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  #1  
Old 12-12-2012
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Small main sail, large jib - questions

I'm about to purchase a Kent Ranger 24 which is similar to a San Juan 24.

It has a relatively small main sail and short boom compared to nearly every other sailboat I've sailed/seen. It handled fine in sea trial. It just seemed a bit foreign to me. The San Juan is similar, but its main sail area is about 10% larger than the Ranger 24.

I gather this was more common a few decades ago and most newer boats have much larger main sails and longer booms.

Any comments on the relative merits of this design? I kind of like the idea of not worrying about my family getting bonked on the head during tacks/jibes.

Any major disadvantages to the smaller main? Any advantages?
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Re: Small main sail, large jib - questions

An SNer tenuki has a review of one here.. not detailed though and he/she hasn't been active for a couple of years.

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This rig geometry was very common in the 70s and early 80s when the IOR racing rules kind of held sway over a lot of designers, and was the 'in' way to set up fast boats for a time. In reality these boats were often 'rule beaters' that weren't necessarily as fast as they could be, but they could win on the rating sheet.

In any event many many boats were produced in that time frame that to some degree emulated the winning racers of the day. We have owned a couple of these ourselves and they can be reasonably decent boats. In their extreme form, though, they had some issues primarily with sailing DDW in a stiff breeze.

On a 24 footer the issues are reduced, i.e. large, difficult to handle and sheet genoas and spinnakers - serious loads on a 40 footer, not so much on a 24. What you will probably find, though, is that when the breeze is up a bit you'll end up using very little of your main (it will be half inverted) going upwind as most of the power of the rig comes from the headsail. These boats can go to weather well when properly set up.

But the 'bad habits' downwind are not an insurmountable problem. Carefully choosing your sailing angles, wisely choosing whether or not to fly a spinnaker, etc, can make for a pretty enjoyable boat. We had a 40 footer along those lines and we had 12 years of great sailing on a boat size we couldn't have afforded any other way. But we were careful.

Our current boat's hull design is of the same era, but it has a fractional rig with a very large main that seems to have dealt with some of the issues we dealt with on the bigger boat.

In short, I wouldn't worry about it. On a 24 footer even the 'big' sails aren't.. though you may still find your winches undersized at the upper end of the wind range for the genoa. Choosing a smaller sail to start with may make it a bit easier to get to know her and her habits. - but of course in light air you'll need the oomph of the larger headsail....

Good luck!
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Old 12-12-2012
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Re: Small main sail, large jib - questions

This topic seems to crop up around here from time to time, often with very strong opinions on all sides. As my esteemed fellow moderator said, with skill, care, and good crew work the short comings of these rigs can be tamed and made manageable, especially in a 24 footer. But I tend to look at big jib-small mainsail rigs from a different perspective.

If you look at the evolution of sailing rig proportions, when you look at small working craft, cruising boats until the CCA and IOR racing rule era, race rigs on boats before and after the CCA and IOR race rules, the norm was large mainsails and small jibs. If you look at wind tunnel testing that seeks to compare drive to sail area, as a broad generality a fractional rig with larger mainsail, and smaller minimally overlapping jibs, tends to be more efficient than the small mainsail, big jib sail plans.

So if this true, why does the big jib-small mainsail rig exist? As Faster noted this rig resulted from designers trying to create a rig that was faster than the race rule expected. In this case the rig proportion came from a rule which under measured the sail area related to the leech of a headsail. It resulted in boats that relied on huge jibs to sail in light to moderate breezes, but which were quickly overpowered as the wind increased. As Faster notes, initially this can be addressed by under trimming and eventually 'flagging the mainsail', but at some point there is not much you can do to keep the boat moving and under control. The net result is that the headsails on boats like these have very narrow wind ranges. For example, an AP 150% genoa may have a workable range between 2-3 knots apparent and 12 or so knots apparent, and at the upper end, the main is typically undertrimmed. If I look at the headsails on a boat like mine (and I only cite my boat since I know it very well) my AP 109% minimal lapping genoa has a range from 2-3 knots apparent up to around sustained 25 knots apparent (with a single reef in the mainsail).

