Sunday, May 26, 2024

Chain  doesn't stretch (enough to matter in the math), but if enough is deployed and depending on the wind strength, the catenary formed by gravity absorbs energy. Nylon can stretch a great deal, according to the weave, about 7% at 12% of breaking strength, its practical fatigue limit when wet. (AKA working load limit, or WLL)

Polyester stretches less, only about 3% at 12% of breaking strength, but its fatigue limit is much higher, so it is safe to work at higher load factors. In fact, the 5% stretch of polyester at its WLL of 20% compares very favorably to to nylon's 7% at its WLL.

The chafe resistant of polyester is about 2-3 times that of nylon. Not load related, but important.

8-strand polyester is not listed in this graphic, but if you compare DB nylon and polyester, and compare 8-braid nylon with DB nylon, you get the same picture.

Next, consider that an all-nylon rode may actually stretch too much, increasing yawing and thus increasing rode tension. I studied this for Practical Sailor and came to t he conclusion that somewhere between 60 and 100 feet of nylon snubber resulted in the lowest loads, and that beyond that, the load increased with longer snubbers. The conclusion seemed to be that nylon is too stretchy beyond some length.

One solution is oversized nylon. That is what I did for my F-24; the required anchor line is only 3/8-inch, but 1/2-inch is easier to haul by hand and reduces stretch. But not a good answer for larger boats or if a windlass is used.

Another solution is a polyester rode. Popular in England, as long as there is a good length of chain, it works. What is a good length? Optimally, at least 100 feet. Steve Dashew was a proponent of polyester rode after several hundred feet of chain. 

Finally, remember that combination rodes with 15-50 feet of chain rely on the rope portion to absorb energy. The corollary is that there must be enough nylon to dissipate the energy, and rodes have failed when there was only 5-10 feet of rope out. That means about 25 feet minimum with nylon, and probably about 50 feet with polyester. 

The forces on the anchor and deck fittings will be slightly higher with polyester rode. The risk of chafe and fatigue failure will be less.

I need to look into this further. Polyester has many merits, but perhaps it is less idiot proof, particularly in shallow water.

Thursday, May 23, 2024


The problem with most paint mixers is that they are a pain to clean. Use them a few times, and they are so clogged up with a thick layer of paint that they lose their hydrodynamic shape.  The one of the left was used maybe twice, the one right many dozens of times. The difference is that I can wipe it right off. The flat plate design can loosen the thickest solids without clogging.

You really can't buy the sort on the right. Most of mine were lab mixers. I have dozen and will leave them to my children. A few, for special sizes, I made by welding a rectangle to a length of rod. If you can't weld, I'm sure the plate could be soldered to the side of a flattened rod.

Saturday, April 20, 2024

Borax: Formula B, Stopping Mildew Cheaply and Effectivly, and How the EPA Can Make Everything Complicated

rev. 4-20-2014, rev. 4-9-2024

This 10-year old blog post describes some work I did on mildew prevention 10 years ago. I took it down because I published a few articles on the topic, but here it is again. I'll post a follow-up in a few weeks with some other stuff I've learned.

Websters' version

Borax: 1. a white crystalline compound that consists of a hydrated sodium borate Na2B4O7·10H2O, that occurs as a mineral or is prepared from other minerals, and that is used especially as a flux, cleansing agent, and water softener, as a preservative, and as a fireproofing agent.

EPA's Version

Borax: pesticide products containing boric acid and its sodium salts (borax) are registered in the U.S. for use as insecticides, fungicides and herbicides. As insecticides, some act as stomach poisons in ants, cockroaches, silverfish and termites, while others abrade the exoskeletons of insects. As herbicides, some cause desiccation or interrupt photosynthesis in plants, while others suppress algae in swimming pools and sewage systems. As fungicides, several are wood preservatives which control decay-producing fungi in lumber and timber products.

While generally considered safe--still used in many big-name laundry detergents--if I claim a cleaning formulation containing borax keeps mildew away, I have to register it with the EPA before marketing. But I can sell you a box of borax without registration. Go figure. Is it really about safety? I don't think so. Borax is only about twice as toxic as washing soda (LD50 borax and boric acid are about 2500 mg/kg BM. Although borax is suspected in certain reproductive problems in laboratory animal testing, it is not associated with cancer and does not bio-accumulate.).

It seems that anything that works must be poison, or at least regulated. That is governments purpose.

