Listen, I am no offshore expert at all so this advice is worth about what you paid for it.
That said, I speak to alot of sailors, have built a few small boats and read alot on this kind of stuff.
I read the story here on this forum of a large production boat doing the transpac to Hawaii, and having to turn back partly due to the boat leaking too much. It had never leaked in coastal conditions. But in the rough seas it encountered, with the deck being swept by a wave every minute or so, enough water came in to get everything inside the boat wet and require running the pumps. Death of a thousand cuts so to speak. I have heard that modern thinking on offshore boats is the "tupperware" principal, that the boat should be able to be sealed up perfectly, including the companionway. Many production boats used less than ideal caulking methods, and after only a few years they develop leaks (check out the bedding with butyl tape thread he gives some good examples). After 40 years, that sealant is just gonna be gone. I am going through this on my own boat, which leaks when it rains. I have begun re-caulking all through deck fittings, including the toe rail. I hope the hull-deck seem is still in good shape, because that would be one hell of a job to re-do lol... point is, people say that if the hatches/fittings can be sprayed with a pressure washer and not leak, then they probably won't leak if hit by a wave. I don't know how true that is, but at least a few people seem to believe it.
While recaulking, you may want to inspect the through-deck fittings for corrosion. 1/4 inch stays won't do much good if your chainplates are corroded inside the deck.
As for bulkheads, the hull flexes while in heavy seas and this can de-tab bulkheads. Happened on my own boat, though not on a crucial bulkhead. I simply re-tabbed it, using two layers of cloth instead of roving. If I were going "offshore", I would sand and reinforce the tabbing on my bulkheads with a layer or two of cloth. This is cheap and easy to do, and gives you a close up look at the structural condition of your boat, including whether the (usually ply) bulkhead is beginning to rot or is in good shape. A few through-(tabbing and bulkhead) 1/4 inch bolts on each tab is cheap insurance to ensure that the tabbing won't become detatched from the bulkhead (they are usually attached with polyester resin, not epoxy, so the bond may weaken over time).
Another thing to consider is a forward crash compartment. James Baldwin raised his v-berth a few inches and sealed up the compartment underneath, creating a crash compartment. He did this after a collision with a fishing vessel which could have been worse if he were not a lucky guy...
Again though, I am not talking from experience as I have never made an "offshore" passage. Just reiterating what I have learned from others and from my limited practical experience.
Last edited by peterchech; 02-02-2012 at 12:15 PM.