I apologize that this is a long explanation and that it is a draft an article which I wrote for another purpose:
I would suggest that the center cockpit versus aft cockpit discussion is another one of those topics for which there is no one universally right answer and yet it still seems to elicit near religious faith in one or the other view point. My sense is that there are cases where a center cockpit works well and cases which make almost no sense to any fair and impartial judge.
As someone who has designed the interiors for both, I will start with the practicality issue. When you design a boat, and if you start by assuming that the hull form is controlled by the hydrodynamic needs of the boat, the physical dimensions of the human body are so controlling that that for any given length of boat there are relatively few layouts which balance being efficient in their use of space with providing reasonable sized amenities. And while it is true that sometimes the shape of the hull can be tweaked to improve accommodations some, there is a practical limit on which layout will fit and which won't fit without compromising sailing ability.
To explain, as a general rule, designers try to save the best real estate for interior accommodations. Prime real estate needs enough bilge depth and a location near enough to the center of the boat to get adequate headroom in the passageways and standing work areas, and enough beam to get reasonable sized bunks, or dinettes, or heads or galleys plus the necessary passageways.
This goal of preserving prime real estate and not altering hull forms, begins to set a practical minimum size for a center cockpit boat. Since there is a practical minimum size to an aft cabing, as a center cockpit boat gets smaller, the aft cabin pushes the cockpit location proportionately further and further forward, so that the cockpit and passage to the aft cabin are occupying some of the most valuable real estate in the boat. And since there is a practical useful limit to the width of a cockpit, this in turn results in wasting an excessive amount of this prime real estate for items (engine compartments, sail lockers, narrow side decks and so on) which could and should be located in narrower portions of the boat.
Similarly, as a boat gets smaller, it is difficult to obtain adequate headroom in the passageway to the aft cabin without artificially altering the cockpit and deck. For this reason many smaller center cockpit boats eliminate the passageways and become ‘walk overs’ rather than ‘walk-throughs’ as the literature used to call them.
From a motion comfort standpoint, cockpit seats
should be as low as possible and still have adequate drainage and vision forward, ideally at or below the height of side decks. As center cockpit boats get smaller the cockpit seats
are typically raised to provide a little more headroom in the passage. And as the seats
get raised, so do the occupants so that they experience more violent motion both in terms of amount of roll angle but also the whiplash at the end of each roll.
It is for that reason that you often hear that small center cockpit version have poorer motion comfort than their aft cockpit sisters. This may be seen as being offset in part by having less pitching motion, but pitching, especially near the stern as compared to the bow, tends to be the gentler of the two motions.
As boats get longer, there is less of a need to raise the seat tops for headroom in the passageway and less of a need to preserve key real estate since more length of boat has an adequate width for accommodations. In a practical sense, it is very hard to design a center cockpit boat that is much below 42 feet that has adequate passageways, proper sized berths, and which does not have a deck plan or hull design compromised to make the design work. This is especially true if the designer includes enclosed forward and aft heads since the aft head almost by necessity ends up under the cockpit seats
. Once the boat gets smaller than around 42 feet, without altering the hull and deck adversely, the passageway becomes overly confined and more difficult to use.
In terms of wetness, because the cockpit on a center cockpit is proportionately closer to the bow, passengers in center-cockpits that are otherwise unprotected, experience more spray and solid water than make it aft.
Center cockpit boats often require more complex and higher maintenance steering gear. They sometimes require more complex deck plans as well with turning blocks and slant base winches
making ergonomics and low friction harder to achieve.
With the extra companionway, and more opportunities for operating portlights, ventilation tends to be better on center cockpit boats especially in the aft cabin.
The storage issue is one that is more or a liability on smaller center cockpit boats. Walk through center cockpit boats simply have more circulation area. There is no way around that since there is no way to double load the passageway to the aft cabin. And if a head and or berths tuck under the cockpit seats then more bulk storage is lost. It’s just the way it is.
But as boats get larger, these issues fade away quickly and at some point the sheer length of travel between the cockpit and the main cabin make an aft cockpit less practical.
There is a perception that performance sailors buy aft cabins and only cruisers buy center cockpit designs. I am not sure that is all that true, but I will say that from a performance sailing standpoint, lower friction and direct feel steering is easier to achieve with an aft cockpit, and it is easier to get a clear view up the slot without craning your neck while still being in a spot where you can see the leech telltales on the mainsail from an aft cockpit.
So in the end, like so many sailing decisions, the choice of center cockpit versus aft cockpit comes down to personal taste, sailing objectives and aesthetic sense. Now that we put that one to rest, does anyone want to debate which is inherently better vanilla or strawberry ice cream?