The View Up Here

Random scribblings about kites, photography, machining, and anything else

Archive for May, 2012

Fresh Out

Posted by Tom Benedict on 29/05/2012

A boat is a hole in the water into which you throw money, or so the saying goes. It’s not too far from the truth. All in all we spent more than I expected on our boat before we even got it in the water. A few nights ago, Rydra, who takes care of all our banking, came to bed and told me, “That’s it. Fresh out.” We had set a cap on how much we were willing to spend to get a boat in the water, and we’d hit it. (Actually, we’d gone past it, but she let it slide. It’s her boat, too, after all!)

Boats are a lot like cars this way. If you live somewhere with junk yards, owning and maintaining a car becomes a lot more affordable. Bust a side mirror, and you may spend ten bucks at a junk yard. Bust a side mirror where your only choice is to replace them in pairs with new parts, and you may be in the hole for a hundred dollars or more. With a boat, if you have a source of used parts to draw on, a surprising amount of money can be saved. Take a simple shackle. Boats use shackles like candy. If you’re scrounging them off of dead boats, you may have a buck or two invested in each of your shackles. Buy them new and they range from five to twenty dollars, depending. Given the number of shackles on a boat, that’s the difference between thirty bucks in shackles and several hundred.

We don’t have junk yards out here on the Big Island. We also don’t have a lot of beach cats. I had to buy most of the hardware for this boat new. Oh sure, I picked up as much as I could off of Ebay, but there are limits. If the person doing the selling doesn’t know much about boats, you may bid on something that’s described as “1 lot shackles, perfect for boat!” thinking you’re getting stainless marine fittings, only to find out you spent thirty bucks on a box of rusted galvanized shackles for trailers and chain. We bought some of our stuff off Ebay, but the bulk of it came from Murray’s, Sailcare, and Sailrite. It all just added up in the end.

Discouraging? Sure. But Rydra’s news came at a time when all the major and 99% of the minor work on the boat was done. I think she timed it that way on purpose.

The jib is still out, and the winds have been atrocious. So the boat is still sitting on its trailer in the yard waiting for a chance to sail. Yesterday my daughter had a ballet performance in Captain Cook, south of Kailua-Kona. We left the house in the morning with the heavy tradewinds hammering the trees. We don’t often go as far south as Captain Cook, so we spent some time at a really cool park down there. My oldest sat, reading her book, while the other two kids played. I stared out over the cliffs to the ocean, watching the wind on the water. I enjoy seeing my daughter dance, and I was looking forward to the performance. But I couldn’t help thinking how many months it had been since we got our boat, and still the ocean was out of reach. And now, I had no more resources left to throw at it.

The dance performance was a lot of fun. The theater group she’s part of put on a production of Alice in Wonderland using a mix of ballet, hip-hop, and tap. It went together far better than I thought it would, given that description. The choreography was impressive. Two of the dances combined two different dance forms in a single performance. I’m glad I was able to go.

On the way back I couldn’t help staring at the ocean, judging what the wind was like and guessing at how far we’d be able to sail in a day if we put in at Kawaihae or Puako or any of the other spots we passed along the way. As we drove I spotted several sails on the water. At least someone was out there. I just wished it could’ve been us.

By the time we got home the sun was starting to set, and a rainstorm had blown in. The kids were spotting rainbows and guessing at the treasures to be found at their ends. And that’s when my own questions were answered.

Rainbows

Ok, ok. I see the pot of gold. I can wait a little longer to go sailing with it.

– Tom

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Older and Wiser (or Older and Easily Fooled)

Posted by Tom Benedict on 27/05/2012

Older and wiser, or maybe just older and totally hoodwinked by my own design work. Time will tell. In any case, it was a little less than a week ago that Rydra and I managed to dismast our Pacific Catamaran while trying to raise the mast. Now, a week later, the boat is fitted out with new parts and a new mast raising system that should keep us from a repeat performance. The jib still isn’t back from Sailcare, so essentially we lost no time on the water. Not bad!

