A Very Brief History of Men’s Swimwear.

[Torchwatch]

I have a photo from a netted pool in the River Medway, Rochester, Kent dated 1895. It is a competition swimming event, the swimmers posed about to racing dive. Seven of them are wearing cotton swim briefs, one is possibly wearing a cotton Tarzan style loin cloth but it's hard to see. None of them feel compelled to cover up their thighs. In the audience there is a least one boy, this is competitive sport not something indecent to be kept hidden from the children.

There are 2 types of jammers; those made of "shark skin" water repelling fabrics, worn downsized and really tight and those made of normal swim Lycra but worn down to the knees.
The expensive sharks skin fabrics have less water drag than naked human skin and allow you to go faster, while swimming Lycra has greater water drag than naked human skin and will cause swimmer to go slower than if he were wearing Lycra swim briefs.
As is so often the case the sponsored top swimmers get the good kit while the poor kids joining the sport get stuff that looks right but doesn't do the job. I suspect that many boys who do swimming lessons in shorts are dropping out from joining their clubs racing squads because both they and their parents are confused and prejudiced against all skin tight male swimwear.