While we are interested in doing a modern version of any kind of traditional mono-hull boat, our main focus in sail has been on the New Universal Rule of Measurement: bringing back the mid-size Universal Rule boats (classes M, N P, and Q) in a new design development competition version, permitting certain carefully-chosen design features, and permitting modern construction. For detailed information on the New Universal Rule of Measurement, Class M or Class Q, please see www.universalrule.com.


There are a number of key components in the design of a good boat such as an M-boat. We'll take a look at a couple of them in this section.

Interior Arrangement

While the deep, narrow hull of a Universal Rule boat contains an inherent advantage for the interior (lots of headroom), it's long, narrow form also makes it a real challenge to put in a good interior. Yet, we think it has become clear that the boat has to be good for limited cruising as well as racing, or it won't be a true value for the money and time that the owner puts in. It is simply too difficult to get boats to the starting line for constant racing, even in an established class, as anyone who has tried to do so has learned. So we had to find a way, without compromising the sailing traits of the boat, to put in a nice interior.

The original M Class had somewhat accomplished this, so we had something of a starting point there. While Dave Fladlien had spent a great deal of time on an M-boat as a youngster, it was long ago and he doesn't remember the details of the interior of Barlovento as the boat was then. There are drawings of the boat's more modern interior, though, and we have spent a number of days sailing on Pursuit, so we are familiar with the interior of that boat. So we did have some reference points which turned out to be quite handy. From there, it was a whole new game.

Over a period of time, we tried fitting in a lot of berths, and tried to make part of the boat available for sail stowage, etc. Eventually it became clear that the objective we wanted to offer was one which provided a nice owner's cabin, and decent accomodations for either 4 guests and 2 crew, or 2 guests and 4 crew. While it was sure to be very tiny and would have to use mostly seawater, we did want a shower, and at least a couple heads with a private one for the owner. Dave wanted a space where he could check the financial markets, etc., each morning, as that is an interest of his and we suspect of many potential owners. Cyndel enjoys cooking, which may be true of many potential owners as well, so a good galley was also indicated. Quite honestly, that is how we went about developing the arrangement plans. We ended up wanting a boat that would be a good boat for, say, a 1 week cruise, and since we knew roughly what the hull had to be like – determined by the measurement rule – we knew what we had to fit in, and what hull form we had to fit it into...

As if that wasn't challenging enough, Dave had a number of elements for safety that he wanted included, having been on many boats that didn't have them. One of those is that, in each stateroom, there must be two ways out of the compartment, even if one is very inconvenient, in case one is blocked for some reason. Another is narrow passageways. While we won't be at all surprised if a number of people disagree, Dave is of the strong opinion that a wide passageway on a sailboat is simply a long way for a person to fall if he/she misses grabbing a hand-hold while walking along the passageway with the boat heeling 30 degrees or rolling fairly violently. When those concepts were also incorporated, a pattern did begin to emerge.

There are, no doubt, a great number of possible arrangements which could meet these criteria, but we offer a couple of possibilities, that we especially like, to the right. The principle difference in these is how the galley is managed; version 13 (Figure 1 at right) has the galley forward, which permits a very logical flow of motion through a fairly conventional arrangement, but with an especially nice owner's cabin for a boat of these proportions. This arrangement also provides a very good shower and dressing area near the middle of the boat where there is maximum headroom (over 7 feet at that point). The galley, though, is fairly spread out. Version 15 (Figure 2) isolates the food preparation area further aft in the boat, which is accomplished along with a good owner's cabin by using one side of the area beside the engine for a compact but very centralized food preparation area, and the other side of the engine for the narrow passageway. Forward of the food preparation part of the galley is a pass-through area for handing things off to the galley table area.

In both arrangements, a key element is the folding table and removeable seats. These removeable seats – which are securely anchored to the floorboards when cruising – can be lifted out of the boat when racing. When the seats are removed and the table folded, a good-sized working area becomes available for packing spinnakers or even folding jibs (though sail storage while racing is primarily on deck). The interior arrangement drawings on this page show one arrangement with the racing (folded) table, and the other with the cruising (open) table. We think either of these arrangements, preferrably further refined through full-size simulation, will make a very nice interior.

Developing a Good Hull Form

In the section about interior arrangement, we talked about what these boats are intended to be like. In this section we will focus on the hull design aspects, illustrating with some of the other boats we have tried and left behind, but which will again serve to illustrate certain design qualities and also design approaches. Please note though, that none of these boats is competitive today (you didn't really think we'd publish the fast ones, did you?).