But let me backtrack…

When we broke the mast hinge, I really didn’t know if it would be possible to replace it. Spare parts for the Pacific Cat are almost impossible to come by. I do mechanical design and machining for a living, so making a new part wasn’t out of the question. But judging by the color of the mast hinge, I figured it was made out of bronze. I have scrap material of almost every kind of metal that comes across a machine shop floor, but no bronze.

When designing replacement parts, it’s always important to see what was there in the first place. If you replace a stainless steel part with an identical one made out of aluminum, it will break well before the old one did. Likewise if you replace all your high tensile strength bolts with stainless bolts, the stainless ones will fail long before the old bolts did. If the mast hinge truly was made out of bronze, I had two choices: go out and buy some bronze bar stock, or find a chunk of stainless. Neither prospect was very appealing.

Turns out it was never an issue anyway. I took the bits in to work to show to one of my co-workers. “Cast aluminum, huh? Colored to look like bronze?” I couldn’t believe it! The surface of the crack was clearly a white metal, not the more golden color of bronze. The coloring was only a paper thin layer near the surface. Part of me was a little peeved that the mast step had been colored like that, but the rest of me was pretty happy with the news. Aluminum I can deal with.

So over the weekend I made a new mast step hinge.

Broken Mast Step Hinge

No CNC on this one. It was all manual machining. Unfortunately it’s a lot uglier than it should be, because I tried to replicate the broken part rather than produce something that would do the broken part’s job. Note to self: Don’t trace ugly stuff onto metal prior to saw cutting, and expect to make anything but an ugly part. But the lesson is learned: If I ever have to replace this hinge, I’ll design the new one from scratch.

The new mast step hinge is made from 6061-T651 aluminum; common fare in a machine shop, and a lot tougher than cast aluminum. Cast metals tend to be brittle, and will crack before they bend. Metals that are ductile tend to bend before they will crack. 6061 is an alloy of aluminum that includes other metals to increase its mechanical characteristics (tensile strength being one of the more important ones). T651 heat treatment increases hardness, but also increases how brittle the aluminum is. 6061-T651 will bend, but only up to a point. Then it cracks. But it bends a heckuvalot more than cast aluminum! Structurally, this was a win.

The original hinge pin was a stainless tube, which was peened into place once it was installed. This was a major PITA to get out. The tube had been so deformed over the years, it wouldn’t just slide out. I had to pound it out 1/8″ at a time, cut that section off, then pound it back the other way to cut that side off. After going back and forth about twenty times it finally gave up the ghost and the last little nubby of tube popped out. I replaced it with a solid steel rod, held in place with split rings. This is how the Prindle mast step pivots. Good enough for me.

So we were back in business, but no better off than before. Rather than risk a repeat performance of the downed mast, I sought to remedy the root cause. So during my spare time over the week I designed a new doodad for the boat:

Mast Step Assist - CAD

It’s a contraption that creates a virtual pivot axis for the mast that will constrain the mast to the fore-aft plane. It’s strapped down to the boat just behind the mast step hinge. The geometry of the side plates locates the eyebolts along the axis of the mast hinge. Once the thing is strapped down to the deck of the boat, side stays are attached between the mast and the eyebolts. This prevents the mast from swinging off to one side the way it did during our last disastrous attempt to raise it.

The width of the crossbeam is critical. It places the eyebolts so the straps coming up from the trailer attach to the eyebolts at a 10 degree angle off vertical. This is the same angle the side stays come off the mast. This keeps the side plates from being subject to any torquing motion. All the tension forces acting along the stays should go straight down the straps to the trailer.

I had most of the material to make this in the scrap box. But as with any scrap box project, the design evolved to match the materials available. The feet at the base went from 1″x1/4″ to 1″x1/2″ because I had a good sized bar on hand. The side plates went from 1/4″ to 3/16″ thick, and were clipped a little deeper on the rear corners. The cross tube and eyebolts came from Ace Hardware. All in all I had less than $30 rolled into it. After a test fit on the boat I added some split lengths of 1/2″ fuel line to the bases to make rubber feet so it wouldn’t mar the deck any more than it already is. Here it is installed and ready for use:

Mast Step Assist Installed

The wind is still too gusty to try to use it, but it was nice to see it in place and ready to go. Since our boat is rigged with two pairs of trapeze wires, we plan to use one pair as the baby side stays for raising the mast. Once the mast is up and the real stays are all locked in place, the trapeze wires are removed from the doodad, and are clipped back onto their shock cords for use on the water.

