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CS15 with a lug yawl rig

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Hi all, 
 
I'm not really sure how to broach this subject.  I feel like I'm violating some tenet of the community, but there have been a few lug sail posts on the messing-about forum over the years, and even one where Graham put up a drawing of a cat-ketch lugger.  Here's the thing.  I built a puddle duck and put a Storer-designed lug on it, and I loved the sail (the puddle duck, not so much, but I'm now hooked on building.)  Before the puddle duck, I raced (poorly) a Penguin near DC for about 10 years - cat rig, one triangular sail. What I loved about the lug is the simplicity of rigging, and the fact that it just goes up and down so easily since the sails aren't directly attached to the mast.  The triangle sails seem to need to be pulled down.
 
I think that the lug-yawl rig I sketched below preserves some of the genius of the cat ketch like simple rigging with unstayed masts and the ability to heave to with the mizzen, and a low center of effort.  The main is 87 square feet and the mizzen is 15 sf, so roughly the same total sail area as the CS15 cat ketch, and the center of effort is maybe a few inches higher than the cat-ketch at 8' above the water line, but in the same fore-and aft position.  The lug is lower-aspect ratio, so probably a less effective wing for up-wind performance and maybe a better parachute for down wind.   (BTW, that's actually the BRS 15 profile from the B&B website)
 
So why not just stick with the proven cat-ketch design?  Three things:  I think it will be easier to step the mast when it's a little further from the bow.  I'm guessing that it will also be easier to reef, since the whole sail, boom, yard and all, can be retrieved into the cockpit for reefing, and then re-hoisted.  Last, everything but the main mast is short enough to stow in the cockpit.
 
So whaddya think?  Space is tight for my build, so I'll have more room if I do the spars and foils and such first, and I'm itching to get started.  Thanks in advance for any thoughtful comments.
 
Bob McMichael
 
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Good to see someone else is thinking about a balanced lug rig on a CS15. 

 

Here is my CS20 with balanced lug sails with one reef tied in when the wind died during the 2014 Texas 200. I have been considering downsizing my CS 20 and up-sizing my S10. If I do I will probably do a balanced lug variation of some sort. 

 

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Here is my CS20 in the 2008 Texas 200. The standard sails are prettier than my one poly tarp one Dacron home sewn sails. 

 

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There are pros and cons to each of my setups. Shorter masts that are very easy to step on the BL. No boom on the cat-ketch. Reefing difficulty is about the same.

 

It is always fun to mess with the boats and try different things.

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Bob,

I've sailed my standard rig CS17 many times in the company of boats with the rig you are proposing.  They seem to have an advantage reaching while I have an advantage on most of them regarding pointing.  The other significant thing is the lug guys avoid sailing dead down wind out of concerns about "death rolls" and I've never seen them let their sails fly forward like we do with the standard rig.  As you probably know the standard rig on the CS is a joy to sail downwind and you can let boom out past 90 degrees if you need to depower.   Sounds like a fun experiment. good luck

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Hi Randy and Terry,

 

Thanks for the pictures and voices of experience.

 

About letting the sails fly forward -- there's nothing like shrouds or anything that would stop a lug from being allowed to fly forward, although I imagine that if the sail started "lifting" it would generate a sideways force that would tend to roll the boat.  Is the key difference in the cat ketch that the two sails can be set wing-n-wing so that these rolling forces oppose each other?

 

Bob

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Bob,

I think it has more to do with the "self vanging" effect of the sprit booms or perhaps the weight of the yards up high.  Perhaps someone that knows more will come along shortly. 

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You're right, Randy; it is the self-vanging effect that makes a sail docile off the wind. When a sail twists off so that the top is forward of the mast and the lower part is aft, it gets unstable and the boat starts rolling. A friend capsized a Ness Yawl this way in the Great Glen Raid and nearly got into deep trouble.

 

Let me define some terms, as I understand them:

cat ketch and cat yawl are generic terms for a two masted boat with the larger sail forward and no headsails. The ketch has a larger mizzen, stepped farther forward, that contributes significantly to the drive of the boat. A yawl's mizzen steps aft and is more of an air rudder for rig balance and heaving to.

 

'lug sail' refers to a half dozen different rigs that all have a yard at the top of the sail that isn't attached to the mast (as a gaff is)

 

a balanced lug has a yard and a boom, neither of which is attached (well, some have parrels...) to the mast and carries the luff well forward of the mast. It has a boom downhaul some ways aft of the tack, which when pulled tight gives some vanging effect. Sprit booms like Graham's have much stronger and more positive effect because of the slanted boom pushing down, as well as out, on the clew.

 

vanging effect is the force that holds the clew down and the leech straight and limits the twist in the sail. Excessive twist is what makes sails squirrelly off the wind, as they oscillate and shed vortices alternately on one side and the other, resulting in the classic "death roll"

 

Bob, your sketch looks like it should work fine, if the areas come out the same. You'll need a boomkin to sheet the mizzen to. And I notice that you mention my balance lug hero Michael Storer in Australia. He's great; here's a link to some interesting reading:

http://www.storerboatplans.com/wp/design/rig/sails/making-balance-lugs-faster-2013-setting-up-sails-spars-and-rigging

 

Hope I haven't confused things too much...

