Slickest folder ever

In case I forgot to mention it, my article "Why I Love Leeboards - 13 reasons why leeboards are better than daggerboards / centeboards" is now up on my web site.

http://www.diy-tris.com/2012/articles/1-leeboards-why.htm

And yes, I have definitely considered making the amas an important part of the lateral resistance -- not so much by making them asymmetrical as by putting a fin or skeg on the bottom. Ted Warren's "Little Wing" tri conversion does this, and many cat hulls also take this route. I also used skegs/fins on my tandem tri amas, and it worked just fine. The fins have the added advantage of keeping the tri more horizontal in shallow water (launch time, etc), but may have the disadvantage of increasing your turn radius by moving the pivot point away from centerline. But even so, I think it's worth a try, and I'll do just that on the latest version of my "slickest folder ever" -- as Mr. Dierking so kindly labeled it.

- Frank

 

Basil,

I believe the good thing about an asymmetric on a tri is that only the leeward ama would be in the water. Dick Newick used Hobie 16 hulls on the original Tremolino, but also a big daggerboard. He also used the same Hobie 16 rig. Obviously he felt the asymmetric hull was not good enough, but his designs are certainly aimed at performance. The latest versions have symmetric hulls and daggerboards of course.

 

movable daggerboard

I enjoyed your 13-point list of advantages of a leeboard over a daggerboard or centerboard. I thought I'd mention Frederick Fenger's Yakaboo, a ketch-rigged sailing canoe, which he sailed through the Caribbean islands in the early 1900s. It was an unusual boat in that it had no rudder, control of direction being done with sail and a moveable centerboard. Fenger often amazed folks by his apparently magically controlling Yakaboo with no rudder.

http://ambergriscaye.com/pages/mayan/alone_contents.html
http://ambergriscaye.com/pages/mayan/alone_01_2.html

"She had no rudder, the steering being done entirely by the handling of the main sheet. By a novel construction of the centerboard and the well in which the board rolled forward and aft on sets of sheaves, I could place the center of lateral resistance of the canoe's underbody exactly below the center of effort of the sails with the result that on a given course she would sail herself. Small deviations such as those caused by waves throwing her bow to leeward or sudden puffs that tended to make her luff were compensated for by easing off or trimming in the mainsheet. In the absence of the rudder-plane aft, which at times is a considerable drag to a swinging stern, this type of canoe eats her way to windward in every squall, executing a "pilot's luff" without loss of headway, and in puffy weather will actually fetch slightly to windward of her course, having more than overcome her drift."

 

Control of a boats straight line course has been done in multiple ways, all of which center around matching the COE (sails and hull above the water) and CLR (boards, rudder, and hull below the water). Match those and the boat sails straight.

A rudder is really just an unsophisticated way to change the CLR. For example, if the board and hull are matched to the COE for a certain condition, the rudder does not have to do anything and is just extra drag. If the COE and CLR are not matched, the forces try to turn the boat, the rudder has to be used to provide a balanced total force to keep it on course. If the mismatch is not much, the rudder is turned just a little and the drag is not bad (not ever as good as no rudder). If the force mismatch is big, the rudder is turned a lot with the drag increasing significantly (the bigger the angle the more the increase in drag).

Everyone knows all that.

One "nonstandard" way to improve course keeping and speed is to use two boards, this was done by Dick Newick on Cheers (proa, although he also used a rudder) and on 3 Cheers (trimaran). One of the 1960's AYRS publications described a monohull built the same way - the fwd board was significantly smaller than the main board and was used for adjustment.

I had not known of the Yakaboo method, but it seems obvious and similar to Franks concept (if he were to pull up the rudder).

Another method was also used on a small boat with an outrigger. A Bruce Foil (canted daggerboard on an outrigger) was set up so that the akas could swivel and place the outrigger forward or aft to balance the sails.

The ability of some of these systems to self steer (relative to the wind) without a rudder is really of interest to me. Steering by control of the position of CLR also allows control without any speed, an interesting capability.

Of course the most classic way to do this uses a split sail rig - schooner, yawl, ketch.

Too many choices, not enough time.