Our main focus in hull form development has been on Class M. Immediately above is the demonstration boat for this class, our Hull 66F2. This is the same boat featured on mclassyachts.com, and also the boat whose hull lines and construction plan appear as part of the New Universal Rule of Measurement for Class M, which can be downloaded at www.mclassyachts.com. This boat was, frankly, drawn both to illustrate the type of boat, and to do so without compromising any of the things we have learned in literally thousands of design hours spent on M-boat hull designs. This demo boat is not at all competitive with our current designs -- and we knew when we drew it that it wouldn't be -- but still serves to give a good general idea of what one of these boats might be like.

At one point in the design process, we commissioned an independent study on optimum primary coefficients (Cp, LCB) and a couple of other parameters, for which we furnished several sets of lines, and that study gave us a very solid foundation for our primary coefficients and those other key parameters. Before we commissioned that study, though, we did quite a bit of experimentation ourselves. And the results very much varied with other factors and with the other parameters. In other words, one prismatic coefficient would be better for one boat, and a different one might be better for a different shape of boat. It wasn't until we had done enough design work to be fairly well settled on a hull form and keel form that we could then draw several hulls in which we varied just one parameter, and actually commission the study that we had done. While we might have done the study ourselves, and had done one in-house earlier, employing the services of an independent authority on performance prediction gave us a strong assurance against unintentionally biasing the results, and also gave us the benefit of our Consultant's exceptional knowledge and expertise in use of performance prediction methods.

What resulted was a set of optimum values, varying with the wind speed, so that one has to either design to a particular wind speed, or choose a "best all around" compromise value. Following are a couple of the hulls that we experimented with before our basic parameter study. As we now have hulls considerably faster than these, we'll put several of them up here to illustrate the process, but again please note that these are old boats, and are definitely not competitive with our current hull designs.

Immediately below is a variation on Hull 66F2, this one is 66F2b(t), which is a beamier version of 66F2, and which happens also to have the traditional transom instead of the forward-sloping transom. Both are legal for Class M under the proposed New Universal Rule of Measurement, which also contains some requirements which minimize the weight-distribution advantage inherent in the use of the forward-sloping transom.

It isn't easy to see the differences between the hulls (except for the transom which has almost nothing to do with performance), but it can be seen clearly on the accompanying overlay of the two midship sections.

As you can see, the change is fairly small, and mostly right at the waterline, where the Universal Rule measures beam. But the result is pretty noticeable, as the graph to the right of the midship section comparison illustrates. Please keep in mind though, when viewing this and the other comparative performance graphs in this section of the web site, that speed differences expressed in seconds (rather than boat lengths) per mile exaggerate the speed differences in light wind: since the boat is going a lot slower (taking more seconds to go a given distance) in light wind, time margins are larger for light wind. For instance, in moderate wind, it might take a particular boat 6 seconds to go one length; in 4 knots of wind might take more than twice that. So if one boat is one length per mile slower than another in all wind speeds, that boat will appear 6 seconds per mile slower in moderate wind, but 13 or 14 seconds per mile slower in very light wind, even though it is one boat length per mile slower in both conditions.

Below is hull 39F6, which is another beamier boat.

Notice though, that it's performance doesn't compare directly to the base boat (66F2) in the same way that the first beamier boat, 66F2b(t) does. The latter was definitely slower in light wind; 39F6 is too, but not by as much, and above 7 knots of wind, it is faster. More important, above 10 knots of wind, 39F6 is way faster: 2 1/2 to 3 1/2 seconds / mile faster. On a typical windward leg, that might translate to several boat lengths. The different performance between the two beamier boats is because of the variation of other design characteristics.

We think it is very important to keep these 4 key points in mind (which may seem obvious but are surprisingly easy to lose sight of as one continually tries to improve his/her design):

  1. There are number of well-known key parameters or coefficients for a boat, and these have to be pretty much "right" for that boat. The right parameter set for one boat may not be right for another.
  2. Even with all the optimum parameters, the "parts" of the boat have to be integrated with each other in a beneficial manner; it is possible to have all the basic parameters right and still not have an especially good boat, though with all the basic parameters "right", it probably at worst would not be too bad.
  3. When determining what values of the design parameters to use, it is important – after a basic hull form seems indicated – to do a fairly systematic study of the basic design parameters, to determine which are best for that specific basic hull form. One or two experiments can be very misleading, and if not accompanied or followed by a systematic study – in which just one key parameter is varied on each test – it is very possible to get a long way from optimum and not notice it.
  4. Except for the possiblity of pure luck, there is no substitute for putting in a lot of hours over a long period of time in order to be fully receptive to inspiration, and to ensure that all the directly-related considerations in a design are being explored. While no doubt theoretically possible if one were lucky enough, it is going to be pretty difficult for anyone to just step in and draw a few hulls and accomplish all that, which is why most of the great design firms spend a lot of time and do a lot of studying for their key designs.

