All the labour saving devices in the world won't make a jot of difference to the fact that men will always produce more work in a shift working production lathes etc, it's just one of those things that are natural.

My work has taken me to buildings, sites, engineering depots, mines etc., where over the last 25 years or so more women have been employed. So I am calling on practical experience.

In one situation (water storage management) the boss was very safety conscious. Anyone who tried to lift 100kg or more (Nicknamenick!) without gear would be considered a fool. Taking the engine out of a vehicle? Use the overhead hoist. Lifting a huge truck tyre or moving heavy stuff? Use the trolley. Reason 1: It's faster and more efficient. Reason 2: One person can do it, doesn't need two or three. Reason 3: the last thing I need is you idiots off on dick-leave (originally a typo, but decided to leave it).

I once worked on a project with a major earth-moving and excavating contractor. Several of the drivers (notably the driver of the largest bulldozer) were women, and the boss said he far preferred women, couldn't get enough of them. I got to drive a huge Volvo tip-truck (the tyres were taller than me, you climbed a ladder to the luxurious cabin), on a lake-bed because I didn't have a licence of course. Driving these trucks requires finesse, not strength; repairing those tyres requires the right gear, not a strong man.

As for the Navy stoker story: if you had 2 male and 2 female stokers, and accepting the women are on average smaller and not as strong; why pair them 2 men v. 2 women? If it had been four male stokers, of different physiques, the sensible thing would be pair each of the smaller men with a larger man. The description of the difficulty of moving the gear makes another point: because men tend to put so much stake on strength, they are maybe slower to come up with more efficient ways of doing things.

Re men's and women's tennis. There are a number of sports with weight classes: https://en.wikipedia.org/wiki/Weight_class. The purpose is to reduce the exclusion of smaller athletes in sports where physical size gives a significant advantage. Men's v. women's classes are in effect a weight class division. There's room for more separation on genetic grounds: how about separate races for black and white runners? http://www.livescience.com/10716-scientists-theorize-black-athletes-run-fastest.html.
Paralympic sports has the same effect: it reduces the exclusion of athletes where presence of all limbs, sight etc. gives a significant advantage.
Perhaps it would be possible to mix men and women in tennis, but introduce weight classes? In any case, I can see no reason why women should play fewer games. That's a test of endurance, and women are pretty good at that, biologically. (I have never been an athlete, but I once walked a competitive sprinter into the ground. He was brilliant over 100m, but not so good over 10km.)

Sorry cos but i would hardley class the Williams sisters as 'light weights'!