Plusses and minuses of beaminess

[JeffM]

I've been looking hard at boat designs again. (Yes, I know, I'm about to start a couple of birders. One can't look too far ahead, though!) I'd considered a Bolger Teal because it would be completely different from my cs20, small enough to car-top, and a quick and cheap build so I wouldn't feel too bad if I didn't like it. I talked myself out of it on the grounds that it would have too little capacity (as a small, narrow double-ender) to be good for much. (Also, double-enders are hard to get up on a car roof.)

This got me to thinking about length vs. capacity: the boat would have to be moderately short and light enough to put on a roof rack, but had to carry me and one other person (or maybe me and two kids). To me, that translates into beam, and/or a pram shape with a bow transom.

And that, in turn, got me to wondering why so many of the designs I've looked at feature fairly narrow hulls. It seems to me that you get the most bang for your buck with something like a pram or a broad catboat style hull. With that shape comes capacity, roominess, and the stability to carry enough sail to overcome the cat's resistance.

The only drawback I know of is that a good angle of heel changes the underwater in such a way as to make weather helm severe.

Learned opinions, anyone? How about the pram shape?

[ScottWidmier]

You have got several different issues in the question you posted which tend to contradict eachother in terms of what hull proportions are best. For cartopping the boat has to be really light for ease of lifting or you will soon find yourself buying a trailer just for ease of launching (like I did). Also, longer boats like canoes or dories are better for cartopping IMHO because you can lift the boat up and put it on the cartop without bumping into the car. I have a flying mouse that is actually harder to put on the cartop than my 12' dory (see the photo gallery on this site for my boats) despite being lighter in weight. The car gets in the way with short boats and you find yourself reaching to put it on and take it off.

Duckworks awhile back posted the niftiest system for one-person cartopping I have ever seen and it was so simple! Basically, your cross-bars on top of the car are hollow and another bar slides out one side from inside of them. Put the boat upside down next to the car, lift one end, slide out the bar so the boat is resting on it, go to the other end, lift, and slide out the bar as well. Then, all you have to do is slide the boat over then slide the bars back in. Haven't yet put this on my car but plan on it. In oder for this system to work you need a longer boat.

Narrow boats main advantage lies in cartopping and the easy with which they are rowed or paddled. They don't need as much sail to propel so the spars can be shorter. However, I find the lower initial stability of narrow boats makes them more tiring to sail in variable winds with gusts like we have on inland lakes. Also, having more than one person on a narrow boat can be challenging with the lower initial stability especially if the other person likes to move around a lot. All of this applies strictly to lightweight boats you can cartop. I do love my skinny 12' dory though and find it to be a nice set of compromises.

I once heard adding one foot of beam is equivalent to adding five feet of length and my experience bears this out. Beamy boats are excellent sailors if well-powered with plenty of stability to stand up to variable winds. They are most comfortable for all-day sailing and can comfortably accomodate more than one person since the captain and crew don't have to be concerned as much with moving around. However, beamy boats need a little more effort (read "a little") to row and longer spars to move the beam through the water. I still row my 12' catboat but it does take a bit more effort than my 12' dory. As for cartopping, really beamy boats can overflow the sides of the car rack and/or the width of your roof. Short beamy boats, like prams, can be difficult to get up on top of the vehicle as mentioned earlier.

[JeffM]

Thanks, Ray. You're the second person on this forum who has had something nice to say about a Bolger design. I'd thought about the Elegant Punt for other applications, but I want to sail. (Actually, I want to do a lot of things!)

Scott, it is true that it's hard to get capacity from a boat still light enough to car-top. It seems to me that you displace the most water with the lightest boat if the boat is basically a square box (even a little better still if its round) --that argues in favor of a punt. Your point about it being easier to car-top a long boat is well-taken, though. And I, also, admired that clever telescoping roof rack. Thanks for your input.

I've just bought the plans for Michalak's Piccup Pram, which is 11" long with a beam of 4'6", multichine, and weighs in at around 100lb. Besides good capacity, the design boasts fore and aft flotation/storage lockers, and a cockpit long and wide enough (thanks to the leeboard) to sleep one person. (As I said, I want to do a lot of things!) It's meant to be equipped with Michalak's favorite rig: a balanced lugsail. Sailing it will be a new experience.

