Originally Posted by Melrna
These are just my observations from looking at boats and doing some reading on what generates a Cat A bluewater boat.
1. Hull structure - How the hull is made to take the bending and flexing movement. Bonded bulkheads, stringers and interior pieces to the hull create a stronger hull.
Actually, many coastal cruisers are made this way as well... it has more to do with the strength and thickness of the hull laminate and the amount of reinforcement it receives.
2. Hardware - beefier and attachment points stronger
3. Ports - No plastic here. Ocean waves will create failure of most plastic ports.
Most hatches are glazed in plastic... Lexan is perfectly suitable for marine ports, as is thicker acrylic.
3. Cleats - Be strong enough to deploy a drogue or chute without being riped out by the forces.
Drogues and chutes should have their own dedicated hard points IMHO.
4. Anchor platform - Beefier to stay on the hook during a blow without bending or failure
5. Stability Curves - Boat be able to right itself in-case of a knockdown over 110 degrees
Self-righting isn't a necessity. It is very important for ballasted monohulls, which will sink if they remain inverted for any extended period of time.
6. Hull Shape - Be able to ride out rough seas and still be in control of the boat, Ease of motion helps here too. No long overhangs to keep following seas out of cockpit.
Long overhangs also present other problems. However, a bluewater boat should have a fair amount of reserve buoyancy both aft and forward.
7. Rudder attachment points - at least two(top and bottom) - three is better.
Lots of bluewater boats make do with a spade rudder.
8. Deck - being able to clear water over deck fast
9. Cockpit - small to medium with ability to clear water out fast.
10. Liferaft storage to be deploy easily
11. Rigging and chainplates - beefer and oversized. Chainplate attachment points to hull vs bulkhead with beefer stringers to spread the load.
12. Fuel and water tanks - below waterline for more stability. Also in my humble opinion min of 100 gals fuel, 150 gals water for 40' or less boat.
Those numbers are a bit high for a bluewater boat of less than 40'. That's 800 lbs of fuel and 1300 lbs or so of water. Given that you need about a half-gallon of water per person per day, and most boats are sailing with a couple aboard, when would you be making a passage that takes 150 days??? Let's be generous and say you need a gallon-per-person-per-day, and that means you have enough for a 75 day passage... Umm... not many passages are much over a month, unless you've done something really wrong.
13. Quality of construction of boat.
Not all bluewater boats are well-built... not all coastal cruisers are lightweights and shoddily built.