 

It's amazing what a well-balanced boat can do without a rudder. A few months back, one of my other boats (No Commotion, the one in my frist video) snapped its lower rudder mount. Well, OK, that was my fault due to underbuilding. But nevertheless, there I was -- in 12-15 mph winds, and more than 2 miles downwind from my launch point. Fortunately (and because I had discovered this earlier) I could actually steer that boat just by pivoting the leeboard for and aft. So with the rudder dangling from its upper mount, I was able to actually tack all the way back to my launch point. Not as efficiently as with a rudder, of course, but this event perfectly illustrates both the beauty of a perfectly balanced helm and the joys of a good leeboard. I can't even imagine trying to tack home by adjusting a daggerboard or centerboard (though I'm sure some skilled sailors have done it many times).
- Frank, the DIY-Tris guy

 

St Lawrence River Sailing Skiff

At least some variants of the St. Lawrence River sailing skiffs had no rudder and were controlled only with sail trim and sailor weight placement.

http://www.grapeviewpointboatworks.com/slrs_history.html
http://www.antiqueboatamerica.com/ab_articles.htm
http://www.woodenboat.org/boats/boat_detail.aspx?processid=557

 

Did they have a centerboard, etc, or just an exposed keel? I didn't notice a picture or drawing of a sailing skiff.

 

Frank,

I enjoyed reading your posting link about "Leeboards... 13 reasons". I think that you have unavoidably painted yourself into a thin water corner with your take on the topic, though.

Lateral resistance devices exist in a variety of configurations for a reason. There is no one best answer to solving the problem for every boat out there on the water. Perhaps, if you had confined your comments to the thin water argument, perhaps there would be a reason to seek leeboards as a viable solution over other design possibilities?

WG

 

WG, Franks states right off the bat about his local skinny water conditions and this would also apply to our texas bay systems as well.

 

WillyG,

Did you have any specific points you think were a problem? What do you prefer, why?

Seems to me the comments about interference in the cockpit is reasonable, given the boat we are talking about. The discussion about adjusting the CLR seems viable also. Personally any comments I made just offered an alternative which might fit anyone's specific boat. It also seems to possibly be related to the expected level of performance. Not everyone, actually almost no-one, is concerned about racing level performance.

You should see the number of standing dead trees in my closest local lake. Damage from hitting them is an actual concern. Not a shallow water issue.

12-15 kts in a modest wind seems pretty good. Without the ability to measure the best tacking angles its difficult to discuss that.

I'd like to see some actual performance comparisons, cause if leeboards work as well as other options, the construction aspects would be cheaper. Much as I don't usually admit it.

The great thing about a forum is we get to exchange actual ideas. Those with data or comparisons might even convince someone else. We all have opinions.

 

Okay, let's go over the list by the numbers and I'll post my comments within via italics.

1. Leeboards Give You Flexible / Dynamically Adjustable CLR. Leeboards can pivot as need to perfectly balance the helm. This, all by itself, is enough to make leeboards better than centerboards or daggerboards. I can still have virtually all the functional length of my leeboard in the water (to provide lateral resistance) yet shift the CLR fore and aft - by 24" or more if needed -- to balance the helm. This takes strain off the rudder, thereby adding speed. It also provides maximum CLR under all conditions, thereby improving upwind performance.

Unless the leeboard is mounted to a longitudinal rail on the boat's gunnel, there will always be a loss of effective performance in the boards swept angle. If the board is built to a specific foil section, then the sweeping aft of that span will alter, significanty, the section properties, changing the performance issues along with the sweep. Further, if the board is being swept, then another loss of efficency due to span reduction will be present.

If the board is mounted on a rail to move the CLR, then the mechanical complexity goes through the roof in the name of a minor bit of utility.


2. Leeboards Require NO Cutting Into The Hull or special care or attention during framing. How much simpler does this make life for the builder, especially amateurs? Now much less can such a boat weigh? How much more likely is a hull to say intact when it doesn't have a big hole or slash in a critically important section of the keel? Leeboards don't require any of that stuff!

I would suggest that the placement of any lateral resistance device requires structural care and attention during the build if one does not want to experience eventual fatigue failure of the hull at the mounting point. One might be able to avoid this issue if they confine their rig sizes to seriously undersized areas, reducing the lateral loading below the inherent, non supported areas of the hull. Thus, the builder is required to allow for a structural issue from a leebard mount, same as for any lateral resistance board chosen.