[PAR]

The beam/length debate has raged for generations among designers and owners.

The most efficient shapes are long and drawn out hull forms. Catamaran hulls bear this out, as do canoes and kayaks. The introduction of beam provides elbow room, but can dramatically increase hull drag too. If you place enough sail area on the beamy hull, it will perform, but may have some bad manners under certain conditions.

Getting the right amount of balance between beam and length is difficult. Modern owners want beam, where in the past length and efficiency were more important. I expect this will come full circle, especially if fuel prices continue to rise as they have.

This has happened before. During the golden age of sail, in the last few decades of the 1900's, we had similar difficulties among designers. Some favored the deep, narrow forms that their model testing proved were efficient, but others went after what was then called "skimming dish" shapes, which were fat and shallow hull shapes. In the races (where all things of most importance are sorted out) the skimming dishes kicked butt in light conditions and the narrow designs killed them in heavier going. Since most racing was done in reasonably fair weather the skimming dish hulls won out.

Hulls became shallower and shallower. Their sensible, built down garboards removed and the under water body flattened. This decreased wetted resistance, but cost tracking, comfort and sea keeping qualities. At the same time a revolution in yacht design was taking place. Materials were replaced wholesale and the boats become lighter and stronger. Appendages were now smaller and more centrally located.

All of these changes were of course taken to extremes and some true "freaks" were developed. Sandbaggers were a classic type of freak (that's what they called them), tossing a 40' boat rig on a 18' boat was real fun, if you could carry enough crew to hold the boat upright.

Eventually a few reasonable designers rose to the top of the heap with original designs that did what they were designed to do well, without having to venture well out onto the design limb. Yachts like Stormy Weather, Dorade, Nina, Virtue, Finsterre, Hestia and Ticonderoga proved that intelligent design didn't live within a fad, though most of these yachts had to conform to very specific racing rules, governing their shape and sails. Ticonderoga has a racing record that is likely the most enviable record ever had and she wasn't intended to conform to a rule, she was just an fine example of a sweet hull shape and ketch rig. She still kicks butt and it has to be embarrassing to get stomped by a 1930's era wooden yacht.

These reasonable designs tried to balance sweet, efficient underwater areas with the need for elbow room. Sure you can have a fat butted boat, built light, get up and plane, but there is a trade off for this performance and are you willing to accept it in exchange.

Bolger knows well enough that narrow shapes are very easy to propel, under oars, sail or power. He often takes advantage of this simple concept. Narrow boats are naturally light too, not having as much boat, literally, as beamer one of similar length. Tender hull forms are fast, but have to be managed with care. When you combine all these things into one boat, you get a light, narrow, tipsy, efficient and fast boat. Change any of these elements and you'll effect all the other elements.

Bolger's Light Schooner is fast. I've had one over 15 before, but it wouldn't be, if it had just a few more inches of elbow room. I like Bolger's work, though many of his small craft are butt ugly, I certainly understand and enjoy the concepts he's used and fiddled with, during his compromises to a finished design. He's very clever and a major talent.

[JeffM]

Thanks, Paul! I can't believe that this is still a matter of art, rather than science. Given a clear set of priorities--in my case, good carrying capacity in a car-toppable package, self-rescuable, uncluttered cockpit, able sailor in bumpy bay waters, cruising rather than racing speed--it must be possible to draw a design that would perform reasonably well and predictably. So what, exactly, are the "bad manners under certain conditions" of a beamy hull with enough sail to move her along? And exactly what causes these bad manners? Is it the asymmetry of the hull's wetted surface when heeled?

[ScottWidmier]

"Bad manners under certain conditions," are mostly caused by skippers not understanding the sailing characteristics of a beamy hull. The beamier the hull the greater the curve to the side of the boat. When the boat heels, this curve up near the bow digs in and tends to thrust the bow towards the wind thus increasing weatherhelm. This is either a great safety feature (rounding up when overpressed) or a pain depending on how much heel the skipper wants or expects out of a sailboat. As a result, a beamy hull (like that of a catboat) should be sailed flat and the mantra "reef early reef often" should be applied. A skipper used to a narrower boat might not feel like the are going fast unless there is a decent angle of heel so will overpress the boat creating turbulence as the rudder resists weatherhelm actually slowing the boat down. Now, I did experiment with a balanced rudder on a catboat and that rudder counteracted weatherhelm (the water helped me hold the tiller) and I was able to get my catboat to heel rather well.

