None over sampling is sort of like a gif works. it's a number line color system. This pixesl here is this color and that's it. Scale just magnifies the error. Simple like if the center pixel is black and surounded by white and you resize it to 4 X the size you'll have 4 perfect black pixels in the center surounded by white pixels. Seems to be the way to go ay? Problem is your not rendering a flat cube and circle shapes get munched with such a system. Like you must be able to see the difference of a gif and jpg image. That's sort of the difference. But it's worse in a way because the image is being scaled. Take a big gif make it smaller with out oversampeling then make it bigger again without oversampling. That is sort of what is happening to your boat texture, Then on the antiailasing pass comes it just looks at the original and no blending happens.

Keep in mind this most important fact. You're adding pixels or taking pixels away from the original image to make it fit on the boat. You can decide how that's done. This is taken from photoshop help file Um the first setting is the same as Vue's None oversampeling.

Nearest Neighbor (Jagged) for the fast but less precise method. This method is recommended for use with illustrations containing non-anti-aliased edges, to preserve hard edges and produce a smaller file. However, this method can result in jagged effects, which become apparent when distorting or scaling an image or performing multiple manipulations on a selection.
(Photoshop) Bilinear for a medium-quality method.
Bicubic (Smooth) for the slow but more precise method, resulting in the smoothest tonal gradations.

Bicubic takes blocks depending on the program but it's usually at least 9 pixles square and then with that decides how that center pixel will look at a different scale. it's much more accurate. It's the one to use but the trade off is speed, not much though. Resampeling happens really fast. .0001's of a second even for really huge images. Um that above sample way up there you would get a blend from white to gray to black to gray to white.

Now explain to me why you would render in the higher quality setting when you sampling the textures at the lowest quality setting?

Make sence now?
Btw your texture size is fine and is not the problem. Oh and add to this it's a jpg and even though you claim that you cannot see the damage till you look at it really large. None oversampeling changes all that because of the this pixel right here is going to remain this color reguardless of size. So it shows up then easily. Take the texture and sharpen it about 4 times and you see the same effect without having to render it. Jpg kills sharp edges depending on the system used to compress it. Jpgs are bad news and are hard to work with the best of times. Even at 100% they still goof up and progressive (better) and standard optimized (bad News), None (best) add to the crud. Most programs you can set that though and they use standard optimized by defalt because it gives the smallest files. Lossy type images compresions should be banned in the art world. There a pain. There is now jp2 or there called jpg2000 and there lossless. nice stuff, That is what we should all be using.
But bmps are lossless too they all use some sort of compression. Bmp's use RLE same as zips use.

There is no way to fix a jpg. Damage is done. You can sort of repair it a bit but the damage is done. It's like trying to make a poster with a stamp sized original. Good for the web but poor for rendering perfectly.