i copied this for you from the TPWD website:
Display of Your Number
The number must be painted on, or otherwise attached to each side of the vessel, near the bow, in such position as to provide easy identification.
The number shall read from left to right, be in block characters of good proportion not less than three inches in height and be of a color that contrasts with the background.
The numerals must be separated from the prefix and the suffix by hyphens or equivalent spaces such as the following example: TX 0123 AB and TX-0123-AB.
The validation decal must be affixed in a line with and three (3) inches towards the rear of the boat from the registration number.
USCG Documented Vessels:
May display ONLY the Validation Decal (not the Registration Number) on both sides of the bow of the vessel and maintain current USCG Documentation