The only job left is to give this thing a name other than “doodad”, “contraption”, or “thingy”. Mechanical design and machining I can handle. Names? Er…. HELP!

– Tom

Posted in Engineering, Sailing | Leave a Comment »

I’m Getting Old

Posted by Tom Benedict on 22/05/2012

There’s nothing like failure and imminent mortality to put the fear into you. This morning I was made painfully aware that I’m getting old.

It started off as such a simple idea: Step the mast on the boat so I can go through the last of the rigging work before this coming weekend. I figured two lunch sessions and two evenings with the mast up should just about do it. Put the mast up in the morning, and the next two days are rigging days. Simple, right?

Wrong.

When we built the mast support on the trailer, we got a winch to help lift the mast. The one time we manually stepped it, I realized how easy it would be to drop this thing. It’s heavier than the mast on our Prindle. And when we were sailing the P-16 we always had three adults to step the mast. We figured the winch would fill in for that third person. In a way we were right, but in other ways we were dead wrong.

About halfway up, Rydra was on the winch and I was guiding the mast. The wind was gusting, and blew the mast sideways. It had been gusting the entire time, but I’d been able to gorilla the mast back into position through each of the gusts. This time I simply didn’t have the strength.

The mast step hinge was only designed to pivot fore and aft, not side-to-side. The gust of wind blew it sideways, and despite everything I threw at it it just kept going. I yelled to Rydra to look out and get clear. I could fee when the step hinge started to go. Rydra said she heard crunching sound coming from the step hinge, and suddenly the hinge cracked into three pieces. Everything came crashing down. Luckily neither of us was killed. Rydra was behind the mast support, and didn’t get touched at all. I wasn’t so lucky. The mast hit my shoulder on the way down and pretty much drove me into the ground like a pile driver. Nothing broken, but plenty bruised.

So now I have two more projects on the to-do list. The first is to set up a good solo mast raising system using a 6′ gin pole and a good system of baby stays so the mast can’t swing to the side any more as it’s being raised. The other project is to make a new mast step hinge. The original was cast out of bronze some years before I was born. I can’t buy a replacement. They simply don’t exist. So I’m going to make a new one out of stainless plate. It should be stronger, just as corrosion resistant, and shouldn’t be too hard to make. But it’s just one more thing I have to do before we go sailing. Pain in the ass.

Except for the step hinge, the boat survived fine. It’s an amazingly tough beast, all things considered. I expect if we take good care of it, it’ll last forever. Me, on the other hand? I’m clearly mortal, and not as strong as I once was. I wish I’d realized that before putting us both at risk.

– Tom

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Tourette Syndrome Awareness Month

Posted by Tom Benedict on 17/05/2012

Guess what? May 15 – June 15 is Tourette Syndrome Awareness Month! (Don’t sweat it if you didn’t know this. Until about an hour ago, neither did I. And I have TS! So relax.)

I tend to roll my eyes when someone mentions an awareness month. “Did you know this is Fuzzy Puppy Awareness Month?” “GOSH! NO! ‘Cause puppies need help being noticed. Really.” Just kidding. But honestly, I think the TS awareness month is a good idea. I’ll get to why in a minute. But first I want to touch on why I think a lot of awareness months really don’t work.

The problem with most awareness months is that people use them to brow beat their fellow creatures. “This is Bad People Suck Awareness Month.” “Ok.” “Are you aware bad people suck?” “Umm… Yes?” “I doubt it. You might think you’re aware of this, but I’m going to make you really aware of how bad they suck.” “Uhh… Can I just go back to reading my book?” “See?! You’re ignoring me! You suck! You’re a bad person!” It’s not much fun. So when people hear that Feburary 13 through March 18 is awareness month for thing X, Y, Z, most people just tune it out or point out those dates are longer than a calendar month. At the very best it’ll be for something they don’t relate to. At the very worst someone will make them feel bad for not relating to it. No fun!

