In terms of cruising
boats, prior to my cat I have owned full keels (Folkboat,
Alberg 30, Bayfield 32C) and a long fin with a skeg mounted
rudder, well aft (Cartwright 36 Pilothouse cutter). I would not hesitate to go to sea with either arrangement.
With proper sail trim, my
folkboat sailed a better course upwind than I could when helming (up perfectly in the puffs, off in the lulls, no
rudder braking effect from unnecessary
steering corrections). My
Alberg 30 and Bayfield both tracked exceedingly well and could maintain an upwind course for a significant period without touching the
helm, although the Bayfield required the
wheel to be locked a couple of degrees to leeward. Neither, however, could handle extremely gusty conditions (nor close reaches) without some
helm adjusment in the way that the
Folkboat could.
My Cartwright proved to be able to track as well as either the Bayfield or the
Alberg, and was much more responsive to the helm. Remember, all of these except the Bayfield have done successful circumnavigations, albeit not in my hands ( indeed, it is even possible that the Bayfield32C has circumnavigated - I just don't know of one). All were noted for their
tracking ability and their 'sea-kindly' motion in heavy seas, although due to the higher beam/waterline ratio and lower relative
displacement, the Bayfield did tend to get bashed around more than the others when sailing into heavy seas.
The point is that the ability to track well can be accomplished without a
full keel, although the fin must be kept fairly long. Ted Brewer is generally credited with creating the 'Brewer bight' - this was, as it sounds, a
full keel with a 'bite' ( a small semi-circular section removed from the
keel just before the rudder). It is not to be confused with a long fin
keel with a separate skeg mounted rudder. The purpose of the 'bight' was to reduce the surface area of the keel (and therewith some drag) and to improve the
steering response in relation to a full keel, while maintaining good directional stability. Both designs achieve that to a varying degree.
Like directional stability (or 'tracking'), a 'sea-kindly' motion is just as possible in a
boat with a (long) fin keel. According to Robert Perry, NA, the key issue is not 'U' or 'V' sections in the underbody, it is rocker (the fore/aft curvature) of the
hull. It is the rocker that tends to keep a larger amount of the
hull in contact with
water when sailing in large seas. Here too a moderate to moderately heavy
displacement helps, as does either a 'U' or 'V' shape to the underbody (flat is great in light monos for planing, but will tend to pound when sailing to windward in heavy seas).
The point is that the same desireable sailing attributes for
extended cruising can be achieved with either fin or full keels, so long as the fin is kept fairly long and the underbody has adequate rocker and no flat sections to promote planing (or more commonly, greater
interior space). Of course there are those (eg, the Dashews) who promote light, relatively narrow and flat bottomed
boats for
offshore - and they will certainly be quicker in most conditions. But I suspect that most people would still prefer the more tradional 'sea-kindly' motion and
tracking ability of a heavier displacement
boat with either a full keel, or a long fin.
Robert Perry designed full keel cruisers, although his preference was (and is) for a long fin with a skeg mounted rudder well aft. He believes that it provides the best compromise by maintaining a sea-kindly motion and good tracking ability, but with better helm response, better steering control in reverse and better pointing ability (even a long fin can be designed to provide some lift). His Valiant 40 paved the way for a whole genertion of 'performance cruisers' and the basic premise of the design still has huge merits for the
offshore sailor.
Are spade rudders appropriate for a distance cruiser? They would not be my choice, although I can acknowledge the advantages of a balanced rudder in terms of steering response (and reduced effort at the helm). The problem is that there is still (and will always be) a greater tendancy to lose the rudder through contact with cargo containers, or
logs or (?) than there is for a rudder hung behind the keel, or an adequate skeg. If the rudder post is made of carbon fiber, you are virtually guaranteed to lose the rudder with any significant contact (witness some Hunters who experienced
lost rudders offshore). Even with a very solid,
stainless steel rudder shaft, the best case scenario will result in a bend to the rudder shaft. Frequently this will completely disable the steering; indeed, it can be worse than no rudder at all if it becomes fixed in an off-center position (as is typically the case).
Another arrangement that has its proponents is a full shoal
draft keel with
centerboard. This can
permit an even shallower
draft than a full keel alone and better performance to windward. While not everyone's cup of tea (and recognizing that the added complexity of the
centerboard is more apt to cause problems), it is a terrific compromise that is currently out of vogue. That such an arrangement is suitable for offshore passages was proven in the mid 1950's by a Sparkman and Stephens design that won the Marion to
Bermuda race and various other offshore
events. Sorry, I can't
recall the name (although I am sure somebody out there can help me - she was quite famous.).
Anyway, I vote for all of the above. The issue revolves around your intended use (including the desire to gunkhole), the shape of the hull, the shape and length of the keel and the method of attaching the rudder. All are quite capable for offshore use so long as the boat was (well ) designed and constructed for offshore sailing.
Brad