I think you will get as many opinions as there are boats. Firstly though, I am not experianced at taking long off shore trips yet, but I'll add my two cents and the following is what we based the decision of buying
our boat on.
The first area would be interior
layout. It's lovely to have an open spacouse layout, but in open water
, that can be deadly. You need to be kept safe physicly. So reducign distances that you can be thrown and impact on is essential. Sharp corners are a no no. Narrow passage
ways that you can brace yourself along when walking is great. One thing we really like about our Galley
is the "wrap around" feel that it has. Not that you are cooking
much, but you still need to prepare some food
The next essential is storage
space. Dry storage
space. You simply can't ever get enough storage space. You need lockers from small to large. Plenty of food
storage and that needs to be dry and able to be kept dry in all but the worst situation (that would be sinking)when food would be the least of your worries. Cltohing of course, you need plenty of good breathable lockers for clothing
etc. and verticle lockers are the best as clthes can be hung and the maximum air flow can be around them. Of course, this room is luxury on smaller boats and may not be possible or practicle.
Being able to retain everything. I am talking all the little things like plates, cutlery and all the little nicknacks you have on display. You may find the everything stays in place in normal conditions and normal heeling angles, but get into ruff weather
and you soon learn you have to find better ways to hold stuff.
That then takes me to the mechanical side of things. Engines MUST be held down with captivated engine
mounts. Batteries MUST be retained incase of the worst situation happening, a Roll over. Good bilge
pumps, plenty of them and well placed through out the boat.
Outside, the fitrst critical area would be hatches, ports
and windows. All need to be blue water
capable. Large Pilot house windows while nice, have to be able to withstand enourmouse water pressures. One cubic metre of water weighs a tonne. Now send it against the window with some speed and the impact is simply scary. I am using a toughend glass with an impact strength equal to 100mm(4") of normal glass. But it isn't just the glass. What and how it is held in needs to be equaly as strong.
drainage. It's not the first wave, it's the second and third, can the cockpit
drain fast enough to ensure water does not build up adding emmense weight high up. Are companion way doors well sealed from water and water build up from flooded cockpits.
Saftey rails and jacklines
. You need to be kept safe and well held in the worst of circumstances should you have to go forward. Having rails around the mast
can be a pain in many circumstances, but when it is ruff and you have to stand at the mast
, you will fall in love with the rails. They make an almost impossible job possible and keep you safe.
The rest is personal stuff you can easily add afterwards, like Lifraft, EPIRB
, flares, lifejackits, MOB
pole(colour of your choice;-) etc etc.