Loss of a vessel: We know of a number of situations where dedicated people lost a vessel and then repurchased another vessel and continued. Again, this goes to commitment. Certainly there are people who loose a vessel in a storm, and this is such a traumatic event, that they stop cruising. But, my feeling in interviewing is that they didn't have that long term commitment.
Fouled props, hitting debris, etc--are all just part of cruising, and should not be a valid reason to cease a voyage. Many people attatach cutters to the shaft--but there are nets, plastic, scrims which will still disable a vessel. Even large masses of floating kelp can disable a vessel. I believe that you must have both the equitment and skills to dive and remove the material. We had several instances where this was necessary--and cutters would not have been of value. Incidently "light" line less than 1/2" can certainly be a major problem, as it heats and fuses to the shaft. Large ropes--and we have seen ropes up to 3" diameter floating--can actually damage a prop/shaft/engine mount/tranmission output gears.. Be cause of this I am of the group who thinks that an auxillary propulsion is necessary--and I include in this engine/shaft, prop--and ideally rudder. The rudder is not offered in any production boat I am aware of.
A whole other issue is "things back at home". This can include family which needs help. A house which has been rented and problems arise, and perhaps more commonly a business which needs attention. Many times these issues can be resolved with good communications systems. But we have seen a number of voyages terminated because fo these issues.
Finally--at least for this set: The boat. As I noted for coastal cruising there are many boats which are satisfactory. For ocean crossing--where a range of at 2500 to 3000 miles is necessary there are more limited numbers of vessels. Some may have precieved my comments about Nordhavn as "bashing". Far from it--I stated in the past and again recently that in my top list of boats were several Nordhavn's. When we crossed the North Atlantic there was a Choy Lee LRC in VHF contact the entire Bermuda to Azores stretch. We saw a number of custom steel power boats. Daves's Rough Water 57 (if adequate fuel tanks are fitted) is a vessel, the Scokum 53's are excellent passagemakers and I know of several which have made passages. My own preference is for a boat with full displacement lines--and tending to rounding of the buttocks area with a full ballasted keel and running gear protection. My own thoughts tend to longer, narrow beam vessels for better effeciency.
Bob Austin