170N is the accepted standard for recreational sailing. It is a comfortable, wearable size that is not too intrusive and it provides significant buoyancy when in the water.
The 275N provides significantly more buoyancy so is suitable for situations where additional weight might be carried, i.e. tools, steel toecap boots, etc. Remember additional buoyancy and size is not always an advantage as it is heavier to wear and harder to use in the water, i.e. if entering a life raft, etc.
The Volvo Ocean Race sailors helped in the design and development of their lifejacket harness for the 2017/18 race and chose to wear 170N. The Clipper Race also chose the 170N Deckvest VITO for their sailors.
