These could be fishing net buoy beacons - used by fishermen to find drift nets. They tend to operate in the 1600-2000 kHz (1.6-2.0 MHz) and 26-30 MHz range and usually transmit a CW identifier at low power. The CW identifier is usually somehow related to the associated ship's radio callsign or name.
Here's a well-compiled list of 26/27 MHz fishing drift net buoy beacons and their IDs:
http://www.qsl.net/n2sln/driftnetbeacons.htmlThere are several "real" 27MHz 11 meter beacons as well, most of them in the 27500 - 27600 region, although there are others, mainly operating within the "legal 40" CB band (26965-27405) on 27125, 27140 and others. 27500 is the "official" 11 meter beacon frequency, apparently. CW activity has been heard on this frequency as well as PSK31.
The frequencies you list - 27878 and 27003, aren't on any 11m / 27 MHz beacon lists I've found.
Here's a list I've compiled from a couple different sites:
27125 kHz - 16mW power - California - 2QRP and AOH - "AOH" in CW
27140 kHz +/- 3 kHz - 500mW power - France, IDs in CW - 14RS000 followed by a long tone burst.
27175 kHz - unknown power - Thailand - 153SD101
27405 kHz - 1W power - Germany - 1 pip a minute
27499.6 kHz - 2W power - Moscow, Russia - 50KS00 in CW
27500 kHz - unknown power - Mexico City - pips in CW
27500 kHz - unknown power - Greenland - Voice ID in USB "38 voice beacon"
27501 kHz - 25W power - Kansas - 2KP
27504.4 kHz - 1W power - France, IDs in CW/PSK31 - 14RS000 (may have moved to 27140 kHz)
27540 kHz +/- 5 kHz - 1W power - East Coast USA - FM signal modulated with tone, no ID. 10 kHz wide FM signal.
27550 kHz / 27610 kHz - 25W power - Costa Rica - IDs in CW as "69BY". Apparently moves around in frequency. Originally on 27500 kHz. Also on 6775 kHz, 13555 kHz, and 40680 kHz.