Air Subduction in Kayak Paddles and cavitation in lee boards

I dont know if subduction is the right word to describe the phenomenon of air getting sucked down along the back side of a kayak paddle, but there I am using it.  Dictionaries indicate that common usage of subduction only applies to the geologic phenomenon of one piece of the earths crust getting shoved under another but here I am with no one to stop me and so I am expanding the usage of subduction.
I mention subduction because it is a phenomenon that impacts paddle efficiency adversely but looks so normal when it happens that its easy to miss entirely.  Subduction happens because pulling the blade of a paddle through the water creates a low pressure region on the back side of the paddle.  If the pressure is low enough, air will get sucked down along the blade of the paddle in response to the lower than atmospheric pressure there.  The result is reduced efficiency of the paddle.  Why? Because the amount of thrust you get from the paddle depends on the pressure difference between the front and the back of the blade.
Furthermore, this phenomenon seems to happen only with paddles that have long narrow blades.  At the start of the stroke with a long bladed paddle, only part of the blade is in the water and part of it is still out of the water, as you pull on the paddle, low pressure is created on the back side of the blade and the relatively flat surface of the blade that is sticking out of the water directs air down the back of the blade.  I suspect that water coming off both edges of the blade creates stable vorteces on both sides of the blade with a low pressure area in the middle that becomes the pathway for air subduction.
Commercial paddles with short, wide blades dont generate this phenomenon because the blade is fully immersed in the water before power is applied to it and the only thing sticking out of the water is the circular loom which does not produce any pathway for air to travel down to the low pressure area behind the blade.
But the phenomenon of air subduction with a long skinny blade is not unavoidable.  Depending on how the paddle is held and moved through the water the phenomenon can be avoided.  If the paddle blade is moved sideways as well as straight back, water moving across the face of the blade will not form the vortices that allow air to travel down the face of the paddle.
Since air subduction is dependent on low pressure on the back of the paddle blade, the lower the pressure, the higher the likelihood of subduction. Pressure is force divided by area so the same amount of force on a smaller area will create a greater pressure differential. And since on paddles with long narrow blades, only part of the full blade area is submersed at the start of the stroke, much more of a pressure differential is created across the face of the blade than in a paddle with a short wide blade where the whole blade is already fully submersed at the start of the stroke.

Lee board on a shallow draft Dutch craft.

The lee board deployed.  The angle at which the board is deployed controls the amount of lateral resistance that the board supplies.  The backward rake also allows the board to kick back and out of the way harmlessly should it hit bottom.

Not surprisingly the phenomenon of air subduction can appear anywhere that you move a  fin shaped object through the water like for instance a lee board on a sail boat.  The purpose of the lee board is to provide lateral resistance to a sail boat when it is sailing at an angle to the wind.  Some sail boats use keels to achieve the same results but lee boards are more handy in places where the water is shallow.  And they dont take up space in the cargo area of the boat like a centerboard does.  Lee boards are generally used on relatively slow moving boats which cargo boats generally are. And the triangular shape of the lee boards on Dutch craft puts most of the surface area of the board toward the bottom of the board, keeping the top of the board relatively narrow to minimize air subduction.
A slightly related phenomenon to air subduction is cavitation.  Unlike air subduction which happens when a foil pierces the surface of the water, cavitation generally happens when a foil is moving rapidly while fully submerged. If the speed of the foil is sufficient, it can create pressures low enough to cause water to vaporize. If you remember your high school physics, the temperature at which water turns from a liquid to a gas gets lower and lower as pressure drops.  The net effect of water turning to vapor is the same as air getting sucked into the water, it reduces the efficiency of the moving foil.  Generally, cavitation occurs in high speed propellers, but it can also happen in vertical fins on fast moving water craft like the one I posted about a few days ago.  Read more about it on the Vestas sail rocket site.

