Planning to rig; messing about

Click on image for enlarged view

Since I am coming up to steam on this sailing rig project , I'm chasing down some bamboo -- I'll probably have to settle with Bambusa oldhamii -- but a ready supply isn't so straightforward as visiting the local hardware store.

Once I get my hands on the canes I get to fiddle some more with my rig design which is an adaption of Bill Mantis' .

With these nautical issues you change one parameter and you have to adjust the rest. (Image uses  large figures -- larger measurements than I will be deploying).

But since I am in the mock up stage, I'm surprized how much sail I can 'potentially' generate for my craft. Early calculations suggest that I could approach, give or take,  2.5 square metres -- which amounts to something like 3-4 golf umbrellas worth of wind harvest.

Of course if it turns out I'm carrying so  much sail that the paddleski wants to tip over or the centre of effort is so far forward that the nose wants to dive all the time -- then I'll be getting very wet and will need to return to the workstation.

Just quietly, with this ingenious design for a mast at a diagonal like this, the centre of effort looks good as it seems comfortably back -- and the more I lower the mast, such as when the wind  and  waves rise,  the further back moves the centre of effort.  Of course with the mast in a perpendicular I'd need a smooth sea, such that I doubt that  an absolutely vertical mast is an option.

With some adjustments to my single rudder scheme (now only on the starboard side despite my intial duel rudder setup) I think I can hope to remain upright. I have the option to consider adding  leeboards to the craft if the catamaran like hull isn't enough to keep  me in the horizontal or prevent too much lateral drift.

While I'm not keen to be overly ambitious (read 'stupid'), it is fascinating to ponder what practical limitations would determine the total amount of sail I could potentially  carry.  

Since my short stubby vessel is only 2.4 metres long I'm tempted to take my mast to 3 metres which will give me a bottom length of a little over 2 metres. (In the sail design the ratio to mast and sail is determined by the balance of a square along its diagonal).

But I wonder what happens 'at the other end'? I'd run a rope, of course, swapping sides as I tact*,  but would a sail that is as long as the boat be too much to handle not only in the air, but  stored on board? And what about a mast that is taller than the boat is long? (But remember it isn't vertical...)

And what do I do with the mast and sail when its reefed?

Answer: mess about some more, because:

"There is nothing - absolutely nothing - half so much worth doing as simply messing about in boats." -- Kenneth Grahame, Wind in the Willows. 

For now, sail-less

"swapping sides as I tact*"Another great element in this very simple rig design is that there's no absolute necessity to incorporate a boom/spar. This was a major issue for me as I considered my rig options. It may be a crude setup, but 'changing sides' when coming about or what have you is as simple -- touch wood -- as pulling the sheet of the sail across my paddling person and, if necessary, hooking the rope to the opposite side. There's nothing to get in the way of this manoevre, such that I can drop the sail very close to the water line as I allow the wind to billow it. A fixed spar would mean I'd need room set aside under the sail so that I could swing it across the craft and my head and body would be in the way of the boom. (unless I followed an upturn crab claw/lateen sail design) Similarly, when sailing directly down wind I suspect that I can feed the sail out one side or the other so that it sits diagonally to the craft (assuming I don't then capsize).That then leaves the challenge of swapping my rudder over....