We'll be up there too from the 25th! Only there for a week tho.. 

you should come across the ruby grounds while you're trolling for marlin. 300m is about the mark where they are at. Look for large schools of fish on the sounder. Zooming in at depth will help to identify them. The tighter contour lines are good indications of drop offs etc which can hold fish. 

cheers

Thanks for the info . Been Marlin fishing there for years but never had a crack at a Ruby or any of the deep drop species . Didn't know if I should be looking for ground or fish schools