Can't Splice Old Line? Try a Sewn Eye.

rev. 10-27-2013, rev. 8-1-2024

Splicing is the gold standard for forming permanent eyes and joining lines; unfortunately used double braid generally lacks the flexibility required for splicing; the cover won't open and the core won't slide. Knots are a standard solution and work in most cases; yes, there is some loss in strength, but lines generally die from chafe and I can't remember having one fail at the knot, other than in testing. But sometimes there simply isn't enough space or a knot will snag.

Seizing is traditional and just as reliable as ever. I've seized a dozens of eyes over the years and never had a failure. I helps if you cover them for UV and chafe protection, but if the seizing is double layer like the old days, the outside layer is the UV protection and the inside layer holds the load. But seizings are long and stiff and can hang up, since the tail is neither covered nor tapered. So occasionally I use a hybrid sewn/seized eye. This isn't an idea I dreamed up, it is an old one that I read of many years ago in the New Glenans Sailing Manual. They also speak of stropes, the precursor to soft shackles.
  ____________________________________

First I remove about 1 1/2 rope diameters of core. This will allowed the end to be stitched down to create smooth taper. The New Glenans Sailing Manual calls for 3 1/2 to 4 rope diameters of core and I've got 4 1/2 diameters without counting the taper.

How much stitching is enough? Select a whipping twine that is 10-15% of the line diameter; for example, 7/16-inch line is about 11mm, so #10 whipping twine is a good match.  In this case I used 90-pound Kevlar this time, just because I had it and because it is about the same strength as #10 twine. Doubled that suggests about 12 round stitches on each side to reach 5000 pounds. Sure, it is not loaded in-line, but most of the load (about 35-55% in testing, depending on the roughness of the line) is actually carried by line-to-line friction, just as in a seizing. Also remember that due to friction of the eye around the shackle or fitting, the free end is only carrying about 25-35% of the load, depending on line stiffness. The results is that the stitching is only carrying a working load of about 1000*0.30*(1-0.45)=165 pounds and a line failure load of about 825 pounds (assuming 5000 pounds for aged 1/2" Staset); not nearly as demanding as you would guess and as usual, the splice is stronger than the line. The stitching is scattered so that some are in every part of the core.

Whipping Twine Summary

Twine Number        Diameter       Strength

#4                            0.4 mm         35 pounds

#8                            0.8 mm         70 pounds

#10                          1.0 mm         90 pounds

#15                          1.5 mm         130 pounds

(In retrospect Kevlar may be a  poor choice, given its poor performance in flexing applications. Although the stitching does not flex, more polyester twine might be more reliable.)

After stitching I add 2 seizings for good measure. The throat seizing is the important one, as it keeps the first row of stitches from getting over loaded.
(Skip the seizings; they add nothing and become loose as the line shrinks under load.)

(Crowd as much stitching into the first inch of the tail as possible if working with nylon; the nylon stretches so much under load that only the first inch carries any real load. Think about playing tug of war with a bungee cord. A double pass, center and edge, can be a good way to do this.)

Then cover it with something for UV and chafe protection. Heat shrink is fast and poor choice (doesn't last). Webbing is better in severe applications... like winching a sheet along a shroud.

The New Glenans Sailing Manual only calls for 3 1/2 to 4 rope diameters and I've got 4 1/2 diameters without counting the taper.

8-1-2024. The video demonstrates a slightly different method, called a sailmaker's eye. It is not quite as strong in lines larger than 1/2-inch, but it can be >90% strength in smaller lines and is more abrasion resistant for applications where it can't be covered. The clips were made for a Good Old Boat video.

  (Even though the load is carried in the first 3-4 diameters, pull testing shows that stitching in diameters 5-6 does contribute to splice stability. Just don't count those threads in the calculation; only those in the first 4 diameters.)

(Note: when I discovered the line was Warpspeed, 22,000-pound test, I added another solid layer of whipping. Also good for abrasion.)

Notice the strope in place of a shackle. Less steel to flog, removable, and as strong as the larger line because it is doubled.If the eye is small it can't fall out easily. The failure point is always the same; the loop cuts off the stopper knot.  

After just 2 days I learned that heatshrink is not enough, not when winched across a cable shroud. I also switched to Amsteel soft shackles (home-tied) for a bit more long-term security. That and the they fit the clew better; the yacht braid stropes worked fine and would no doubt last for years, but I really didn't have room for 2; the big knots would jam on each other. The yacht brain

strope would be fine for a single set of sheets.  
  