 

cheers,

Lynn

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HI Lynn,  Thanks for your post.  I'm also a Storer fan and I thought long and hard about his Goat Island Skiff design.  In the end, I decided to build the CS15 hull.  After studying some videos of people zooming along, I noticed that the CS sailors just looked more comfortable in the chop, perhaps because of the CS's V-bottom.   Anyways that's just a little back story on how I ended up here.

 

On the Storer site and in other places, the "word" is that downhaul tension is critical for controlling twist in the balance lug so I'll keep that in mind.

 

BTW, The link works better without the trailing "/"

http://www.storerboatplans.com/wp/design/rig/sails/making-balance-lugs-faster-2013-setting-up-sails-spars-and-rigging

 

Cheers,

Bob

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Hi Bob,

I agree about the v-bottom being superior; never cared for flatties anyhow. Graham's hullforms are brilliant. And the tensions that Storer advocates for downhauls are appalling, but that seems to be what they need for good sail shape. I guess that calls for heavier scantlings in the boom than I'm used to; mine have usually been little more than heavy battens and slide over my shoulders easily in a tack. Oh well.

 

About the link - something seems to be adding a bunch of metatext junk to my link, so, everybody should use Bob's link to Storer's site, not mine.

 

Lynn

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I love it!

I have often thought about adding a third mast step just to be able to throw an alternate lug rig on my CS17. I actually did some scribbling on it last week. It seems like setup time at the ramp would be cut in half.

For me though, I would probably rake the mast aft and skip the mizzen just to keep it simple. If it was the primary rig, sure, the yawl makes a lot of sense.

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Hi All,

 

Here are some pics showing some of the progress on my CS 15 build.   I'm trying to get everything I can done before I start on the hull.   Right now, my first fiberglassing job  (center board, exciting!) is curing in the garage.    In one of the pics you can see that I built my work bench on top of a red and black puddle duck.  There's also a Platt Monfort designed "Nimrod" I built. that serves as a lamp shade.  The spars are in the varnishing stage.  Eventually, I'll have to figure out where to put the puddle duck reconfigure everything so I can build as CS 15 cradle right on the trailer.    Can anyone tell me the "V" angles and separation of the supports in the CS 15 cradle design?

 

I haven't settled on a name for the boat, but these past few weeks, "Festina Lente" has been the favorite.  It's a Latin phrase, that means "make haste slowly"    I think it captures both my impatience to make progress and the slow speed.

 

Thanks,

Bob

 

 

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Hi Bob. Looks like a good start. I think that your shop is even smaller / more crowded than mine. But it CAN be done in these cozy little places. i like your "lamp shade". And a Puddle Duck work bench yet! Wowzers. Looking forward to following your build. And modified rig. Done in true "Puddle Duck spirit".

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I'll be watching this thread for sure.

 

On finding the angles for the cradle supports, we just copied the shape of the fore and aft bulkheads on the CS-17 and directly under these bulk heads is where we supported the hull.  I see that for the CS-15, the forward bulkhead is further forward so it may be different but on the CS-17, the lower portion of the forward bulk head is rounded where the ply twists to the bow.

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Mattp - thanks for the hint on matching the bulkhead shapes.    You are right about the forward bulkhead edges being rounded but that's not a problem.

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Hi All,

 

Glassed the one side of the centerboard yesterday, and the other side today.  

I used the rope trick with 5/16" polyester double braid, first planing off a 1/2" flat and then using a Stewart Special Screw Scraper to dig the groove.   Alan demonstrates the SSSS in this youtube:  https://www.youtube.com/watch?v=xydnwWe9x6w.

 

There's a fairly thorough discussion of the rope trick in this topic:  http://messing-about.com/forums/topic/9387-lapwing-20-aka-hirilondë/?p=84068.

 

I used clear packing tape to hold the rope in place while it cured.  The clear tape showed bubbles, and helped me gauge how tight to pull the tape.

 

I drilled holes in the CB and tucked the ends in, as Alan's youtube shows.   It added some sticky fussiness to the process.   Double braid would rather collapse and puff out than to be pushed into a hole.    If the epoxy does a good job of linking the rope fibers to the wood fibers I wonder if just trimming and taping the ends down into the epoxy would have been strong enough. 

 

Cheers,

Bob

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I am doing the rope trick on my BRS 15 blades, albeit reluctantly.  I still can't see how plastic-soaked polyester is stronger than a brass leading edge.  Maybe they covered it the day I skipped my Strength of Materials Class in engineering school.  Anyway, I'm following the herd, and will maybe learn something in the process.

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I think that the idea is that the rope gives a "wear edge" that won't rot or splinter as it would on a wooden board as the wood is exposed. When it gets badly worn, just patch it up with some epoxy and....whatever.

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  I still can't see how plastic-soaked polyester is stronger than a brass leading edge.

It isn't stronger, it is more forgiving.

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The "rope trick" offers a resin rich, high elongation, high modulus material to absorb the impacts, of a bottom or object strike. This is much better than a metal strip, which simply transfers loads from the impact into the substrate (the board). Simply put the resin saturated rope absorbs, spreads and dissipates the impact, with more efficiency than a metal strip, so what's behind it doesn't have to tolerate as much abuse. Have you ever walked around the back of your pickup, just to kick the tow ball hitch with your shin or knee? How'd it feel? Now, if the hitch had a rubber boot over it and you kicked it with your shin, how do you think that would feel and would you like, the wooden portion of your board to have this same luxury?

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