Monday, May 11, 2015

1 down 749 to go


We don't (officially) leave until tomorrow, but Mathias and I moved Ripple to the ship canal so as to avoid the Fremont Bridge embargo in the morning.

Mike at the Ewing Street Marina graciously afforded me a spot for the night, and wished us well on our voyage.

Sitka here we come!


Sunday, May 3, 2015

Obsessing About Anchor Rodes

Buying a mattress is about as dull, and opaque, a consumer choice as any of us has to make.  You can't take your friends for a ride in (on) it, however much you like the color, it is quickly obscured, and you really can't test it out... in spite of the fact that you're going to spend a third of your life on it for a long time.

Ground tackle is like that.  You might get some cred for your choice of anchor (probably not), and every sailor loves to debate the virtues of chain and lay and scope and flukes

I purchased a new anchor, and obsessed for a time about the rest of the ground tackle.  My existing rode was a mere 200 feet of 1/2" triple strand nylon, and twice that will be barely enough for some of the more extreme Inside Passage anchorages.

Conventional wisdom suggests an eighth inch of rode diameter for each 9 feet of boat length (for a working anchor). That would be 3/8" line for Ripple, but 3/8" is hard to grip and haul, especially with 50 lbs of anchor and chain, plus the weight of the anchor line itself.  So I narrowed my choice to 7/16" and 1/2" three-stranded nylon.

These are by no means the only plausible choices.  What about braided nylon? Single braid? Double braid?  Three strand nylon offers elasticity (about 25% stretch).  Braided, about half that.  Every primer on anchor rodes extolls the virtue of elasticity to absorb energy and reduce shock loading.

Boat designer Steve Dashew alleges that less-stretchy polyester line minimizes some of the negative aspects of elasticity: with less stretch, the boat should do less sailing on the anchor in a blow.  The loss in elasticity can be accommodated by letting out more rode, which one would be inclined to do so in heavy weather in any case.  Apostasy or simply evolution of technique?

Then there is the question of strength.  How much is enough? The forces on a boat at anchor include tide, wave action (and, in particular, shock-loading from such waves), and wind.  Resisting these forces are the holding power of the anchor (modulated by the bottom characteristics of the location), the strength of the anchor chain, the strength of the anchor line, the strength of the connections between components, and the strength of the boat fixture to which the rode is attached.

The bitter-end of Ripple's rode is made fast to the sampson post, so failure there would entail disintegration of the boat itself, in which case, all else is moot.  Estimating the loads suffered by the other components is non-trivial.

I came across a formula for determining wind loading forces on a sailing vessel, and worked out the numbers for Ripple:

F = (A * Sf * Gf * V^2 ) / 390
where
F   = Horizontal force in pounds
A  = Area in square feet
Sf  = shape factor (.9 for round, 1.1 for a flat plate)
Gf = gust factor at sea surface
V  =  wind velocity in MPH (knots * 1.15)
AreaWidthheightNumbershape factorArea
Mast0.53010.913.5
cross trees50.1110.5
shrouds0.053060.98.1
halyards, lifts0.053060.98.1
house51115
hull831124
stanchions, pinrails0.12.560.91.35
Dinghy on deck41.510.95.4
dodger51.5117.5
Projected Area73.45
Fudge Factor (20%)14.69
Total Projected Area88.14
Wind Loads
Wind Velocity (knts)Force (lbs)
25205
50822
751849


Anything under 50 knots of wind is pretty clearly near or under the recommended working load limits (WLL) for triple strand nylon of 7/16 or 1/2 inch diameter (WLL is by convention 20% of tensile breaking strength load, though I have seen 'safety factors' as high as 12:1).  Assuming 5:1 safety factor, even the 75 knot winds are still roughly only 50% of the breaking strength load (for new line under test conditions).

Exceeding WLL is known to damage nylon rope, though the rarity of such events makes it unlikely that the anchor line would sustain such stress frequently.  A prudent climber replaces his or her rope after a single fall.  Perhaps the prudent mariner should do the same with an anchor rode that sustains more than a 50 knot night?