As part of a future Practical Sailor article I began exploring fumigating agents and anti-mildew products. I truth, most projects I take on are because I've had some troubles related to the subject in question and thus have some understanding and some additional motivation. Every boat has at least one damp spot prone to mildew, and in my case, I have a basement prone to wet carpets every few years. Not flooding, but mildew potential.

I began exploring the formulations of some successful products. Concrobium is one, dreadfully over priced at the local hardware, particularly considering you can look up the underlying patents (EP 1104450 B1) and learn that each quart bottle ($18.00) contains nothing but:
  • 1 tbs baking soda (sodium bicarbonate)
  • 2 tbs washing soda (sodium carbonate)
  • 2 tbs TSP (trisodium phosphate)
Simple and effective. The chemistry makes perfect sense; it is applied without rinsing and thus leaves behind a thin alkiline coating that repells bacterial and fungal growth (fungi require acid conditions) and provides no food for growth (soaps contain fatty acids and make great fungi food). More is not better because it is used without rinsing, the limitied concentration is important.

That got me thinking, so I began trying other variations including my favorite, also in 1 quart:
  • 2 tbs baking soda
  • 2 tbs borax
  • 1 tbs TSP
I've been testing all three on some mildewed carpet sections, cleaning by scrubbing lightly and then extracting with a vacuum. Which is best? After 6 months they are both perfect, although the borax version killed the smell a bit faster.


Other Applications

Basement Carpets and Walls. We've had problems with a wet basement and biannual flooding for 20 years. I've washed and dried a lot of carpets. Learning to use this formulation as the rinse was a revelation. No more mildew smell, no more mad rush to get them dry. No more black stains. Simply use this as the rinse water and the carpets stay fresh.

Preventing Wood Rot
Borax is VERY effective in preventing wood rot. I've used it myself mixed with ethylene glycol (Goolge it) to preserve a common pine totem pole in damp soil and remain impressed; it's staying as though it were pressure treated, 6 years and counting. West Systems Epoxy has posted on this subject. The National Park Service posted this on preserving totem poles in the PNW with borate/glycol.

Obviously, they can't stand boric acid. One of the most common extermination products, particularly around kitchens and bedrooms (works on mattresses). It's not going to work on the flying pests, though, the only ones I have trouble with. Darn.

Wooden Decks
Seems like a good cleaning choice. Should help keep the algae away. Limit the TSP if you wish to be bay-friendly. Try it on your home deck for a little boost to the pressure treatment.
Combine it with some bleach as needed.
A less alkaline variation is well known and should keep the mildew away. Reduce the dose:
  • 1 tsp baking soda
  • 1 tsp borax
Oh, the power of good marketing. I swear I'm not just trying to be trying to be cheap. Furthermore, I'm a chemical engineer and have no phobia regarding synthetic chemicals. I'm not pushing this because of some hidden green agenda or because it is less toxic. The strength of these formulations is basic:
  • No organic mildew food
  • Mildly alkaline film
  • Borate as mildewstat
I'm also reviewing some nice complex organic formulations that promise better water resistance. We'll see.

Correction. The Series Drogue has Flaws as a Steering and Speed Limiting Drogue.

I did a little testing of a shortened JSD and some other drogues over the weekend (8 years ago--publication was delayed due to agreement with Good Old Boat Magazine). It seems that the notion of a short JSD as a steering or speed limiting drogue is a failure. I have corrected that post.

It seems there are four fatal flaws:
  1. The characteristic JSD "droop" does not occur at high speed. It is not a design characteristic, just a low speed characteristic. At higher speed (6 -7 knots) a JSD runs along the surface.
  2. Cones are inefficient shapes. The Seabrake or Shark are about 50% more form efficient.
  3. Cones are more unstable near the surface.
  4. Small drogues are less stable near the surface.
  5. The cones are too close together.

 The result of these factors is that a good drogue design (Galerider, Seabrake, Fiorentino Shark) is more stable and far easier to use than a series drogue for emergency steering and speed reduction.

A real survival storm? I still think that drogues in tandem, well-spaced, have a lot of merits, right up there with the JSD. For more discussion and data, read either "Faster Cruising for the Coastal Sailor" or an up-coming Practical Sailor article (though it will surely by hacked to size). A tandem drogue is easier to manage than a JSD, gives more options, provides the same drag (braking power), and runs just as deep.

 [Note. The secondary rode is NOT attached to the primary drogue, it is attached to the primary rode. It passes through the center. The drogues can be of other types--the illustration simply shows the pair I use. The Fiorentino Small Shark is excellent. The Delta Drogue is also good, although it is a bit less stable when near the surface.]

