Tandems are so much fun - I built one with a mate back in 1989. We had never made even a surfboard before, let alone something like a tandem.

Our design was based more on guesswork than science - my mate had an Bombora Astro Toy and I had a John Hall 295 and we laid them on the ground with the Astro Toy at the back and the 295 at the front and slid them together and when the overlap was equal that became the length and the width - roughly 13" long x 30' wide x 4' thick.

With no blanks of that size, we spliced two surfboard blanks together then had a local surfboard maker install two stringers that were nearly an inch thick! I am sure his garage floor became 2' thicker due to all the fibreglass we used in the process!

The bottom design was based on the Astro Toy and had the stepped rails that were so cool at the time.

The fin is still the original - a Multi-fin Hyperslot with a nasty wobble.

Sails - originally at was a 7m2 gaastra cammed sail and the back and a 6.2m2 Bombora on the front. Now we just use wavesails (5.3 and 5.2)

Performance? Incredibly for what it is. At first we didn't think it would even float but after our first outing off Wamberal in a NE it was amazing. I still recall that first run out and even getting a 'jump' (being on the front as we went over a wave i was nearly three foot in the air and the back half had not even left the top of the wave yet!. It carves like a dream (albiet a bloody big carve)

Where is it now? Under my house and still gets used ever so often in a westerly in Narrabeen Lake. A few posters on this site have been my co-pilots recently and they may give their opinions - just make sure you know your co-pilot's standard as it can get quite hairy. I would not take it out in the surf any more as the spliced blanks maybe not withstand anymore jumping!

Suggestion - do it but make check out what is available first. Starboard do one called a Gemini and i remember seeing some recent footage of guys sailing it on here somewhere.

I'm not sure if I have any photos of it but will try to get some soon if you are interested.

(We even named it - MAJK (magic) BAJK. The BAJK was a combination of our names - Ben Jackson and Adrian Kendall)

Good luck

Here is a recent article

www.seabreeze.com.au/forums/Windsurfing/General/Tandem-sailing/?SearchTerms=tandem+board

ka43 said..
Ive seen Chub's tandem in action and it definitely goes!!!!
The guys were having a blast zooming back and forth on Lake Dangerous. Its not pretty to look at but it works, good luck if you build it.

I was at windsurfnsnow at Collaroy 2 weeks ago and there was a new tandem ready for delivery. It was akin to an aircraft carrier. I think it was a starboard gemini mark 2. Tufskin construction; had to be 4m long. Not sure how one turns it.