Stambaugh Sailing Skiff Build in Virginia Mountains

[UCanoe_2]

RAN lofting triangulation_02.jpg
Please refer to pp. 40-46 of this document:

http://www.boatregister.net/Library/Maritime%20History/Lofting_RAN_AprrenticeTrainingEstablishment.pdf


The Royal Australian Navy needed an on-the-ball technical editor. Various drawings use the same letter to designate different points. Even my high school geometry class used labels like a, a', etc. I followed the instructions for development by triangulation as far as drawing the true distance between the first two points of triangulation, but didn't get the next step.

Photos of my attempts may be enlightening, and if anyone can explain this stuff, please do so. Maybe I should retire my WW II era French curves held together with tape.....

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[UCanoe_2]

Befuddled by the graphic techniques, I went old school and built a half model. It has plenty of errors and inaccuracies, but now I can scale up patterns for side panels that will at least sort of fit the boat.

Attachment 43534

I even glued up a scarf joint in scale lumber to create a miniature batten.

Attachment 43535

The scale lumber is two pieces of HO scale 6" x 8". HO scale is 3.5 mm = 1'-0", or 1:87. Whose crazy idea was that?

What are the scale dimensions of this lumber in 1:12 scale (1" = 1'0")? We multiply by the ratio of the two scales, so:
12/87 * 6 = ? and 12/87 * 8 = ?

Before those forumites who are encumbered with the metric system turn on your calculators, an approximation will make the mental arithmetic easier. Every carpenter in the US knows that 7 feet = 84 inches. 87 ~ 84, so our "close enough" calculations become:

12/84 * 6 = 1/7*6 = 6/7 and 12/84 * 8 = 1/7 * 8 = 8/7.

So the 1:12 scale measurement of the batten is 6/7 inch by 1-1/7 inch. That's just a little larger than 6/8 inch (or 3/4 inch) by 1-1/8 inch. We are in the ballpark of reasonable batten sizes for this curve.

[UCanoe_2]

Here is the finished half model.

Attachment 43536

The side of the half model is 1/32" thick basswood. That scales out to 12 * 1/32 inch = 12/32 = (3 * 4)/(8 * 4) = 3/8 inch.
3/8 inch is almost exactly 9 mm, which is the plywood thickness specified in the plans. The blue sheer strake is a second layer of 1/32" basswood.

Enough math for one evening. Here is Mickey, the shop cat, reviewing boat plans:

Attachment 43537

[UCanoe_2]

The photos in my last two posts are not visible. Let's try again.

Half model frame:

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Lofting side panel pattern with miniature batten:

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Completed half model, with blue sheer strake:

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Mickey studying boat plans:

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Thanks for looking!

[UCanoe_2]

"...there was never a boat built in which too much lofting had been done." But for any boat there must be a limit to how much can be done. I've thought before that I was on the home stretch, but now is time for filling in details.

Corrected some errors in the sheer strake profile, which does not photograph well.

I liked the proportions of the curves of the breast hook...

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... and decided to make the curves of the stern sheets, quarter knees, and forward deck match. Sort of a repeating design element. Used one sheet of the $40 carbon paper to trace a pattern.

Drawing the quarter knee, the really flexible plastic batten may have reached its elastic limit and become permanently deformed. We'll see if it straightens out.

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Stern sheets

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and forward deck, cut away for mast gate.

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[UCanoe_2]

Drew cross sections of chine log, sheer strake, and seat/deck risers on the body plan...

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... and drew hull side panel full size to dimensions taken off half model. I knew the side panel would only be sort of close due to errors in half model and in scaling up dimensions. But at least there will be an approximate pattern that can be adjusted to the hull as-built. Here is the glorious array of confusing lines from the only available photo angle.

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Next: making patterns, building a scrieve board, and at last assembling frames.

[UCanoe_2]

Distracted from boatbuilding for a while, but getting back on track.

Salvaging doorskin from $1.20 hollow core door:

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Salvage materials always involve more work than new materials. Inside the hollow core door.

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Trading time for money by sanding old glue and peeling varnish.

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[UCanoe_2]

Tracing breast hook pattern from lofting onto vellum:

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Transferring tracing onto plywood with carbon paper and tracing wheel ($1.73 at WalMart).