Consequently, because the headsails are used for a much narrower range of windspeeds, these boats need more frequent sail changes and so are less suitable to dealing with a building breeze shorthanded. Because these headsails are so big, the ability to adapt to building breezes by furling the jib becomes more limited as well. Most times these boats are casually sailed with something like a #2 genoa. The problem here is that these sails lack capability at the lower end of windspeed range (say less than 5-8 knots). To be fair, that simply many not be a problem for many people since many casual sailors tend to motor at this lower end of the windspeed range anyway. The other issue is that it is simply harder to drag these larger overlapping sails around the shrouds, and baby stay, making tacks way less convenient short-handed.

In a general sense the issues associated with this rig proprtion was not so bad on a well crewed race boat. But for short handed sailing, even on a small boat, these rigs are very inconvenient. And while efficiency and ease of handling are not an end all, to me, if I were looking for a different boat to own, while I still had a choice of picking a rig for easy handling, I would have a very hard time seeing these big jib/ small mainsails as the right choice.

Respectfully,
Jeff
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Last edited by Jeff_H; 12-13-2012 at 09:02 AM.
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Re: Small main sail, large jib - questions

Thanks guys. I don't plan to race the boat. I was looking for a quality entry level day sailor / pocket cruiser.

As far as downwind misbehavior.... I have heard this many times about the San Juan 24. Some have called it a "broach coach". Specifically, what happens?

Overpowered spinnaker pushes bow down... boat oscillates? sudden weather helm? rudder out of water? excessive heel? all of the above and resulting broach?

Just thinking aloud.

Would a strategy to avoid unruly downwind runs be to avoid the spinnaker in heavy conditions and choose the jib conservatively (tend to use smaller than required?)
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Re: Small main sail, large jib - questions

Research Chinese (downwind) jibe (or gybe) and windward broach on the interwebs.

What happens with a broach coach in a Chinese jibe is the top of the spinnaker begins to oscillate (move from side to side). While dead down wind, the spinnaker may be positioned to one side of the boat, pulling on that side, and encouraging steering difficulties. The IOR style boats roll more easily because they lack the wide, flatter stern sections that more modern designs have, and they do not have the fuller keel, narrower beam and lower, greater ballast that dampened motion in prior traditional designs. Consequently, the boat will roll in tandem with the oscillations of the spinnaker. As the boat rolls and the stern lifts out of the water, the keel trips the boat up in the wrong direction, causing a jibe and a turn to windward, at which point the spinnaker drives the mast toward the water, and the boat broaches.

Solution: judicious application of twings (tweakers, barber hauls, etc.) when running dead down wind or near DDW to control oscillations. (I bring my sheet and guy to the rail near the shrouds as the wind approaches 20 knots.) Undertrim the pole (forward) to center the spinnaker closer to the centerline of the boat. Steer the boat to stay under the sail. Don't fly the spinnaker in too heavy air.

In a windward broach, the boat heads up excessively, the stern lifts and the boat loses steerage way, causing a broach. Again, the spinnaker drives the mast toward the water.

Solution: Overtrim the pole to windward (more guy trim), undertrim the spinnaker sheet and the mainsail sheet so both sails will immediately begin luffing as soon as the boat starts to head up, allowing the boat to stay on its feet and not heel excessively. Tension the boom vang to keep the mainsail flat so it is depowered and there is less weather helm.

I like IOR-style boats. They are beautiful boats and, although they will not plane, can be fast if sailed well. If you learn how to compensate for the idiosyncracies of the design, they can be great boats, and will often go to windward like a freight train, better and more comfortable than the lighter, modern designs that tend to pound into the waves, and faster than the traditional designs that have greater wetted surface area. Many of them are now incredible bargains because they are no longer competitive in racing and lack the modern amenities the picnic sailors seek.

Faster and JeffH are right about the design characteristics. I carry 5 different hanked-on jibs and 2 spinnakers on my boat with only a single reef point in the relatively-small mainsail. In a moderate breeze, trimming the jib can require considerable effort, along with the sail changes. On the other hand, my masthead rig allows me to fly an 800 sq. ft. spinnaker in a light breeze, putting up almost 1,000 sq. ft of sail area on a 28 ft. boat. When the wind pipes up, I drop the spinnaker and run wing and wing, and/or jibe downwind, sailing on deep, broad reaching angles at hull speed with the jib poled out to leeward. Upwind, my boat loves a full #1 genoa with a reefed main in a breeze - it will crank over to 30% heel and drive through the waves at hull speed with very little weather helm.