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Five Gyres and More

 I saw this photo of kayakers on facebook and the thing that popped into my head unbidden was, Plastic Gyre.  Of course this isnt a plastic gyre, the real plasic gyres are in the worlds oceans and there are five of them and they are huge, and while there may be some plastic kayaks or kayak parts in these gyres, the majority of the plastic is from other sources.  So whenever kayakers decry plastic pollution, I see some irony in their stance.

 

I posted this picture before under the heading, how many kayaks are there? and this massive assembly of kayaks really does come close to being a genuine plastic gyre. And before you accuse me of being holier than thou with my wood frame skin on frame kayaks, I confess that yes,  there are plastic resins used in its construction, mostly in the skin and the lashings and the coatings used to seal the skin.  And I also wear some plastic garments when paddling and the small fibers that theyre composed of break off during washing and end up in the ocean where they displace plankton in the bodies of animals that eat plankton.

Lets let the issue of whether I am a hypocrite or not rest for a moment and look at the obvious problem of plastic pollution in the worlds oceans.  The organization Five Gyres has devoted itself to the problem. Click on THIS LINK to find out more about them.

Policy director Stiv Wilson of Five Gyres explains in an ARTICLE that plastic pollution on the worlds beaches is not the main problem but could be a big part of the solution. While the five gyres collect plastic that has made it into the oceans, they also spit out a certain percentage of plastic each year.  Some of the plastic moves on to different gyres, but some of it also gets spit out and ends up on beaches.
If we were to stop making plastics tomorrow, and did annual beach cleanups, plastic would be gone from the worlds oceans in a matter of decades.
The problem with the plastic in the oceans is not that the plastic ends up on our beaches and assaults our esthetics but rather that when in the ocean it harms the animals that live there. Inundating the world in plastic products and then expecting none of them to end up in the oceans is not realistic.  Maybe stopping the production of plastic is not realistic either but it sure would fix the problem.  What we have to decide is whether not having plastics in our lives is a bigger inconvenience than having it in our oceans. Weve lived without plastics before and we can do it again.

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Pleasant Bay and a simple rig adjustment

Last week I returned to my old stomping grounds off Harwichport / Chatham to see how the boat would strut her stuff in a little breeze.  I was able to sail out to the whistle, bell, and back in no time as well as do the three harbor cruise.

Issues with the way I rigged the boat crop up gradually as the wind increases.
1.  There was no way to cleat the mainsheet in without using two hands as I had failed to put a fairlead in just ahead of the clam cleats, leading to a poor lead to the cleat and too much work on the part of the skipper.  Easily solved with trading out the fairleads from the rudder head for the uphaul, and the one I put on the sprit.

2.  The mizzen sheet kept getting hung up on the motor, necessitating the use of a paddle to keep pushing it off the motor cowl.  I added a ring on a bungee cord to the sprit and ran the sheet up through it.  As the sheet tries to move outboard, the shock cord tensions and brings it inboard, thus avoiding the motor!  When the sheet is tensioned, the ring moves out to allow for trim.

12 miles under the keel in a nice breeze.  Looking forward to the next sail.  

September 8th - 

Great sail in Pleasant Bay today with another retired educator.  We sailed out of Areys Pond (small fee for the ramp, but they put it in and retrieve it!).  Owner, Tony Davis, and his crew run one of the best sailboat yards on Cape Cod.  They specialize in Cape Cod Catboats, and have a special place on Areys Pond.  It is a first class establishment.  

Throughout the day, we sailed through some very skinny water only grounding out a couple of times.  Lifting the board and backing the main allowed us to carry on.  

The ring on the shock cord worked wonderfully!  No hang ups on any of the stern fittings or motor.  No stress sailing.  I do need to change the clam cleats for the main to cam cleats for a more positive grip on the mainsheet.  Next project!  

We sailed upwind for about 2 hours, measuring 9 miles of tacking, and got as far as the entrance to Ryders Cove in Chatham before heading home.  ON the way back, we took some great shortcuts that can only be done in a boat that draws 7".  We sailed full blast of the eel grass, sand bars, and clam flats making short work of the trip home (40 minutes).  After derigging, headed home.  At times we had little wind, other times, gusts to 18kts.  I cant say enough about this boat.  Wish we had some pictures under way, but were too busy gabbing, eating, and just enjoying the day.  