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Pattern traced onto scrap plywood paneling, ready to cut out with bandsaw.

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[UCanoe_2]

Once again, I have been distracted by work.



More patterns drawn on the salvaged doorskins:

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Oops. When the A/C in the shop was running, the doorskins warped like potato chips:

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Fortunately, when I turned off the A/C and exposed the doorskins to ambient humidity, they mostly flattened. They are usable, and I coated them with shellac:

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[UCanoe_2]

One side benefit of my retirement job is getting lumber dressed and cut to size at no cost by the vocational school woodworking students. Unfortunately the program is closing. Here is my frame lumber, a mixture of Phillipine mahogany and true mahogany:

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Took a side trip to the Mid-Atlantic Small Craft Festival. After visiting the museum boat shop, I have bandsaw envy. Mine is a 10" ShopSmith from 1957. The 14" Delta in this photo is dwarfed by the huge shipsaw:

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[George Ferguson]

UCanoe_2, I love this thread, and your cat. That's cool about the garage door.

I'm curious about the shell expansion lofting. Was that in place of lining off planking and spiling for planks? I'm a novice at this stuff but I'm interested in all of it and like to learn different ways of doing things.

I can understand what they are doing in the "diagonal method", assuming x, y, and n, represent lines you would produce in the lining off process for planking that are transferred to the body plan and then the diagonals are drawn. I think this is what someone who would line off the hull other than using the batten over form method typically seen in wood boat building, and instead did it on the drawing first. When you draw those lines onto the body plan you end up with the x,n, and y lines, and then you need to know the curvature of plates that would be used for the hull skin between the four points you chose at intersection of "plank" lines and station lines. This is actually kind of a neat concept for being able to check the fairness of your hull on the body plan by being able to use diagonals across the skin of the frames.

The photo below is an example of a drawing for a boat where the plank seams have already been lined off. If you visually bend a batten between all the intersections of the plank seams and stations, you will be able to see they are "fair". That "fair" line would be the same as the diagonals being produced in the diagonal method of the shell expansion chapter in the lofting manual you are using. If you are building a ship with a steel hull before the days of specialized AutoCAD programs for designing boat hulls, this would the way to do it. .................As I type this, I'm actually able to think through it and see how it's working. I've never even though of this. Now I'll be tempted to try this, LOL!

I think with your hull, making your molds, setting them up, and lining off with battens would be the best way to do it. That's essentially what you did with building a model, and then lining it off.

EDIT: Now the folks who recognize this lines drawing I have put in this comment will be chiming up about it. I used this drawing for my first practice at lofting. I was thinking of building it at the time and then changed gears. I hope to go back to it some day.


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[UCanoe_2]

Thanks, George. Sorry to be away so long. I will have to reboot my brain and try again to wrap around the expansion techniques. But I sure am glad I am building a flat bottom skiff. You chose a really ambitious first lofting project!

I actually have done some work that I have not posted, partly due to the forum being wonky.

I laid out the body plan on a screive board:

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And sketched some alternative sail plans. Karl's original leg-of-mutton is still my first choice, partly to build as designed, partly because it is an efficient and weatherly sail, and partly because the traditional Chesapeake look is way cool. But I am a bit concerned about handling a 19 foot mast in my old age. Karl drew a 70 sq. ft. spritsail for the Bay Skiff 15, and a Michalak 74 sq. ft. lugsail rigged standing looks like it might work as well. The COEs of the three sails would fall within a few inches of each other, and adjustment could be easily made by slight changes in the rake of the mast.

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[UCanoe_2]

The second hollow core door did not give up its skins as easily as the first! I had to split the reinforcing ribs with a chisel and wedges.

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[UCanoe_2]

I cleaned and lubricated the 1957 ShopSmith bandsaw. Replaced the blade, installed new Cool Blocks, and squared the table to the blade, which does not show up well in this photo. I also installed a dust collection port, which nobody thought of in 1957.

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Blew the sawdust out of the old ShopSmith with compressed air. Cleaned, lubricated, adjusted, and waxed everything. These unusual machines are really not complicated, just different. Some service items are accessed through a hole that my hand just barely fits through -- that could be improved.

