Extending fence concrete gravel boards (longer than 6ft)

[swebb99]

Hi, I'm planning on fitting new fencing in my garden, concrete posts, concrete gravel boards and feather fencing. There is one spot which is a problem though because I have an old concrete base about 7ft across near the end of the garden with an air raid shelter under it. So the base is wider than the typical 6ft space of the posts. I can fairly easily make up an extended feather board but I'm not sure what to do about the concrete gravel boarding. I could cut one down and use a normal 6ft plus the cut bit but how would I join the ?

Thanks

 

[Tigercubrider]

you can get 8.6 foot gravel boards

 

[swebb99]

Ah OK wasn't aware of that, I'll take a look around. Thanks