Saturday, April 12, 2014

New Main--Mack Sails

The original sail had slowly turned into a shapeless bag. I priced this one at the Annapolis boat show, and months later, here it is! Certainly, there are some adjustments to be made--batten tension, for certain--but the fit seems good.

I need to fabricate a proper tack strap. The original sail had foot slides, but this one is loose footed. I like it.
Note the jury-rigged boom strap at the clew. I'll have to sew something better... though it worked perfectly.

Draft forward, lots flatter

  • 8.62 oz High Aspect Dacron Mainsail
  • Five full battens with adjustable battslide fittings
  • 3 reefs
  • UHMW wear strips
  • Sail area equal to original design specifications
  • Standard boom cover
 And by way of comparison... Before. We're be zipping to windward!

Friday, April 4, 2014

Not all Winterizing Products are the Same

As part of an up-coming Practical Sailor article I tested the anti-corrosion properties of a number of leading winterizing agents:

The test rig...

The coupons after 2 months...

The right hand products I like, all propylene glycol-based. The left hand column, all ethanol-based.
  1. water
  2. vodka
  3. I won't tell... just avoid ethanol.
But the clear point is not to be a cheapskate. Stay with something reputable, and stay with glycol.

Sunday, March 30, 2014

The best chafe sleeve, and why a cover is NOT a chafe sleeve.

After a little more time with the chafe machine, a champion emerges. and the knowledge that it is as much about the weave as the material.

What? Being Spectra is not enough? A it turns out, there is an enormous difference between braided covers and tightly woven tubing. In fact, our lowly nylon tubular webbing typically out-wears Dyneema and Kevlar covers. No wonder we have been so happy with our experience using nylon webbing as a chafe cover for docklines.

Top to bottom:
New England Rope ARC. 10 minutes against grindstone.
New England Rope Dyneema Chafe Sleeve. 10 minutes against grindstone.

For reference:
New England Rope Regatta Braid. 1 minute against grindstone.
New England Ropes StaSet (not pictured). About the same as Regatta Braid.
9/6-inch 7x19 rigging wire parted in 13 minutes.

But I hadn't tested nylon webbing in the same run, or plain Amsteel...

Top. ARC, as before.
Center. Plain Amsteel, Dyneema Sleeve, 9/16" nylon tubular webbing, all for 10 minutes.
Lower. Regatta braid, 1 minute, as before.
Notice that the nylon webbing outwore the high-tech cover by a mile (it's still running, at just over 30 minutes, and not through)! Notice that plain Amsteel is 30% through the first yarns, worse than the webbing.

Which is not to take anything away from this Dyneema webbing sleeve that wears like iron. Wow.

Before we question why New England Ropes even make the cover material, realize they serve a different purpose. ARC makes a nice cover, holding in jammers, minimizing core slip, and not stiffening the line. The Spectra sleeve and tubular nylon does none of these things. All it does is wear hard.
It seems it is more about the weave than the material.

Wednesday, March 26, 2014

Stitching and Chafe--Not All that Vulnerable

I've been busy testing coverings and coatings, certain that stitiched eye needed consierdaerable protection. But then I started test the eyes themselves. First I sewed a pair of eye in 3/8" Samson XLS, both with the stitch count limited to break at about 2500 pounds. I could sew a stronger eye, but stitich strength is easier to measure accurately when you are not too close to the line breaking strength (stitch/rope interaction become important beyond ~ 60% BS).

 The upper is Robline #10 whipping twine, the lower Robline #10 Dyneema whipping twine. The Dyneema is smaller, but the strength is similar.

Then I abraded each on fresh-sawn yellow pine for 20 minutes on my abrasion machine.  This is just long enough to wear through the line cover, as can be seen.

The polyester stitching is worn (74% of original strength when pulled to failure), but so much as the cover, which is just into the core.

The Dyneema twine suffered no measurable wear (failed at calculated value). However, the cover is gone below the splice, and considerably scuffed where the Dyneema twine did not protect it.