A properly built structure for either a center, or daggerboard, is much more likely to seriously strengthen a hull, rather than create a place where it will be weaker. The vast majority of small craft do not have a structural "keel" as such and are therefore not a part of this discussion on this point.


3. Leeboards take up no space in the already-small cockpit of a trimaran, small dinghy, etc. Being entirely outside the boat, the entire cockpit is available for feet, seats, stuff, whatever. If you've ever experienced a small cockpit with a daggerboard / centerboard trunk, you know all too well how annoying and inconvenient the obstruction can be. How much more enjoyable would it be to sail in a wide open, completely unencumbered cockpit?

It's very simple. One pays for what one gets. There is no best solution for all the various types of boats out there under cosideration. One can just as easily make the argument that having an external, surface piercing foil, mounted to a hull is the same as admitting that one's boat has no speed component as part of the design consideration. A leeboard equipped boat will get you to where you would like to go, as long as one recognizes that it will suffer from less efficiency the second that it is driven hard while trying to keep up with a daggerboard boat of the same design.

Clutter is a relative term in its best interpretation. I've seen plenty of leeboard equipped boats that have regular issues with sheets and lines getting tangled around the board and its mount, so the argument is not compelling to me.

4. Leeboards Are Never In Your Way. I remember the first time my wife and I took out our Laser II dinghy (it was also to be the last time, as we dumped it within 15 minutes of launch). I clearly recall how the daggerboard always seemed to be in the way, either as a tripping post, something to snag lines, or something to block free movement fore and aft or side to side. I didn't like that at all, and neither did Laura.

This is a personal preference comment collection, more than anything. Again, one picks one's optimal style and learns to work with the limitations, or move on to another style that better suits one's needs. Every single boat, style of board, rig, color, mantenance schedule, etc. have similar considerations, no matter what kind of sailing you wish to do.

5. Leeboards Can't Foul The Boom. For reasons I guess I can understand, lots of small dinghys are designed so that when the daggerboard is raised (as alas it must be in shallow water) it invariably is in the way of the boom swinging from one side of the boat to the other. Not only is this very annoying and inconvenient, it is also dangerous. Not being able to put the sail where you want it -- need it -- is a shortcut to disaster. Just as bad, you have also eliminated your main source of lateral resistance, so your boat goes wherever the wind blows!

I guess this comment is strictly limited to daggerboards, because none of this applies, at all, to centerboards and their proper use. I would not consider this a major arguing point since the point being made is irrelevant when applied to centerboards. One could just as easily say that any CLR appendage that is mounted on the exterior of the boat, totally ruins the aesthetics. Some would also say that transom hung rudders are just as ugly.

6. Leeboards Kick Up Instantly (And With No Drama) When They Hit Anything. Is that a big deal? Maybe you just have to sail with leeboards for a while to appreciate how incredibly flexible they are. You can have "business" portion entirely in the water, entirely out of the water, or anywhere in between -- in a fraction of a second, with no effort, and without moving from your seat. When I come into the beach launch point, I don't even have to give a thought to my leeboard. It will instantly and automatically adjust itself to the ever-decreasing water depth. Can your daggerboard do that?

Nope, a daggerboard is not likely to do that, though there are design solutions out there for daggerboards that allow them to pop-up upon impact with an obstacle. Again, it looks like the same argument can be applied to a centerboard. A centerboard is not a surface piercing design solution that invites entrained surface air to rush down the low pressure side of the foil when trying to get the boat up to speed, creating a total loss of lift and therefore, effectiveness for its designated job.

7. Leeboards Can't Stop Your Boat In Its Tracks. Maybe there's always a ton of water beneath you where you sail. But hereabouts we have to contend with very shallow launch areas, sandbars, oysterbars, and other assorted underwater obstacles. I recall with trepidation bringing my Laser II back to the launch point a few years ago. The daggerboard was all the way down -- as it must be to make any progress upwind. Well all of a sudden, the boat slams to an abrupt halt. Yep, the daggerboard smacked the bottom, about 500 yards from shore. Had to paddle in! One more reason to hate centerboards…


As to leeboards not being able to stop one in their tracks; I'm going to have to suggest otherwise. Picture this one: You are out in the shallows, the wind is very light and the flow over your rudder has come to such a sorry state that you can't make turning inputs that amount to anything significant. The boat begins to make leeway and is pushed right onto a nasty mud pack under the surface. A gust kicks in and there you are, pinned like a listing rat on the mud, your leeboard holding you side-on and your rudder now useless
as a device that might be able to alter the situation.What to do? Well, it's the same as what one does for a daggerboard equipped boat, raise the board out of the mud and try to get the flow attached again so that you can steer your way into some headway.