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Seat Blocking Kind Words and a Testimony

Seat blocking & angle finder

My planer / jointer & a bunch of shredded mahogany

Seat Blocking?
Yesterday, I made the 2 pieces of blocking that will go under the ends of the rear thwart. Thanks to my angle finder, I knew the bevel on the blocking needed to be 15°. I cut that bevel by adjusting the fence on my planer / jointer, and running the pieces of mahogany (roughly 12” x 2” x 1” each) over it a few times. Everything looks like it should fit just fine. I’ll trim the pieces of blocking down about a half inch or so, before actually installing them. 

The next step will be to remove the seat and attach some reinforcing pieces to the bottom, in an effort to straighten out the slight bend in the plywood. 

Kind Words
?Earlier in the day yesterday, I had attended a funeral mass for a friend’s mother. I’m not very familiar with Catholic services, and I was sitting in the back with others who weren’t really sure when to sit, stand, or what words to repeat. Some people can feel pretty uncomfortable about that, but I find the awkwardness a little fun. Some of the rituals of the mass were similar to Episcopal services I’m more accustomed to, so it wasn’t entirely foreign to me. But ultimately, such ritualistic expressions are not the main point. “Religiousness” and “faith” are two entirely different things. 

That was on my mind as I walked through the narthex, greeting old friends… many of whom I haven’t seen in a long time. One of them, who knew a bit of what I’ve been through as far as divorce, heart surgery, and other things, spoke the kindest and most affirming words to me that anyone has ever spoken. I was entirely humbled by the man’s eloquence and consideration. I was not worthy of it. 

What totally floored me was when he said that, whenever he faced difficulties or hardships in his own life, he thought about me; that in doing so, he found inspiration in separating what really is, and what really is not, worth worrying about. I was speechless. I was even more speechless when he gestured toward the altar, with the crucifix on the wall above it, and said that he had no use for the supernatural, but instead found inspiration in other people. I understood, because I knew that my friend is a devout atheist… Just as I professed to be for the majority of the time he & I have known each other. 

What changed? 

I thought of the words of Peter: “Be prepared to give an answer to everyone who asks you a reason for the hope that is in you.” All I could do was gesture back toward the crucifix on the wall. 

A Testimony
Don’t worry. This is a boatbuilding blog, and not a platform for proselytizing or shoving religious agendas in anyone’s face. Of all people, I completely understand how irritating that is. I just wondered, how would I share with my friend who I admire and respect, the reasons I had gone from sharing his very same viewpoint to the one I hold now? 

For one, there is this: Most atheists I know are very sensitive to notions of right and wrong, and are almost all advocates of kindness and social justice. From a humanist standpoint, I began to ask myself, “Where do all these sentiments of knowing good from bad, right from wrong, come from? How and why are these sentiments so innate in most people?” 

You may have also heard the expression “there’s no such thing as an atheist in a foxhole.” True enough… when most people are pushed to points of absolute desperation, why do they say phrases like “please, God… don’t let this be.” Is it only an expression? If so, why is it so instinctive, even for the non-believer, in those most desperate moments? 

Also, I began to question why I had such a disdain for religion. After a lot of honest self-examination, I realized that I truly did not have a problem with a God… if there was one. Instead, I had a general disdain for “christians.” You know — those hateful, rude, self-righteous people who express their moral superiority over everyone else & tell the rest of the world they’re going to hell. Those people. 

I have come to believe that “those people” with “that attitude” have done FAR more to alienate people from faith than they have done to share it. 

So, at a point in one of my darker moments during the early stages of my divorce, I made a decision. I decided I would discard EVERYTHING “those people” EVER told me about God. I decided to discard every sermon, from every denomination…. every shaking, judgmental finger that had ever been pointed at me. I jettisoned it ALL. 

