Monday, March 24, 2014

The New Bronze Age


This past weekend I took time out from dinghy-building to participate in the bronze-casting workshop that has been offered by the Center for Wooden Boats for a couple of decades.  Originally launched by Sam Johnson, it has been ably taught by James McMullen for the past decade and a half.  The two-day workshop at the Camano Island CWB facility takes you though the basics of managing and using a simple low-volume foundry for casting parts of bronze that can be put to work on a boat.  Take your spouse and rent one of the Cama Beach waterfront cabins.


Most of us rarely use anything hotter than our kitchen stoves.  To bring 15 lbs of metal to 2000+ degrees and pour its molten spirit into a sand mold is an uncommon experience, at once primitive and technologically powerful.  Literally, transformative.  An undifferentiated chunk of alloy is transformed, by dint of conceptualizing, patterning, molding, melting, casting, and finishing, into a durable, useful boat part (or perhaps an object d'art) over a period of hours. To proceed over a mere pair of days from complete novice to, well, a novice with the rudimentary skills to effect such changes is nothing short of exhilarating.


There are many patterns made by the instructor that can be used to cast useful or attractive objects... Plaques, oarlocks, cleats, rings, pintels, gudgeons, and many others, including the ever-popular busty-mermaid marling spike (I did two, the second patterned from the first).  Some of us ventured into parts of our own design, as well, as with the tiller comb I patterned onsite and brought home to do final finishing.  A future post will show its installation and use on Ripple.

You'll also learn how to bootstrap yourself into all the tools necessary, including the foundry.  I am hopeful that some of the veterans of the workshop may coalesce into an informal casting cooperative to fire up some molten bronze on occasion.  Cast in stone has nothing on cast in bronze.


Want to play?  Demand for the workshop has occasioned the scheduling of a second workshop this Spring, to be held in late April.  Contact the Center for Wooden Boats for details.  You won't be sorry.


My productivity for the weekend included a rattler (a tool used in the making of the mold), two marling spikes, a bronze towing-eye for the dinghy,  and two pieces which I patterned myself, intended for use as a tiller comb when finished out.  I also had two casting failures, both with the towing eye.  Leaving the pattern in the mold is the most basic of bone-headed failures.  Glad I got THAT out of the way.


Monday, March 3, 2014

the punchlist grows tiresome


On the advice of my brother I mixed up some epoxy and diluted it with acetone to coat the dagger board, making it slightly more impervious to swelling.  I coated the entire piece with the epoxy and then wiped it down with a rag saturated with denatured alcohol, leaving the wood with a (penetrating) epoxy coating that will help keep out the moisture when it develops dings.  To not do so would be to court swelling that would make it difficult to use the board in the case.

I'll sand and varnish as with other bright finishes on the boat.

I used my remaining modest aliquot of Brightsides (Hatteras White) today, and it isn't enough.  I'll buy another $40 quart and sand the interior semi-seriously and see if I can get a good finish coat or three.   I can feel the resistance of my patience flagging... I want to be done, I want to be in the water.  I need to suck it up and get a good interior finish in place.  I'm guessing three coats.


Wednesday, February 26, 2014

Interior lives

Recent days have witnessed a series of two hour spurts of progress that seem to stretch out like silly putty, distorting time and results.  I finished the daggerboard case, multiple epoxy glue-ups that finally came together as a piece: case cheeks, logs, vertical spacers, floors, forward cap, and top cap.  I got them installed and the result is very solid, tied together and screwed into the keel and epoxied.

I shaped the daggerboard so that it would slide easily into the case, and profiled the cross section below the water line according to the plans.  Handplanes and random orbit sander did the trick.

I glued in the inwhale spacer blocks, figuring they would benefit from being painted with the interior of the hull, with only the tops varnished with the entire rail assembly.

The breasthook went in, with epoxy and bronze screws in from the outer rail.  Shaping it with a nice crown was pretty straightforward.

I put two coats of undercoat on the entire interior.  It went pretty well, but the finish coast... well, we'll see.  The first went on today, and it looks pretty sad.  But i think i did 6 exterior coats before I ended up with an acceptable finish.  The interior will me harder still I think.

Tuesday, February 11, 2014

Little stuff



I started assembling the case today, realizing it is going to take several stages (days) of glue-up to put it all together.  Taking a cue from the book (duh), i decided to glue just one of the cheeks to the case uprights.  It will be best to paint the insides before assembling the case, and I may even include a few inches of anti-fouling paint on the lower few inches.

Tomorrow I'll glue the other cheek to the assembly, and fit it into the slot in the keel to make sure it will go together and mate with the floors at stations 2 and 3.   The third stage will be to add the end cap, logs, upper rails, and topcap.  There will be some additional cosmetic trim pieces that will hide the aft edges of the case cheeks and improve the visual balance of the case.  All but the top-cap will be painted.  The top cap will be finished bright, as it will be perpendicular and contiguous with the midships thwart.  The other thwarts, quarter knees, knee braces, and floorboards will also be finished bright.

