Yawl conversion

Mike
Alas after ten hours of working on 113 today I've completely stripped her of hardware, cleaned her above and below and am ready to start making a mess of her. I can't get the yawl conversion out of my mind and since I have alot of work to do in the lazerette I'm going to go ahead and glass-in some backing plates in the corners of the stern just in case somebody here can't stop me! Probably beef up the forward bulkhead of the lazerette to withstand the mast step and help carry some stress from the traveler. Because I haven't had the mast stepped since the morning I bought her I haven't a clear idea of boom clearance for locating the mizzen forward shrouds. I would like to keep from mounting them on the outside of the hull. Should be able to place the boom directly on the cabin top to get fairly acurate measurements. Any last minute advice? Tony G

Tony an Ebb,

I don't know nothin' about yawls. I cut my teeth on a cutter, and both boats that I have owned have been sloops. I realize that a mizzen sail has other advantages for self-steering, and for other purposes, but I thought that the idea of a double mast rig was to spread the sail area among a greater number of sails to ease sail handling, and to give greater flexibility. So if one is converting an Ariel sloop to a yawl, would not one wish to reduce the length of the mainsail boom at the same time?

If more sail area for light air sailing is the objective of course, the above would not be relevant.

No change in boom necessary for yawl rig! The boom is well forward of the aft bulkhead and the mizzen forward shrouds dont need much forward lead of the mast . Remember , the shrouds angle back and the boom swings forward as it goes outboard , so if the base af the shroud is even with the tip of the boom when it is amidships , the two will never meet . There is not much load on the mizzen shrouds either , the sail should be about 12' luff and 6' on the foot or not much bigger . A 16' mast is all you need .

Scott,
A yawl, if also available as a sloop on the same hull , will 99% of the time have more sail area than it's sloop rigged sister . Think of it as a trunk rigged spoiler, not 4 doors .

Mike,

Very interesting. Like I say, I have virtually no yawl experience, but still, if one were to rig a mizzenmast and sail on an Ariel with the as-designed mainsail configuration, the center of effort would move to some degree. I wonder what if any effect this would have on balance, degree of weather helm under windy conditions at various points of sail.

Scott
I sometimes start to fret but then I remember C Pete's post of Bob Lincoln's factory Commander yawl. Good points though. Most of the time I get out sailing 'round here there isn't much wind so 'light air ails me' or else it's blowing 25-30 mph! I'd rather douse and run rather than motor sail. Tony G

Tony,

I appreciate the light wind concerns. I guess that I am remembering the leech on my 1974 90% jib ripping about a month ago in some pretty interesting and unexpected wind. Crawling around the foredeck in attempt to save a shredding jib while single-handing when the boat was healed at 35 + degrees under near-zero visibility conditions was very interesting. Then again, I was over canvassed with the full main.

The yawl rig is an exciting possibility for many reasons. I might be induced to give a mizzenmast a try were it not for the fact that my boat has an outboard in the well, so a mizzen mast would present an interesting obstruction. Perhaps there is a way to avoid that through the application of some sailboard technology to create a removable mizzen.

But then again, we could give the Yahoo engineless sailing group a try and see what a "jib boom" could do for your boat in the way of a "scutter rig": http://photos.groups.yahoo.com/group...ss_sailing/lst

If you join Yahoo engineless sailing group, you will find that the group presents some interesting perspectives. A jib boom on a Pearson Renegade is featured under photos in the Renegade album.

I worked Quite Hard to talk David out of converting MANDARA to a yawl.<G>

It's Funny to read this thread here, since we just looked at a lot of the same things! Our friend Jeff Maher is taking some pictures for us of the details of the Trion yawl he was helping to splash, and I think Dave will be putting them up on the engineless group once Jeff sends. There has been a bit of discussion between David and another member who is a Naval Architect on the topic as well, if anyone is interested.

Mary
Triton #397

I copied this from another Board. One guy's opinion about sloops, yawls, etc.:


Boats are systems and when it comes to one size fits all answers, there is no single right answer when it comes to yawls and ketches. A pet peive of mine is the mislabling of these rigs today and in particular the mislabling of multi jib versions. Either rig can have either a single jib or multiple jibs. When a Yawl or a Ketch has multiple jibs it is referred to a Yawl or a Ketch with multiple headsails. It is considered lubberly to refer to that rig as a 'cutter ketch' or 'Cutter Yawl'.