A truer "bad manner" is that of the greater force needed to punch the beamy hull through waves. When tacking, a wave hitting the bow can cause enough loss of momentum to stall the boat and let her be caught in irons. More likely to happen when there is little wind but big waves (motorboats!!). A rounded or V bottom hull will help alieve this a bit.

Another "bad manner" is the tendancy of a beamy hull to fall off the wind when tacking. However, experienced sailors of beamy boats are used to this and allow the boat to fall off, gather speed, then bring the boat back up to the wind. Again, a matter of what your are used to sailing.

The good manners include greater capacity for length, ability to walk or move around the boat with ease (great when stepping from shore or dock to boat), and finally much more relaxed sailing especially in gusty conditions. A beamy boat isn't as quick to heel as a narrow boat.

Some mention needs to be made of the advantages and disadvantages of a pram hull. Prams are increadible for their carrying capacity on such a short and light boat. The only big negative is when a wave hits the forward transom which can both make for a wet ride and bring the boat to a stop. A well designed hull is very important for this reason so look at Welsford's Sherpa or the Nutshell pram both of which have a lot of rocker and a strong V up in the bow to cut through the waves. Of course, more rocker makes for a more tender boat to move around in...

One of the things I love about boats is that there is no perfect boat. Every design is a set of compromises and you must consider how you plan on using the boat and the water you will spend most of your time in. One of the sad things about the fiberglass boats (and I own one) is how generic they are ignoring the utility of different rigs and hull shapes.

Here is my Bateau.com C12 (12' catboat) which is capable of carrying four adults and which I have cartopped with an extended rack. I also have put it on top of my camper. However, I much prefer to use my 8X10 Harbor Freight folding trailer to get her to the lake. This picture was taken on a blustery day and you can see how fast I am going by the way the spray is coming off the back of the boat. You can also see how level the boat is sailing despite the wind and the speed.

Here is another picture so you can see how much the hull was digging in.

That is my then 7 year old son sailing while I take it easy. Blustery day but he is easily able to handle the boat even when heeled due to the design of the rudder.

[JeffM]

Many thanks, Paul! That was a clear and precise explanation.

Two further questions occur to me when I read your post. First, my understanding of a balanced rudder is that it makes it easier on the muscles, but that should have no effect on weather helm. If you have to take a significant fraction of the boat's lateral plane on the rudder (Bolger's Cartopper, for example, has a cb set far forward in order to clear more of the cockpit), you simply need more rudder in the water and a good foil shape so it doesn't stall readily. (And an end plate on a rudder would have the effect of increasing its effective size.) Not true?

Second, what is the point of rocker? Flat-bottomed designs tend to have a lot of rocker so that the boat meets the water with her bottom rather than stem. You mentioned that good rocker keeps the pram's bow transom from plowing. What little I've learned of design suggests that "easy buttocks" reduces drag and therefore increases speed. From this I gather that the more the rocker, the greater the drag. Aficionados of the Weekender have commented that their deep forefoot aids in lateral plane. Have I got it basically right?

[ScottWidmier]

A balanced rudder basically uses the force of the water on the part of the rudder forward of the pivot point to help you hold the rudder straight. The only problem of a truly balanced rudder is it also eliminates feedback the boat may give you through the tiller such as being overpressed. So, instead of straining against weatherhelm and having a sore arm at the end of the day, I was able to control the tiller with a few fingers even when there should have been strong weatherhelm. Now, there must have been something else in the rudder design I used on the pocket cruiser because it also eliminated the need to oversteer against the weatherhelm meaning the tiller was centered. The endplate prevents water from slipping under shallow-draft rudders forcing it to run off the back edge instead giving greater controll even with shallow draft. I still think a deep foil shaped rudder is more efficient but as it swivels up for shallow water you loose that efficiency. So, if you sail in ankle deep water, a shallow draft rudder with endplate would be the best option. If you sail in water over 3' I think a deeper draft foil shaped rudder is best. Of course, asthetics and tradition should be taken in consideration to. One of the fun things about building your own boat!

