The International Swift Solo

The Ultimate Single-Handed Skiff

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The reviewer "at work". Julian flying to weather
Julians review
Comments on Bram's 24 1/2er

Having a jib on a single-hander combined with the main/jib sheeting system keeps the boat balanced across a wide wind range; it also has excellent windward performance. It needs a softer mast to take full advantage of the sheeting feature, but even as it is rigged now, when bearing away in a puff the boat responds immediately and impressively! Most single-handers can't respond like this.

A second advantage to sloop-rigging is that it lowers the rig plan compared with cat-rigging. This allows the 24 1/2 er to perform well without wings because the rig aspect is more moderate (compared with a boat having racks and a cat rig setup) therefore the boat is easier to sail through gust/lull wind variations. You won't get dumped in the water when the wind drops and it is easier to respond to sudden wind changes. The moderate sail plan has low drag and goes upwind surprisingly fast. I easily stayed in front of a 5o5 going to weather.

The spinnaker is big-possibly too big-but it works and is very manageable. It is possible to sail low and fast downwind.

Some other pluses:
1. Gunwale angles set up well so no need for foot loops.
2. Very positive steering
3. High boom so easy to tack
4. Main sheet, effectively 1:1 so easy and simple trim
5. Great feeling going upwind
6. Feels comfortable to get low on the wire.
7. No vices in bearing away.

Some minuses:
1. Hull a bit full 3ft back from bow
2. Top of mast too stiff
3. Main sheet is stiff
4. Footrails not high enough


In conclusion, this is a very good design! This boat would be great for sailing by yourself whenever you want. It gives good skiff feel and would teach great boat handling.

I commend the designer/builder.

Julian Bethwaiteback to the home page

Three sail skiff racing is the future of single-handed sailing

 

Why opt to sail a single-hander with three sails?  It’s got to be heavier, more expensive, and more complicated than a single-hander with a main and spinnaker.  Dealing with the jib during rigging has got to take longer and trimming it and two other sails on the water, single-handed,  has to require skills beyond extraordinary. Right?

 

Maybe the place to start is to first discuss issues with two sail single-handers.  Cat rigged boats have been around since the beginning.  The principle was fairly simple.  Put a sail up a mast, place a keel or centerboard below a point approximately centered on the sail and add a rudder to provide directional control.  While boats with multiple crew members largely abandoned this design well over a century ago, this has been the standard of single-handed sailing right up till a couple of years ago.  Recently, however, a handful of sailors came on the scene with a low threshold of boredom.  Certain that there had to be more exciting ways to sail a boat alone—especially downwind, they added a spinnaker to the mix. 

 

Cat rigged boats traditionally had the mast well forward for balance but when the spinnaker was added it became apparent that this was not a good idea because of the tendency to make the bow dive like a submarine.  To compound the dilemma, skiff designers had discovered the speed advantage of needle-nosed bows—not friendly to forward centers of effort typical of these boats.  Mitigation of this problem required a combination of changes.  First they moved the mast aft and the centerboard far aft.  By staying with rather small fractional spinnakers they could keep the center of effort lower to help reduce the nose diving problem.  What they ended up with was a boat that is fairly fast to weather and acceptably fast down wind.  Because the rudder and centerboard are close together, the amount of momentum lost tacking and steering through waves is high (very short lever turning a long resistant waterline) so these boats are not tactical.  Additionally, the propensity for the rudder to wash out is high.  At the end of the day, the compromises made these boats quite difficult to sail but certainly a lot more fun than their predecessors without kites.

 

The entire approach was based on the age old theory that single-handed sailing necessitated using cat rigged boats. While at least one single-hander (the International Canoe) had dared to challenge this one sail rule with the use of a jib, nobody had become serious about developing a three sail single-handed trapeze skiff.

 

In July of 1999, after a day of competing in a 49er regatta in the Columbia River Gorge, I watched Kris Henderson sail his 49er alone in about 4 knots of wind.  Kris had obviously been doing this for some time and I was taken by how fast a 49er can move in really light air with just one person on board.  Since the jib was self tacking, he kept the main and spinnaker sheets in one hand and was able to jibe quite easily.  It occurred to me that with a cleating system on the boom for the mainsheet and single sheeting system that controlled both jib and main he would be able to concentrate on flying the kite from the wire.  Because of the huge asymmetrical kite the main has to be sheeted nearly to the centerline downwind anyway and it becomes fairly irrelevant as long as it’s far enough in to keep it from luffing.

Shortly after that regatta, I cut about 38” out of one of my 49er masts, cut down some old 49er sails and began experimenting single-handed in my 49er. While the boat was really difficult to right from a turtle, I learned a lot about beam/sail area ratios since I could move the wings in and out.  I also measured and recorded the sheets movement and relativity of the main and jib.  Because the main moves in a fairly simple in and out direction and the jib in a very non-linier fashion the solution to the problem of sheeting them from a single sheet was baffling.   On New Years morning 2000 I was awakened by some rather delayed fireworks at about 3am and as I lay in bed contemplating the problem, I realized that I’d been approaching the problem from the wrong direction entirely.  The solution was obvious. I needed to use the changing transom bridle angle on the mainsheet to make it mirror the non-linier movement of the jib sheet.  Using different purchase on each of the two sails combined with the right bridle base width and height, I thought it might be possible.  I spent New Years day doing the calculations and designing the system on my computer. The system would work, at least in theory.  I began designing the Swift Solo and started construction shortly thereafter. I tried the system for the first time in the spring of 2001.  The sails maintained proper relativity right through a broad reach.  While I’ve changed some minor things on the sheeting system since then, the theory was correct. The primary deterrent to having a jib on a single-hander is gone as it is both self-tacking and self-sheeting.    Adding a jib no longer requires an additional hand.