Monday, April 15, 2024

Broken Boat Hook = Outboard Tiller Extention

The first time I tried this trick it was on a Nissan 18 hp on my Stiletto 27. This time for a Merc 3.5 on my tender. And it's made from something every body has or can find leaning next to the dumpster. A broken boat hook.

The raw material was a Garelick pole that was intentionally destroyed during destructive testing for a magazine article. The only tool was a hack saw. Pretty basic.

The tiller extension did NOT cause that scratch. Just a weird coincidence. I like to have it just long enough that I can reach it behind my back if sitting on the seat facing forward. If it came up beside me it would limit my ability to turn.

Although technically "rod holders," more often these PVC tubes are used to keep other things, like paddles and this extension, out from under foot. 

The nice thing about free is not just that it saves money. A few months ago I dropped the prior extension (also from a salvaged boat hook) overboard; knowing it cost nothing made it less stressful. I just had to wait to a fractured pole to show up at my doorstep.

Saturday, April 13, 2024

Batteries and Water Quality

What do the battery makers think about water quality?  They are pretty particular:

What difference does it make? This is what Trojan thinks:

How does yours stack up?

 And so now you know. I use either kitchen RO or dehumidifier water. 
Interestingly, the spec for engine coolant is just as strict as for batteries. Even the smallest trace of seawater leakage can be very bad for separate circuit engines, which is why there is no such thing as long life antifreeze in marine applications. Too much risk of seawater contamination from leaks.

Monday, April 8, 2024

Where Would You Attach the Tripping Line?

I have only used a tripping line during testing as an aid to locating anchors for placement and diving inspection. However, I observed the following while investigating tandem anchors for rocky locations.

There is the traditional location. Nearly every anchor has a hole high on the crown, though honestly, I think it is only useful for lashing. It certainly is not going to release this chain anytime soon.

 On the other hand, if we move the tripping eye to either the bottom of the shank or the back of the foot, we can actual l pull in the right direction.

granted, the Claw is the worst case. But still this seems, well, obvious. And I'm not the only one to notice. Rocna added a tripping eye to the back of the fluke years ago.
Likewise, I've been using a hole on the back of the fluke of my Manson Supreme for both tandem rode and tripping.

 I'm setting recovering a tandem anchor rig. The carabiner in my hand holds the trip line to the secondary anchor, which I will now use to recover it and bring it on-deck. This is a rocky location, so it's very likely hooked under something.


Does drilling a hole weaken the anchor or cause corrosion?

  • Weaken. Obviously this depends on the location. In the shank, maybe, although the area near the fluke is never a failure area. In my case, drilling through a thick, non-structural area of the fluke, no risk. In fact, the fluke would probably have been thinner there if it would not add cost an complexity to splice the thinner plate.
  • Corrosion. Not really. The near by coating seems to be protecting it just fine. And normally I would have a galvanized shackle in there, which helps too.

Saturday, April 6, 2024

A Slow Leak

11-12-2019 (see 2024 update below)

 What do you do when the boat develops a 1-2 gallon per day leak, where you can't get to it, and it isn't time to haul for a year? The F-24 is a trimaran and cannot sink due to main hull flooding. Add that there is nothing other than fiberglass below the probably flooding limit (no wood and no wiring to speak of). Most people would just let the sump pump handle it. Except there is not sump pump.

As an added complication, the sump is only 3/4-inch deep before it reaches the level of the floor. On the other hand, the floor is a bath tub-like hull liner that unless holed, can easily manage 6 inches of flooding.

First, you plug any holes you can reach with underwater cure epoxy. No kidding, the stuff really does work, and I'll be doing a review for Practical Sailor soon. 

I used JB Waterweld. Scrub the area clean, but it does not need to be dry. Wet you hands. Sounds funny, but do this or it will stick to you more than the boat, which doesn't work. Cut off as much as you need and mix by kneading. rolling between your palms and folding can also work. Then press it into the hole with your fingers, with special attention to rubbing down the edges. This takes a few minutes of steady, gentle rubbing. You have to move the water out of the bond area. But within a few minutes it will be sticking well everywhere you rubbed. Keep rubbing it down for a few more minutes, until you can feel it begin to firm, which takes about 10 minutes. It will be hard within an hour.

It is not as strong as conventional epoxy, but it is strong enough for the purpose and may be permanent. 