So when you have an awareness month, keep it upbeat. Keep it interesting. And truly try to improve awareness rather than just shoving it in people’s faces. That’s how I’d like to see Tourette Syndrome Awareness Month handled.

Now on to why I think it’s a good idea! Most people are aware that TS exists. Hey, I’m a lot less subtle than a cute fuzzy puppy when my tics are going full-throttle. The problem isn’t with the awareness of the condition itself. The problem is that most people aren’t aware of what TS actually is. The stereotypical image of someone with TS walking around swearing and barking is precisely that: a stereotype. Certainly there are people with TS who have coprolalia (uncontrolled swearing) and barking tics. But not everyone does. There’s more to it than that. Here’s what TS is to me:

TS is a neurological disorder. I really was born this way, kinda like I was born with blue eyes. Sorry. I didn’t come with a money-back guarantee or a 90-day warranty (just ask my parents!) As Popeye said, I yam what I yam.

TS is only a part of who I am just like being left-handed is only a part of who I am. But just as being left-handed doesn’t define me as a person, neither does having TS. Knowing I have TS is just scratching the surface.

TS provides me with all manner of quirky behavior. I twitch. I jerk. And sometimes I let go with an explosive sound or two. But the truth is everyone has quirky behavior. Some people have to have their coffee just so. Some collect little glass figurines. Some have to vacuum daily or they feel unclean. Everyone has quirks. Mine just have a label.

TS is distorted by the popular media, and as a result is largely misunderstood by the general public. This is unfortunate, and is the main reason why I think having a TS awareness month is a good idea. The image presented by the media is a stereotype. Move past it.

TS has been a vehicle by which I learned to have a sense of humor about myself, and not take life so seriously. It presented very real obstacles as I was growing up. Sometimes it got so bad I had to choose: should I cry or should I laugh? TS taught me to choose to laugh. And the punchline to the joke? Everyone faces obstacles growing up. We could all stand to take ourselves a little less seriously and laugh a lot more.

And finally, TS has been an avenue to meet so many wonderful people who also have TS or who know someone with TS or who are just curious about it. The TS community is one of the most compassionate bunches of people I’ve ever met.

Don’t believe me? Then you’re in for a treat. This blog entry is my way of spreading awareness of Tourette Syndrome during TS Awareness Month. And this video is how a fellow TSer decided to spread her awareness of Tourette Syndrome. Take a look. Meet her. See for yourself that TS is more than just tics:

So have a great Tourette Syndrome Awareness Month! Bake some cookies. Call a friend you haven’t talked to in a while. And if you see someone ticcing while you’re out and about, give ’em a wave and a smile. It’s a recipe for a better day.

– Tom

Posted in Tourette Syndrome | 2 Comments »

Nearly There

Posted by Tom Benedict on 16/05/2012

The last big boat hurdle has passed: the trailer is now legal.

Our friend finished the last of the welding work on the trailer over the weekend. It was waiting for me at work on Monday. I stopped long enough to drop my bag in my office, then ran back outside to hook it up to my Jeep. That’s when the fun started. At that point I hadn’t driven a trailer in over fifteen years. It was parked on a really narrow strip of grass behind our parking lot. Getting it out was straightforward, but like I said, I hadn’t driven a trailer in over a decade. I sweated. But it came out fine.

I had four things to do: weigh the trailer, get a provisional safety inspection, register the trailer with the DMV, and get the final inspection. Over the next two days I got all of it done. But between driving an empty trailer around the local cement quarry looking for the trailer scale and finding out the place I get my car inspected had lost their state inspection license for a year, I wound up pulling more hairy trailer-in-reverse tricks than I’d done even when I did know how to drive a trailer. Reversing onto a highway, driving in the dirt, backing it between multiple parked cars while turning a right angle, maneuvering it past the trees around my driveway… By the end of it I was back in the swing of things. I also shaved a couple of years off my life from stress. But hey, I can get them back by relaxing on a sailboat!