It seems the polyester whipping twine is a more abrasion resistant weave than the cover of the line. Perhaps the wax helps. So while I will still cover my sewn eyes to protect them from UV and wear, I far less concerned than I was. I also need to rethink Dyneema twine; For reasons of stretch,  polyester will remain the choice for nylon webbing and line, but for polyester and Deneema line... I need to do a little more testing. Polyester makes slightly stronger constructions, but perhaps not in the long run. The jury is out. 

Conclusion: polyester twine was basically as durable as the line, and the Dyneema considerably more so. Interesting.

Saturday, March 22, 2014

Want Your Ropes to Wear Like Iron? Maxijacket!

I investigated this product primarily on a whim. A magazine editor had asked about it in passing, and someone had given me a sample of a related product, Spinlock RP25. I didn't expect a whole lot from some liquid coating, or at least not the results I would get from some physical covering. And I was dead wrong.

Both were sawed on the grindstone for 4 minutes: Spinlock RP25 on the top and Maxijacket on the bottom. As a baseline, bare rope looked like the RP25 in 2 minutes.
The Spinlock RP25 does have its applications too. It performs better on HMPE ropes (Amseel et. al.), reducing both wear and cover/core slippage, and has the flexibility to use on running sections of rope. I'l use RP25 on section of my Amsteel lifelines.

Who would think a simple coating could out-last plain rope by 6-8 times? Who would think it could out-last clear vinyl tubing by 10 times? Where the grindstone could cut a rope in half in 5 minutes, with Maxijacket it is barely scuffed.

Applications? I'm testing many things, mostly applications where traditional chafing gear doesn't fit. Defender marine is dipping all of the chain-to-rope splices, and Brian Toss tells me he's dipping most halyard splices.

Mooring lines, with and without coating. I tried chafe gear, but it kept creeping off. This is easier to clip and extends the life of the wear section to match the rest of the line.

Topping lift. Abrasion was the problem, so I used some webbing as a thimble and dipped the whole knot. This allows me to down-size from 3/8" to 5/16", saving some windage.

Just too good not to share. It seems impossible that a product resembling thick latex varnish (you can get clear and colors) can make such a a difference. While West Marine charges more than you want for more than you need, Knot and Rope sell a small jar--probably all a sailor needs for a few years-- for $7.10. A bargain.


 It seems my marine science project business has gotten completely out-of-control, with no less than 9 projects underway plus follow-ups. Clear vinyl, glycols and coolants, rope, vapor filters. Then there are possible investigations into heater efficiency and operation. Crazy... and fun.

Sunday, March 16, 2014

Wire Cable vs. Stanchions

I've been investigating chafe protection and Amsteel as it relates to lifeline replacement. Certainly, wire cable is the gold standard. But now I'm not so sure....

After an hour of sawing back-and-forth through a 10mm hole in SS tubing, it had eaten a nice grove and built a corresponding burr on the inside:

After 1 hour.

And though the wire did not look very worn, when we flexed just a bit there was a different story....

Also 1 hour. The damage was not apparent until flexed. Most of the broken wires were inside.

How did Amsteel fare, in the same hole? Before the wire created the burr? Much better with very little wear in an hour. Afterwards, no as well, but still the damage was little more serious than that to the stainless cable. Given that I plan to use 1/4 Amsteel, which is nearly twice as strong as the cable to start with, I'm feeling OK. 1/4-inch it is sufficiently strong that even after 10 years in the Chesapeake sun (not so strong as the desert southwest or tropics) it should have equivalent strength, and with proper chafe guards, the strength loss in the holes should be less than wire. Protected from the son, the pass-troughs may be the strongest part by then.

How does Amsteel like the new hole? Not so bad as you might think and about the same as it like the raw hole, just after I drilled it without deburring. By way of comparison, after the hole was deburred it showed ~ 1/3 this much wear, and if coated with Spinlock RP25, no wear after 2 hours (840 cycles).

After 1 hour on the wire cable gouged hole. About the same as a raw drilled hole, yet much worse than a polished hole.

Alternatively, I tried a dyneema anti-chafe sleeve floating for 3 hours. It could have run for 100 hours without showing wear.

A floating dyneema cover reduces wear to zero.