I realized that, throughout much of human history, during times of the most corruption and evildoing in the name of God, “the church” held the power of one particular point of leverage over common people: Literacy. 

Much of human history has been filled with unwritten, average, everyday people who could only dream to read. These people had to rely fully on “the church” to explain the words of the bible. With the power of literacy and the fear of a wrathful God in their hands, “the church” gained an almost absolute power over common people. 

Today, we largely take literacy for granted. I realized that my impression of faith had largely been based on what I had seen and heard from “those people,” and NOT what I’d read for myself. My impression of faith had also been formed by things I’d heard and read from vociferous opponents of religion, and what THEY had to say about the bible…. NOT what I had read for myself. I had absorbed everyone’s opinions but my own. Maybe it had just been easier that way. 

In any case, I decided to change it. 

I discarded everyone else’s interpretations, explanations, and opinions of the bible. I bought one, and simply began reading it. It was a turning point. 

Have a great day.

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The Giant Sequoia and Some Random Thoughts on Trees and Wood

It is one thing to see wood at a lumber yard and it is quite another thing to see it in the form of a living tree.  Unlike the stuff in the lumber yard which gives little evidence of where it came from, the living tree obviously speaks for itself.  It is not a product but an individual being with a considerable amount of character that makes it distinct from others of its kind, especially when old.
The musings I am about to deliver on the nature of wood were prompted by a trip to Kings Canyon and Sequoia National Parks.  The two parks are adjacent to each other, with Sequoia to the south and Kings Canyon to the north.  The only way to approach these parks by car is from the Central Valley of California.  Kings Canyon is adjacent to the city of Fresno and Sequoia is adjacent to the city of Visalia. Giant Sequoias can be found in both parks, although Sequoia National Park has more of them. Coming from the Central Valley which is flat and almost devoid of trees except for fruit trees in the orchards, it is hard to imagine that one is about to enter a mountainous zone where the huge sequoias live. 
But on to some pictures. I would like to say off the start that it is impossible to convey the massiveness of these giant trees in photographs.  The best one can do is show part of the tree with a human or two next to it for scale.  But even then, the photograph cannot capture the sense of presence that these large trees convey. Nevertheless, here are some photographs.

This trunk of a Sequoia has been hollowed out by fire and decay and so it is possible to walk through and along the trunk. 

 

Here is another sequoia that has fallen.  Someone cut a hole through it that one can walk through. The hole by the way is about seven feet tall.

Here is a picture of the tree named the General Sherman.  This is the worlds most massive living being.  It is suspected that some of the trees cut down when logging first began were larger than this, but General Sherman is currently the largest individual.  Its diameter at the base is in excess of 30 feet. 

 

 And here is the root ball of a recumbent sequoia, 30 feet from side to side.

 And using a deer for scale.

 And more humans for scale.

 And a tree hugging human for scale.

Even the branches of these trees are huge.  This one fell off a tree and the park service left it laying where it fell to give people an idea of their large size.  The largest branches on the General Sherman are about 7 feet in diameter.

 

The sequoias are not the tallest trees in the world.  That distinction goes to the coastal redwoods.  Neither are they the oldest trees. That distinction goes to the bristlecone pines of the White Mountains, one valley to the east of the Sierra Nevada.  But the sequoias are the most massive trees. Their trunks seem to be columns of almost constant diameter rising some 300 feet into the air and then seeming to end abruptly in the older specimens.  

Someone took a slice of a sequoia trunk and propped it up at an angle for the edification of the public. This slice represents roughly 2000 years of growth.  Age is determined by counting the annual growth rings.  The age of standing trees has to be estimated because there apparently is not any equipment that can remove sample cores of the requisite length, roughly 18 feet needed to count all the rings from the center of the tree to its edge.

 This is a side view of that specimen.

