I bought two sets of ferrules and I am making two paddles with each paddle half a differnt length as follows:

Paddle 1 - left half 122-1/2 cm + right half 107-1/2 cm = 230 cm Paddle 2 - left half 102-1/2 cm + right half 117-1/2 cm = 220 cm

now the trick, switch the right halves and you have:

Switched Paddle 1 - left half 122-1/2 cm + right half 117-1/2 cm = 240 cm Switched Paddle 2 - left half 102-1/2 cm + right half 107-1/2 cm = 210 cm

So by making two paddles you can create paddles of four different lenghts i.e. 210, 220, 230 and 240 cm. Anyone in the family can find their choice of length.