Join Date: Feb 2000
Location: Annapolis, Md
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Your post raises a complex set of somewhat contadictory goals. You talk about going to areas of the world that place a premium of seaworthiness and comfortable motion. If you only end up doing the East Coast of the US and the Bahamas, you can get by with almost anything in the size range that you are predicting but if you care more about comfort than anything else I think you will need to focus on comfort of motion, and to a lesser degree reasonable speed more than Beam.
To explain, like so many things in sailing and cruising yacht design, extremes should be avoided. Moderation is expecially critical when talking about beam. For the kind of thing that you are proposing the last thing that you want is "the beamiest boat possible". (I am not suggesting an extremely narrow boat either. Just moderation.) Wide beam brings a lot of negatives to the table. All other things being equal, a boat with a lot of beam will feel very stabile tied up at a dock or anchor in flat water, but as soon as there is any wave action, the wide beam means that you will be in motion and all other things being equal that you will also have a quicker, ''corkier'' motion than a boat with a moderate beam. There are two components that really affect comfort at sea, the amount of motion and the accelleration and deaccelleration rates of the motion. Beamy boats tend to have much quicker accelleration and deaccelleration rates than more moderate beamed boats. This quicker motion tends to wear out crews more quickly and the combination of fatigue and fast accelleration is more likely to cause seasickness.
Beamy boats tend to be less seaworthy as well. With extreme beam comes several areas of negative impact on seaworthiness. While a beamy boat offers a lot of stability when comparatively upright, as a beamy boat heels the righting energy decreases more rapidly than a more moderate beamed boat. The extreme beam creates a lot more weather helm as the boat heels making steering more difficult, tiring and requires greater battery capacity for the autopilot.
All other things being equal, a beamier boat will have a smaller angle of positive stability. This means that you more quickly reach an angle of heel where the boat prefers to be upside down rather than right side up. Beamier boats have greater stability inverted and so take longer to reright in extreme conditions. While a moderate beamed boat cannot be capsized by wind alone, extremely beamy boats can.
About this time you are saying that you would never be out sailing in those conditions but if you ever end up in the Bahamas when a ''Norther'' rolls in you easily can be. Which brings up the case for moderate speed. Distances between safe havens in the Bahamas can be fairly long. Many of these places should not be entered as night is falling since you need to be able to see and find your way through the Coral heads that often protect Bahama anchorages. In the absense of reasonable speed (and I am not talking about a race boat here) you will spend a lot more uncomfortable nights lying exposed in the big bounces of the ''Banks''.
Which brings up the affect of beam in a chop. When you study the behavior of different boat types, you find that different factors affect how a boat behaves under way. For example, light weight boats tend to go over waves and so have more motion but feel less impact. Because of their greater inertia, heavy boats don''t lift as easily with each wave and therefore tend to drive through more of the wave (and so tend to be wetter) but thier sheer inertial mass reduces the de-acceleration of that collision with the wave. A beamy boat tends to physically collide with the wave face with greater force than a more moderate beamed boat and so is slowed by each impact making a slow, wet and far more uncomfortable and exhausting trip.
Beamy boats just plain have more drag than a boat with moderate beam. Even if you are only ''vacationing'' drag is your enemy. It means that you need to carry more sail area which also means more work for the crew. It means more fuel consumption, when you are running the engine and also means that you need to run the engine more frequently. (I am inferring from your $100,000 budget that like most of us, you too have some kind of limit on your funds and so would like to keep fuel and engine maintenance costs to a reasonable limit.)
With all due respect, and this is not meant as a put down since we all had to learn sometime, you may think that you have done a lot of reasearch and reading, but from your post it is clear that you have a lot more to learn. I strongly suggest that you lower your target a little and satrt by buying a smaller coastal cruiser with good sailing abilities and spend time sailing and maintaining this simplier better sailing boat. You will build sailing skills and maintenance skills, and learn about the way boats really work and what it really means to have a comfortable boat. At that point you should know enough to buy a boat capable of doing what you propose as well as perhaps taking on the longer voyages that your girlfirend suggests as her ideal.