Per Steve Cramer:
Are you wearing a PFD? Goretex doesn't breathe as well with 1" of foam
strapped over it, in my experience.

I've done it both ways. Been wet both ways, but didn't bother to compare the
shirt weights.

Sweat's sounding like the explanation to me.

Especially because of the smell of my inner layer - Whew!!!!!!

I can usually get away with wearing a biking shirt a couple of times between
washes, but the Capeline shirt/long johns that I wear next to my skin definitely
have tb washed after every use.
--
PeteCresswell