If you think you want a tandem then build a triple. There is no real downside to adding an extra cockpit other than a little more work and there is a lot of upside. The Sailrig matches the CLC triple very well. The rig centers on the middle cockpit so it sits right in the middle of the boat. The boat can be sailed singlehanded from the center cockpit or doublehanded from the front and rear cockpit. The bow and stern have enough volume to handle big seas. In general, the bigger the boat the better when it comes to the sailrig. A longer waterline makes for a faster boat and allows you to carry more sail. A triple is also a lot of fun without the rig.

I've started building a Wood Duck 12 with the Mark III sailrig, following John Harris' suggestions.  It sounds like you've read his blog on the subject in the Life of Boats, so you know what he recommended.  But I can understand the desire for a double, now that my girlfriend has seen pictures of these trimarans and thinks it would be "...a lot of fun....." for us to be able to go out together.  I've been wondering about the Wood Duck Double and the Mill Creek 16.5 as a base for that.  Short waterline for easy maneuvering, large cockpit for comfort and full bows to counteract "submarining".  John mentions that the SailRig has been fitted onto a bunch of the Mill Creeks, so hopefully someone who has done that will chime in here on its suitability.  I still intend to finish the Wood Duck 12 first and fit the SailRig to that, so I may have to build a new set of akas with the proper deck spacers for a second boat, but that's really not a crisis.  The akas have to stay in the glue forms for a week each, anyway, and that can happen as the second boat is taking shape.  

Hi,

Thanks for the replies.  I admit I didn't read all the way down in John's article, where he does detail the best kayaks to use.

So I'll give it another read and go and ponder the options...firstly to decide if I go single, double or triple, then which model.

But I need to re-build a workshop for it first so have a little time to make my decision...

Thanks,
Darren

   Currently building a MC 13 and sail rig. So many questions have come up. Mostly regarding the aka placement. I chose the MC for the spacious open cockpit 59 inches in length. The sail rig as built per plans spaces the akas 48 inches therefore not spanning the cockpit so unless you don't mind them cutting across your then spacious cockpit major (at least in my mind and skill set) modifications need to be made and more questions come up ie leeboard placement, rudder mounting on a non vertical stern? Manual is a basic guide not much in detailed instructions on some points. 

I'm in the middle of this so still in the thought stages but on this boat it's not just build it and drop it on unless you don't mind where it lands. Had minor consultations with CLC so far and I'm confident we'll get through it in the end. Should be interesting.

Any advice would be welcomed at this point.

Also BTW try and find a photo of a MC 13 with a sailrig mounted anywhere online not much there??? It would certainly help with ideas!