 above) must be made AFTER the tiller has been fixed in its vane steering position.
32. In order to increase the space in the cockpit when on vane steering gear, some owners modify their tillers by inserting a hinge fitting just forward of the tiller eye plate, so that the forward part of the tiller may be hinged up vertically when on vane steering, yet be instantly available if required.

    FORWARD STEERING BLOCKS

33. Two loose blocks are supplied c/w stainless shackles. Vertical deck eyes must be supplied by the owner to suit these shackles; these eyes must be accurately positioned on the deck, and maybe either eye bolts or eye plates.
34. If a line is drawn straight athwartships across deck and/or cockpit, vertically below the centre of the tiller eyeplate with tiller amidships, then each deck eye must be positioned so that:
    • In plan view, its inside after edge (where the shackle bears) is 1/2" (13mm) forward of this line, when it will be found that the FORWARD edge of the sheave of the block will lie about 3/4" ABAFT the line.
      But note that with the "Low Tiller Layout" and the tiller eye plates at 20" radius, these distances should read - 1/4" ABAFT and 1 1/2" ABAFT the line, respectively.
    • The deck eye is at least 18" (0.45m) (24" (0.61m) for "Low Tiller Layout") from the yacht’s centreline. The greater the distance from the centre line the better.
    • The line of the deck eyes bisects the angle made by the ropes on either side of the sheave. (This can be noted in Figs 2SP and 3SP of publication No V1SP)
    • The height of the deck eye is not above the level of the tiller eye, and not more than 4" below it
35. After the rope system has been finally set up taut, it may be advantageous to fit smaller timber pads under the cheeks of the forward steering blocks, with their top surfaces carefully aligned to prevent the blocks from drooping when the ropes go slack. This will reduce friction in light weather sailing.

    HOLE IN COAMING

36. If desired, the rope from the forward steering block to the tiller eyeplate may pass through a hole in the cockpit coaming, provided that the hole is of a size and shape to avoid rubbing the rope at any angle of the helm. The optimum hole is more or less elliptical, and can be best made by passing the steering rope through a circular hole of 5/16" (8mm) diameter, drilled in the correct place, then enlarging this hole wherever the rope rubs. It should be necessary to pass the bowline knot, or snap shackle, through this hole. (see paragraph 39)
37. The steering ropes as supplied are intended to be longer than will be needed for any normal installation, and therefore must be cut off with say 3" (80mm) of spare length, the end being fused over a spirit lamp to make a blunt point.
38. The lengths of rope are determined by setting up the complete system with the tiller amidships and the servo blade vertical, then testing the full movement each way before cutting the rope.

    CONNECTING TO TILLER EYEPLATE

39. Each steering rope should be connected to the tiller eyeplate by the small bronze snap-shackle (supplied) to which the rope should be attached with a bowline knot, which may be used for fine adjustment of length.

    CONNECTION TO END OF TILLER

40. In a few boats, it may be difficult for the watchkeeper to reach as far aft as the tiller eye plate. In this case, two small blocks should be shackled to the tiller eyeplate, and the steering ropes led through them and forward along the tiller. Another eyeplate should be fitted to the top of the tiller at or near its forward end, with the hole in its eye facing athwartships. One of the two standard snap-shackles should be attached by bowline knots to the ends of the steering ropes, and clipped to this forward eye.

    1:2 PURCHASE

41. The "Low Tiller Layout" involves the use of a 1:2 "fool’s purchase" on either side, between the forward and after steering blocks, as shown in figure 4SP, Publication V1SP. The purchase blocks, which are identical with the steering blocks, should be arranged so that they are suspended in mid-air in any convenient fore-and-aft position., remaining clear of all obstructions at all angles of the helm, whether the boat be heeled or upright.
42. The rope between the servo frame and the purchase block need not be adjusted, but in fact the best way of securing it to the eye of the block is to tie a Fisherman’s Bend, with tits end tucked in to the end of the rope.
43. Having positioned the purchase blocks, the surplus rope may be cut off and used for the purchases. It is best to fit two cleats on deck for the standing ends of the purchases, and these will provide a means for adjusting rope tension, but it is best to cast off the steering ropes by letting go the snap-shackles on the tiller eyeplate thus preserving the previous adjustment.

    WHEEL STEERING

44. Instructions for fitting 1:4 "fool’s purchase" and a wheel steering drum, are given in a separate leaflet, Publication No V3SPW.

    EXTRA ROPE SHEAVES

45. It is not recommended that extra sheaves should be used to lead any part of the steering rope system "round corners", but if this is absolutely necessary, not more than one extra sheave per side should be used, preferably in the forma of a fixed cheek block carefully aligned at the correct angle.

    WORM LINE

46. The worm line is supplied already spliced so to form an endless loop rove through the wormline block. It will be found that this length (6’ (1828.80m) loop) is correct when the wormline block is positioned about 3’ 3" (0.99m) forward of the baseplate, but the exact position musrt be found by rigging the actual wormline. The block maybe positioned to port or starboard of this position provided that the wormline is taut and does not chafe against anything.
47. If the line supplied is to short for you purpose, please ask M.S.Gibb Limited to supply another, stating how much longer you want the loop to be, and returning your old worm line and its block. If too long please unpick the splice and re-splice to a shorter length, as described in leaflet V3J (Splicing the Worm Lines). NEVER attempt to shorten the worm line by taking an extra turn on the sheave, as this will jam.