There are often multiple approaches to achieving a particular objective. One of the key objectives we have at times focused on has been to improve strong-wind performance upwind. In addition to trying the beamier boats as indicated just above, we also tried a higher prismatic coefficient. As a general statement, the faster a displacement vessel (traditional type of boat) goes, the higher the prismatic coefficient needs to be. In simple terms, this means that a greater proportion of the body of the boat is located toward the ends, and less in the middle. In Hull 42F2 below, we tried a higher prismatic coefficient without the greater beam. The results were similar in some ways, as the performance graph above shows (compare to the results with 39F6 when we increased the beam instead). Again, though, these results do not necessarily apply to all boats, and are not part of a systematic series. As we said just above, it is vital to get all the elements of the design integrated together, and it is also vital to run many experiments including systematic series, as just one or two experiments can be very misleading. But these are the kinds of things that we look at in the hull development process.

Another question that arises is whether it is advantageous to take any penalties, and if so, which ones and how much. Very early in our design development program, we drew the first version of the boat just below, Hull 26F4. That was before we were fully settled on what the revised measurement rule should be like, and so by now this boat is not only obsolete, but also takes several (very small) penalties. That fact affords us an opportunity to see how those penalties might be beneficial or detrimental to performance. For this demonstration, we didn't draw several more hulls, systematically eliminating each penalty, and comparing to the base boat. Rather, we used the same sail plan used for the other tests described here, and then also reduced the sail plan by the amount required by the present form of the measurement rule, and compared the two configurations.

The result is interesting: the reduced sail area essentially matters only in very light wind, as the performance graph illustrates. And, as mentioned above, performance differences tend to appear exaggerated in light wind, so even then there is not all that much difference. As long as the wind is at least 10 knots, it essentially makes no difference. However, this hull, even with the added length contributed by excessive breadth forward, excessive breadth aft, and excessive Quarter Beam Length, isn't decisively faster than the other boats mentioned here, even in strong wind. So clearly to make a large difference in strong wind with penalties would probably requre reducing sail area to the point where light wind performance would be poor, if not hopeless.

Based on this analysis, use of penalties is probably not a promising place to put a lot of time. Interestingly, the late Norman Skene, author of the famous "Elements of Yacht Design", concluded way back in the early 1930s that taking a Quarter Beam Penalty (the only length penalty there was at the time) was probably "never warranted". However, there is another point worth noting as well: since the penalties hurt Hull 26F4 very little, there is also no point to being significantly under penalty value for any of the rule parameters, unless the reason for doing so is an inherently better shape. If being right at the limit of a parameter gives better performance, it may well be better to be slightly over the limit, taking a very minute penalty, than to be "safe" by being a bit under, and losing performance that way. We have not tried the penalty question on all measured parameters yet, though, so the penalty question is still a work in progress.

Do we ever try something radical? Yes, once in a while, and mostly to check to make sure we aren't missing something. One example of that is the hull that follows, 49F4. Looking at the body plan, you'll find that this boat has a much shallower, flatter underbody.

One would think that would be a good thing to try (unlike the International Rule, the Universal Rule has no minimum hull depth, so there is no rating penalty for doing this kind of shape). So we did try it. Here's what happened...

We left the 4 knot wind speed off because the boat was so slow in that wind range that it wouldn't fit on any reasonable size graph. This boat really illustrates why we don't often work on radical concepts, and also why this rule should tend to produce very closely-matched boats: the radical ideas almost never work out.

In this case, we could do some things to improve its performance, but probably not to improve it enough to be worthwhile. It is somewhat high on wetted surface, but not enough to account for the deficit. The keel is too large, since it gets larger due to the shallower underbody, and this is the most serious issue: we could make the keel smaller, but that would raise the center of gravity, making the boat considerably more tender. So we would pick up performance in some conditions from reduced parasitic drag (drag due to wetted surface), and probably gain some more ground from reducing the induced drag (drag due to the lift of the keel), but we'd lose performance back again in all but the lightest winds due to lack of stability.

As in any project, we need to keep making steady progress. This boat showed no promise at all, so -- while we did take another try at the shallow profile concept later on a different hull -- this boat was not developed further.


Some time ago, we began work on a modernized Q Class yacht designed to the New Universal Rule of Measurement for Class Q. This new Measurement Rule can be downloaded at www.qclassyachts.com. We have completed several potential lines plans, a few keels, a preliminary set of contruction scantlings, and several arrangement and layout plans. Our performance predictions indicate that we have a solid foundation for an outstanding new design.