Last edited by jameswilson29; 12-13-2012 at 12:21 PM.
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Re: Small main sail, large jib - questions

Here is an example of good spinnaker trim on an IOR-influenced boat (Pearson 28) on a deep running angle, not dead downwind. The pole is not square to the wind, instead it has been eased forward to bring the spinnaker closer to the center of the boat. The twings have been trimmed to bring the guy and sheet down to lifeline level. The sail has a nice "beetle" shape due to the proper pole height and it luffs evenly starting below its shoulder. The boat is not rolling excessively, even though it is being pushed by small swell from behind.

In the video, I am making about 5-6 knots in about 10 knots of wind in the Atlantic Ocean south of Ocean City, Maryland, pretty good for a 35 year-old boat:

Last edited by jameswilson29; 12-13-2012 at 08:46 AM.
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Re: Small main sail, large jib - questions

This is already a small boat (much smaller than a Catalina 25, a little smaller than a San Juan 24). Having to carry so many headsails is going to eat into your space quickly, and make it tough to cruise on with a family. Don't forget that you'll also need space below decks to carry an inflatable dinghy if you are going to sail from Seattle to the San Juans. The smallest Zodiac rolls up to a tube about 3' wide and 20" in diameter.

A more balanced jib to main size is certainly a lot more friendly to handle and trim. The main sheet has a lot of mechanical advantage without using a winch. This will make it easier to teach kids to trim the sails.

I bought a Catalina 25 for the same reasons as you and loved it a lot. I like how smaller boats sail. However a 12 day trip to the San Juans (with a one other crew person, first a friend then my wife) convinced me that standing height and some organized storage spaces were really useful for cruising.

I look at the interior of a KR24 and wonder where you will store 3 headsails, a dinghy, a small amount of food and clothing (what you would take backpacking for example), and still have space for 3 or 4 people to sleep. The engine well also limits cockpit storage greatly.

I'm used to lightweight travel and do a lot of kayak and bike touring, but was surprised at hoe quickly space disappears in a sailboat.
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Re: Small main sail, large jib - questions

What's somewhat interesting to me is that our '82 Choate 40 (Kaufman) was a mid-range IOR design, without quite the 'pinched sterns' typical of earlier renditions, and with a 16 foot J and a 14 foot E not the most extreme example of those rigs either, it was a handful DDW in a breeze and needed careful attention, esp since we sailed her in an area of consistent breezes over 20 knots.

My brother had a 76 Ranger 28 (Mull) (12.5 J, 9 E) that was such a broach machine we could have produced an annual calendar of great shots nearly every windy race had we wanted to. We modified her rudder to a balanced version that was a great improvement in control.

Our current boat ('84) is a more extreme pinched end Holland design from '79 (Holland) but with a 3/4 frac rig, with a 13 foot J and a 14.5 foot E.. very different proportions. We have never come close to a serious broach and rarely gotten into any of the preliminary 'death rolls' that these boats were known for. So despite having the 'shape' that was often blamed for this behaviour, the very different (for the day) rig has made a big difference.

FWIW the Brazilian manufacturer changed the boat to a masthead rig version in a quest for more 'horsepower' sometime after our boat was built.. and while we do find our boat underpowered in the light stuff, we love the smaller headsails and manageable chutes of her present configuration.. once the breeze is over 6 or 8 knots we move along just fine despite not even running a 'genoa'...
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Re: Small main sail, large jib - questions

Very common back in the day. My Father's first boat a '78 Cal 25-II, the boat that I grew up on had a huge headsail, I mean the thing was like a 180! (and a 110 for heavy air).
The sail would actually come back to the cockpit, but for us it was normal and we never thought anything of it.
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Re: Small main sail, large jib - questions

Great insight everyone.

I found a number of these types of boats and I agree, they are an incredible bargain.

For me, it is going to be mostly a day sailor, lake boat. Then one to take out to Blake Island or one-two nights somewhere. Not a week long family cruise in the San Juans just yet. And I am not planning to race it.

I have little experience using a spinnaker, but hope to learn on this boat. For the time being I will never fly it in strong winds.

If I and my family enjoy it enough then the plan is ultimately to get "THE" perfect boat.

For down wind runs, would you guys suggest setting the main and the 150 or 130 wing-and-wing?
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