The to-do list is getting short. Last night I ground down all the sharp points on the mast support and treated all the bare metal and welds with Ospho. Today at lunch I painted everything with Zophar so it has plenty of time to dry before the weekend. Past that I need to glue carpet into the mast supports, install the winch, step the mast, and finish installing the rest of the trapeze hardware. By Monday the boat should be ready to go.

With one exception: the jib.

Sailcare got back with me this morning with an estimate for the work on the jib. Between cleaning, repairing holes (my holes that I put in my sail… doof), sewing the zipper on correctly, and shipping it back to us, we’re over $200 in the hole. I winced when I saw it. But in the grand scheme of things, at this point it’s mouse nuts. That’s the last thing we need in order to sail. “Git ‘r done!” I told them. It should be here in a couple of weeks.

– Tom

P.S. What I actually told them was, “No, that looks fine. Go ahead and do the work on the sail.” I’m not so crass as to squawk “Git ‘r done!” to anyone on the phone.

P.P.S. No one who doesn’t know me intimately, that is. My co-workers hear me say that all the time.

P.P.P.S. Maybe that’s why my co-workers think I’m crass.

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Recognizing Indaba

Posted by Tom Benedict on 14/05/2012

I recently learned a new word: indaba. “Indaba” is a conference held by the Indunas (the headmen) of the Zulu tribes in which much is discussed, but because of the large quantities of home brew served at such conferences, very little is actually accomplished. In colloquial usage it refers to expending a huge amount of effort to get what seems like a simple job done.

Oh boy…

There are tons of stories I could tell from work that fit this to a tee. At the moment our telescope is shut down because of something that seems so simple, but becomes more complex day by day. But because this story is ongoing and because it would be too easy for feelings to get hurt by what I write, I’ll share a recent story of my own instead:

The sailboat we bought came with three sails: two mains and one foresail. In an earlier post I mentioned that the foresail overlaps the mast, so it’s actually a genoa rather than a jib. But the overlap is on the order of 5% or so, so the whole jib vs. genoa is really just a technicality. Anyway, the jib attaches to the forestay with a zippered pocket. This kind of arrangement is typical on small cats like the P-Cat. It also means your sail has this ginormous zipper that it depends on. Completely.

When I bought the boat the previous owner went through the sails and pulled them all out for inspection. When he pulled out the jib the zipper pull came off in his hand. “Oh well,” he said. “That’ll need to be replaced!”

Well yeah!

The boat took so much work to get ready for the water, the jib more or less sat around for weeks. Eventually I got around to it and started looking for a zipper pull. Zippers come in all sorts of sizes and styles, so I had to take a look at the zipper to see what kind of pull I needed. Then when I tugged at the zipper, several teeth promptly broke off and fell into my hand. I thought to myself, “Oh well. That’ll need to be replaced!” Well… yeah…

I ordered a new zipper almost 30′ long. It wound up only being a few feet longer than I needed, which was perfect. The idea with a jib zipper is to sew a too-long zipper in place, trim to length, then treat the lower end of the zipper so the pull can’t come off the track. I had just the one I needed.

Except I didn’t have the right thread or needle. So I placed yet another order and packed the sail away until I could work on it. Eventually the thread and needle came, so out came the sail once again. While trying to get the old rotten zipper off, I gashed the sail with my seam ripper.

The rip was short and not in the main body of the sail. Nothing that couldn’t be repaired with Dacron repair tape and some more stitching. So I placed yet another order for the Dacron tape, and packed the sail away yet again. When the tape arrived I pulled everything out. After the patch was on and stitched  in place, I just had the zipper to go. Fifty feet of zig-zag, and I’d finally be done!

Except that my machine couldn’t punch through the reinforcing at the head of the sail. There must be seven thicknesses of sail cloth at that point, and my poor machine just didn’t have the horsepower to shove the needle through. Rather than kill the machine I packed the sail up, swapped back to kite making needle and thread, and put the machine away. Then I boxed up the sail and sent it to Sailcare along with a note:

In addition to the sail cleaning, I need the zipper sewed on properly. The old zipper had rotted away, and I thought my machine was up to the task. I was wrong. Unfortunately I didn’t figure this out until I was halfway through the job. Do what you have to do.

