Saturday, August 1, 2015

The Perfect Jackline Terminator--Better Than Sewn Eye?

I've done substantial testing on sewn eyes in nylon and how to make them strong. The sewing is a little particular, subject to wear, and only reaches 80-85% strength with a reinforcement insert.

On the other hand this little trick has tested at greater than 85% breaking strength and 100% of minimum rate strength in my first few trials, and seems basically idiot-proof. It is based on stuff a sailor has on hand and is as strong as professionally sewn ends. I found 3rd party testing that confirmed these numbers.

Step 1. Double the end of the webbing and thread it through the eye of a chain link twice. The link will need to be 5/16" minimum to have room for both strands. This is grade 30, and any higher grade should do. The shackle must have width for the webbing. I used a 5/16" shackle and 15mm webbing; a 3/8" shackle is required for 1" webbing.
 
Step 2. Put the shackle pin through the hole.

Step 3. Dress it up. The top strand should be loaded (longer radius) as it is about 10% stronger.

Detail. If the webbing is wrapped around the other end of the shackle (tempting, since a 5/16" bow shackle will fit 1" webbing) there is no space between the chain link and the shackle, causing a shear point.  The webbing will shear at about 50-60%; still better than most knots and much easier to untie. On the other hand, if the webbing is wrapped around the pin, as shown, the metal surrounding the pin creates the required gap between the link and the pin, preventing shearing.


 There remain 2 potential weaknesses:
  • Working loose under cyclic load, just as a bury splice can work loose. A back-up knot or a few stitches solve that.
  • Scratching the deck. A chafe guard would solve that.
Since it includes a shackle, it seems like a winner for jacklines attached to pad eyes or bolt hangers, since a shackle is already required. The cost? $1 for the link ($4 if you like SS) and $14 for the shackle, but you were buying that anyway.


Other applications?
  • Attaching webbing shore anchor rode to anchor points; strong and can be untied after loading.
  • Endpoint attachment when testing webbing splices. Yeah, probably just me.
  • Other?
A solution is search of a problem.














A Poor Solution to Non-Problem

For most of us with all-chain, simply getting the chain straight between the anchor and the gypsy will keep the anchor coming up straight, perhaps with an occasional un-twist (lower and re-hoist) if we have spun. Some like swivels. But then there are bad solutions:

While this gem is only offered up to 22-pound anchors, the leverage  in a side pull, should the anchor get stuck, seems pretty rough on the bolt at the anchor end. Worse, it adds 6 inches more length to the anchor shank, increasing the odds of bending or breaking out.

Raspberry Award.

Wednesday, July 29, 2015

Muddy Water

I wish I could take beautiful pictures in turquoise water, but that in not what the Chesapeake is like.

Guardian G-4 (2.2 pounds), 600-pound holding, but unstable on some veers and did not always set.
[Not Pictured]

Mantus Dingy (2.1 pounds), ~ 150-pound holding

2.2# Claw, ~ 25-pound holding

Grapnel 3.2#, 6-pound holding

Guess which one is in my dingy, which one is in my kayak, and which ones went home.

(I kept the Mantus and the Claw)

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Yes, I tested these in deeper water using a load cell. I also tested them in mud and with veers.

Sunday, July 26, 2015

Want a PDQ of Your Own? This One's Already in Paradise.

From my friends' blog, in the process of selling their cat before heading really far south in a new-to-them expedition boat.

  

2015 July 25
by Mike
While all of my recent posts have been focused on the new Amel, it’s important to remember that there is a very beautiful and well-maintained PDQ 32 for sale, just waiting for the right owner to start making memories on her!
People may not fully comprehend the benefits of purchasing a boat here in Grenada. In most cases, the trip south from the US to the Windward Islands can be a tough one. It typically involves a number of uncomfortable passages, beating against the easterly trades. They don’t call this route the Thorny Path for nothing! Whoever ends up with ZTC will not have to deal with that though. He or she will be able to start cruising in beautiful Grenada, gaining experience at a comfortable pace by sailing here, and in the nearby Grenadines. It doesn’t get much better than that!
Want to help us out? Share the following link to all of your friends, and on your social media pages:
—–> http://www.pdq32forsale.com

Saturday, July 18, 2015

Tandems Anchoring VI

How to attach/detach the secondary rode, if it does not continue to the chain locker?

Like this if I set it from the dingy...

... with a closer detail. The carabiner is only to hold the chain and secondary rode together while I thread the soft shackle. Make certain the soft shackle is long enough for easy handling; I like 8-10" open length. (The secondary rode is across my lap, obscured by my hand and arm. Also, I would not normally have the rope across my lap in a way the could pull me off the boat; it was the best way to make the work visible to my cameraman (wife).


Like this during retrieval, or if setting from the boat.In this case I have attached a white polyester extension line so that I can ease it off, without letting go, while I recover the primary.

All physically very easy, so long as you get the sequence right. Tricks of the trade, born of long practice. The key is to use a carabiner or snap shackle to take the load while you pause to attach the soft shackle, and to have an extension line so that you can keep control of the secondary rode.