While  I was messing with epoxy, I glued the floors for stations 4 and 5 into the bottom, using some poplar battens to spring-clamp from the ceiling.



I finished the day making the oarlock caps from a piece of iroko I had around from the summer's replacement of the chafe strips on Ripple's mast.  Iroko is an inexpensive teak substitute, and should stand up well to the battering it is liable to suffer in this application.


I drilled the holes for the bronze gudgeons, traced the outline of each gudgeon, and drilled the corners of each with a small forstner bit to approximate depth.  I knifed the outlines so as to start a knife wall for chiseling, wasted the insides and then progressively brought each to a constant depth with the router plane.  I really like this tool!  I will find many more things to do with it, I am sure.

About 4 hours, and a real relief for the temperature to have come back up into the 40s and 50s.

Monday, February 10, 2014

The daggerboard case



Today I sorted out the daggerboard case.  It is the focus of quite a lot of stress during sailing, not a component to be underbuilt.  It wasn't clear to me how best to integrate it with the midships thwart and the floors at stations 2 and 3.  My MO is to work through it a a component at a time, and see if they all work together.  I just don't have the experience to lay it all out on paper and do it.

At a late moment, I decided to make the dagger board only 9 inches fore-and-aft (the plans specify 12), and the slot in the bottom is 12 1/4 inches long.  My reasoning was that I've seen lots of daggerboards for small boats closer to 9 than 12, and on Ripple, storage is an issue, and a 9 inch board would be easier to stow.  Oh, and I had a suitable piece of sitka spruce 9 inches by 4 quarters.  And straight and true.

This meant re-engineering the case verticals to fill in the 3+ extra inches.  Doing so has the additional benefit of strengthening the whole assemblage, both by increasing the gluing area of the case verticals and the case cheeks, and by extending these verticals down into the 12 inch slot to the bottom of the keel.  The first image shows these verticals.  Note that they are notched to bear on the floors at stations 2 and 3.

From that point, it was a matter of working out the dimensions of the case logs (the pieces that meet the keelson and the cheeks), the forward end cap, the upper rails (that also help support the thwart), and the top cap.  It all fell into place, though it is not entirely clear to me at this time what the sequence of assembly should be.  

I am very pleased that the case and the floors and thwart will all be integrated both structurally and visually.  I think it should work well and long.


Below is a picture of my benchtop at the end of 5 satisfying hours of work on these components.  Uncharacteristically, I cleaned it up before I left for the day.


Sunday, February 9, 2014

Floors

Floors are really just partial ribs, giving some additional structure to the bottom of the boat, as well as providing bearing surfaces for the removable floorboards.  They straddle the keelson, spanning the garboard and second strake, and are glued in with epoxy. 

I elected to pattern each with scraps of planking material... easier to shape than the 4/4 yellow cedar.  Still, spiling the shapes to the bottom at each of 4 stations turned out to be fussy work, especially for the first couple.  Running out of propane for the heater in the middle of the work made for a long session.

When each pattern was close, I traced the profile onto cedar blanks and bandsawed them to shape, and adjusted the profile as necessary with a block plane.  I improved sufficiently over the sequence to motivate me to redo the first of them.

I left the floors at stations 4 and 5 un-shaped on the top. as I have not yet decided how to tie them into the daggerboard case.

About 6 hours over two sessions, including thickness-planing the stock.



Friday, February 7, 2014

Thwarts and ledgers


This week's temperatures have made it difficult to spend much time in the shop.  Well, that and the Seahawks parade, for which I took the day off.  Yesterday I glued in the thwart ledgers, which took two hours or so of fiddling, measuring, remeasuring, gluing, clamping, and double-checking. 

The glue-ups worked out well enough... one had slid slightly out of alignment, but I had left them square, to plane subsequently, reasoning that this would afford good opportunity to make any fine adjustments that might be necessary.  It did.

I resolved to cut, fit, and sand the thwarts so as to be able to bring them home to varnish while I continue to work on the interior.  Le Tonkinois, the varnish I use and love, has such low solvent content that you can varnish in the house without much in the way of noxious odors.  This I will do with a number of parts.  The workship is no fit place to varnishing.


I got the thwarts done, including rounding over the edges, and figured I might as well do the stanchions for the sternsheets and the forward thwart now.  Its a bit tricky, as you're dealing with odd angles both where they meet the keelson and the underside of the thwarts.  The midships thwart bears on the aft member of the daggerboard case, and hence requires no separate stanchion.

The stanchions are let into the keelson and the underside of the thwart, which gave me occasion to try out the router place I acquired for the oarlock caps.  It works like a dream, making quick work of the bearing pockets, leaving a flat inside bearing surface.

A successful and productive day -- everything worked out well.  On to the daggerboard case, which I have only roughed out, and which requires some additional thought, as I want to make it structurally integral with the floor beam at station 3.  This will require moving the floor beam aft an inch or so, but that shouldn't present any problem.

About 5 hours in very cold temperatures.