Before the imported mesh can be used, some scene and mesh prepping in Blender is usually required. It basically cleans up the model imported in Blender.
Google SketchUp is another free, 3D software option. You can build models from scratch, and you can upload or download what you need, as you have seen. People all over the world share what they've made on the Google 3D Warehouse. It's our time to do the same.
Download the program from http://sketchup.com and install it. You can uninstall it later. Open the boat file in SketchUp, click on Save as, and export the 3D model using the COLLADA format.
*.dae Collada format is a common, cross-platform file, which can be imported directly into Blender.