I have had more embarrassing moments in my life, but this one ranked up there. I’ve also had more than my fair share of simple jobs like this one where I spent more time and energy than should’ve been required to get them done. But this one is right there at the top of the list.

Indaba. Now I know what to call it.

– Tom

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Trapeze Harnesses – Critical Design Points

Posted by Tom Benedict on 12/05/2012

In an earlier post I mentioned my wife and I are rigging our P-Cat with trapeze wires. One of my favorite things to do with our Prindle was to sail on a nice fast reach, hiked out, just barely flying the windward hull. I could go for hours like that. I’m also pretty sure I laughed like a maniac the whole time. Yes, it’s just that much fun. Think about it: For a guy who likes to lift cameras with kites, what’s more exciting than lifting myself and my boat with what amounts to a really big kite? Blow, wind blow, so I can git up ‘n GO! YEEEEHAAA!!!

Ok, getting ahead of myself. Writing, not sailing…

Aaanyway, the more we looked at our new (old) boat, the more we wanted to hike and fly, just like we did on our Prindle. So we went through the whole song and dance of getting all the rigging for trapeze wires. Then we got down to the matter of picking harnesses.

Our Prindle came with two lace-up full body harnesses. I HATED THEM! When you’re hiked out, all your body weight is being suspended from a hook positioned right in front of your navel. With a lace-up, the bulk of that weight is being distributed around your hips. TIGHT around your hips. After an hour in the harness, it felt like my femurs were being embedded in my pelvis with a hydraulic press! As soon as I could afford one, I got a new harness.

The new one was a full-body rig from Murray’s. (Ok, so I got it from The Sailboat Shop in Austin, but it was a Murray’s harness.) Rather than lacing, it had adjustable nylon straps. To climb out of the harness you popped three quick release buckles and shucked it off. To get back in you stuck your legs through the loops, pulled it up, and clipped the three buckles shut. No worries. You adjusted it once and you were good to go.

But the best part was the spreader bar. The hook was welded to a 9″ bar that suspended your weight from your butt rather than from your pelvic bones. No more crushed hips! I loved it. My butt provided plenty of padding, and even after hours on the wire I felt like I could keep going. And going. And going!

But then we moved to Hawaii and the Prindle stayed behind. My Murray’s harness stayed behind, too. Yeah, there’s some irony to be had here. We moved from Central Texas to an island in the middle of the ocean. The movers packed everything (and I do mean everything! They even wrapped up one of my trash cans with the trash still in it!) One of the few things we left behind was our boat. Go figure.

That was about fifteen years ago. I was in my twenties. I was young, dumb, and relatively invincible. These days I’m middle aged, just as dumb, and utterly mortal. I have chronic back issues. My biggest fear, hiking out on a wire, is that my back will go out and my family will have to haul me in like a big bloated fish on a hook. I can already imagine myself flopping around on deck making “Garg garg garg!” noises as the kids poke at me with sticks, daring each other to be the first to sit on me. Unmitigated hell. Or typical parenthood. Same difference, some times.

So when I went shopping for a harness, I wanted to find one with some real back support. Lo and behold, there were a bunch of harnesses that offered full back support! Ok, so some of them were an utter joke. But some took the job seriously. A number of them included battens (think of corset stays made out of thick fiberglass, stitched into the garment with thick nylon webbing.) More than one also included a hard shell for the lumbar region of the spine. HOT DAWG! I made my list, checked them twice, and narrowed it down to two models I was interested in.

I showed what I found to Rydra, figuring she’d respond with a “HOT DAWG!” of her own. To my utter confusion she stared at both of them and shook her head. “But what’s not to like? They have spreader bars! They have lower back support! I could hike for hours on these things!” She looked at them again, pointed to the shoulder straps, and said, “There’s no way that’s fitting around my chest.” I gave them a second look. Sure enough, whoever designed these was either a man, a misogynist, or both. I put myself in her shirt, so to speak, and winced. Hours in that rig would be sheer torture.