 

And here is a closeup of the growth rings in that slice.  The top of the picture is closer to the center of the tree where the older wood resides.  The crack running horizontally through the picture is a fire scar.  Moving downward toward the crack, the growth rings get ever closer together, an indication of ever diminishing growth.  After the fire, there is an explosion of new growth that again diminishes over time.  Apparently, fires burn the vegetable matter on the ground and release nutrients into the soil which spur new growth for a few decades until most of the nutrients are once again tied up in vegetable matter until the next fire comes along.  Also, note the little circular impressions just above the crack.  These are probably cores taken for carbon 14 dating and then plugged. 
When botanists try to estimate the age of trees based on diameter, they look at slices like this one and try to get an average count of growth rings per inch since as this picture shows, ring density changes with every fire and also with annual precipitation.

There was no sign indicating what sort of wood these park benches were made out of, but I suspect that they were made of sequoia wood. Yes, they haven;t stopped logging sequoias.  Not all of them are protected. Some of them are on private property and some of them are in national forests which are administered by the US Department of Agriculture which regards forests as cropland meant to be harvested. Not an editorial comment by the way. If we want to make stuff out of wood, we have to cut down trees.  More on that at the end.

Here the park service has done a prescribed burn or someone dropped a cigarette. In any case, not much damage was done.  For a long time, the park service used to suppress fires but found that periodic fires are better than monster fires fueled by debris on the ground that has accumulated for too long.  Also, they found that sequoias will not reseed very well without fire.  Fire turns vegetable matter into ash, releasing nutrients for the seedlings to grow.  Fire also kills off young trees that would otherwise shade out the new seedlings. And fire also opens up the cones to release seeds.  So now the park service does prescribed burns which do little damage but reduce the amount of fuel that could produce more dangerous fires.

This picture shows young sequoias coming up with the older fire scarred sequoias in the background.  The ash and the light also allow ferns to grow.

Another view of the burned ground.  Yes the ground burns since the top six inches are a compacted mass of needles and small branches.

Almost every old tree shows fire scars. As a matter of fact, I have never seen so many burned trees as I saw in Kings Canyon National Park.  In the national forests, fire scarred trees are more rare since those are logged over on a more regular basis and fires tend to be suppressed because the trees are regarded as a crop, not a part of an ecosystem in which fire plays a beneficial role.

This is a side view of about eight inches of fibrous sequoia bark which lacks resin and therefore does not burn readily.  Bark on sequoias can be up to two feet thick and this is what lets them grow old in an environment where fires occur naturally every seventy years or so.

Here the fire burned into the trunk of the tree but the segment at the left is still alive.  Every yearn the bark spreads sideways to cover over scars and in time will cover them completely.

 

Here is a segment of  a branch. The heart wood is red and the sap wood is a lighter color.  The heart wood of the tree is dead.  The sapwood is the part of the tree that is still alive and growing and is where the tree adds more wood around the outside of the tree under the bark. For purposes of lumber we want heart wood because the sap wood decays more readily.
So I was curious what kind of wood sequoias are made out of or perhaps more properly, what kind of wood they grow.  Right on the ground near this broken branch above I found a small piece that had broken off when that branch came down.  It was red in color like that branch but on carving some off, I found that the red color was mostly a product of weathering and that the wood was a lighter color.  It was also surprisingly light, similar to redwood but with a consistency that felt more like cedar.  And then it occurred to me, why not?  If you are going to grow large, why not build yourself out of light wood.  Since most of the weight of the tree is in the trunk, the lighter it is, the larger you can build it.  Sequoias and other conifers dont have huge spreading branches like oaks and so most of their strength is needed to resist the compression of the mass that piles up on top of the roots, mostly in the trunk.  Hardwoods like oak on the other hand that put out large lateral spreading branches need stronger wood to resist bending forces and stronger wood is heavier.  And so boat builders like conifers because they produce long straight trunks that can be cut into long straight boards.

As a boat builder I use wood. And as a paddle maker I also use wood, especially wood from older trees since they are the ones that have the wood that is clear of knots. But to use wood without a knowledge of what happens to the forests where that wood is taken from is akin to buying a pork chop in a supermarket without knowing that one needs to kill pigs in order to make that pork chop.