    WORM LINE BLOCK AND SHOCK CORD

48. It must be possible for the watchkeeper to reach the worm lines easily on either tack. Normally the worm line block and shock cord lie flat on deck, as shown in figure 1SP of Publication V1SP, but it is possible to arrange them on a vertical bulkhead at the after end of the cockpit coaming. With the worm lines passing over the top of the after coaming on their way aft.
49. If it is necessary to guide the worm lines "around corners" between bumkin frame and worm line block, any guides should have separate grooves for each line. Do not pass the two lines through a single hole without fitting a separate stud (as done in the hole below the latch gear).
50. The purpose of the shock cord is to provide VERY SLIGHT tension (only a few ounces) on the worm line, (pulling the latch up has to work against this tension) and also to prevent the worm line block from twisting.
51. In order to hold the worm line in slight tension, the shock cord should be arranged to make an angle of 60 deg. to 90 deg. where it passes thorough the eye of the block.

    REEVING THE WORM LINE

52. Once spliced, the worm line cannot be removed from its block, but can be rove into the latch gear "on the bight", and removed again, as often as required. The "starboard worm line" is the one, which runs aft from the starboard side of the worm line block. It passes over the horizontal stud on the portside of the bumkin frame, then down under the lower tube and up through the hole in the Tufnol block immediately under the worm sheave on the latch gear, but passing on the starboard side of the small horizontal stud beneath this hole. Now take it to the after side of the sheave, and wind it anticlockwise round the score of the sheave 1 turn, so that it leaves the sheave passing downwards from its forward side and so through the hole again, but on the port side of the stud. It now becomes the port worm line running forward parallel to the starboard line but under the stud on the portside of the bumkin frame. Check that pulling the port worm line causes the forward side of the sheave to move downwards.

    LATCH LINE

53. Before rigging the latch line, ensure that the latch button (on top of the latch gear) is lying athwartships, allowing the worm carriage to drop fully down. The latch line is bent to the small hole in the top of the PORT cheek of the worm carriage. It then passes upwards through the eye on the top tube and another eye on the port side of the bumkin frame, then forward to a position within easy reach of the watchkeeper where it is bent to the loose Stainless steel ring supplied. A stud, such as a 14 guage woodscrew with its head cut off, is positioned so that when the ring is on the stud the latch line is taut and the worm carriage held fully up. When released from the stud the latchline should be quite slack with the worm carriage fully down, (a pull on both worm lines will ensure that it is down and in mesh) . Some of the latch line, after leaving the ring, may be secured to any convenient anchorage to prevent the ring drifting out of reach.

    FURTHER DETAILS

    TRIPPING LINE

54. The tripping line is supplied already fitted to the servo shaft, and should be set up and adjusted as described in paragraphs 6, 8 and 11 above. The two ends of the tripping line should be knotted together with a single Sheet Bend, and this know should lie inside the tube of the servo shaft, at all times. At the bottom of the servo shaft, two parts of the tripping line should pass either side of the adjustable blade stop, before turning aft to pass round the servo blade. If it is desired to remove the tripping line without untying the knot, this may be done by first removing the screw of the adjustable blade stop.

    TRICING LINE

55. The tricing line should be rove as described in paragraph 5 above. If desired a small cleat maybe fitted near the starboard baseplate for use when the line is holding the servo blade up horizontally. When the blade is fully down, the line should be slightly slack, but not trail in the water. A stopper knot maybe arranged to effect this.

    LIFELINES

56. If required, lifelines maybe rigged so as to lead forward from the eyes provided on the top after corners of the bumkin frame, but they must not foul the vane.

    SPARE OR EXTRA PARTS AND FITTINGS

57. You may have to purchase certain fittings to complete your installation, and you may wish to obtain locally certain spare parts or fittings. To help you order the correct or most suitable we list here some parts mentioned in the preceding instructions.

    CORDAGE

58. This may be obtained from M.S.Gibb Limited, or though Hasler Vane Gear stockists, made up in standard lengths for the SP Gear, or you could obtain any lengths you require (not made up) from Britis Ropes Limited or their distributors.
    • Steering Ropes 3/4" CIRCUMFERENCE, 3 strand Terylene (Dacron)
    • Tricing line 1/2" CIRCUMFERENCE, 3 strand Terylene (Dacron)
    • Tripping Line 1/2" CIRCUMFERENCE, 3 strand, pre-stretched Terylene (Dacron)
    • Worm line No8 Viking Brand plaited Terylene
    • Latch Line No3 Nylon Blind Cord

    FITTINGS

59. These maybe obtained from M.S.Gibb Limited or their distributors.
    • Steering Blocks Gibb 900-100A M.S.Gibb Ltd only
    • Shackles for steering blocks Gibb 528L
    • Tiller Blocks (see para 40) Gibb 101
    • Shackles for tiller blocks Gibb 863
    • Worm Line Block Gibb 493
    • Tiller Eyeplates Gibb 900-73A M.S.Gibb Ltd only
    • Deck Eyeplates Gibb 520
    • Eyebolts Gibb 886
    • Snap-shackles (steering ropes) 2" Bronze
    • Cleats for rope purchase Gibb 517A
    • Cleat for Tricing line Gibb 517
    • Cheek Blocks Gibb 491