The tiller extention (extendable) works great. It allowed me to sit further forward and balance the boat a lot better. The springy tiller yoke took a little getting used to, but it was really nice to be able to move away from the back of the boat.
The extention added one other aspect of sailing, the ability to hand the tiller off to my three year old son. He still doesn't quite understand stearing. He didn't figure out that you could go straight if you didn't fully push or pull the tiller extention, but I am also sure that this will come to him soon enough.