Summarizing the choices between 7/16" and 1/2":

Factors favoring 7/16" nylon triple strand:
  • greater elasticity - the ability of a rode to absorb additional energy (force) by stretching
  • weight - all that line has to be hauled up after every anchorage
  • compactness - it all has to be stored in the anchor locker
  • cost  - 7/16" is a bit cheaper
Factors favoring 1/2" nylon triple strand:
  • handling - a slightly larger size is easier to grip
  • brut strength - this may be as much psychological as anything else
  • resistance to chafe - the extra cross section of 1/2" line provides a significant additional margin of chafe resistance 
The dilemma is a common one in managing risk, cost, and convenience, and there is no perfect answer.  At the end of the day, you're asking yourself how severe an event (a storm or severe williwaw) you're trying to protect against, and how much in treasure and inconvenience you're willing to invest in this protection.

My friend Terry scoffed and said to stop fretting... the anchor set will fail long before anything else. Probably true.  I ended up with 400 feet of 7/16 rode plus the 20 feet of chain.  I will have the old anchor, the old rode, and the kedging anchor rode in reserve to deploy in the case of a big blow.

Friday, May 1, 2015

Boat Instrumentation


The first of May.  All the canvas work is done.  A wee bit o varnishing to do, maybe some touch up paint.  The punchlist still includes first aid and provisioning, and this 'n' that.

I acquired the last bit of instrumentation for the trip today.  Installation tomorrow.

May 12 is the scheduled day of departure.

Sitka, here i come.

Monday, April 27, 2015

The Dodger: A Gentleman's "B"



I finished the sewing for the dodger on Saturday, but didn't have the nerve (and the snaps) to try to fit it to the boat until today.  The most difficult aspect of the process of patterning and sewing is that you have little sense of whether you're accurate enough until the end.  The very end.

Today, under warm sun, I installed the snaps (every 4 inches) and studs, working from the front and moving around 1 snap on each side at first, then a pair at a time.  They all went in securely and easily.
I set the snaps in the canvas by hand, rather than with a fancy snap tool, but it went ok.


The straps I will set to the forward jamb cleats in the cockpit, the forward most hardware that exists in the cockpit.  The angle is slightly acute (less strong), but the whole assembly seems to be plenty strong enough, and not too difficult to move around in order to gain access to the foredeck.


I am thinking about how to do an extension (about 24 inches) aft from the aft bow, to increase the rain protection.  I installed a long zipper the length of the tails on the dodger in anticipation of this possibility.  I'll use a collapsable tent pole to spring the aft edge and keep the whole thing taut.

The sewing was challenging.  The SailRite LZ1 is about the lowest level of machine competent to do the sort of sewing called for.  The walking foot is essential to feeding through multiple layers of canvas, window vinyl, and leather, without skipping stitches.  The problem comes when you have to feed an unwieldy 9 foot assemblage and keep it feeding past the needle evenly so stitches are straight, fair, and even.  I failed in this objective many times, and the result is drunken stitchlines or worse.

I improved as the process went on, but it is hard to do 20 feet or more of curvaceous top stitching at a go without making mistakes.  More experience and talent would help here, but the whole process would be far easier with a larger sewing surface that is smooth, slick, and easy to maneuver the work on.  My side table is a mere 2 feet by 6.  Four feet by eight would much better and twice that would not be excessive.  A dining room table might work for an exceptionally talented sewer, but that ain't me.

The video from SailRite was excellent. There were points where things might have been clearer, but over all, it was very good, and essential, really.  I don't know how one could do the job without it.

The folks at King Marine Canvas were very good to me.  The got me materials in a timely fashion and a good price, and their expertise at frame design and construction really worked well for me.  No one will mistake my workmanship for a professional's, but I am very pleased with the result, and it passes muster for the "50 foot boat" test -- looks good from 50 feet.


Monday, April 20, 2015

Sewing Station for the Dodger


Having watched the Sailrite video on dodger construction 4 times through (completely, twice, various sections as many as 4 times), I grow envious each time they pan across a sewing table (a loft floor, really) that exceeds the size of some bowling alleys of my youth.  I've put together a sewing table that I hope will suffice to build my dodger.

The pieces for the dodger are as long as 9 feet, and in order to sew them without skipped stitches and wavy stitch lines, it is necessary that they move serenely through the sharp bits of the sewing machine. My feed table is a mere 6 feet in length.

I should get the materials by tomorrow and get busy cutting and basting and seaming.

