Good work! We're not quite through yet, though
For sail decals, the structure of the sail needs to be clearly visible. This means if you cover large areas of the sail, you need to use a lot of transparency. My suggestion: Leave the blue areas (with "A" in them) as they are. Make the white areas (upper right corner, lower left corner) with 100% transparent background.
As your decal is, it will probably get sent back because the white areas are too opaque.
Does that make sense?