Unlike conventional epoxies, it does not generate a run-away thermal reaction and over heat. Underwater there is cooling, of course, but even in the air it will not seriously exothermic. In fact, I know often use Splash Zone for certain filling applications, for example around through bolts, because it tolerates moisture in the laminate, because it does not exotherm, and because the cure is also relativly quick.

Then you add a sump pump. I went with something smaller than the standard Rule pumps, because I wanted to such lower and because rate was not that important to me. This one will remove about 2 gpm through a 1/2-inch ID hose, which is what I had in mind. I mounted it to an aluminum bridge, which I bonded to the hull with ... underwater epoxy.

I played with micro switches that would activate the pump at lower water levels than the standard 2-inch on, 3/4-inch off settings, but found them unreliable. So I went with a rule switch which I mounted with ... underwater epoxy.

I then added a sub-panel. I had some other lighting circuits that needed straightened out too.  A piece of Coosa Board, a terminal block, and a bunch of crimps did the job. The water hose was relocated later. The hose ties into the sink drain with a through-tee, so no added through hulls. This also gave me a chance to clean up the hose runs so that there are no low spots that can freeze; all of the water drains either to the sump or overboard.

The timer is the neat twist. I wanted the pump to have a chance to keep up with small leaks, before the water reached 2 inches, so I set the timer to trigger the pump for 1 minute every 24 hours, but I can adjust that if the level rises.

 And so far (4 weeks) this seems to be working nicely. I did jump last time I was sailing and the sump pump came on. Surely, I have a leak! But it was simply the scheduled 1-minute run time.


Coosa Board Bluewater 26 is a fiber reinforced (several layers of woven cloth, just below the top and bottom surfaces) polyurethane foam that is lighter than plywood and will not rot, but not quite as strong. It sort of holds screws, but not like wood. It is MUCH stronger than non-reinforced foam, nearly as strong as plywood. It is normally laminated with fiberglass for structural use, but not always. It's really neat for fabricating small parts that need some strength and which you will glass over. Little flanges. Shelves. Braces.


Five years later and still holding. In fact, I did a bunch of tests for PS. The winners were Splash Zone from Pettit (strongest) and JB Waterweld (fastest plugging). The Waterweld is still holding, in part because we could never find the source of the leak from the outside. Amazing stuff, I will always keep a package handy in the future.

The pump and timer are doing fine. With only minute of run time per day there is little wear. It will move more water, however, when I clean the bilge, for example.

Wednesday, April 3, 2024

Chafe. Which Nylon Rope Weave Last Longest

I’ve suggested climbing ropes for a number of uses around the boat, including tethers, traveler control lines and snubbers. Some folks misunderstood, believing I was suggesting that climbing rope is globally better, and some misinterpret climbing test results, conjuring up negatives that don’t actually exist (climbing ropes are sacrificial, some how crumpling to absorb impact). Time to set a few myths straight.
Climbing rope is among the highest quality products out there. Logically, there is no market for anything less, since your life, very literally, hangs by a thread. But that does not mean it is better in all ways. In fact, the base material is no different than good quality marine rope, it's just woven differently.
The Cover. Or mantle, as it is called by climbers, is woven more tightly than double braid because this makes it less snag prone on rock. This also makes it more abrasion resistant against rock, coral and rough materials, because strands do not snag and cut. However, this does not make it wear longer through a chock. Double braid carries 50% of its material and strength in the core and 50% in the cover. This provides balance in spliced eyes. Climbing rope, on the other hand, typically places only 28-35% of the material in the cover, saving space for more core, which is what absorbs impact. Additionally, the tight cover makes dynamic climbing rope practically impossible to splice. You can’t open it enough to milk the core out, and if you do, you have no chance of burying it back in the main line far enough to make a strong splice. The core and cover are not balanced. Climbers don’t care, because a splice would only snag in a crack when they pulled the rope up. They use knots. And coincidentally, the core design is less sensitive to strength loss in knots, because the floating yarns do not feel the short radius. They are also less prone to fatigue, because there is less yarn-against-yarn friction. Climbing ropes are sometimes supplied with sewn eyes in the end; this should be only be done by companies familiar with sewing climbing rope and fall protection assemblies.
Core. Instead of braid or lay, the core consists of free floating yarns. Half are twisted in the conventional direction (s-twist) and half in the opposite direction (z-twist).  Unlike laid rope, this make the line non-rotational under load; you hang on a 3-strand rope, the lay will straighten a little and you will spin. Darn inconvenient for the climber and prone to hockling or twisting in tackles. This free floating construction also maximizes stretch and reduces the tendency to cut if stressed hard in a fall over an edge. This latter characteristic is vital to climbers, since in the real world, climbing ropes only fail over sharp edges.
UV. Climbing ropes are somewhat more vulnerable because the mantle (cover) is thinner. However, climbers retire ropes after relativly few (compared to sailors) hours in the sun, so this is not a big issue. It often looks worse than it is, because climbing ropes are dyed bright colors for visibility and fading is obvious.
Fatigue. There is an annoying myth that somehow climbing ropes have poor fatigue resistance because they fail within 5-12 drop tests. The folk leaping to this incorrect conclusion assume they are somehow sacrificial, because that feels like common sense to them, but this is without any basis in fact. The truth is exactly the opposite. First, only climbing ropes can pass the drop test. All other weaves and rope types fail in less than the minimum number of cycles, or if strong enough, result in an impact force that would either tear anchors loose from the cliff or injure the climber. Second, the drop test, which is sudden, severe, and intentionally takes place across a sharp edge, has no relevance to actual use within the allowable working load. In fact, the free floating yarns naturally experience less yarn-to-yarn chafe and withstand fatigue much better than other weaves. Obvious, really. The fatigue life of climbing ropes is several times better than other nylon weaves and comparable to polyester double braid, but with more stretch (wind farm research into mooring lines).