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 rev. 1-1-6-2014

I'm currently engaged in a much deeper exploration of the subject for an up-coming Practical Sailor article. I've learned more than a few things, a few highlights of which I have added above in RED.

Freshwater Tank -- Are Bugs Swimming the Back Stroke in There?

6-13-2014, rev. 8-1-2024

According to the plumbing code and AYBC, there should be a screen on the freshwater tank vent to exclude mosquitoes, other bugs and reduce dust. But many builders, including PDQ, leave these off.  On the PDQ 32 the vent line simply goes up and then down through a mushroom fitting under the bridge deck. Yup, I've seen bugs in there, so while I was up-grading my water system, I decide to fix this too.

Clean, huh? Though a strainer won't stop bacteria, it will reduce convective airflow.

The solution was to splice in a simple strainer. The code calls for 16 mesh, but no-see-ums are known to crawl through that, and 50 mesh is common anyway. This strainer is large enough to manage any air venting flow and serve as an over-flow too, though when filling fast, water will back out the fill even without the strainer in place.

Shurflo 255-323. Be warned, PDQ used 1/2" hose on 5/8" barbs. I stayed with the 1/2" hose (cleaned out the gook with a 1/4" rope, soaped up and fished back-and-forth a few dozen times--tie knots in the ends while you're scrubbing) and used a little K-Y to get it back on the 5/8" barb after cutting a fresh end. Great stuff for working with hose.

The PDQ is a catamaran and the pressure water system is located on the bridge deck, between the hulls. Thus, the tank vent actually discharges down, through the floor, about 20 inches above the water line.

A 15 minute fix. No more bugs. Fewer bacteria and mold spores. Mostly self cleaning, every time I over fill the tank, but also easy to clean and easily accessed. I suppose I should clean the tank one last time, but the new filter is doing great.

 

 Look what we found in the spring! Bugs that crawled in the vent.

 

And look what a dockmate found! A tree frog climbed in, and they had eggs coming out the galley tap! Extra protein?

 

Woodwork: the Finishing Bench and the Sea Chest

10-17-2012, rev. 8-1-2024

 

 Certain objects cry "nautical" from the first glance: A wooden ship's wheel, a brass lantern, wooden shell blocks. Not practical, though, and cliche on a modern boat. There are items we accept as functional and usual: a stitching palm, a life ring with the yacht's name, coach whipping on the wheel or tiller. And then there are half forgotten objects with real utility, in my opinion at least, underutilized.

 The Finishing Bench. Still used by traditional sailmakers, a simple bench holds the implements used for roping, adding a grommet, or mending. I made this one about 5 years ago from nothing but scraps and a little varnish, a very pleasant way to spend a few winter evenings. Mostly it sits by my favorite chair, holding magazines and what ever books I'm reading, but my stitching tools and materials are ever present on the far end. Yes, I catch a pant leg on the bench hooks now and then. But whenever sail work is required I carry it out in the front yard where it serves its traditional purpose very well. Smaller projects get sewn up right in my chair, reaching back for traditional tools and materials that are kept conveniently at hand.

No directions. I just followed an old illustration and fit it to the scraps I had. I suppose they were generally built that way, from bits and pieces.

• Cleats on the underside reinforce the legs.
• Numerous holes and vertical dowels on the cutting block secure spools of thread or hold knives and fids. Some holes only go part way through, holding needles and small things.
• Dowels angled just above horizontal on the cutting block end hold scissors, palms, webbing, thread, and a small ditty bag.
• Bench hooks need to be sharp, and it is handy to have 2 different lengths. These were bent from steel tent skewers.

 

 

That first step is about 30 inches.

Sea Chest. Although my boat has some cavernous lockers under the bunks and salon seating, there are never enough small lockers handy in the staterooms. Additionally, getting into the bunk is rather athletic, as the bunks are high and without steps. Additionally, a seating platform with storage blocks the way to the bunk, and it is at an unfortunately awkward height, far too high for putting on shoes. At first I built stools, but they were really too small and too single purpose. A small sea chest, fit to the space, is the perfect answer.

Though I didn't take any pictures of the construction process, anyone with the carpentry skills to make a box should be able to do just as well.

