I did not do this on purpose, I assure you all! I imported the kayak, checked all the shaders as usual, then imported the motorboat, and found the situation as described above.
This morning I deleted them both, and imported the motorboat with no problems. Then I imported the kayak. Again, no anomalies. Then I imported another object, and lo! It got stuck in with the kayak's shaders. So the kayak is the problem. It has a strange shader called "None" that I have been unable to track down in Blender (in uvimages list, regular materials list,or orphan data). You can't delete materials in PoseRay. I'm going to throw the model obj out and start from scratch because that "None means there's something I haven't attached a material to in the blender file, and I can't find the guilty mesh.
Incidentally, I am having a wretched time with the net today, with timeouts, drop outs, and assorted other errors. I live in a nursing facility with a public wifi whose password hasn't been changed in 7 years. Seven years! We're probably being used to launch all those denial of service attacks I'm hearing about.
So I apologize for any tardy responses.