We have established the boat in this section as the example boat for the Q Class. Like the M Class demo boat, this boat was drawn to be a demo boat, and again to do so in a way that would give an adequate general impression of what a modernized Q-boat might be like, but again without giving away any of the very valuable things we have learned from our M-boat development work. (If anyone is wondering, it isn't clear yet just how much carries over from the Ms to the Qs, but a preliminary indication is that a lot of features do carry over, though it is probably not a good idea to count on it until we get a little further in the design development process. Interestingly, Olin Stephens once made a somewhat similar comment about carrying over development work from 12-Metres to 6-Metres).

Interior Arrangement

This is always a problem in a smaller boat, and the Q-boat is no exception. However, since it is somewhat beamier than the almost equal length 8-Metre, a Q-boat can sleep 4 or even 5, whereas in general an 8-Metre sleeps 2. To us, wanting to use the boat for short cruises as well as day racing, that is a pretty important difference. It took Cyndel only a very short time to put the arrangement plan together for this boat, and we have not yet had time to refine it (there are many hours of refinement in the M Class arrangements shown earlier in this page). But, while it can no doubt be refined, it seems to have a good amount of potential. On this boat, though, some space has to be kept open forward as there is, unlike the M-boats, no place on deck to put sails when racing. Even if it is decided to allow them to occupy the main cabin sole during a race, there will need to be a place to which then can be removed immediately after the race.

There are two nearly identical versions of this arrangement. The difference comes with the deck layout, and is hardly at all reflected below deck. The norm for this boat would be to steer with a tiller. No matter how we tried, we couldn't get that to work comfortably with the number of people who have to be in or right around the cockpit. The person steering was crammed right in between everyone else, where both visibility and mobility would be adversely effected. Unfortunately only one member of our team has ever sailed on a Q-boat, that being Dave Fladlien, and he was child when he did it, so we really had no experience to go on. We do have some pictures though, of one of the few Q-boats left sailing today, and it shows the same situation: the person steering is buried in other people. So we tried a layout with a wheel. That immediately gives the driver some room to work with, where he/she can see over the other people by standing (which is pretty uncomfortable with a tiller), and put all of his/her attention on steering the boat, not staying out of the way of the rest of whatever is going on at that moment.

Regardless of the deck layout plan, though, the interior provides for 4 berths and a nice dining / sitting area. There is an enclosed head, and a galley adequate for meal preparation on short cruises. Use of a hydraulic drive permits the engine to stay out of the main part of the cabin, and a 3-blade propeller (which will have to be mandated in the rule) provides smooth propulsion under power to a speed of 7 knots.

Hull Form

The lines of the Q Class demo boat do have considerable resemblance to the lines of the demo M-boat, as would be expected. Smaller boats are proportionally deeper than larger boats, and have proportionately more draft, so that there is not as much of a problem getting enough ballast low in the keel. This is even more dramatic in comparing Class M and Class Q, as the length-to-beam ratio is much lower for the Q-boat, meaning that the Q-boat is proportionately beamier. While the hull depth of the Q-boat is proportionatly greater than that of the M-boat, the draft (including keel) is proportionately considerably greater for the Q-boat. This means that the keel is considerably "taller" – has a proportionately greater span to use the technical term – than the M-boat keel. That gives the Q-boat keel a higher aspect ratio, which is more efficient aerodynamically. Further, this boat doesn't have the generator and other heavy items that the M-boat does, or at least not as many of them, so we don't anticipate the benefit of the inverse taper ratio (upside down) keel being nearly as much as it is in a larger, shallower boat. What the permissible keel configurations will look like has yet to be determined, but it would be nice if we could make a keel with an aft-sloping leading edge work out, as those of us who live on the West Coast of the USA have to deal with a lot of weeds in the water and vertical, or especially forward-sloping, keels can be a weed-catching hazzard.

Possibly the most noticeable feature of this boat is the very long forward overhang. Again that will have to be mandated if it is to remain, or everyone will simply shorten it. There might yet be an attractive way to do that, but the ways we've tried so far didn't look as nice. Also, and we think this is important, the history of the smaller Universal Rule boats is one of very long forward overhangs. Photos of at least one Q-boat show that, as do photos of several R-boats. The headstays on those boats are far aft of the steam head. The lines of the famous Charles E. Nicholson designed R-boat Lady Van make the point very clearly: the forward overhang is proportionally even longer than the forward overhang on our demo Q-boat, and the headstay is far aft of the stem head. In trying to maintain a traditional appearance in these boats, we think it desirable to maintain that characteristic. The question is simply how precisely to specify it in the rule. Most likely, it will be a simple minimum forward overhang, as there is in the proposed new M Class rule.

