Dockhead,
I think that the idea which you're pursuing is a wise one. But, it's all been done many, many times before. By folks who get paid a LOT to both design, & to "test" (in RTW races) such systems. That & by professional designer/sailors like the Dashews.
So emulating what's worked under the utterly torturous conditions encountered by the solo, Non-Stop RTW racers. Who circle the globe via the capes, would be a pretty safe bet. Ditto on borrowing bits from folks like the Dashew's. Who's solutions run towards
equipment & system designs, using
Commercial Marine gear. As proven by professional mariners, in multi-layered, redundant setups.
Oh, also, BTW. Please refrain from freaking out the newbies by giving them ideas of death by over-helming. They can always heave too for a few hours... or days. Put out a
drogue, etc., etc.
Hundreds, if not thousands of sailors have made it safely into port/home, post self-steering failures. Or without having a formal system of it to begin with.
Back to these high end racers, & their AP setups:
One of the key things which many (or rather almost all) of them do, is to have multiple copies of the (
completely) same
autopilot onboard. Thus, you have full compatibility of spares. As well as the ability to cannibalize from one, in order to
rebuild another.
Also, when I say multiple, I mean in excess of 3 (copies). There are plenty of said sailors, who go so far as to have 5+ pilots, even. And given the $ figures you're throwing around... likely you could spring for 3 or 4. Along with some of the key spare
parts (read electronic brains for the units) too.
Albeit some of them will also carry a stand alone AP or as well. Which uses the same "brain" as their other units. Again, for commonality, & cannibalization, etc.
Plus, with that many pilots onboard, then one or more complete AP. Plus the fragile,
electrical bits. Can be stored in fully WT, Farady boxes. As I alluded to before.
And if you like, it's easy enough to build a two layered Farady cage
storage device. IE: One within another, seperated by electrically isolative materials.
Ditto on sealing your spares in plastic, prior to putting them inside of WT cases... like Pelican Cases, if you want the top end in protection.
As if a
lightning bolt can jump from the sky, all of the way down to the
water, it'll have little trouble jumping the gap in any switch, in a system that you set to the Off position.
And were it me, I'd be a bit careful with vacuum packing everything. As vacuum pressures can exert quite a lot of force on things which were never designed to be pushed on hard. Such as compressing a chip a bit too far into a circut board, for example (hypothetically). But the sealing in plastic thing, along with dessicant packs isn't a bad idea (especially when they're inside of a Pelican Case, too).
And if you're full on paranoid about
lightning. Then look to the aircraft industry for their data on
equipment testing. As well as isolating systems from lightning strikes of various quantifiable levels.
For if you've done much flying, commercially, I can guarantee you that you've been on a plane when it's been hit by one of "Thor's bolts". Likely sans much effect (or to your knowledge), thanks to said industry's R&D on the topic.
Regarding the failures of mounting points of AP rams. Knock on
wood, the specifications of such things aren't usually laid out by yacht designers unless/until:
- You start to talk about
boats which are really more in the way of small ships, size & expense wise.
- You specifically hire an NA or
Engineer to design the system for you. One who's designed many such, successful, systems/installations, before.
So that he can calculate all of the forces involved, add in the appropriate
safety factors (and then some on top of that). Followed by his delineating (in text, & blue prints/drawings) the materials & construction of said installations. Just as he would for a
rudder, or any other, critical, technical system comprising the vessel.
On
Wind Vanes:
I'd reckon that they'd
work on a
boat that size (they have before). It's just that you'll need a custom/semi-custom unit. Designed to match the scale of the vessel. And her performance characteristics.
As there have been a good number of
boats in that size range which have had them in the past (& now). So, odds are, a little
research will turn up some leads... probably to include some drawings to
work from too.
That, & I'm thinking that some of the manufacturers of the
gear which is out there already, would be happy to work with you as well; in fitting the right gear to said
boat.
Likely the biggest sticking points in boats that big, & vane gear would be;
- Loads on the system:
Which is something that can be dialed down to reasonable levels via proper
hull design shape (ie; a balanced
hull form as she heels over), rig design & balance (plus of course, proper sail trim), & proper foil design & placement.
- What kinds of speeds the vessel will sail at:
As on something sailing at normalish speeds, vane gear will work okay. But on boats which rarely drop into the
single digit speed range, the gear may not be able to respond quickly enough to steer the boat properly, in order to compensate for the rapidly shifting apparent
wind.
FYI, 90%+ of
all of the above, is Fully laid out in the Dashew's
Cruising Encyclopedia vol. II And the majority of it is also well covered in the video tape which they put out at the same time as Vol. I of the same book.
Yeah, it's a lot of info (to dig through in their book - Great Stuff!!!), but if you want to build your systems in a way which has already been
well tested... Then for $15USD on Ebay, the book's a dirt
cheap investment. Plus a damned good read (and reference).
Although IMO, were it me, I'd just go to
SetSail » Products & pick up all of their
books for $70.
As there's hundreds of pages of stuff on ~ both boat design; big picture. And boat design; systems, in said tome. On all manner of the things you mention desiring in a vessel. And IIRC, there's even a dozen or two, pages on design/build contracts, etc.
Given that it sounds as if you're heading down that road.
Finally => RE; Hydraulic system ruptures. On any boat which has
any hydraulic systems aboard (or just plain old
diesel for that matter), you simply carry several bags of absorbent cat litter, or buckets of sand onboard. Well, that & a gallon or three of Simple Green (for de-greasing/cleanup).
As blowing a seal or hose on above
deck hydraulics, turns things into a true horror show nightmare of a skating rink. The likes of which, you'll never forget if you've experienced it (such fun on 12m's, sans
lifelines, in 25kts of breeze).
And even with one belowdecks, the
oil has a nasty habit of migrating everywhere, including topsides. Ugh!
PS: Can we all please switch to decaf now ;-)
) - but we did 
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