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My boating buddy was a bit insulted when I told him the continuously variable transmission on his new Honda operated on the same principle as the ShopSmith -- but it's true. It's called a Reeves Drive, and it was patented in the 1890s.

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[UCanoe_2]

Cutting out patterns from doorskins. The ShopSmith at right is only supporting the workpiece on its table. It is not powering the bandsaw, because I am missing a power coupling part.

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Patterns at last! Forward deck, stern sheets, centerboard, centerboard case, inner and outer stems, transom crown, and skeg. Quarter knee and breast hook patterns were shown previously.

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[pelicanbuilder]

I see that the Wooden Boat Store offers these plans and notes that "no lofting necessary". Are you lofting for the experience or do you have different plans?

[UCanoe_2]

Hi, Pelican. As far as I know, I have the same plans. Most of the "no lofting required" plans I am familiar with show expanded side panels, which my plans do not have. That's why I made the half model shown in post #39 above.

I have found lofting to be a great benefit, and think it would be difficult to build from the Sailing Skiff plans without lofting. Karl sells full size frame drawings for an additional $75, which I do not see listed in the WB store. Maybe with those you could build "without lofting," but then you would take off dimensions and develop patterns from the boat under construction. You would make mistakes with expensive lumber and plywood, rather than on a drawing. Also, I found a discrepancy between the full size frame drawings and the table of offsets, which lofting helped me identify.

Don't be afraid to loft this simple flat bottom skiff. You don't have to let your OCD come out and draw in as much detail as I have. It's basically applied plane geometry from high school. (At least, when I went to high school. Kids these days often just memorize formulas and don't get to draw stuff, which is the fun part. Don't let me get started on my rant about today's educational system.) The only formal training in drafting I have had was part of a semester in 7th grade shop class. I learned a little bit from my dad, and from reading his old correspondence school textbooks. I sketched model railroad track plans in my school notebooks when I was bored in class.

So I have basically learned a bit of lofting as I went along with this project. It has really helped me think through details of the building process and in the end will save a lot of time and frustration.

[UCanoe_2]

Here is Flora, my canine shop helper. She's very modest and a bit camera shy. When the boat is finished, she is a much more likely passenger than the cat.

Oops! Who left their undies on the workbench? (The photo does not show that they are labeled "RAG.")

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Having made all these patterns, now I needed a place to stow them. Just by serendipity, when we built the new garage it turned out to have a 10 foot ceiling, giving a little more storage space. But first I had to relocate the cow pelvis, a souvenir from a canoe trip on the South Fork of the Shenandoah River.

I thought of naming my shop "Cow Pelvis Boat Works," but that is not very euphonious.

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Larger boat patterns hung over the shop door, out of the way but easily accessible.

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Cow pelvis now hangs over a window, with smaller boat patterns above the bandsaw.

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[UCanoe_2]

At last I am actually making boat parts! I made a simple cutting guide for the circular saw.

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Plywood frame bulkheads for Stations 1, 2, and 4, plus double thickness transom skin. Karl recommends doubling the transom if the boat will have an outboard motor. (Station 3 in this plan is just ribs, without a bulkhead.)

Mickey, of course, hamming it up for the camera.

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[UCanoe_2]

Seems like I spend as much time organizing the shop and tweaking my 50-60 year old tools as I do actually boatbuilding. Now it's time to work on the radial arm saw, which will be handy for bevel cuts on larger pieces of lumber. This particular saw is Craftsman's economy grade from the late 1960s -- made with aluminum components rather than cast iron. It may not be a top of the line machine, but it has better potential that the awful stamped sheet metal saws that came later. The saw spent much of its life in a damp basement, has been moved several times, and the table was beat up. There is definitely room for improvement.

The new table it 3/4" MDF with two coats of shellac for moisture resistance. It's reinforced with electrical channel, so it will stay flat and stable.

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The bevel lock and carriage pivot were loose, so they got tightened.