• Traditionally these were painted a muted color and only the inside of the lid would be decorated and bright. Paint best withstood hard knocks, and the interior decoration reminded the sailor that his chest was the one thing on board that was his. However, my wife liked it varnished--all of the reproduction examples I showed her on-line were varnished--and it works, I think. Perhaps I'll paint it later; if so, going from varnish to paint is more reasonable than the reverse process. Because I originally planned for paint, I made no special effort to hide fasteners; I focused on building it strong enough for regular use as a step. I think I like the utilitarian look.
• Strap hinges are traditional, but a piano hinge fits better, and I had a cut-off. I cut a recess for the hinge so that it closes perfectly, with no need for a chain and with all of the weight transfer directly to the sides.
• Be mindful of protruding hardware. While a few scratches didn't matter on a whaling ship, they do to us. For example, the handles were traditionally attached with exposed rivets, but I substituted counter sunk brass bolts. Same on the inside; nothing to snag on clothes. I smoothed all interior hardware with a Dremel tool.
• Side Relief. A characteristic of sea chests is that the sides lean inwards. The practical reasons for this only became obvious as I measured the intended space: if slammed against a bulkhead (ships move) the lid will still open and the handles are still accessible; they better resist tipping; there is less binding when push into or pulled from a tight space. The trim strip on the bottom also helps; it takes a beating and thus should secured with screws, not brads.
• Rope handles. Mine are boring. Starting with a bit of old 3/4-inch 3-strand line, I placed 2 whippings about 9 inches apart, unlaid both ends for about 3 inches, and pinched the strands between handle blocks and the chest sides (I had drilled 1/2-inch holes with the handle blocks clamped together, making half-round groves for each of the three strands), trimming the excess. Tape held the strands in in the groves while the bolts were tightened. Strong and compact enough to fit the narrow space I had to work with, but not fancy; I lack the marlinspike skills to do a proper job. However, even simple rope handles are strong, comfortable, and non-scratching.
• Square the sides up on a flat floor before screwing them together; you don't want a rocker. Likewise, true the lid to the top; otherwise the hinges will work loose in time. When working with scraps, never presume anything to be square or true.
• No latch. I didn't see the need for my purposes
• Hold down. In the stern of a catamaran the motion is never lively enough for the chest to move, but I can certainly imagine boats and places where this is not true.
• Lid cleats. These not only hold the 2 boards that make the lid together as one, they are also carefully tapered to lock the lid in place when close, transfer lateral forces when used as a step to the sides and away from the hinge. Remove the hinge and the closed lid does not shift, not a fraction of an inch.

 

Something more traditional

Tool Box. There is a window shelf outside the head that is of no particular use. Sometimes we keep shoes there. Because of the hatch, spray is always a possibility, limiting possible uses. Nothing tall that might block the hatch. I reason a light box I can pick up and move will find some purpose and stow some clutter. I like the semi-traditional look, it kind of works on a sailboat that is only semi-traditional; though sailing is by nature nostalgic, multi-hulls have to keep there distance.

A simple scrap lumber project, it is made of 3/4-inch pine and 1/4-inch ply. What will we keep in it? I won't know until we've been cruised with it for a while.

__________________

All from scraps. In the first example, I used a few boards that were left in the basement by the previous homeowner and a bit of left over shelf. The dowel was from a discarded seasonal decoration. In the second example, I salvaged a neighbor's old garage shelves and some line left over from a Practical Sailor testing article--the stuff we found under a dock and cleaned. The brass bolts--16 x #8 x 1 1/2"--were also left overs from a writing project--laboratory corrosion testing of gasoline anti-corrosion additives. I think that is the way these sailor's tools would have been made, from the bits and pieces. The finishing bench was free, the sea chest a $2.45 project (a bit of 1/4-inch plywood for the floor--I wanted something lighter than the scrap I had on hand). The tool box was even cheaper and quicker, though I took my time and finished it neatly and well. Very affordable.

When is Smaller Better?

9-16-2017, rev. 8-1-2024

Human nature--or at least American nature--is to covet and to believe that bigger is always better. But if that were true, I wouldn't get so much enjoyment from my thrice weekly bike rides. My theory with rode vehicles is that fun is inversely proportional to size:

• Skate board or in-line skates. I haven't been on skates in a several years, not since I injured my knee. Maybe it's time. I have several pairs.
• Bicycle. 
• Sporty car
• SUV
• Van
• Winnebago
• Semi-trailer

 Actually, the last two are fun for the first little bit, just for the adventure. Each has certain utility. But if I just want to head out for a few hours of smiles, the bicycle wins, hands down. I even switched from SUV (Subaru Forester) to sporty car (Mazda 3 hatchback) a few years ago, and I'm loving it (and the 43 MPG doesn't hurt either!).