By way of comparison, this hole wore a polyester line through the cover in 20 seconds and in half in 5 minutes. Amsteel is tough stuff.

Saturday, February 15, 2014

Rope Abrasion--The Chafe Machine Starts Its Work

Learning how to sew strong splices leads to a secondary question: how the protect them from UV and chafe. Measuring UV protections will take time; I have a bunch of sample splices in the sun and on the boat, where they will remain for 2-4 years. Yes, I could accelerate UV with lamps, but I'm not confident that it would be the same as the combined effect of rain, oxygen, sun and time. Investigation of chafe protection is more amenable to accelerated testing; just don't give it any rest!

The Machine

I modified a wood lathe to provide a torture test that produces results similar to what you might see on a dock line over 2-4 years. No melting or cutting, just fine fraying.
  • Oscillating motion, 3/4-inch in amplitude and 7 cycles per second. Peak speed about 1.4 feet/second, average speed about 0.9 ft/second. A little faster than docklines, but slower than other on-boat flutters.
  • Variable pressure and angle. These must be moderated to control heating; we don't want to measure melting point.
  • Variable surfaces. Pine end grain seems like a good choice at this time, though I will try other things. I do know, for example, that the pivot end of the rig (polished steel) causes almost zero chafe, since some of the samples ran for hours, while testing different sections.
  • Today's tests are on very lightly used 1/4-inch polyester double braid (it was a fuzzy-finish line to start with). I'll be testing other things as well. I will probably focus on new 1/4-inch Sta-set and new 1/4-inch Amsteel.
My docklines cycle on a period of about 1/minute, but zero perhaps 30% of the time. That makes for about 350,000 cycles per year. The machine cycles about 25,000 per hour, but without bending around a sharp wooden edge. While there can be no true equivalence, because every situation is so different, the untreated wear patterns look like the fuzz I get a few places in a year or so without proper chafe guards, so at least the mechanism is fair and comparisons are possible.  
The Results--Coatings

There are several rope-specific coatings on the market (Spinlock's RP25 and Yales Maxijacket) claiming, among other things, to reduce line abrasion. RP25 is solvent based and soaks in, while Maxijacket is water borne and leave more surface coating, though it too soaks in deeply. Both dry over night and both stiffen the line to some extent, though Maxijacket is more severe. Thus, RP25 would be a better choice for running sections (jammers, blocks, winches), while Maxijacket is very suitable for protecting sections that won't need to flex much (splices, docklines and standing parts).

Maxijacket top, RP25 bottom. Both are far stiffer untreated line. The assertion these coatings don't interfere with splicing seems off-base. I would dunk them after splicing, which is what the riggers do.

Wear testing confirms what they claim; that these coating reduce wear by 25-50%, depending on surfaces and pressure. I need a lot more testing before I would say which I like better; each has its pluses and minuses. It is interesting that both quickly wear off the surface but yet somehow still reduce wear at deeper levels.

Top to bottom: No treatment, Spinlock RP25, Yale Maxijacket. Normal fraying on the untreated sample, and significant protection on the treated samples. 10 minutes of torture over a wooden edge, at 30 degree bend with a few ounces of pressure.

Same thing, side view. material is not so much worn away as the lines are flattened out.

The Results--Coverings

I have only looked at 2 things at this point: tubular nylon webbing and PE airline tubing.

Covering moving over the wood. Same conditions, same 10 minutes.
  • The nylon webbing wore about the same as the rope. The rope inside was perfect.
  • The PE tubing was unaffected. The rope inside was perfect.
Covering fixed to the wood, line moving inside. Same conditions, same 10 minutes. But this time the results are reversed!
  • The nylon webbing gets a slight crease but no wear, and the line is very slightly pollished.
  • The PE tubing signifigantly frays the line, with bits of dust collecting at the ends. Not as worn as unprotected rope (about 20%).

The webbing is unchanged, while the tubing takes a toll on the line.

It seems clear that in cases where the dockline will slide back-and-forth on the dock, hose makes sense and it must be fixed to the line. The hose should be long enough that there is no bend or pressure at the tubing end. On the other hand, at the chock end where the dockline will move in-and-out, webbing that floats and is attached to the chock is a better choice. In my experience, it will last 10 years in this application, until it sun-rots and the whole line is done.

