Re: Cat 27 100 -110 - 115 Headsail?
Your boat is a masthead rig and the engine on a masthead rig is the jib - on a fractional rig the engine is the mainsail. A 100, 110 or 115 are similiar to a storm jib. In my opinion, the best all around choice for a jib would be a 135 and if you team that up with a roller furler you'd have an excellent performance setup.
Originally I had a 155 on a C30 but it was a pain for me to deal with singlehanded so I sold it and bought a high cut 135. After the first sail I didn't much like that sail either so I sold it and bought a 135 that was cut just about the level of the safety lines or a bit below. I really liked that sail.