 For the last six years, this aluminum and carbon toy has helped keep me in shape. And it is fun.

Does the same hold true for boats? I think it does, perhaps even more so if we include the difference in maintenance requirements. Big boats are work. And even more than the bicycle-to-RV continuum, small boats teach sailing, while large boats teach systems. Everyone should learn to sail a small boat first.

Not counting a few rentals, my first sailing experience was eight years with a Prindle 16 beach catamaran. When the wind gets up, small, over-canvassed boats are strict teachers regarding sail balance, trim, sea state, and situational awareness. Of course, I couldn't leave well enough alone, and I eventually added hiking racks and a bow sprit for a chute, making her quite the rocket.

I got married, decided to get something just a little more group-friendly, but still lively. The Stiletto 27 is really just a beach cat on steroids, just as fast and only a little more stable. This is not a boat to learn sailing on; capsize is possible, and unlike a beach cat, you can't just flip her back on her feet and laugh it off. She taught me more conservative sailing and introduced me to cruising. Although her accommodation were primate, she took us on some long trips (weeks), germinating the cruising bug. Although she was not as nimble as the beach cat, she was still quick to tack, would motor at 12 knots, and we once hit 23 knots with the chute up. Scary. And fun.

Soon I had real cruising ambitions. A larger boat--my current PDQ--would accommodate the family and some of my daughter's friends on long trips in a reasonable level of comfort, and with a fair turn of speed. Motoring is only 7.5 knots and sustained sailing is generally 7-10 knots (not surfing), but we can maintain those speeds for 10 hours, because she is much less tiring to drive. In fact, her stability is so great she is on autopilot 95% of the time. I measure wind speed by a gauge on the dash and direction by wind vane, not by the wind in my hair. She's comfortable in a near gale in the winter, but now I'm insulated from the actual sailing. And yet in a good blow she does come alive, and 9 knots to windward is not unusual. She can really drive.

But it's not like riding a bike. The intimacy is lost when a boat becomes large enough for cruising. In bad weather we want to be insulated from the elements. We call that comfort and seaworthiness. 

The next boat, just month after writing this, turned out to be a Corsair F-24, which I had coveted since the first came out. It looked like fun. It is. I consider it my daysailer for grownups. Lots of strings to pull, easy enough for one person but easy room for 2-3, fast enough, weatherly and fast to tack, yet stable and seaworthy enough.  I'm going to keep her for a while. I might change the waters rather than my boat if my abilities change.

 

A longer Lasting Joker Valve

11-30-2012, rev. 7-31-2024

Every sailor with a manual head knows that the joker valve is the check valve at the bottom of the head, the one that everything has to pas through, the one that must be changed every 1-2 years, and... the place you will find most clogs.


This time of year folks start talking about winterizing and what they pour in or how they drain out to prevent ice damage. Sometime I hear of things I know are damaging the head, and I just cringe. A resent letter-to-the editor of Practical Sailor got me thinking; we haven't reviewed joker valves and the details.

The Problem: Not all valves do well with chemicals, and few last as long as we'd like.

Don't worry; this will only happen if you use Lysol in the bowl... which a few people do.

 Also, some head treatments contain formaldehyde (stinky blue stuff) and will do the same thing if not well flushed. Ban these from your boat

This Jabsco valve (left) saw only waste and ethylene glycol and lasted 5 years. A valve in this condition actually leaks less than you would expect; although it is gaping, the lips are smooth and the back pressure holds them together. Occasional use of vinegar keeps the lime at bay. The head itself is 16 years old, though I replaced the pump assembly at 13 years (like new now).

First, all common joker valves are dimensionally interchangeable. Yup, Raritan, Jabsco, and Groco all use the same basic dimensions. However, they differ in some molding details and use different rubber compounds. The correlation, of course, is that their chemical vulnerabilities are different and that no single chemical compatibility list will cover all heads. Some are not compatible with vegetable oil, while some are. Some are not even compatible with propylene glycol, though the PG manufacturers would tell you their product is safe for everything.

Propylene glycol can be rough on other parts as well. While PVC and polyethylene do very well, my clear potable water strainer crazed in just 2 winters. Though they were good about replacing it, I just leave it off in the winter now.

