Sailsite

Can anyone tell me how long my tiller extension should be please?

I am in Cornwall and have just found a place to keep on land very close to the river fal.

So I've just bought myself an ottter sailing dinghy. I am completely new to sailing and of course will be having a few lessons in the new year. Can anyone point me towards a few useful rigging YouTube videos? I'm not sure what other sailing dinghies are similar. I have the mast up and that is as far...