Our group opted to put in downstream of the portage in the dugald bremmer section the silver fork, in order to add one large double drop slide into the uncommonly run but nevertheless 'traditional' slides section of the silver fork. One of our group read and ran down the left channel here, and was pinned against a sieve while in his boat. Another boater was able to paddle over the sieve with an extra 100cfs or so a few weeks prior, but at the flow of Saturday that was not possible. I was able to get to him and stabilize him long enough to get his skirt off and pull him out of the sieve. The boat remained trapped, and required mechanical advantage to remove. A swimmer would not come through the other side.