So how do they stack up? Among nylon rope constructions, which should you chose?
[The images are of tests performed by swinging a heavily weighted rope pendulum so that it dragged across a cinder block, simulating rocks, coral, and concrete docks.] 
Double Braid
  • Good flexibility.
  • Fair knotting.
  • Medium grip.
  • Moderate splicing difficulty.
  • Medium to poor chafe resistance .
  • Less stretch .
  • Poor fatigue resistance.

Economy, good hand, medium chafe resistance, economy, and reasonable splicability makes it is popular for docklines and smaller anchor lines. 3-strand is a better choice for docklines if chafe is a serious problem. 3-strand or brait is preferred for larger dock lines. The same loose braid that makes splicing easy makes it prone to snagging on rough surfaces, increasing chafe in some cases. Not a great choice for anchor rope, since combination windlasses can’t grab it, it is hard to store, chafe resistance is limited, and so is stretch. OK for traveler control lines.

Plaited rope
  • Better flexibility.
  • Good knotting.
  • Better grip.
  • Easy to splice.
  • Poor chafe resistant.
  • More stretch.
  • Better fatigue resistance.

The primary advantages are ease of splicing, compact storage (it is very limp), and increased stretch. However, the loose weave reduces chafe resistance because it can snag very easily on rocks. The only thing I like it for is big docklines. Some favor it for anchor lines, but they haven’t looked at the chafe test results.

  • Less flexibility.
  • Better grip.
  • Poor knotting.
  • Easy to splice.
  • Good chafe resistance.
  • More stretch.
  • Better fatigue resistance.
Good grip, chafe resistance, ease of splicing, and stretch make it the top choice for anchor lines and docklines in tough locations. Also excellent for anchor snubbers, particularly if chafe is an issue. If you need more stretch, make the snubber a little longer, up to about 40 feet.
Dynamic Climbing Rope
  • Good flexibility.
  • Best knotting.
  • Less grip.
  • Very difficult to splice. Use knots or professional sewing.
  • Moderate to good chafe resistant. About equal to polyester double braid but not quite as good as 3-strand..
  • Most stretch.
  • Best fatigue resistance.
In spite of having a lighter cover, climbing rope is very chafe resistant, This is because, like webbing, the tight cover resists snagging. Instead, it fuzzes, resisting wear.

Limited grip and chafe resistance limit the usefulness of climbing rope as anchor rode to boats less than 27 feet long, where it excels. However, it is a top choice for traveler control lines because it wears well, runs well through blocks, will not tangle, is comfortable in the hand and has superior stretch (eyes are sewn--DIY is acceptable because the load is low). If you need extra long tethers (a multihull thing) it is just the thing, but you will either have to knot the ends or have them professionally sewn (not a sail maker, but an arborist gear company—it’s a specialty). Use 8mm for this; larger climbing ropes roll underfoot too much. .Finally, dynamic climbing rope is only available as twin (6-7mm), half (7-8mm) and single (9-11mm).
Conclusions. Unsurprisingly, the best product depends on the application. I like 3-strand for anchor rope and snubbers, double braid for docklines, plaited rope for big dock lines, and climbing rope for long tethers, travelers, and snubbers. Horses for courses.