Rocker is an interesting topic that I am sure someone can discuss a lot better than me. The longer the water line the faster the possible displacement speed of a boat and rocker shortens the water line on a given length boat. So, rocker does slow a boat down...on perfectly flat water. However, rocker alows a boat to easily rise to the waves, bow goes up and stern goes down, so a boat with rocker is better able to take waves (more seaworthy). That is why river dories have so much rocker. The mouseboat is a V bottom pram with a small amount of rocker for the type of boat. I have one and love it but when chop builds up she can easily be stalled by a wave hitting the bow transom (and showering me with water). Welsford Sherpa and the Nutshell Prams are designs intended for tenders to larger boats so are designed for rougher water either when being towed behind or transporting people to shore. Again, it all depends on what type of water you anticipate sailing or boating in regularily. Will you have to contend with waves, chop, or will the water be relatively flat? How much wind will you have on average? How steady is the wind or is it fluky? All of these factors can influence the hull and sail arrangement that is best.

All of the above is from an amature based upon experience with some different homebuilt boats and some reading. So, take it for what it is worth!

[JeffM]

Thanks, Scott. Sounds like your PC rudder is simply a good, effective one--balanced or not. Regarding rocker, I was thinking "all other things (including waterline length) being equal." Your description of a highly rockered hull riding over waves brings to mind an image of a rocking horse! I wonder if that's all there is to it.

[PAR]

Yacht design is a lot like the study of women's relationship with men. Just when you think you have a fair understanding, something comes along a screws your perception all up.

A balanced spade, of reasonable aspect ratio, rudder is about as efficient as you can get. It isn't a substitute for balancing the sail plan over the appendages and hull form, curing weather helm or slowing an inevitable divorce. There can be several reasons you can't afford a deep spade, so a compromise must be struck, get use to it, that's the business of yacht design, much like taking out the trash or picking up your dirty socks that you aren't completely finished with this week.

Weather helm is visible by noting the angle of incidence the rudder has with the boat's centerline. A well balanced boat will have less then 5 degrees of rudder deflection. Anything more then this and you have weather helm, which just gets worse as the wind speeds increase. Balancing a blade can relieve much of this pressure, but if the boat is not balanced, she's not living up to potential. In other words, she'll feel better at the tiller, but the rudder angle is acting partly as a brake. If the balance issue was resolved, the boat would gain power, possibly without the need for as much, maybe no balance in the blade.

Personally, I dislike the use of balance to cure weather helm, unless all other reasonable options have been exhausted. Some hull/appendage configurations seem to require additional help. Many owners of the Stevenson's designs have had common complaints about "a heavy helm". Most can be discounted from lack of sailing experience, improper trim (all small boats biggest issue), incorrect rake, construction deviations, sail plan setup or changes, etc. I've never had to add balance to a Stevenson design, but was able to remove most annoyances with rig and weight trim. On one boat (not a Stevenson), the main sheet was tacked to the top of the transom. This was a small dayboat about 14' LOD with a big gaff main. The boat was near imposable to steer, she just wanted to round up hard. After a few sails I suggested the owner move the sheet attachment inboard on a bridle, over the end of the tiller and the purchase on the boom moved an equal distance. Bingo, the boat suddenly behaved like she was designed, when I learned the owner/builder moved the sheet aft, to provide more cockpit room. This acted like a longer lever on the light weight stern and yanked it leeward as the sheet hardened, which of course pointed the boat up. The moral of the story is everything is connected. Things that you wouldn't think are very important in the big picture, can have dramatic results, possible not what you desire, similar to suggesting, in the nicest way, that you enjoy her love handles.

Rocker serves a few different functions. In small craft of conventional form, a slight amount of rocker will permit the boat better maneuverability, align the aft surfaces of a squatting hull (at speed) with the LWL for a better flow, generate some lift and a few other things, most are beneficial to the boat moving along nicely. As you increase the amount of rocker, you gain usable storage space, develop a place to hide a center/daggerboard case which possibly could be under the sole, but you also can loose some longitudinal stability, disturb the flow aft, pile up a substantial lee surge wave and drag along a pretty good size "hole" in the water as the boat moves. In a perfect world a displacement boat should move the water down (mass and momentum), to the sides (deadrise) and permit it to cleanly detach from the stern, with as little disturbance as possible. Looking at different wakes, you'll quickly notice some shapes do a much better job of this then others. A lot of the rocker selected has to do with the target speed/length ratio you're aiming to hit with the finished project.