I own a leeboard equipped boat. They have many of the same fun little quirks in scenarios like described as do my daggerboard boats. The board you may use is no magical panacea for a problem free sailing session.


8. Leeboards Can't Damage Your Hull (Or Trunk) From Impact With The Ground Or Other Underwater Obstacles. I have heard endless (horror) stories about daggerboard trunks being damaged when the board smacks bottom, a reef, a bar, or anything else down there. What can happen to your boat -- and to your otherwise enjoyable sailing experience -- when that happens? I leave it to your vivid imagination…

I have also seen leeboard mounts yanked right off a hull, broken into pieces, bent into a pretzle logic shape, etc., after the boat hit an obstacle with any kind of momentum. The issue is not exclusive to other types of boats with daggerboards, or centerboards. Sail enough in an endless series of conditions and soon enough, you'll see just about all the hallowed chestnuts come back to haunt your sense of practical.

9. Daggerboard / Centerboard Trunks Can Leak! I was at a meetup just a week ago where somebody's homemade boat started leaking around the daggerboard trunk. Hard to fix, and very annoying to experience out in the middle of the bay! Admittedly, on a monohull, you'd need two leeboards to do it right. But they would never cause leaks! BTW, my boat, No Commotion, actually has twin leeboards, connected by a small beam so they always act in tandem. Maybe overkill (hey, it was my first shot at leeboards) but boy are they effective!

This is one point where I agree. Any through-hull fitting, trunk, or otherwise, can leak if not properly built, sealed and maintained.

10. Leeboards Can't Break Off Because Of Impact With Underwater Obstacles. More horror stories come to mind. I'm constantly reading online where somebody's daggerboard snapped off at the keel because it was overstressed by impact or lateral loading that exceeded design specs. You know what a leeboard does when it hits an obstacle? It just moves gently up and out of the way -- still intact, still fully functional, and ready to be rotated back down.

I beg to differ, but leeboards CAN break right off and go spinning off in the waves. If it's a weighted board, it can go right to the bottom and stay there. There's no such thing as a boating appendage that can't break in normal use. Every material has a cyclic life span and when it gets enough load, enough cycles of load, or is poorly maintained, then say goodbye to mr. leeboard. The mythology and horror stories abound.


11. Leeboards Weigh Less Overall Than The Combined Weight Of A Daggerboard / Centerboard And Its Trunk. Maybe that's not very important to you, but I'm trying to make the lightest boats possible. Lighter boats sail faster, draw less water, and are easier to load / unload / handle overall. And since my "new generation" of hulls weigh just 60 lbs, every pound matters a lot. Leeboards to the rescue!

Again, I beg to differ with you. The info is out there on the web. Google is your friend.


12. Leeboards Are Infinitely Superior For Sailing In Very Shallow Water. You can easily, instantly, and continuously set your leeboard at the ideal depth for whatever shallow water you're in, providing not only maximum lateral resistance at all times, but also maximizing your ability to steer and get the boat where you want it. How important can that be? You tell me!


Maybe. It depends on the overall purpose of the boat within a series of design solutions for what one intends to do with the craft. Some folks would tell you that a boat completely devoid of foiled appendages is the best for very shallow water work.

I have found that a boat that is highly specialized for a given environment is pretty much pablum once it gets out of its element. Put a whitewater kayak out on a touring sea kayak trip. Have a hundred passenger catamaran enter an offshore race. Stick a Puddle Duck Racer on a 500 meter Olympic kayak sprint course. I'm sure the point is made.


13. Bonus Reason: Daggerboards Just Won't Stay Put! This reason probably shouldn't be last, because it can be SUCH a pain in the butt to get your daggerboard to stay up -- or down -- or wherever the heck else you want or need it to be. I mean, do you really need all that aggravation when all you really wanted was to go sailing and have a good time?

