I can see that I'm not expressing myself very well--that or you guys really do think I'm an imbecile--which of course is your prerogative. ;-)
No, I wasn't proposing that a 47-year old, 17' LWL toy is a model for modern offshore raceboats. I said it was the first I'd seen specifically designed to keep its crew out of the weather. I might point out that it *did* come second on that first OSTAR, beaten only by Chichester's Gypsy Moth IV, something like 10X the displacement. One might ask oneself if there is any significance in the smallest boat ever to run the transat coming so close to an outright win--as you say, she wasn't nearly the fastest... Could it have had anything to do with the ease with which she was sailed?
Nor do I recommend that modern offshore crews climb into their bunks and set the autopilot--how my statement that they should not be on deck could have been taken as a suggestion to put them all in their racks and start the autopilot is beyond me, and yet obviously I wasn't specific...
And yes, I have noticed that some of the best sailors who have ever lived prefer to steer and handle the boat from above deck, without their autopilots, and demonstrate faster speeds because of these beliefs--yes, crewed records are still faster than single-handed records.
OK, if I wasn't suggesting pure idiocy, what, then, was I talking about? I'll try this again:
The sports of aeronautics, automobiles, landsailing and (water) speedsailing all used to run with their crews exposed. Perhaps surprisingly (and perhaps not, in context), the best operators of each of these sports *insisted* they performed better outside than inside, where they could "feel the wind" and be "closer to the elements." Each strongly resisted the enclosure of their vehicles. It should not be surprising that each of these men was proven to be in error, and that the speeds--top, sustained, whatever the metric--significantly improved when they were enclosed. Duh.
"But sailing's different," I hear you thinking. Is it really? Have we suspended the laws of physics, and specifically, the rules regarding parasitic drag?
A better statement might be, "Can the crew operate the boat as efficiently from within an enclosure as they can now, outside?" This is a good question, and could be profitably argued both ways--always remembering the pilots, drivers and skippers of those earlier vehicles--*all* of whom were proven wrong. (Not what they *believe* they can do, but what they actually *can* do--with specially designed equipment, perhaps, and much practice.)
An even better question might be, "If we put the crew inside and forced them to completely relearn their jobs, and *if* they were found unable to perform to the same extremely high efficiencies they can while on deck, can an argument be made that the reduction in drag on the boat due to putting them inside some enclosure might/can/will overcome the loss of efficiency due to removing them from on deck?"
Bringing it all around to where I started, I believe the answer to this question is yes, it *can* be done. Not by doing something like we've done before (putting a plexiglass dome on a Folkboat, or switching on the autopilot and playing canasta), but by doing something new, perhaps even something untried.
Just how much drag are we talking about here?
Well, let's look at air drag. It's been said that, for each man standing above the deck of a sailboat, beating at 10 kts against a 20 kt true wind, an identical amount of drag can be created by removing the man, standing in air, and substituting a 4" tall model of that man, cemented onto the hull underwater. This was s simple demonstration to bring home just how important air drag is--nobody in their right mind would go around gluing 4" tall toy soldiers to the bottom of their hull, and yet few give a second thought to a crewman on deck--even though they create the same drag on the system. Now, have a look at the entire boat--men, cockpit, mast base, stanchions, winches, blocks, line, etc, etc and let's imagine moving *all* that to an enclosed, streamlined structure. Could this make any sense?
What about crew sitting to windward? Forgetting for a moment what a barbaric custom this is, couldn't it be done by stacking these guys into windward wing bunks? They aren't on duty, put 'em in the bilges. Yes, they create a tiny advantage by getting their c/g's a few more inches outboard on deck, however, see below regarding tradeoffs. (Plus, do we *really* want to encourage a level of sport where off-duty crew must sit in the teeth of potentially fatal wind and wave conditions, just to remain "competitive?" I thought that's what rule-making bodies were for, to make the sport more healthy?)
Let's talk about waves coming across the boat, as this one was what started the thought for me. A published data point says that a V70, doing its "max" speed of 35 kts on a broad reach is generating just about 400 hp from her rig. A bit of arithmetic suggests that this equates to roughly 3700 lbs of thrust (defined as the sails' resultant, parallel to the boat's average motion), or a shade over 1.5 metric tons of thrust. As the boat's at equilibrium, it can be inferred that this number also equals the hull's total drag at that speed. I'm happy to be disputed on this, but it both looks and "feels" right to me. At 25 knots, drag should be roughly half that at 35 kts, so we'll postulate the rig is creating about 3/4 ton of thrust at that speed.
How much drag is there on a man, then, stopping a wave with his body? We can play around with calculations, but as a worst case scenario, let's say that, usually, this force is less than that needed to rip him off the boat to his death (though, literally according to evidence, thus "evidentally," this is not always true--men are dying this way). As a strong man can hold his body weight plus likely 100% of that weight, I think we can set this force as something less than 200 kg, on average. Let's dial it down a bit (OK, a lot) and call it an average force of 50 kg. Further, let's suggest that this wave force might last for 5-6 seconds, perhaps once/minute, in rough seas.
What's this come to? If we've got 6 men on deck and each man suffers 50 kg of drag when each wave hits (as above), we've got something like 300kg of combined wave drag across the cockpit, 6 seconds out of every minute of the time. This is equivalent to losing 40% of the boat's total thrust, just as wave drag on the crew, during fully 10% of the time she's sailing in rough seas. How much added efficiency must the helmsman achieve, in order to overcome this sort of dead drag?
OK I know, you want to tell me I'm full of it, but consider this: I have completely ignored the drag due to waves washing across the cockpit structure, the mast base, the dodger, winches and pedestals, the wheel itself, the sail bags "breaking" the force of waves on the helmsman, etc, etc. D'you really think a well-designed enclosed boat, crewed by men who are determined to do as good a job "under glass" as on deck, couldn't lead to overall increases in average speeds?
Single handers must use shortcuts, because of crew fatigue. Think of this; if a full crew were "under glass" wouldn't the raw physicality of their job be reduced? If so, couldn't their performance level increase? Couldn't, for instance, a helmsman maybe stand longer watches (longer than the 20-40 minutes max they can achieve today, out on deck)? If the men could stand longer watches, could there perhaps be fewer of them? It's a commonly accepted figure that, depending on length of race, one crew = .5 to 1.0 tons of added displacement, given man, gear, food and water (or watermaking capacity). How many men could you leave ashore, and how much faster, on average, might this leave the boat?
I'm not saying this is a "lay-down" position, but wouldn't one agree that this concept--enclosed offshore racing boats--ought to be considered?
Cheers,
Dave
