The Peculiarity of Shipbuilding and the Employment Standards Act

As some may recall, I'm a bit of an HR nerd.  I enjoy learning the intricacies of Ontario's Employment Standards Act, and contrasting them with the conventional wisdom.  This post, however, will just point out a seemingly odd amendment to the act.

I'm doing some work-related research regarding termination (I may expand on that at a later date), and in so doing, I came across this interesting tidbit from Ontario Regulation 288/01:

Employees not entitled to notice of termination or termination pay

2. (1) The following employees are prescribed for the purposes of section 55 of the Act as employees who are not entitled to notice of termination or termination pay under Part XV of the Act:
...
12. An employee,
i. whose employer is engaged in the building, alteration or repair of a ship or vessel with a gross tonnage of over ten tons designed for or used in commercial navigation...

Huh.

I am sufficiently ignorant of the nature of shipbuilding to understand why an employee working on a vessel with gross tonnage of exactly ten tons deserves notice of termination, but an employee working on a vessel with gross tonnage just slightly over ten tons does not.

Anyone care to explain?