Making a steering quadrant

Dissatisfied with a standard production boat quadrant, Isaac Adam-Azikri sets about making his own.

It is not often we hear about a steering quadrant breaking to pieces, but talking to other cruisers made me realise it was more common than I thought.

The cast aluminium quadrant we had on Rhythm was in use for approximately 15 years. It looked perfectly sound when removed and checked in 2006 during a major refit. Three years later, in the middle of the Tasman Sea, we encountered a storm 280nm NW of Cape Rienga. To cut a long story short, the port steering wire broke, the loose rudder slammed to port hitting the rudder-stop, causing the quadrant to break apart. Luckily we carried an almost identical spare quadrant including wires to effect repairs.

Since that incident I have had little faith in production-line quadrants. Now I am not an engineer, but I do like to fabricate or improve things.

With the spare quadrant now in use, I decided to fabricate a stronger one using thick mild steel. The challenge was to fabricate a cheaper but better product using only basic tools and a welding set, with no machining required. The only difficulty I could see was how to make the key-way that locks the quadrant to the 2” rudder stock.

Materials

I ordered enough material with some to spare, all mild steel. Pipe 2” internal diameter x 4mm thick (boss section), angle-iron bar 50mm x 50mm x 5mm thick (framework), flat plate 75mm x 10mm thick (boss flange), flat plate 600mm x 600mm x 6mm thick (strong back), flat bar 15mm x 5mm thick (wire channelling). Total cost of steel: $50.

There was some scrap steel pipe and plywood around the house which was handy to use as formers and templates.

Consumables — welding rods 2.5mm x 1kg = $10, grinding disk (8”) = $10, cutting discs (4”) x 5 = $10

Total cost of materials and consumables: $80

Tools — Angle grinder, power drill, hammer, vice, hacksaw, arc welding set, tape measure, files.

Before you start draw an outline copy of the quadrant to be made. I placed the old one on a 3/4” ply and drew a reasonably accurate outline. This will be used as a reference during fabrication. It is important to note that the outline drawn included the wire channelling on the arced side of the quadrant’s frame — these channels will be welded on later and will increase the overall size.

Framework

The 50mm x 50mm x 5mm thick angle iron bar was used for the framework of the new quadrant. Use a slightly longer bar section than required and trim to size later. Mark up the centre of the bar which will also be the centre of the quadrant’s arc or angled section. From this centre line, measure left and right to the points where the angle iron bar is to be bent to shape giving it a triangular shape (use the outline as guide).

The angle iron bar will have to be shaped into an arc in the middle section and the corners formed to shape.

I used an old steel boiler as a former — alternatively use an anvil and gently form to shape. Again, the outline drawing is used as reference.

Once the arc is formed, the corners of the quadrant are to be bent giving the angle-iron framework a triangular shape.

Using a 1m length of 25mm (1”) steel pipe as a former, the angle-iron bar was positioned in the vice at the marked point to be bent with the 25mm steel pipe clamped together in the vice. The angle between the angle iron bar and the former pipe needs to be 90 deg. I used a 1m x 60mm ID pipe to slide over the angle iron for leverage which made bending easy. This procedure had to be repeated again for the second bend.

I kept comparing it to the reference ply drawing, checking that the correct shape is obtained. Once the corners are bent and formed to shape the quadrant’s frame was placed on the 6mm flat plate to check for level.

Making the boss clamp

My rudder stock has an outside diameter of 2” so I used a pipe with 2” internal diameter x 4mm wall thickness. The idea is to use two layers of sliced pipe to form the boss section. The first layer will have the key-way cut without using a lathe.

I cut the required length of pipe (75mm in my case).

This 75mm pipe slice had to be cut again, but this time lengthwise, ending up with two equal halves (shells).

Some of the cutting can be done at the steel merchants when ordering material for accuracy and time saving. (Retain the second half pipe/shell for later.)

The key-way is marked next. I marked an area 10mm wide x 50mm high in the centre of one half pipe.

The key-way was to be cut by a hack-saw, doing two parallel cuts to create a slot of 10mm wide x 50mm high. The bottom of that slot/key-way was completed by drilling a 10mm hole at the bottom of the hack-saw cuts. I did a few dummy runs with a hack-saw beforehand, cutting outside the scribed line and filing the slot to size. 

The two boss flanges are made out of a 75mm x 10mm flat plate. These will be tack-welded to each side of the keyed boss (half pipe) made earlier. The 11mm bolt holes can be drilled in later.