I lump yawls and ketches together here because the share many similar characteristics. Ketches, in one form or another, have been around for a very long time. In the days before winches, light weight- low stretch sail cloth, high strength- low stretch line, and low friction blocks, breaking a rig into a lot of smaller sails made sense. It made it easier to manhandle the sails and make adjustments. Stretch was minimized so the sails powered up less in a gust and although multiple small sails are less efficient, the hulls were so inefficient that the loss of sail efficiency did not hurt much. Multiple masts, along with bowsprits and boomkins, allowed boats to have more sail area that would be spread out closer to the water. In a time of stone internal ballasting this was important as it maximized the amount of drive while minimizing heeling. Multiple masts meant more luff length and more luff length meant more drive forces to windward. But multiple masts also meant more weight and much more drag. There are also issues of down draft interference, meaning that one sail is operating in the disturbed and turbulent air of the sails in front of it, which also greatly reduces the efficiency of multi mast rigs. .

Yawls really came into being as race rule beaters. They are first seen in the 1920's as a rule beater under the Universal and International rules. They continued to be popular under the CCA rule as well. Under these rules, the sail area of jibs and mizzens were pretty much ignored in the rating. This popularized the masthead rig and the yawl.

There was a basis for not measuring the sail area of a yawl under these rules. On a yawl going to windward, the mizzenmast and sail actually produce more drag than they do drive. This is because the mizzen is sailing in really turbulent air and has to be over trimmed to keep from luffing which can effectively act as an airbrake. This is slightly less of the case on a ketch where the size of the mizzen is large enough to provide a larger percentage of the drive.

Downwind mizzens also are a problem. In this case they are forcing the main or foresail to operate in their bad air and so again they are not adding as much to the speed of the boat as they are taking away. BUT in the predominantly reaching races that were typical of offshore races of that era they offered a number of advantages. First of all on a reach the sails are not acting in the slipstream of each other and so each contributes a fair amount of drive for the drag produced. Also with the advent of lightweight low stretch sail cloths, mizzen staysails, which are great reaching sails, came into widespread usage in racing. Here again a ketch has the advantage of having a taller mizzen and so can fly a bigger mizzen staysail.

In comparing yawl and ketch rigs to sloops, the broad generalities are that for a given sail area a sloop rig will generate a greater drive for the amount of drag generated pretty much on all points of sail. That means that a sloop will be faster or will require less sail area to go the same speed. Sloops are particularly better than Multi spar rigs such as Yawls and Ketches on a beat or on a run. A sloop rig would tend to be taller for a given sail area. This means it would be better in lighter air but it potentially might heel more or need to be reefed sooner as the breeze picks up.

Sloops work best on boats with reasonably modern underbodies. Both are more efficient and so can point higher and make less leeway.

Ketch and Yawl rigs work best with heavier boats with less efficient underbodies such as full keels and Vee'd hull forms. These hull forms often need a lot more drive and the hull is the limiting factor in how fast or how close winded the boat will be. The yawl or ketch rig's lack of windward ability is less of a liability when placed on a hull that similarly lacks windward ability. Also, the ability of a ketch or yawl to carry more sail with less heeling moment also makes it a natural for a heavier hull form which often has comparatively little stability when compared to the amount of drive required to make a heavy boat move.

In theory the height of a Ketch should be shoter than a sloop rig but unless you are looking at a big boat or live in an area with low bridges the difference in height should not be significant. As to draft, the lower height of a multimast rig should mean less heeling and less draft required but this potential advantage is usually offset by the multimast rigs larger sail plan and weight aloft.

Much is made of the ketch or yawl's ability to be balanced to help with self-steering and also the ability to sail under Jib and mizzen in a blow. This is one aspect that a traditional ketch or yawl has over a traditional sloop. It is not so true of modern sloops. Modern (especially fractional) sloops can be easily depowered and that reduces the need to reef. With modern slab reefing gear, reefing is far more easily accomplished than dropping the mainsail to the deck on a yawl or ketch. In a properly designed sloop balance is just not all that hard to achieve.

The performance of all three rigs, both on broad reaches and in lighter air, can be improved by the ability to carry kites of different types.

In terms of comfort at sea, ketch and yawl rigs push the weight of the spars closer to the ends of the boat which can increase pitch angles, albeit, while perhaps slowing pitching rates. The taller rigs of a sloop tend to increase roll angles while slowing roll rates.

Then there are structural issues. It is often difficult to properly stay a ketch or yawl rig as the mainmast backstay often need to be routed around the mizzen and the forward load component of the mizzen if often taken by the top of the mainmast. It is also often difficult to get proper aft staying on the mizzen of a ketch or yawl as well. These structural issues are particularly pronounced on Yawls where the mast is so far aft in the boat that on a traditional boat it is hard to get adequate staying base widths.

Anyway, in conclusion, if you are interested in sailing performance or ease of handling, a sloop rig makes more sense. To me the only justification for the yawl rig today is solely romantic charm or a sense of history. I do not mean this to be a put down to those who love historic rigs, but for sheer sailing ability a yawl or ketch is a relic of another time or an obsolete racing rule. Still, if you live in an area that is windier and you like traditional boats, then a ketch or yawl is an interesting albeit complicated rig.