Testing: So I lined up bottles in the lab, filled with common joker valves and common chemical concoctions. After 3 months I measured stiffness and leak resistance. And guess what; some were more compatible with winterizing chemicals than others. Some were more resistant to urine than others.

 Then I donated a bunch of valves to friends, both live-aboards and weekend sailors. I waited to hear which valves failed first, and which lasted for years.

Head Manufacturer    Material        Urine Compatibility      Durability (years)   Comments
Jabsco                        Neoprene       Excellent                           1-3
Raritan                       Nitrile            Good                                  2-5
Groco                         Nitrile            Good                                  2-5                     Hard to pump (stiff)
 

Solution: Raritan pH II valves fit Jabsco manual heads and last nearly twice as long. They withstand propylene glycol antifreeze without complaint. They fit perfectly. Yes, they do cost a few dollars more, but less in the long run, and who likes working on heads?

I still use ethylene glycol in my head (automotive antifreeze), even though the Raritan valve can handle it. Why? There are additional neoprene parts in the Jabsco head (flapper and o-rings), and I'm not really all that worried about anyone drinking out of my holding tank.

What about the flexible impeller pumps for raw water and potable water? Some of the raw  water pumps are nitrile and are thus immune to propylene glycol, but some are neoprene. After all, neoprene has a better flex life. There have been reports of PG damaging raw water impellers over the winter, ever since we bought into this well intentioned but wrong conventional wisdom that PG is better for the environment than EG (link). For this, I blow out as much of the PG and hope for the best. So far, so good.

Tip of the day? Winterize all non-potable systems with ethylene glycol.

Hang Em' High

7-16-2012, rev. 7-31-2024

I always liked Clint....

______________________________

Nothing secures a dinghy, specifically a non-RIB inflatable, like lines cris-crossed underneath. No more sway. No more worries about loosing air pressure and strain on the attachment points.

How high does a tender need to be above the water? Surely this depends on the waters sailed, how far it extends behind the boat, and the motion of the boat. It depends on how well secured the tender is to the davits, in case it does take some minor hits.

Often, I see towering, high davits, with tenders swinging far below them. Sometimes it's coastal convenience; they hoist her up when off-shore. Too often, the tackle or attachment bridle were poorly conceived, pointlessly consuming critical space between the tender and the davits. Hoisting bridles waste space and are thus, well... dumb.

In my case, the tender is nestled between the hulls, only extending a bit beyond the sterns. This is typical on cats and makes carrying a tender safely easier. I've also taken steps to shorten the lifting tackle and added a bow spreader bar, such that the tackle is contained almost entirely within the tender, thus consuming no lift space.

An so I can hang her high without towering davits. Triced up, with cris-crossing lines underneath, she snugs up tight in the gap between transoms with no need to remove the engine or hoist her up into the wind. The aft edge is about 4 feet off the water, and top edge just above the deck, convenient for loading.

Very simple.

______________________________

The spreader bar is made from 1-inch x 1/8-inch aluminum square tube that clips the tender floor and D-rings on both tubes, and is clipped to a lifting tackle only 8 inches above the tender floor; you can't just clip the floor of a sport boat, because if the tubes go flat the floor comes out. And tricing lines, of course.

Something Free, Something Lazy

Free is always good, except this is not quite free.

Or rather, it is free if you use any sort of holding tank treatment chemical.

 I've done all sorts of holding tank stuff for Practical Sailor Mag. Chemicals, hoses, vent filters. Fun stuff. And in the process, in addition to learning all sorts subtleties, I solved all of my own odor problems, save one; odor from the bowl itself. If I flush with seawater and leave it a few days, there's some stink; sulfate in seawater is converted to hydrogen sulfide by millions of wee bacteria. If I flush with fresh water, it's better, but not zero; I guess something sneaks back down the waste hose, or perhaps up the feed hose. And either way, the bowl tends to get ratty, as marine flush volumes are limited and the water isn't chlorinated. I hate scrubbing.

The free solution? Place a 20% solution of holding tank treatment in a spray bottle and mist the bowl down each day, or at least whenever you'll be leaving the boat for a while. This cleans the bowl, treats the water in the bowl, and treats the water in the waste hose, preventing stink. And since it's the same treatment you would be using anyway, just subtract this from the usual dosage.

 I haven't scrubbed in months; the treatment eats the waste off. Very lazy.

 
However, not all treatments work.