More Jacklines

Vertical Jacklines

Who says they all need to be on the deck? I installed a pair of vertical lines to deflect the genoa sheets away from the mast-mounted halyard winches (one on each side), around which they loved to foul during tacks. They are anchored to strong points and the line is 1/4-inch Dyneema, selected because I had it and it was non-stretch. At first I was concerned that the deflectors would be in the way, but I soon realized that they were handy holds and clipping points when working at the mast, much better than clipping to the mast base. I can even lean on the tether in rough weather, allowing for better 2-hand work.


Jackline and Lifelines

It is often said that using the lifelines as handholds is a bad habit. While there is truth to this on a monohull (the leverage on the stanchion bases is cruel when hauling to one side from the deck of a leaner), I disagree for catamarans. The difference is that cats do not heel and that most of the motion is vertical (it doesn't show in pictures, but cat sailors know they get light on their feet when pitching up wind). Additionally, my jacklines are relatively high at the beam, since they are secured to the hard top. Thus, the safest way to traverse the side decks between the hard top and the tramp is to hold the lifeline in one hand, the jackline in the other, and pull up. Not to the side, not push down, but pull straight up such that your feet are held firmly on the deck. There is little bending stress on the stanchions because the load is vertical, and the suport is steady rather than surging roughly as the boat moves. Intuitive to a lifelong climber, something may lubbers and sailors have to be shown.



Probably just a catamaran thing.

Friday, July 17, 2015

Ducklings always Follow Their Mothers

I guess it is a universal rule.


Cay of Sea and tender, Unnamed cove

The Chesapeake Bay is a small world sometimes. This week we ran into friends we had met over the internet, who dock only a few hundred yards away in Deale, but had never met, face to face. Good stuff.

Tuesday, July 7, 2015

Chafe

While I am nearly always complimentary of the PDQ and the attention to detail of the designers, everyone makes mistakes. But in this case I can't imagine what they were thinking. It is not just a fitting error, since the starboard bow is identical.

With heavy docklines and my normal heavier bridle this little slot between the rub rail and the deck is too small to be accessible and in 6 years has never cause a problem. However, as I started experimenting with lighter bridles for a Practical Sailor article on mooring loads, I found the thinner 8 mm line could slide right into the slot and that the slot is quite sharp, able to slice a line in minutes to hours, depending on the load.



The chafe gear does a fair job of keeping it out of the slot, but I would rather eliminate the slot. My first thought is to fit a block of something into the space, matching the rubber and secured with a screw and 3M 5200. I'd rather not obscure the forward beam bolts.

Saturday, July 4, 2015

More Active Anode = More Growth?

I read this in a guidance document by maker of lower potential anode material, and I admit it didn't make obvious sense. Then I started soaking a few trial anode/pipe combinations to help develop a test method for an up-coming anode review.


Clearly the more active anode has more growth (aluminum on left, zinc on right, same brand).

Why?

Wednesday, June 24, 2015

Is an Anchor Ever Really Set?

Anchor testing always raises as many questions as it settles. Too many important variables that simple cannot be controlled, and if they are,  cruising will throw something different at you. But one thing was very clear; in soft mud it takes a long distance for anchors to really set.


Other anchors took similar distances, generally 35-50 feet. When we tested 2-pound mini-anchors we got scaled down results; setting took 5-10 feet, sometimes longer, and there was never a hard stop.

What does this mean? Let's look at the green curve showing a good set (most were worse):

27 foot boat, 13-pound Danforth (assume 3x less holding than FX-37 and 1/2 drag distances)
  • Setting force 250 pounds (750 equivalent) = 15 feet setting distance.
  • ABYC storm force = 1200 pounds (3600 equivalent). Drag
  • If 2 anchors set with some allowance for single leg loading, probably move another 25-35 feet during extended setting (see comments in prior post). 

50-foot boat, FX-37
  • Setting force 750 pounds = 30 feet setting distance
  • ABYC storm force =  3200 pounds. Drag unless 2 anchors are set. May stay with good snubber or deep water, but probably not.

34-foot PDQ (me--I've anchored in the area too). FX-16 + Manson Supreme 35.
  • Setting force 250 pounds = 15 foot setting distance on both.
  • ABYC storm force 2600 pounds. With both anchors set in a shallow V. Theory says I should drag, but...
With a good snubber or nylon rode, the force should be less than 1000 pounds (see previous post), and with a asymmetrical V the force is well spread on 2 anchors (400 pounds on the Manson, 600 pounds on the Fortress), explaining why I don't move that far. However, in practice I move ~ 15 feet, which is hardly noticeable (a few thousandths of a degree on the GPS). Additionally, the PDQ does NOT sail around the anchor when on a bridle, and the legs are joined to the rode downstream of the bridle apex; there is no single leg loading.Thus, my single leg loads do not exceed 500 pounds, which is well within the holding capacity of the anchors.

The Delta Anchor moves around even more in mud, which is why I changed to a Mason Supreme (I have also tested Rocna and Mantus anchors--all very similar, which is better seems to depend on the bottom, though I'd buy a Mantus if I had it to do over) and up-sized from 25 pounds to 35 pounds. Mass always helps.
As you can see, a 25-pound Delta is only good for about 227 pounds in soft mud (400 x 25/44=227), and my boat generates about 240 pounds force in a 20-knot breeze (prior post, 20 knots, 3-strand snubber), which is just about when I would experience dragging if I didn't set a Fortress too.

But everyone moves in soft mud. Don't let them tell you otherwise.

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Note that twice the Fortress dis not really set at all.

And a couple more, just to think about...