There are some guide lines, you can use to keep the rocker within tolerable limits, most related to the performance envelope you're trying to stay within, much like saying her butt looks just fine in that dress. After a while a designer gets a good feel for the amount of rocker that will be acceptable on a given set of design parameters.

Some hull types (shapes) need more rocker than others, but generally less is fast and more is draggy. Rocker can affect LWL availability, but usually in extreme shapes, not typically used in most hull forms. A healthy amount of rocker can help keep some hull shapes "engaged" longer, where a flatter rocker will start pounding or pitching.

Rocker is a 2 dimensional relationship with the profile of the hull bottom, "V", round or flat. The most comfortable shapes or the fastest shapes are 3 dimensional correlations, below the LWL. Comfortable means the hull smoothly knifes through the water, leaving a clean wake, like the preacher's daughter. Fast means her hull shape provides dynamic lift, reducing wetted surface and she gets up and scoots on her ass or foils, possibly like an exotic dancer. You are the one that has to decide which one you want to live with (design brief) or how long you can tolerate her habits (hanging from the chandelier) . . .

[ScottWidmier]

This is what I love about boats, particularily the variety you get from homebuilt boats and plans. There are so many interconnected variables that you can get wonderful boats with completely different characteristics. No right or wrong answer!

My PC was perfectly balanced and I could leave the tiller unattended and she would keep going straight when the wind was 13mph or under. However, when the wind started piping up and the chine started digging into the water the weatherhelm would build. Ideally, I would reef the sail and get her balanced again which was a wonderful aspect of the gaff rig. However, sometime I was lazy or the conditions were right with only some gusts going over 15mph.

I am having another experiment in balanced helm with one of my boats I am modifying. I am going from a standing lug to a gaff. In addition, I am moving the mast foward by about 16" on a 12' boat. The gaff should move the CE back but may not be enough. So, I plan on making the first couple of sails out of polytarp until I get the right sailshape for the boat. Should be interesting! Worse comes to worse, I could make her a catketch rig.

[JeffM]

Your PC sounds like a wonderful boat. I'm going to get aquainted with a new rig soon, myself: I just received plans for Jim Michalak's piccup pram, which has a balanced lug as its standard rig. Seems he uses his own piccup for testing various rigs, and has managed to do it all without moving the mast (though that would be fairly easy to do). After a bit of polling, I expect to buy a proper lug sail from Duckworks. Like your gaff, it reefs well without much change in the center of effort.

[PAR]

There are several good sources on line, for figuring out the centers of a sail plan. Given a boat with good balance, a new rig, of different dimensions and configuration can be drawn up and placed over, what is known to be a good location for the CE. Changing a sloop to a yawl, to a schooner, from a lug to gaff, Bermudian to junk, makes no difference (sort of) as far as the CE location is concerned. This assumes a good original CE location for the hull and appendages.

With pen, paper and armed with some cutouts of different sail configurations, you can place their CE over the same vertical line that passes through the original CE, which will produce a new rig with similar balance (generally speaking). This exercise can be interesting and fun to know a schooner rig can be placed on your SunFish, or more realistically, a new sail plan that will keep the boat as balanced as it once was.

Because appendages and hull form are fixed (for the most part) the new rig may take on unusual proportions when compared to hulls and appendages optimized for a particular rig. An example would be converting a gaff catboat to a gaff schooner. A schooner designed as such will have a larger proportion of it's CLP located farther aft then would be typical in a catboat, which would force the schooner rig, if placed on this catboat, to be farther forward then normal.

With some trial and error, drawing up slightly different new rigs, you can pretty much pin a completely different configuration on any boat. If done with some care, scale drawings, etc. you can adjust the rig, rather then cut new sails to correct balance issues.

[ScottWidmier]

Which raises the question of the "ideal" sail proportions brought up in "a Sailmakers Apprentice." What makes these the idea proportions? Shouldn't it be based on the boat?

[PAR]

Good question Scott and hotly debated over the years. Each hull and rig configuration has an ideal range of sail proportions. Darn near every proportion, seen in modern craft, is a direct result of rating rules. Designers, trying to find an edge over competitive yachts, will cheat the rules as best as they can, usually to gain an advantaged rate for their design, which helps out the skipper on the race course, but may not be the wisest choice for a yacht that's not rounding buoys.

