Matariki - a kayak to rowing boat conversion
Part 3 The rowing rig
If you are affluent and live in a country where they are available for you can drop in an oarmaster. In fact you can drop an oarmaster into almost anything that floats. For those of us with some Scottish blood in their veins or perhaps a desire to achieve something by their own hand I have a solution you might like to try.

If anything I overbuilt the rig shown below. I have visions of the boat being used as an outrigger canoe with a sailing rig and the design looks ahead to that.
There is also a glimmer of an idea that the rigger arms could be part of a beach trailer set-up where I just put a wheel on the end and trundle off into the sunset.
My rowing rig was developed mostly from bits and pieces squirreled away in my workshop. I used standard telescope series aluminium tube for this rig. That means they make a series of tubes where one size will fit inside the next one up and so on.
1. The brace is two pieces of tube. A further description of they way this is fitted is given by the photographs below. The flange to which this arm attaches to the rigger was first just a piece of shaped aluminium strip. Later I found a stainless vang fitting off a small yacht did a professional job of this connection.
2. The extension simply slides inside the rigger and is secured by two through bolts (also see by photo below). A series of holes have been drilled to permit the rig to be widened. The end of the tube is plugged with a hardwood dowel and drilled right through to take a standard rowlock. A small block of hardwood under the rowlock acts as a bearing stopping it grinding on the tube.
3. I have a pair of 'proper' rowing gates in my junk box and this type of extension arm would enable these to be fitted to the rig.
4. I had an aluminium pivot welded up. This is bonded to the hull at the bottom and there is another plate about where the number 4 is on the drawing which fastens to the cockpit fore and aft bulkheads. The top plate is in fact a piece of plywood glued and screwed to the deck. You will see below that I actually carried this above deck level so that I could have a vertical adjustment for the rig.
In reality you could replace this with a simple box to take the rigger. It does not rotate in use and a interference fit with the sides of the box would see the tube held firmly in place. I would probably take the sides of the box right out to the hull and bond it all together for extra strength.
5. You could also make a couple of wooden 'bearings' fastened to the sides of the boat or fore and aft bulkhead to take the arms. It will be simpler but I can assure you that your knuckles and shins with seek them out regularly.
 6. I was watching a mechanic bend a piece of exhaust tubing for my old car the other day and it struck me that they could bend you up a piece of pipe that matched your requirements to a tee. There is stainless exhaust pipe around and even standard steel would do the job. When thinking of leverages standing in the workshop we forget that the boat will be moving away from the lever and there is far less stress on the rowing rig than we might think. If you used this bent exhaust pipe technique you could probably get away without needing many of the bits and pieces I have used.
You could correct the bend yourself but with the use of a template I am sure you would get it right first time.

Just a point on welding. If you are having some argon welding done talk to the operator first as some grades of aluminium are welded at different settings to others. This is particularly so between tube and flat.

The real live version of the rowing rig.
Top left. A strip of rubber cut from an inner tube effectively dampens the noise from between the telescoping sections. I prefer an open rowlock so I can clear oars without problems.
I found a rigging screw off a small yacht fits inside the tube at the rigger end. I cut one in half and it is bolted inside the tube. This allows very precise adjustment of the arm.
At the rear of the brace there is a hole which in conjunction with holes drilled in the inside tube allows a coarse adjustment fore and aft. The tube is simply flattened and drilled to fit onto a plate on the deck which has a bolt on it.
On the right you can just make out that the riser tube protrudes above the deck a way. This has been drilled and the whole rig can be raised and pinned with a stainless bolt.

YOU CAN FIND DETAIL ABOUT
THE HATCH SYSTEM IN THE WORKSHOP INDEXUse lock washers or self locking nuts on all the fittings as the will come undone otherwise. The pin for the rowlick has a quick release lock pin to stop it falling out should I capsize.

Part 1 Concept Part 2 Design Basics Part 3 Rowing Rig Part 4 The Steering Rig Part 5