This issue was solved back in the 70's with beach cats that used daggerboards. Real simple. A foam roller with a bungee run through the middle is mounted on one side of the daggerboard deck opening. It is lifted up and over the head of the daggerboard and it holds the board very simply and snugly against the trunk wherever you'd like it to be for different points of sail. No muss, no fuss.

 

EDIT: I posted this before seeing the post before mine

This is a very interesting thread, particularly to me as I am currently designing a 15ft folding trimaran similar in concept to yours (but with a different rig and a daggerboard)

So first I have a question: How shallow is the water where you sail? I am used to sailing in the UK and PNW where basically it is deep. However I know there are many areas of the world, not just Florida, where the water is typically under 3ft deep.

There are many examples of boats being manouverable without rudders, the windsurfer being the most obvious. For example, I have sailed a dugout canoe in the San Blas, Panama where the paddle is held over the side as a combined rudder/leeboard. There used to be a catamaran class in the 1950's that had no rudders. The Kontiki raft could be steered by moving the daggerboards

The leeboard was developed in Holland and the east coast of the UK, both areas of shallow water. I don't think they existed elsewhere in Europe

I think some of the disadvantages of daggerboards you list were down to lack of experience, and certainly many disappear if you use a centreboard instead of a daggerboard.

The big disadvantage of a leeboard is that it is a surface piercing foil. So it makes waves and in effect behaves like a very short hull going very fast. So it is inefficient compared to a foil that goes through the hull.

Less of a problem on small boats, but a major disadvantage on big ones, is that they are noisy and bang around in a seaway, especially when at anchor and they are raised

I don't think you should worry overmuch about getting performance polars. As many have said, that's a complicated thing to do. Much better to do what you are doing and test sail full size with two boats. I assume you are both equally competent sailors and swap your boats during testing?

I write something about performance on the FAQs page of my website. Remember that in theory all Hobie 16s sail at the same speed, as do all Lasers

I have to say I am very impressed with your boats, especially since you say you have only been sailing a few years. You are already doing much better than many other, far more experienced sailor/designers.

I shall continue to read your comments both here and on your website

Richard Woods of Woods Designs

www.sailingcatamarans.com

 

WillyG,

Thanks for explaining.
I have to agree with several of your points, but I haven't sailed with leeboards, much.

But I also have never sailed a boat sideways into a mud bank and so did not consider that issue.

But #11? Got a reference/ link? The vague - on the web - doesn't help much.

I think anyone could make either a centerboard/ daggerboard or leeboard installation heavier or lighter. Difficult to actually compare isn't it?

Relative to Richard Woods post: I understand the difficulty in creating polars, and Frank has the best of all worlds with a captive comparison partner, but I don't. I had hoped the science of sailing had advanced a little more so testing could be less qualitative. It seems hard enough that its not clearly explainable on this forum, at least.

 

It has!!

That's why its now more complicated!

I guess you have now read my Performance Predictions comments on my FAQs page.

If you want to beat a specific boat then its easy to build one to do that, as DIYguy is doing all the time. But it is very hard to predict how fast a boat will be in isolation. That's why so many racers (AC etc) do two boat testing.

After all, changing from a dacron sail to a mylar sail increases performance by 2%. Altering the cunningham 1/2in on a Laser makes a big difference. And you will never win a competitive Laser race without using a brand new sail.

However, if you want to analyse an existing boat while sailing it, then that's fairly easy. Even a handheld gps will give the route sailed, so you can check real tacking angles with it if you zoom in. And by using a compass you can get the apparent tacking angle (not the apparent wind angle). The difference will be the leeway.

Woolies in the jib are virtually as accurate as the best electronic wind direction indicators (within 2deg anyway). And if you have a Windex at the masthead you can adjust the vanes and measure the wind angles. You will have to guess true windspeed though, and that needs experience.

You can also measure leeway by towing a fishing line attached to a horizontal protractor on the transom.

You may find Fiona Sinclair's website useful.

http://www.fionamsinclair.co.uk/yachts/

Richard Woods of Woods Designs

www.sailingcatamarans.com

 

Dang, now I gotta build two boats .......