Not certain, but I think if he's in navigable waters and there is a motor on it, it has to be registered no matter how long it is. I got that ticket last fall while perch fishing on Lake Washington in a 12' pram with a 5hp motor on it.....$257.....YIKES!!! Also, a dinghy can only be used to and from shore, thus the name "tender". I don't think that covers "tending" your crab pots...
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