• No blue sterilizing treatments, with formaldehyde and the like. Toxic, smelly, stain-prone, and well... gross. Too much like a portable toilet. Very tough on joker valves. Ban those from your boat.
• No bacterial treatments, like Bactank T3 or Happy Camper. They grow in the bottle and get gross. They are quite effective in the tank, just not for this.
• Pick an scent you like, preferably very mild. I like Forespar Refresh, Raritan CP, and Camco TST Ultra-concentrate. These are compatible with any type of holding tank treatment, including bacterial treatments.

Less work. Less money.

Gasoline Additive Corrosion Testing

4-2016, rev. 7-2024

I've been playing mad scientist again, conducting laboratory corrosion testing experiments for Practical Sailor Magazine.

In my experience at least, corrosion products often foul carburetors, and I've learned how to field strip and clean carbs far too well. Can storage additives actually reduce corrosion? I ran some modified ASTM tests to see. Since I've done this for years with engine coolant samples in my day job, this was something I feel very comfortable with. The set-up and procedure is a bit different, but it's still familiar ground.

Standard metal coupons are exposed to e10 in varying conditions for 1 month. To induce galvanic effects they are grouped copper/steel/brass to simulate a tank system and steel/aluminum/brass to simulate a carb bowl.

The test bottles look like this.

 

After exposure, the sealed control looks like this.

Without an additive, with the addition of 0.03% seawater and allowing limited venting, we get this.The black spots are corrosion pits, not dirt.

With a good additive we get this--effectively no corrosion even with salt

And with a poor additive it can be even worse than with nothing at all

Not a realistic test? Actually just an acceleration. The pitting looks very much like this 12 -year old Yamaha 9.9 carburetor; I have 4 of them and they all look about the same, just like the aluminum coupons.

And the successful additives weren't always the ones you would guess or be led to believe by advertising and marine catalogs, not at all. Unfortunately, If I give more than a teaser, PS will strangle me.

I will share this:

• Without air and water there is NO corrosion by e10.
• Without saltwater the corrosion is very, very slow. If salt spray, even the TINIEST AMOUNT can sneak into you tank, you're going to have trouble within weeks. The effect was dramatic.
• One of the very best additives did NOT come from the boat store. The worst ones did. Go figure.

It turns out that the NMMA (National Marine Manufacturers Association)has formed a working group to develop standards for gasoline additives. IT seems they have found that some are damaging their engines.

Tall Step Disease

3-30-2012, rev. 4-20-2018, rev. 7-31-2024

As the knees get older, steps get higher.  Last year, at the Annapolis Boat Show I was sitting on a 45-foot VERY expensive catamaran, along with a group of mature sailors who had the rocks to by said boat. It was VIP and Press Pass Day and there were a lot of well healed folks about. Across the dock was an even more expensive Gunboat 50. Very pretty.


I pointed out that these boats all had tall step disease. A standard step is 7 1/2" x  10", yet even on the largest cats where space  was no real concern, the step pitch measured 11" x 5", I suppose because it looked better. In conversation we also learned that fully 71% of our group had either personally or had a spouse go through knee surgery. Two artificial knees were displayed. My wife has an artificial knee, though she was resting it elsewhere, and I have had serious knee surgery. Are the boat builders so stupid--no, I don't think that is too strong a word--that they don't realize the buyers of these boats are either older or will soon become so?

Until now we have used the "runt box" you see under the helm seat. Honestly, only a 6'6" sailor can reach the floor while seated. We would move this box below the step, where it worked well. But while sailing it wasn't really available and often we didn't bother to move it.

Even younger sailors get worn down by big steps over the course of a long day--I can ride a bike 100 miles in 5 hours yet the steps get to me some days--and so I've been fighting my own battle, on a limited scale. The steps leading up from the cockpit are 14 inches and the steps down below are 11 inches.

I built these low stools (the cabin steps must fit under the swing of the bedroom doors) from scraps and a few squares left over from the cockpit floor project. Thus, they cost only a few hours and some left over materials. I don't think any real explanation is required for a carpenter to reproduce them. For the boat owner and tinkerer, hours spent making sawdust on small projects are not subtracted from out lifespan (yup, I bastardized that a bit).

 

 

4-20-2018. My F-24 had a similar problem, heading down into the cabin; a big step and a goo chance of hitting your head because of the motion when going down. You basically you had to do an 18-inch drop and my knee didn't like that, so I added a step, much as I had in my Stiletto 27. Step by step, largely from my Good Old Boat article:

 

Make an oak bracket that will fit a salvaged dinghy seat. The seat makes for a light and strong step with molded non-skid that looks reasonably factory. I sealed the foam core cut ends with epoxy and sanded smooth.

