What is the drag effect on swimwear?
 

My local pool is 25 metres long and there is a countdown clock poolside, so I thought I would try and sprint as fast as I could. So yesterday I did one length backstroke which clocked 35 seconds, and after a short rest did front crawl in 20 seconds. I was amazed at the difference in the type of stroke used, so surely there must also be differences in the type of suit you wear?

If you swam wearing a shirt and a pair of trousers that must be slower than wearing swim briefs, obviously. So how much slower would you be wearing knee length board shorts? Has anyone tried to make a comparison?

slower by sure
 

I haven't measured it but even when wearing mid-thigh length trunks I felt slower and felt more drag. That's why people train with drag suits. I actually wonder why they make specific drag suits. You can just wear board shorts and it will give you a work out. I suppose people want to wear something that resembles their normal suit (i.e. if they compete), so wearing board shorts may mess up your stroke or form?

Though maybe the difference is more pronounced in long distance swimming? I like to swim at least 50 lengths in a session, but to attempt that wearing board shorts sounds exhausting.

Adjust in other ways
 

Yes, I think it's best to use other things, like pull buoys or kickboards to adjust you swimming. I think 50 lengths in board shorts may get really tiring.

Bede,

I try to swim between 20 and 25 laps each time and only having worn speedos since I started swimming 3 months ago, I can't even imagine what it would be like to swim in boardshorts.

D67