When drastic rig changes are made, some compromises will have to be accepted. This is primarily because the appendages and underwater areas are fixed, forcing a less then desirable rig placement for that hull configuration. Some hulls can receive modifications to the appendages to accommodate a different rig type, but most aren't willing to take a reciprocating saw to their deadwood, so the rig gets placed where it needs to be, rather then a more desirable location. An example would be a ketch being converted to a cutter. The forward placement of the main on the ketch may have had it come through the deck, but with the cutter's near midship mast location, it will likely interfere with interior accommodations and run through the deckhouse structure. Such is the life of design.

At the turn of the 20th century, many older yachts were converted from gaff schooners (the fading rage at the time) to gaff or Bermudian sloops and cutters (the latest trend on the race course). They got better windward ability, had less strings to pull, but had hulls developed for the schooner rig. This forced the owners to accept awkward proportions and mast placements, because of the farther aft positioned CLP typical of a schooner hull.

[ScottWidmier]

Again, the variability is what makes it fun. I am itching to cut out some sail shapes and start playing with paper. Have to do it when my daughter is in bed or she will accuse me of playing with paper dolls.

Of rigs, the absolutely most versatile rig for small (1-2 person) boats has to be the squarish sprit rig (not to be confused with the more triangular leg of mutton sprit which most people seem to call a sprit). I mean the rig with the sprit going from midway on the mast to the top aft corner of the sail. I rigged one boat with a loose-footed version with simple thumb shaped cleats to hold the mainsheet. Most important was the brailing line that went from the mast through a grommet on the luff back to the mast. One pull on this line and the sail is held tightly to the mast out of your way for rowing or paddling. Jerk the line out of the jam cleat and the sail instantly fills up with wind and away you go.

I mention this rig as an alternate to a lugrig on smallboats. I like the lug but when you drop the sail it comes down in the cockpit and in the way. Also, raising the lug when there is a lot of wind out can be an adventure of flailing spars. On a boat with limited space and stability, I found the sprit rig to be better than the lug.

I borrowed the sprit from my 12'dory to use on my puddleduck racer. Here it is on a good tack:

A bad tack:

With the brail line pulled and mainsheet tucked around the mast. Wish I had a better picture but I will tell you that at the beach start of the PD racer I was the only one to not have my sail in sailing position. I launched easily without the sail pushing me around or getting me tangled in adjacent boats, yanked the brailing line out of the jam cleat and was off to place third in my first race ever!

[JeffM]

Scott, that's a good-looking rig on a nifty little boat. David Nichols (The Working Guide to Traditional Small Boat Sails) cites evidence that it very close-winded, as well as handy. Off the wind the sprit needs to be prevented from twisting forward, though that's easily done. Was it hard to get the sheeting angle right on different points of sail? I wonder how hard it would be be to draw a reasonable spritsail for the Piccup that would keep the ce over the leeboard, and still have good sheeting angles that would keep the sheet forward of the transom?

I've thought it might be possible to mess with the balance lug on the water if I had a drift anchor that would keep the boat head to wind while I raised the sail, reefed it, or dropped it. I've become rather spoiled by the cat ketch rig I now sail: at any moment, in just about any wind, I can head up, sheet the mizzen in hard and loose the main, and the boat will just sit there bobbing like a duck (drifting downwind, of course) while I mess about with reefing, check the chart, or use the head.

[ScottWidmier]

I get better windward performance than I would have expected with the rig but it isn't a marconi and I have a feeling a leg-of-mutton might beat it to windward. It doesn't seem to have any problems on a broad reach and, with a rotating mast, if you let the sheet go the rig rotates away from the wind even if the wind is coming from directly aft. Similar in some ways to heaving to except you don't have to be at any certain angle to the wind. Pull on the brailing line and the sail is bundled to the mast.

One challenge comes from the boomless sprit which puts amazing amount of pressure on the mainsheet because you are having to hold to dimensions (for-aft and port-starboard) versus letting the boom take for-aft. That is why I switched to thumb cleats (shown below) on my dory where I simply flip the mainsheet over the leeward cleat when tacking. Has more resistance than a pulley so helps hold.

Dory Sailing

Thumb Cleats

The PD racer is an 8' long beamy boat and the dory is a 12' long narrow boat. Funny how the same sail worked for both!