While the proportions are a little different, there is not a great deal of conceptual difference in the design of the Q-boat and the M-boat, at least so far. We have done only a few Q-boats lines plans so far, and so we definitely might find that this conceptual similarity ceases as we do more work on the Q Class, but we really don't expect that. Due to the size change, the change in beam / depth ratio, the change in length / beam ratio, and other factors, some of the key coefficients like bow angle and stern angle will probably be somewhat different, but again that is more a difference in degree than in underlying concept. We look forward to developing the Q-boat design further, both in hull form and in layout and arrangement.


We are not in the J-boat designing business, and as far as we know, neither is anyone else. Several of the outstanding big design firms have put what seems to be a mountain of work into analyzing the existing J-boat designs and coming up with modern construction plans, well-thought-out interiors, and a great many improvements, while adhering to the original lines, except for adding a small amount to the freeboard to deal with the deeper flotation caused by the added interior and machinery weights. They seem to be doing a wonderful job of revitalizing this famous class.

There are no new designs being done for contemplated construction; all the boats being built or planned are boats which were designed prior to World War II, at least at the time this section is being written. These boats do not race under the original Universal Rule anymore either. There are too many variations in how they are outfitted, etc., and so at the request of the J Class Association, John Robinson (who often consults for us here at Fladlien & Associates) led the development of a new handicap system based on a proven Velocity Prediction Program. There is a detailed and excellent report available on this work which we can direct someone too if they would like to obtain a copy. This handicap system seems to be very successful, if the very close racing often found in the contemporary J Class is any indication, and attests both to the excellent job that John and his associates did on the rating version, and also attests to how well the Wolfson Unit's WinDesign program predicts the performance of this kind of boat. This is very encouraging to us, as we also use WinDesign for the velocity prediction work we do in the development of our M and Q Class designs.

While we aren't actively trying to develop a good J Class design, there was some feeling here that we should at least mention the J Class, and to do that, we needed some plans of a J-boat. Unfortunately, we don't have the rights to any J-boat designs, so the logical solution was to (at least partially) design one, even knowing that it can't be built to race with the existing J Class. Dave Fladlien drew the one whose sail plan appears on mclassyachts.com, and which also appears just below:

"Morning Star", Our J-Boat

This boat was designed to fit into the existing J Class fleet, not to be the best boat that could be designed to the 1936 version of the Universal Rule today. Frankly we don't know how good the boat is. We think it it is a nice-looking boat, and a boat that will give the reader a good idea of what today's J Class boats are like from the standpoint of lines and sail plan. There are some drawings (though not a lot of lines drawings) available on the the J Class yachts web site, and some of the boats have additional drawings on their private web sites (the Rainbow web site is a particularly good example of that but there are others too), but there are very few lines plans to view.

Our 64F13 hull rates Class J under one reconstruction of the 1930s Universal Rule: we used B/10 for the height of the QBL measurement above the DWL, while some versions of the rule seem to have changed that to B/8. B/10 is the traditional value, and the height we have kept for our proposed Classes M and Q updated measurement rules, so this J-boat that we present here is consistent in that regard with the proposed M and Q classes.

It is also interesting to compare the stern shape, in body plan or planform (top view), with any of the M-boats above, or with the Q-boat above. One of the changes we have proposed for the Universal Rule is increasing the Quarter Beam Length which is permitted without penalty. This will have the effect of making the after sections wider and flatter. We believe this will have two very beneficial effects: it will make the boats faster by giving them longer effective sailing length, and it will make them steadier down wind. Dave Fladlien's experience sailing an original Universal Rule boat downwind was that the boat's control could be improved, which was suggested by Pursuit owner Ron MacAnnan as well. Harold (Mike) Vanderbilt in one book described his J-boat Ranger as very challenging to sail downwind. In the case of Ron's and Mike's comments, most of the problem was probably the location of the rudder, which the new M and Q Class boats will have resolved with the rudder at the aft end of the waterline. The fuller after sections will also stabilize the boat downwind, which will make steering much easier in any conditions where the boat is inclined to roll.

The lines of Morning Star are not truly finished. We have other work that we need to devote our time to, so if one blows up this lines drawing and studies it very carefully, he/she will find small areas where it is not fully faired, and other minor issues like that. We don't think that detracts from its value as a demonstration boat for the class, and for a size comparison on mclassyachts.com and on this site.

The accompanying comparison sail plan shows the relative proportions of the J-boat, M-boat, and Q-boat.

We hope Morning Star adds to your enjoyment of our web sites.