Reply To: new and weighing at 100Kg
Hi Brian, welcome to the OK forum
At 100kg you are an ideal weight to sail an OK Dinghy, due to the flexibility in choice of mast you should be able to find a spar to suit your build without a problem. I would warn you that the colour of the top section of aluminium masts is not always a true indication of how stiff or bendy a rig is, but as a guide only, the red tops tend to be stiffer as the tube in the top section is thicker. Black and blue top are usually more flexible but the stiffness is usually determined by the height of the first joint above the gooseneck. For somebody of your frame I would look for a measurement of about 2.7 – 2.9m.
As for hull construction, OK’s are exceptionally tough, long lasting boats (there are 30+ year old boats that are still very competitive), as there is no heavily tensioned rigging to put the boat under pressure. The main forces are on the deck and mast bearings as you have already realised, other than that you just need to check the hull over like you would with any other boat looking for general rot and cracking. It is usually wise to check the cockpit floor is reasonably stiff
Hope this helps a little