I second these comments, your niece had a learning experience by just starting a project. Building a yak is a lengthy process she may not be ready to tackle yet, and now she knows. If it were me, and I wish I had a niece close by, I'd finish it and see if she still wants it by letting her use it. Heck, don't let this ruin a friendship.

An idea, you could finish the next/current step(s) and let her get back into it?

my 2 cents -mac

: Motivation to finish a project can be difficult to muster, even for us
: "builders". Don't give up on your niece even though her
: enthusiasm for boat building has waned.

: This is a fine idea, and may I suggest taking your niece out on her maiden
: voyage? Your niece may enjoy the outing and the positive experience might
: go a long way to healing the disappointment.

: Honor the good intentions you had when you invited her to build with you,
: after all, you began the project out of love for building and a desire to
: share that experience...no reason not keep that spirit going. I guess I
: wouldn't want to see such positive intentions go astray when they don't
: need to.
: Bill Cruz