Saturday, April 18, 2015

Fresh Bread


I'm starting to wonder about provisioning... 2 people x 90 days x 3 meals plus per day.  Interesting challenges, especially if culinary interest is one of the objectives.  I did my first experiment with bread making aboard today, and the result was surprisingly close to the mark.  In fact, I slathered some butter on the product and ate the whole thing.  What a treat -- fresh bread amidst the canned stews and freeze dried and prepackaged fare I expect to have going.

The set up:

Dutch oven atop a two-burner camp stove
Cake tin inside to keep the loaf off the bottom of the pan
Small loaves, one at a time.

The fuel consumption for 20 minutes of baking was about 70g, which is about 1/6 of the capacity of the fuel canister.  Half a buck to a dollar for a small loaf, including ingredients:

The recipe:

1 cup all purpose unbleached flour
3/4 cup water
1/2 - 3/4 tsp yeast
a bit of sugar in warm water to proof the yeast.
salt to taste, some in the recipe and some sprinkled on top the loaf


Mix all the ingredients together when the yeast is frothy, knead a bit, set aside to rise. Put the kneaded blob from the first rise in the oiled loaf pan, let rise till morning, cook for about 20 minutes, serve with coffee, bacon, and eggs.  The only downside is you'll want two of them - one for each person.


Of course, this is on our lanai, not on the boat.  Wind and humidity will probably have an impact. I'll fool around to see if I can raise the cake tin a bit higher from the bottom to reduce scorching of the loaf, and perhaps even try a double loaf in the cake tin itself.  Seriously luxurious

Wednesday, April 15, 2015

The Dodger Begins to Take Shape

My brother's picture of yours truly beavering away on the patterning.  (those of you who know him may recognize his thumb in the upper left corner)

In a scant four weeks I expect to pass through the Ballard Locks heading to Sitka.  I've carefully organized my task list so as to maximize the drama of these last few weeks.  Spring varnishing is underway,  and it looks like the weather for that will cooperate.  Why settle for the unvarnished truth when you can have sparkle plenty, as my Mom is wont to say?

But the real drama is all about the dodger.

I've known I needed to make one since a day two years ago in early August in the Broughton Islands with Terry.  The warming summer sun was obscured by a weeping marine layer.  I was wearing every stitch of clothing I had with me -- five layers -- and I was still cold. In August. Protection against wind and spray will be pretty important (which is why I left it to the last possible moment). Knowing you're going to be hanged in the morning wonderfully concentrates the mind.

So, I ordered the Sailrite video on building dodgers, and arranged for a local company, King Marine Canvas,  to fabricate a two-bow, 1" stainless steel dodger frame.  Sailrite offers kits with all the materials, including sectional frames, but I really did not want to go the sectional route.  I want the frame as strong as it can be.  King Marine worked with me to get the frame right, coming to the boat to measure, and they got the job done quickly, in spite of being very busy.  I am grateful!

The prospect of adding a bunch of stainless steel hardware to Ripple's traditional aesthetics is offputting, to say the least, and the dodger further demands the addition of combing boards to the house top to carry the fasteners that will allow the canvas to be fixed along its lower margins.  Ideally the frame would be on the boat to help define the shape of these combing boards, but there is a chicken-and-egg conundrum here, as the dodger pivot fasteners bear on the combing boards as well.


These boards will help distribute the stresses on the dodger as well as providing a substrate for the fasteners.  As my house top is a traditional Irish felt and canvas, this is particularly important, as fastening any hardware directly to the cabin top would almost certainly induce premature failure of the cabin top surface.  I am hopeful that the boards I've fabricated will distribute stress sufficiently to avert this.  I guess we'll find out.

The dodger DIY video arrived Monday, Tuesday I got a call that the frame was ready, and I had it adjusted and installed that day.  Today my brother Randy helped me pattern the canvas, and as soon as I can gather the requisite materials, I'll be sewing.  Maybe not so much drama as I had planned for.

Given that Ripple will spend most of her hours dodger-less, making these additions as unobtrusive as possible and aesthetically consistent with the look of the boat is important to me.  I have done the best I can.  Shelter from a rainy Spring wind will be my consolation for whatever aesthetic indignities I have visited upon my boat.