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The carriage bearings ran smoothly, but were noisy and caked with sawdust. This part has been out of production for years, and replacements are unobtainable. I soaked them in solvent, and then soaked them overnight in heated oil. They still run smoothly and are noisy, but probably this is as good as it gets.
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The "sacrificial" table top is 9mm okume -- it's the flattest and most stable plywood on hand. When the top surface gets beat up, I can flip it over to extend its life. With a little adjustment using a playing card as a feeler gauge, the top is flat and parallel to the saw's arm.

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[UCanoe_2]

More tweaking the radial arm saw. If you have one of these machines, Jon Eakes's ebook Fine Tuning Your Radial Arm Saw gives many tips and techniques for adjustment that the manufacturers don't tell us. https://www.joneakes.com/learning-cu...adial-arm-saws

Checking the fence for straightness with a level and feeler gauge. It's improved since this photo was taken.

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Making shims from .012" aluminum flashing to adjust carriage bearings for vertical heel.

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[UCanoe_2]

The adjustment screws for the miter latch were binding, making it difficult to adjust the saw for square cuts.

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I cleaned gunk out of the threads, then honed the mating surfaces of the screws and latch.

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Reassembled, lubricated with graphite lock fluid, and now everything works smoothly.

Final adjustment will have to wait until next week. There's a trip on the calendar for Family Holiday Celebration #3 (a total of 35 people on the Christmas gift list).

See y'all next year.

[UCanoe_2]

I haven't posted for a few weeks....Here's what happened in the meantime.

Radio Alarm Saw all tuned up, cutting square to table and square to fence.

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We'll see how long this saw stays square....Economy grade Sears saws don't have the best reputation...OTOH, this one is from the late 60s, right at the beginning of the decline in quality, and it was a gift.

[UCanoe_2]

One point of the trip down the radial arm saw rabbit hole was to have capability for bevel ripping of large boat parts. My only table saw is an old ShopSmith, with a small table, and a tilting one at that. Beveling the edge of this plywood bulkhead would have been really awkward.

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[UCanoe_2]

Today was a major breakthrough in boat construction. The stock for frames was previously dressed by the vocational school students. This afternoon I cut the parts to length, 20200121_152226.jpg

...ripped them on the 1950s ShopSmith band saw,

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.... planed them to size,

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... and rounded over the corners.

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The old Stanley No. 29 cornering tool is much quieter, safer, and more convenient than a router -- and just as fast.

[UCanoe_2]

One forum member -- pardon me for not remembering who -- is fond of saying, "There's the plan....and then there's what actually happens." Murphy reared his pretty little head this evening.

The plan: Glue up bulkheads frames/floors/ribs, clamp everything, and then fasten with composite brads. Theoretically, this would speed production by freeing clamps for use on the next assembly.

What actually happened: In previous tests, the composite brads worked flawlessly with my $25 brad nailer from a boat festival swap meet. Today it was a little balky, but after fiddling with adjustments it worked well fastening scraps of frame material together.

OK, time to mix epoxy. I used MAS Flag resin with fast hardener. Reserved some straight epoxy for priming the parts, then added milled glass thickener to the remainder. Spread epoxy on my first parts, lined them up, and clamped them in place.

Time for the brad nailer -- except it would not nail! Frantically, I gave it a dose of air tool oil and fiddled every which way with adjustments. Still nothing.

Of course all this time the epoxy was kicking off. I spread gummy epoxy on the rest of the parts and slapped on more clamps. The temperature in the shop was about 60*F, and I did not have as much working time as I expected. I didn't work as neatly as I hoped, and had a lot of squeeze out to clean up. Next time I will use medium speed hardener and give the brad nailer's magazine a good dose of lubrication.

But, as I said, today was a breakthrough day. I actually assembled boat parts, and the first frame is finally glued up.

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[Woxbox]

Even when I'm working in 60 degree temperatures, I use slow hardener so I'm not forced to rush. If I need it to harden up a bit quicker, I'll just put a couple of squirts of fast hardner in the mix. Even at 60 degrees and cooler overnight, the MAS epoxy I used on my last project was plenty set enough for the next step in the morning.

So carry on. It's gonna come out great.