Peal back the carpet, remove adhesive, and sand.

 

Butter them up with thickened epoxy and bond. Screws secure them while curing.

 

Secure the carpet with contact cement.

 

Nearly done.

 

Much better and the recycled seat gives it a factory look. The step lifts out for access to storage under the cockpit.
 

 

 

Gasoline Tank Vent Filters--Better Boat Keeping?

3-7-2012, rev. 7-31-2024

For all the talk and trouble water in the gasoline causes--far worse with e10--to me it's rather conspicuous by its absence that neither owners nor builders ever took a serious look at vent filters. Cars have had sealed tanks fitted with both pressure controls and filters since 1971. I considered this a few times--I've installed very large descant traps on very large chemical tanks--but figured if it was so against the conventional wisdom in the boating community, it couldn't be right. Funny.... That's not like me.

In a prior post I began a discussion of some testing for Practical Sailor. We've got two test boats going at this time. I've started monitoring the humidity inside and outside. Yup, it's drier inside the tank, after filtration. We expect some positives that should add up to a good value proposition for the owner:

• Drier gas/fuel.
• Less evaporation, to the tune of $8-$12/year. The unit should last ~ 10 years without service, so that will nearly pay for it.
• Less loss of volatiles means better starting, particularly in cold weather.
• Less loss of volatiles means better resistance to phase separation/emulsion blobs. I have only been able to recreate true phase separation from atmospheric absorption if the ethanol evaporates after it is saturated, and I've tried many combinations. This is why we generally only see it in carbs (they're small).
• Less loss of volatiles mean less gum formation (better solvency).
• Less loss of volatiles is good for the environment. Yes, that counts.
• Less oxygen (less convection, more vapor space) means less gum formation.

It won't stop these things from happening in the carburetor, but it should significantly extend gasoline stability in the tank considerably. Preliminary calculations suggest at least double.

But can we demonstrate how this actually effects the fuel over time on a small scale, in a controlled manner? Calculations only go so far, since water condensation and absorption, differential evaporation, and fuel oxidation work together in complex ways. Science project time.

One liter bottles with 500 ml e10, starting levels marked with tape. From left to right:

-  Plain 1/8-inch ID vent.

-  10 ml silica gel descant

-  10 ml activated carbon  adsorbent

 

 There was less gasoline evaporation with silica gel than with carbon.

 

 

 

The metal samples corroded less in the silica gel protected jar.  

 

 The silica gel protected fuel deteriorated least (6 months).

Actually, both carbon and silica gel are both adsorbents that pull water and organic vapors from the air. Silica gel (the packs you find in with your new DVD player) has a high affinity for water, while carbon has a high affinity for organic vapors. However, both adsorb reversibly; that is, if exposed to high temperatures and either clean air, or an excess of something else, they release what they have previously adsorbed. Carbon can be flushed by water vapor and air, while silica gel can be flushed with hydrocarbon and air. Both should have the effect of keeping the tank drier and reducing evaporation, adsorbing and desorbing with each day/night breathing cycle. Both should reduce oxygen in the tank. But how much?

Results in the fall. The long version will be in Practical Sailor.These things can't be rushed. I expect we are going to find the improvements are small and that a sailor won't "feel" any difference. But his engine will start a little easier, he'll buy a little less gas, and have a few less problems. The math works, it just won't bring instant gratification, not like $100 spent on some bit of deck hardware would bring. More like the "pay me now, or pay me later" benefit of changing the oil;   

But meanwhile, like the holding tank vent filter that I installed (and am very pleased with), I've installed a carbon vent filter on Shoal Survivor gas tank and I'm not planning on taking it off.

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Note for the spelling or technically obsessed: sometimes I say absorb, and sometimes I say adsorb; both are correct. Alcohol absorbs water. Silica gel adsorbs water. The mechanism is very different and the reversibility is very different. This is the reason adsorbents are so useful.

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Although the test filters photographed above were fabricated from PVC, this is NOT safe practice for permanant installation. PVC is not highly resistant to gasoline vapors and the adhesive is quite vulnerable over time.  While it won't fail in this laboratory setting, based on refinery expereince with PVC, the joits will fail if I add heat, vibration, and wait several years.