root@sclrdev:/home/sclr/certs/FreshCerts# curl --ftp-ssl --verbose ftp://{abc}/ -u trup:trup --cacert /etc/ssl/certs/ca-certificates.crt
* About to connect() to {abc
In my case it turned out to be a problem with the installation of my certificate on the service I was trying to consume with cURL. I failed to bundle/concatenate the intermediate and root certificates into my domain certificate. It wasn't obvious at first that this was the problem because Chrome worked it out and accepted the certificate in spite of leaving out the intermediate and root certificates.
After bundling the certificate, everything worked as expected. I bundled like this
$ cat intermediate.crt >> domain.crt
And repeated for all intermediate and the root certificate.