The impact that the visit to the sequoias had on me was to see trees as individuals.  Young trees a few decades old, especially in large quantities tend to be rather similar in appearance and lack distinction as individuals.  Every tree seems to look like every other tree and so one can more readily regard them as a crop to be cut for use as lumber.  Old trees however, tend to be distinctive, each one different from the next and since in the case of the sequoias they may have been around for perhaps two thousand years or more, one is forced to realize that cutting one of those trees for human use deprives the rest of the world from the presence of such old trees for another two thousand years.  And so it seems that to cut such old trees is rather frivolous because the gain in lumber does not make up for the loss of the presence of the individual.  

And yet, as a wood worker, I use wood.  And since I make objects for other people, I want to give them a good product free of flaws and blemishes.  I want to give them something that looks like wood is something that is extruded by a machine. 
Perhaps I need to rethink my approach.  If I do not want to participate in the cutting of old trees, then perhaps I need to figure out a way to make paddles from younger trees whose wood is not quite as perfect and blemish free as that of older trees.  Stay tuned, I have some younger trees in mind that I will experiment with

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False battens blocking for deck framing and shiny stuff

Trying to push this project on toward completion, tonight I started measuring for the deck framing. So far, it has been mercifully simple.

I clamped my big adjustable T-Square onto the forward frame at the centerline, and measured the halfway point between the frame and the breasthook. Then, I set my 48" ruler across that halfway point, at right angles to the T-Square. After determining the rulers contact point with the sheer was an equal distance from the frame on both sides, I clamped the ruler into place, and marked the sheers. Then, I measured the angle at the intersection of the ruler and the sheer. Thankfully, it was a very easy-to-cut 20°. 

Measuring for the deck framing.

The blocking for the deck framing required a simple 20° cut. Here is the starboard side being epoxied into place.

Blocking for the deck framing on the port side.

Here, the false battens on the floor are being epoxied into place. All those boards look a little excessive to my eye, but the false battens do serve a practical purpose.

Tonight I drilled the holes & installed the stainless steel grab handle on the forward frame. The first time I rode in a Glen-L Utility, I realized this is a "must-have" item.

Progress...

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Halfway Round Alameda in a Kayak

A week or so back I paddled halfway round Alameda, an island off the coast of Oakland.  People paddle all the way around the island occasionally, a trip of about 15 miles.  A complete circumnavigation is something that can be done in about four of five hours and is a good way to kill a Saturday when you figure in drive time to get to the launch point and a stop at a restaurant afterwards. 
I dont often do these kinds of paddles because they take up too much time.  Usually I drive the half mile to the boat ramp closest to my house and put the boat in the water for a short, less than an hour paddle.  The truth is that I dont much care for paddling any amount of distance.  Distance paddling is quite frankly boring.  It is like driving on the interstate across Nebraska.  Lovely, but unvarying views.  It can be done if one works oneself into a trance.  I much prefer playing around in waves, a little surfing, some rolling and just enough paddling to get warm.  Then back to the car.  But the bay has no surf, just short waves and when there are waves, there is also an unpleasant amount of wind.  Tribulation exceeds excitation.
The trick when trying to paddle somewhere solo is to get oneself locked into some sort of no-return situation where one has to finish the trip or might as well finish the trip when the temptation is to turn back after half an hour and go somewhere for a beer or a cup of coffee. 
This is how it was on this paddle.  My plan was to endure paddling for an hour and then turning back for a total time on the water of about two hours rather than doing the usual turn around after 20 minutes which would have me back at the boat ramp in under an hour. 

The view at the Grand Avenue boat ramp in Alameda.  The nose of my kayak is visible in the foreground. Beyond that, the estuary which in this region goes by the name of Oakland inner harbor. The white ship in the background is one of the coastguard cutters tied up to the pier on Coastguard Island.  To the left lies Oakland Middle Harbor and the Bay.

