the dude

I am building the curlew and am at the point of lashing all the joints together. In fact I lashed a few together already and, out of excitement, I forgot to check the square of the frames. I got all of the inner frames square and upright at 90 degrees. I am having trouble getting the stern and bow frames at 90 degrees. Are these two frames going to sitting at a slightly canted angle or are they supposed to at 90 degrees too?