I make ski/kayak paddles and have a potential customer wanting a double ended paddle (which will be scoop/propellor style incidentally) , Has anyone already got such a thing and if yes how long is it ? I am considering overall length of 3 m 20 cm (10 ft 6in for imperial lovers)

ps customer is 184 cm and using a plastic Nalu hybrid ? SUP

he showed me this website with videos http://www.carbonerro.com/products/el-doble

warning loudish/lame music soundtrack !