As it turned out, I was ready to turn back after half an hour of paddling but hung on and kept going down the estuary and in the general direction of San Francisco bay.

A nice purple boat house about two miles down the estuary.

Some more boat houses.  Jack London used to tie up the Snark somewhere around here before he took off for Hawaii.

The Snark on the estuary.

 Having paddled two miles, I would normally turn back without having wasted too much time and gotten some exercise and taken in some of the sights.  Unlike the scenery on land, the scenery on the water is always changing due to the mobile nature of the nautical bricabrac that floats in the water.

A tug tied up to a barge.  The big white thing behind it is one of the floating dry docks at Bay Ship.  Off to the right, the iconic cranes of Oaklands container port, images of which turn up on tee shirts.

The SF to Oakland ferry passing by a scrap metal carrier.  The soundtrack here is of big chunks of metal being dropped into the metal hold of the ship, creating much clanking.

 And here, in case you never read the country of origin labels on the stuff you buy is a picture of where your stuff comes from (China) and how it gets here (in containers) on top of a big ship.  Most of the ships are black (American President Lines) but sometimes also blue (Maersk). 
Returning to the journey, at this point I was about 45 minutes into the trip.  This would have been a good time to turn back.  I could have been back at the boat ramp in another 45 minutes and would not have done too much damage to the day.  Instead I kept going forward since I could see the channel marker at the end of the estuary, just another mile or so off.  Also, at this point I considered the option of paddling around the tip of the island over to where my shop is, taking the kayak out there and riding my bike home.  More paddling but I wouldnt have to look at all the same stuff I looked at going out.  And so I went.

I did it.  I paddled out into the bay and rounded the corner of the island.  Off to the left, newly installed steel pilings to prevent toxic trash from decades past from washing into the bay.  The VA intends to build a hospital here on top of the toxic soil so the deal is to bulldoze about six feet of untoxic soil over the top of the toxic soil and thats that.  When it rains, water moves in a downward direction so the toxins move down or sideways, but not up.  Anyway, thats what they claim and their lawyers approve.

The view west across the bay, about two miles distant the bay bridge and beyond that, the red lead primer painted Golden Gate Bridge. At water level, decommissioned warehouses where cargo used to be unloaded the old-fashioned way by longshoremen. Now the warehouses are home to restaurants and circus troupes.

The end is in sight.  The structure ahead is in line with one of the disused runways of the former Alameda Naval Airstation.  Runway lights were mounted atop this structure.  Now it is used mostly by aquatic birds.  Gulls, cormorants and on this day, one great blue heron. Visible in back and to the left, the Shop, where the aquatic portion of my journey ends.

So that was it.  For he last part of the journey I had the wind in my back, wind out of the north with me heading south, then for the last mile, the wind off my left flank as I headed east. 
Total mileage according to google maps, 7.6.  Elapsed time, roughly 2 hours.  After that, four miles home on my bicycle.
Since I dont get out in the kayak all that much, I was pleasantly exhausted, with my mind empty of thought, a wonderful state to be in, but came at the cost of spending two hours in a kayak. 

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Tiller Rudder pintles and gudgeons

December 26, 2014

The weather was up in the 50s today.  Therefore, I took the opportunity to do a little work on the boat by installing the gudgeons and locating the pintles.  After several measurements with the help of my daughter (this is a two man job), we decided the lower pintle and gudgeon were on center, and just high enough for the rudder cheeks to clear the water while under way, while giving maximum blade depth. An hour or so later, sealed the holes, bolts, and nuts with 5400.  The tiller clears the deck with room to spare, but is not too high.  It also looks as if the chosen length is just right and with a tiller extension will be a pleasure to operate.  We hope we got it right.

Tiller clears the deck.  

Vertical alignment looks ok.  

Just a nice shot.  

Length of the tiller looks good.  I like a slightly larger handle for long rides.  Most steering will be done from the tiller extension.  I will also add an uphaul in addition to the down haul.  It is not on the plans, so will need to be creative. 

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