[UCanoe_2]

Thanks for the encouragement, Dave. I got the fast hardener to be prepared for winter -- lows outside have been in the teens for the past few days. I can set the shop thermostat for minimum heat and it will be 45-50. I also have plenty of medium hardener. I really like the MAS. I have used it on other projects and found it to be easy to work with and consistent.

[UCanoe_2]

Two more frames glued up this afternoon. This boat only has full frames at Stations 1, 2, and 4. Station 3 has only ribs. After the epoxy cures on these, I will start making the transom.

Once again, the brad nailer worked fine in testing, but jammed once the epoxy was mixed. The Law of Perversity of Inanimate Objects is operational again.

In case anyone is inclined to count, there are 23 clamps in this glue up. Can you tell which clamp pads were salvaged from the plastic recycling bin?

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[UCanoe_2]

The 10 foot ceiling in the shop provides extra space for storing boat parts. The shelf in the photo is 20 feet long with 28" clearance to the ceiling. Two 19+ foot black lofting battens are hanging on hooks below the shelf.

Here the completed frames are stowed out of the way, but with easy access. My glue-up was pretty messy, and there is excess epoxy removal in store for the future. But first, I want to assemble the transom and do all the cleanup at once.

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[UCanoe_2]

Karl recommends doubling the plywood on the transom for use with an outboard engine. Here I am laying out the transom framing on the inner surface.

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Using waxed screws to hold the two pieces of plywood in alignment, I applied epoxy and fit them together. Finally, after lots of lubrication, the brad nailer worked according to plan, so the transom assembly is held together with composite brads in addition to glue. I piled on buckets of paint for extra insurance. This is a much neater glue job, and little cleanup will be required.

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I found the workbench in the background in the local classifieds for $25, less that it would have cost to build one from scratch. It was some kind of assembly work station in a factory. It had been stored in a shed with one leg off the ground, so the 27" x 72" maple top was warped and required lots of flattening with a plane. The legs were conveniently provided with knock-outs for electric outlets, so a little more work gave me a place to plug in portable power tools.

[pelicanbuilder]

When I log on the first thing I do is look for your latest post. I think I want to build this boat but just haven't got enough info to satisfy my curiosity. Would you tell us what type of mast the plans call for?

[UCanoe_2]

Pelican, thanks for following my thread. Just go for it and build. The mast is 3" in diameter at the base, and 19'6" long.

I highly recommend Karl's e-book, Good Skiffs, which you can download from the CMD website https://www.cmdboats.com/books.htm?c...145ba7062ccf0d

There is a chapter on the Sailing Skiff and its sister, the Bay Skiff 15. Karl describes gluing up a mast blank for the Bay Skiff from spruce 2x4s. I see he also has a new ebook about mast construction for small boats.

[UCanoe_2]

Ripping the transom floor timber (is this correct terminology?) and seat riser from 6" wide mahogany.

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The ShopSmith is my only table saw. I was apprehensive about bevel ripping on this machine, but it turned out to be just fine. Gravity tends to hold the workpiece against the fence.

In the 1950s, saw guards were optional, and dust collection was unheard of. One of the first things I did after I acquired the ShopSmith was to install modern upper and lower guards. (The guard set cost less than a trip to the ER.) This required drilling and tapping several holes. The guards work pretty well, given the limitations of retrofitting an older tool. Because of the table tilt, the upper guard falls down onto the saw blade. If you look closely you can see the duct tape which is my present solution to this problem.

Dust collection is less than stellar, but better than nothing. Depth of cut is adjusted by raising and lowering the table instead of the blade. The lower guard has to accommodate this movement, resulting in gaps where sawdust can escape. More duct tape in the future will close some of these holes.

The ShopSmith came to me with a 60 year old, ungrounded, two wire 16 gauge power cord with crumbling insulation. The yellow wire in the photo is the replacement. It is just a 12 gauge three wire extension cord with the receptacle end cut off.

[UCanoe_2]

The transom framing also requires some bevel crosscuts. To keep the same angle as the rip cut, I made these on the SS without changing the setting. This process requires defying gravity. The clamp on the miter gauge helps some, but still a third hand would be convenient. Because of the tilting table, the length of workpiece is limited by the end of the board hitting the floor.

Note Mickey, the shop cat, walking away in the background.

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