 

Admittedly, the jib adds 18 blocks and four clam cleats to the boat.  Three of the blocks and a clam are in the jib tack downhaul, four blocks and a clam are in the halyard, and four blocks and two clams are in the relativity control.  That leaves seven blocks in the actual jib sheet before it is spliced into the mainsheet.  The speed, balance, and ease of handling resulting from adding a jib far outweighs the cost.

 

In Summary, the odds that cat rigged boats with spinnakers will fade from the single-handed scene are fairly high, I think.  Sailing a skiff without a jib is both slower and more difficult—especially when a spinnaker is added.

 

As a side note, my experiments and research have taken me to some conclusions regarding the point where reduction of weight and the subsequent loss of momentum no longer produce desirable results in winds over 15 knots.  With some small adjustments for changes in sailing skill, mast drag, and hull rotational drag, sail area to weather must not exceed about 40% of the sailing weight of a sloop rigged trapeze skiff and crew (sail area in square feet and weight in pounds).  When this rule is violated, expect a skiff to become non-tactical to weather as the loss in speed and time outweighs typical gains associated with wind shifts in short course racing.  Cat rigs likely reduce the ratio to 32% and even less if the boom is low or the sailor is required to move aft during tacks (increased time required to get from wire to wire).   

 

Bram


This much fun in 3 knots of breeze?
The interview by Dennis Williams
The 24 1/2er
Q. What got you interested in skiff designing and building?
A. My decision to enter the high performance single-handed design fray was inspired by my 49er experience and some observation. It seemed likely to me that most of the designers were barking up the wrong tree. I believe that this battle will be won by a skiff with both a jib and a gennaker. Many designers seem resigned to the belief that one person can't handle three sails. I think that they're wrong and that their boats will suffer from this belief.

Q. What made you believe that this would work.
A. The benefits of a non-overlapping jib is well known to skiff designers and sailors and few would argue that once underway a boat with a jib will always beat cat rigs---all other factors being equal. The problem is in handling the jib without a forward hand. A creative method of totally eliminating any need to sheet or handle the jib was needed. The jib would have to be adjusted automatically with the mainsheet. This was the first problem to attack and by experimenting on my 49er, I found some clues to the solution. It was obvious that a combination of "vang sheeting", a little math / trig., and a lot of experimenting would provide the answer.

Q. What other design elements make the 24 1/2 er different?
A. Several design details were important to me. In order to achieve the speed needed wire to wire, this boat had to be a "stand up / run through" skiff in the tradition of the 49er. The wings needed to be built-in and solid--no open racks to get caught in. Because its' a single-hander it doesn't have the luxury of a team member to affect rescue. Also, the rails needed to be curved in the back to eliminate the need for foot straps when the chute is up. The boat had to be easy to enter from both the dock and shore and the wings would have to be dock friendly for landing like the 49er. The boom needed to be high, a feature that could be compensated for by the lower center of effort of the combined sail plan.

Because of the tall rig the buoyancy had to be allocated to allow easy righting from a turtle position. The hull design was mostly inspired by Frank Bethwaite's book "High Performance Sailing". While a lot can be learned from the chapter on "Hulls", more can be learned from comments throughout the rest of the book.

Q. How does this compare to your 49er?
A. Single-handers require quite a different design approach than double-handers for a number of reasons. The 24 1/2er has an entry nearly as fine as the 49er, however, it gains volume faster above the waterline to avoid pitch-poling downwind in big waves. This increased volume increases pitching to weather in big waves a bit but it should minimize bow diving, which is important to consider while training single-handed. The hull has more waterline beam and less rocker than a 49er to facilitate jibes that will be less graceful than on a double-hander. A cut-down 49er mast is used to facilitate the large masthead asymmetrical gennaker. A cut down 49er boom, sails and blades saved a little time until after initial testing. In addition, the boat had to be a design that would instill pride of ownership--like the 49er.

Q. Bethwaite had some concerns about the stiffness of the mast, the footrails and the hull fullness back 3 feet from the bow. What is your reaction?
A. The mast was designed for a two-man boat (the 49er) and is indeed a little stiff. When we go into production, I'll work with the mast builder to get a softer top section but maintain the caps and upper spreaders to facilitate the masthead spinnaker.
The footrails he referred to are the push-off rails about 16 inches in from the gunwale. They are 1 1/4" high and they need to be about 3/8" inch higher--no question that this will get changed on the next boat.

I want to sail this boat in big waves a bit more before I remove any volume up front. If I find that I'm having no trouble keeping the bow out downwind, I'll make the entry a little finer as he suggested. That change should make it even faster to weather in waves. I'll make that decision within a month.

Q. Are there any other changes that you want to make to the boat?
A. Charlie recommended that I move the trapeze exit eyes inside of the spinnaker sheets to make jibing even faster. I will be giving that a try soon.

The sails that I'm using are cut down 49er sails. While the boat seems nearly equal to an International 14 going to weather, I have not attempted to work on optimization of speed yet. Working with a good sailmaker is on the agenda once I settle on the right mast.
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