She finally found a harness that would work. Among other things, it had adjustable straps that positioned the shoulder straps outboard of the torso. (I almost pointed at them and said, “Look! Barberhaulers!” but I held my tongue. Rydra has a good sense of humor, but I know how far I can push before I earn a good  smacking.) I considered getting the same model, but it offered no back support. Instead the design necked down just above the waist so the torso and hips moved as separate units. The list of features proudly stated this harness offered “more mobility than other harnesses!” More mobility? Yeah, for someone without a bad back. Me? That’s a trip to a hospital just waiting to happen.

In the end I settled on the Ronstan Racing Harness, and Rydra chose a Gill Spreader Bar Harness. Two completely different trapeze harnesses based on completely different critical design points.  It just goes to show that there really is no one perfect design. Not even for something as straightforward as how you’d hook a wire to your belly button. Go figure.

– Tom

Posted in Engineering, Sailing | Leave a Comment »

Trapeze Wires – Pull Up or Pull Down?

Posted by Tom Benedict on 08/05/2012

Unfortunately I don’t have pictures to post with this. And without the pictures this topic is a lot more confusing than it should be. (Trust me… I’ve been researching this one for DAYS!) This has to do with trapeze wires on sailboats and how they’re rigged. The question boils down to this: Should the bungee on the trapeze wire try to pull the trap ring up or should it try to pull the ring down?

For those who haven’t sailed on dinghies or catamarans, here’s a hand-wavy description of why you’d want trapeze wires and how they work:

When wind blows on a sailboat’s sails it propels the boat forward. It also tries to blow the boat over. This is true of every sailboat. And every sailboat solves this in much the same way: You make the boat as stable as you can, and finish up the rest with movable ballast. On larger monohulls this is handled through the use of rail meat (otherwise known as “crew”). On smaller boats like dinghies and catamarans, you don’t have the excess crew to order out on the rail, so you have to handle movable ballast some other way.

When a small boat starts to heel over from the force of the wind acting on the sails, the skipper has two choices: de-power the sails or move crew weight outboard. De-powering the sails means you’re not extracting as much speed from the wind as you’d like. So it’s better to move crew weight outboard. If you have straps on the deck of the boat – or in the case of a catamaran, on the trampoline – the crew and skipper can hook their feet under the straps and hang their butts off the side of the boat. If they have strong stomachs (and hey, what sailor doesn’t have a strong stomach?!) they can extend their bodies even further. The further out they can position their strong stomachs, the less the boat will heel.

But their legs and feet are still on deck. Wouldn’t it be better to get their entire bodies off the side of the boat? This is why some classes of small boats started using trapeze wires. These are wires that hang down from a fitting on the mast and extend down to either side of the boat. The wires are fitted with hardware that let the sailors hook onto them with a harness and hike out on the side of the boat, suspended by the wire. Because their entire bodies are hanging off the side of the boat, the righting forces are much higher. And because the righting forces are much higher, the boats can either take on more wind or they can run larger sails. Either way they get a speed bonus.

Without some way to hold the wires in place when not in use, though, the boats would be death traps with these flopping wires hanging overhead. The trapeze hardware on most boats includes a bungee cord that tries to pull the wire back to a parking position when a sailor is not hooked in. And this is where the fun begins…

There are two broad stroke approaches to this. The first, which is common on dinghies, is to tie the bungee to the bottom of the trapeze ring so it tries to pull the ring down. (The trapeze ring is what the sailor hooks their harness into so they can hike out on the trapeze wire.) What this means is that when you are hiked out on the wire, you stay attached to the ring. But when you come back in off the wire, say when you’re tacking the boat, the ring will try to slip off the hook on your harness. This makes tacking smoother because you never have to worry that you’re still attached once you come in.

But it can make hiking out on the wire more of an adventure since the ring is actively trying to disengage from your harness the entire time. Think of this scenario: A boat is tacking and the crew slides across the deck to the new upwind side. They grab the trapeze ring and hook it onto their harness. Then they position their feet (the ring slips off their hook without their noticing) and they push off from the rail… And they promptly go overboard.