As for the coatings, there are places my docklines rub where a covering won't work; I'll be trying a coating. I'm also testing Maxijacket on my bridle apex splice (it lies on the bottom sometimes) and some sewn splices. Defender uses Maxijacket on chain-to-ropes splices, though only the first few inches (stiffening the taper would be bad). Coatings can shine places where a covering won't fit. Does the same pattern apply to Dyneema? I doubt it, so I'll be testing.

One size does not fit all. Lots to think about.

Friday, February 7, 2014

Curring Oven

Numerous times I have post-cured epoxy projects or hurried alone some small painted object by placing it in the kitchen oven set to "warm." The object would be dry already, but probably not so well cured as I would like by the weekend, and a few hours at 150F can work wonders, reducing chipping on new paint and bringing epoxy to full strength. It always causes a little disruption to havea project in the oven.

Another common problem, at least for northern sailors, is to get polyurethane adhesives and caulks to cure in the winter. Even if we take them inside where it's warm, they just don't cure. The problems is that polyurethanes require moisture to cure, just as epoxy requires a "part b," and a heated home is desert dry, the RH typically below 40%.

When I started to repair the exploded hiking boots with polyurethane adhesive, particularly because of the thick application. I knew I would need a very warm humid cure. Because om my work with mold and mildew for Practical Sailor, the solution was obvious.

A heating pad on medium seemed about right, but it has 3 settings. Generally it is better to have a gel cure before going in; the higher temperatures can make paint and epoxy sag.

If humidity is required, add a damp towel.

Bingo. By adding humidity, sealants like 3M 5200 can be pushed in 12-36 hours instead of a week or more. If dry curing is the goal, skip the damp towel. In the photo I had polyurethane coated some straps, but only in the center for wear resistance; by trapping them in the lid they don't touch anything and were cured in the morning.

If some things are so bloody obvious, why does it take us so long to figure them out?

Tuesday, February 4, 2014

The Weakest Link

I've been breaking dozens--no, over 100--sewing samples as part of an up-coming article, trying to quantify what I know and explore every common variation. Ebbing and rope. New and old. Thread sizes and stitch patterns. Thread types. And this latter is the tid bit for today.

Dyneema thread simply does you not good. It is stronger than the substrate, dose not match its stretch characteristics, and much of time fails at lower strength. Same with Spectra, same with Kevlar.

This sample, sewn with 95-pound Kevlar thread failed at 1660 pounds, with a stitching pattern that routinely held 1950 pounds when sewn with 43-pound polyester thread. While the polyester sewn samples  generally show some evidence of webbing damage, perhaps 10-15% of the stitches, when sewn with high strength thread they simply cut through. The same thing happens when I go to 90-pound polyester thread; lower strength and complete failure of the webbing... but oddly, not webbing breakage, which I can get with improved patterns and 40-pound thread.

Interesting. Clearly there is no reason to go > 40-pound test when sewing webbing. At the same time, lighter is not better, as it can be difficult to crowd in enough stitches with 20 pound thread, by hand that is.

Neither of these are much stronger than a water knot. By running the stitching a few more rows and crowding more in the first row, we can get to 2000 pounds. Want to get to 100% webbing strength? The join will need to be reinforced with another layer. But we've covered that.

Saturday, February 1, 2014

A Stronger Way to Sew Webbing

Credit goes to 1950s research by the Air Force, trying to make a better parachute.

The secret is the overlap, which spreads the force.

In three trials, the webbing failed every time.

100%, 108%, 103% of manufacture breaking strength. Granted, this batch was probably above the stated minimum. Still, I consider this to be a perfectly reliable join. Another investigator (current) working with sewing machines uncovered the idea and got the same result; 100% efficiency joins.

There are about 24 full stitches of doubled 40-pound test whipping twine (96 strands), giving a 62% stitching efficiency; probably more than were needed, and I would add even more to a project to insure durability. But you get the idea.

Do NOT use high strength thread (Dyneema, Spectra, Kevlar)--they will only weaken the project, lacking sufficient give.