Check for levels and fully weld flanges to the keyed boss. Care must be taken to minimise distortion.

Clamp in vice

The second half-pipe retained earlier provided the outer shell of the keyed boss. It had to fit snugly against the keyed boss and therefore had to be trimmed and bevelled in order to fit between the flange plates. Once trimmed, drill 4 x countersunk holes in the second half pipe, two holes either side of the key-way area but well away from it. These holes provide a spot weld aperture. I used a 6mm drill bit for the holes and a 10mm bit for the taper/countersink.

The second half-pipe was now offered to the first half-pipe (keyed boss) and clamped in the vice together until they touched all around the perimeter.

Once in position, the two half-pipe shells (boss) were welded together all around the perimeter including the flange plates. The spot weld holes were welded through to add further adhesion and reinforcement between the two half shells. We now have a boss with an 8mm wall thickness. With the boss now complete, the excess weld was ground and dressed. The four 11mm holes in the flange plates were drilled next. These are for the 10mm fastening bolts.

Frame and boss assembly

The angle-iron quadrant frame and the boss clamp were positioned over the plywood drawing. The length of the quadrant’s frame was marked and cut to the correct length/angle to fit and join the boss clamp. Both components were now placed on the 6mm steel plate, which provided a level base to assemble the two together.

Once the quadrant frame and boss clamp were aligned to tally with the original quadrant, they were both tack-welded together and the alignment checked again. The best way to check is to have it temporarily fitted to the rudder stock for reference. The boss clamp and the angle-iron frame were now fully welded together.

Welding was done in sequence, taking breaks to minimise distortion.

Note: The final angle of the quadrant when fitted to the rudder stock will be determined at this stage, so care must be taken to get this angle right before the two components are fully welded.

Strong back plate

Having made the basic quadrant, the strong back plate was made using 6mm steel plate. I used thick paper to make an accurate template for the inner shape of the quadrant. The template’s outline was then transferred on to the 6mm plate. I also marked a cut-out slot for the rudder stop bolt.

I cut 6mm strong back using an angle grinder. The curved slot for the rudder stop was cut in the same manner.

The strong back plate was inserted from the top into the quadrant’s frame, then intermittently welded around its perimeter to the quadrant’s frame and boss (top and bottom). I used up to 30mm weld runs to minimise distortion.

Wire channels (grooves): 3 x 15mm x 4mm flat bars were used to make two channels for the steering wires. All three flat bars had to be slotted
on one side with a disc cutter, this allowed forming them to the quadrant’s outer arc.

Once all three bars have were formed, they were welded to the quadrant’s outer arc. I welded the top and bottom ones first then welded the middle one in between.

Off-cuts were used to complete the ends of these channels around quadrant’s corner.

Wire channels side view

Once welding was complete, the excess weld material in the wire channels was ground using a disc grinder to provide a smooth passage for the steering wires.

The quadrant was further reinforced by adding a few extra gusset plates to the joints between the keyed boss, frame work and strong back.

The rear boss clamp which attaches the quadrant to the rudder stock can be fabricated in the same manner as the keyed boss clamp made earlier. Obviously no key-way is needed here which makes things simpler. Some quadrants may have to incorporate lugs for the steering wire tensioning bolts and others have lugs in the rear boss clamp.

Protective coating: the quadrant can either be galvanised or, as in my case, dipped in hydrochloric acid, washed and painted.

Additional fixings for accessories can be added to suit one’s installation.

I added the following:

(a) An emergency steering fitting. Our emergency steering is incorporated in the quadrant. A square box section stub was welded to the top centre of strong back plate.

(b) Autopilot rudder indicator anchorage point 6mm hole.

(c) Autopilot fixing bracket welded to underside of strong back plate.

Only basic skills needed

It is possible for anyone with good basic skills to fabricate this quadrant or at least prepare the time-consuming components.

The quadrant was fitted in July 2010. It has logged 2000nm on the way to East Timor and worked fine so far. It is a robust unit that should last a lifetime. The weakest point in the system is the steering wires, which, after all, are consumables. Time taken to construct? Plenty! I view it as occupational therapy!!

Detailed diagrams are available upon request for anyone who wants to have a go — just contact carolinestrainig@yaffa.com.au.

IMPORTANT WELDING NOTES

* No welding inside the key-way area or the top lip of key-way.

* Use lower power when welding the spot-weld holes.

* Allow the work piece to cool down between weld runs to minimise distortion.