Catamarans take the opposite approach: The ring is rigged in such a way that as the bungee is pulling the trapeze wire back to its parking position, it’s also trying to pull the trapeze ring up. When the crew hooks in, they have to pull the ring down to their harness. The bungee continues to provide an upward pull, which tends to keep it hooked into the harness. Hiking out on a wire is straightforward: Your trapeze ring is constantly trying to stay engaged, so you know you’re safe just to push off and hike out.

But when you come back in off the wire, the hook will try to stay engaged. It takes an intentional act to disengage the trapeze ring. This can slow down a tack, or even cause a blown tack if the ring becomes entangled. Since tacking on a catamaran is such a tightly timed affair, this can make or break a race.

Which brings us to our dilemma…

After a lot of hemming and hawing, Rydra and I decided to install trapeze hardware on our P-Cat. Some parts of the hardware were already there, so clearly the boat had been rigged for trapeze wires in the past. But most of the other hardware was gone. Initially we decided to get adjustable systems that let you change the height of the trapeze ring on the fly. But completely by accident we wound up with systems that were set up for a dinghy: they pull the ring down. I posted my concerns to The Beach Cats forum and got some good feedback. So I picked up enough hardware to let us re-rig the trapeze hardware for a catamaran, which pulls the ring up.

Now I have to decide what to do. In looking through the hardware, we should have enough bits and pieces to rig a system similar to the one on the Prindle, which used a fixed height ring that you could only adjust when the system wasn’t under tension. We should also have enough hardware to rig a completely adjustable system with a 2:1 mechanical advantage, which will let us change the height of the ring while we’re hiked out. By putting things together in different ways, we should be able to build a pull-up or a pull-down setup for every configuration.

In short, with all the bits we’ve got we can do practically anything we want. (Boat rigging Legos!) Right now I’m planning to set up fixed systems similar to the Prindle. Once we re-learn the basics, we can start experimenting. Eventually I’d like to wind up with the 2:1 adjustable systems installed on all four trapeze wires. But what that system will look like is anyone’s guess.

This should be a fun summer!

– Tom

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I Swear It’s Not A Shiv

Posted by Tom Benedict on 06/05/2012

Apparently I bought a retractable shiv.

I went in with the best of intentions. I’d busted my seam ripper trying to repair the straps on my son’s backpack, and I needed another. Specifically I needed one that could rip about fifty feet of zigzag off of a sail. The zipper on my foresail had apparently died a horrid UV death some years back and needed to be replaced. I had the new zipper in hand, but had no way to get the old one off.

While I was ordering new thread and needles, I saw that Sailrite sold a Ghinger seam ripper. Hey! I love my Ghinger shears! The picture in the catalog didn’t really make all that much sense, but I ordered it anyway. I figured if it was anything like my shears, it’d be awesome.

When I opened the mail today, I was excited to see spools of thread and bags of needles. WOOHOO! And there, at the bottom of the box was… a… um… It said Ghinger.

Honestly, it looked like something a surgeon would use if he decided to turn mafia hit man. Either that or it’s what an alien probe would look like. In short, it’s beautiful. But I’ll never look at seam ripping the same way again. Like ever.

The Shiv

When I approached the sail that night I felt like I was cornering it in an alley. “I’m going to cut you, mang!” As it turns out that feeling was a little too close to the truth.

The dacron cloth in the sail is in remarkably good shape considering it’s almost as old as I am. Even the stitching is in great shape. The zipper? It was like rotting mummy wrappings. Or wet tissue paper. A normal seam ripper had some difficulty cutting threads but not cloth. But the new Gingher? At one point it felt the need to escape, and without any effort at all it sliced a two inch gash in my sail. Luckily the body of the sail wasn’t harmed. It was the forestay pocket that took the brunt of the attack. Nothing some dacron repair tape and a lot of stitching wouldn’t handle. But it sure made me wary about waving around my new seam ripper!

I finally broke down, drove the local hardware store, and bought a fistful of everyday seam rippers. (Yes, our hardware store carries seam rippers. Think small town.) I got the rest of the zipper off without gashing any new holes in the sail, and the dacron repair tape is on the way.

Meanwhile I’m trying to find some sensible, non-sailing project to try this thing on.

– Tom

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