Re: [bolger] Expansions from Bolger. Dart / Cartoon #30 / ...

This is supposed to be the best book on panel expansion, and was probably
used by PCB when he was learning:

Ship and Aircraft Fairing and Development: For Draftsman and Loftsmen and
Sheet Metal Workers by Sam Rabl (yes, THAT Sam Rabl!)

http://preview.tinyurl.com/43939qd

Hoo boy! They sure get a bundle for a copy nowadays! I think mine might
have cost me $15...

On Sun, 21 Aug 2011 17:30:04 -0700, Christopher C. W. wrote:

> [Snarky and sarcastic comments omitted}. He was a trained draftsman.
> Any good manual on sheet metal drafting has the techniques.
>
> On 8/21/2011 8:14 PM, c.ruzer wrote:
>> How did PCB arrive at expanded dimensions before digital computation?


--
John (jkohnen@...)
In politics, absurdity is not a handicap. (Napoleon Bonaparte)

> How about those many Bolger expansions from Bolger?

Still on about true lengths, sort of, just starting the sheet here for the other tack implied...


Dart / Cartoon #30 expansions:

1st SBJ paragraph omitted from BWAOM Dart Dinghy

2nd, 3rd, 4th SBJ paras "condensed" into 1st BWAOM para (eg see SBJ#54 etc.)

5th SBJ para "condensed" into 2nd BWAOM

6th SBJ para "condensed" into 3rd BWAOM para

7th SBJ edited to 4th BWAOM

8th SBJ edited slightly to 5th BWAOM

9th SBJ para unedited unchanged 6th BWAOM paragraph (focus? origin? reference plane here?)

10th SBJ condensed to 7th BWAOM

11th SBJ edited to 8th BWAOM

12th SBJ edited to 9th BWAOM

13th SBJ edited to 10th BWAOM

14th SBJ edited to 11th BWAOM

15th SBJ edited slightly to 12th BWAOM

16th SBJ edited condensed to 13th BWAOM

17th SBJ edited to 14th BWAOM

18th SBJ edited to 15th BWAOM

19th SBJ edited to 16th BWAOM

20th SBJ edited to 17th BWAOM (each corresponding last paragraph)

> Where's the image of Bolger, drafting with a lapboard come from,
> please?

Mark,

I believe it not to be a bad thing at all to mark whatever Jim Michalak observes or mentions. Some of his recollections in isolation are a little questionable, in my view, but at other times he's mentioned the same thing again in passing and described it differently. Allowing for contexts and style then in considering such historical matters I believe Jim Michalak bankable. I mentioned PCB drawing on his lap like that as I have a mind's eye image, viscerally stamped, of PCB drawing that way aboard Resolution surrounded by his books, etc, as sort of described once by Michalak.

Thanks to Tom Raidna's great boatbuilding pages it's easy these days to check back on things Michalak (and the incidental Bolger)http://buildboats.com/bbmichalakindex.html(by the way, I hope Tom keeps this comprehensive index going... it's so handy. I appreciate the time involved in providing other boaties this service... Thanks again Tomhttp://buildboats.com/index.html)

Between my recollection, and that of Peter V, we're apparently on the Michalak money here snipped:

"...

DESIGN EQUIPMENT...

Drawing boats is an inexpensive adventure. With one avoidable exception (determining the shapes of twisted and bent panels) I think no computer gear is required. In fact that gear might get in the way and slow you down. And you might find yourself designing projects that are limited by the capabilities of your gear. An inexpensive hand calculator is almost always sufficient. Drafting tools can be minimal. A three foot by four foot sheet of 1/2" plywood is a good drawing board although you will have to surface it with a layer of heavy paper to negate its grain. I met Phil Bolger about 20 years ago when he was still working in his ancestral house. He was quite famous and seeing his drawing room was quite a treat. At that time he had a full sized sheet of plywood atop a stack of concrete blocks and could make very large drawings on it for some of the very large boats he was drawing. There was no computer gear and he had no intention of getting any although he said the salesmen were hounding him a bit. Ten years later he had moved into his boat home and his drawing board was quite small, maybe 2 foot square at the most. Perhaps he had a larger board on shore somewhere. At any rate I'm sure he is back on shore now in a real office complete with big drawing boards and electronics. He still does his drawings by hand and I'm sure most of you know that he has a true artist's hand and for him to use a cad program to put out final drawings would be a crime.

No T square or drafting machine is needed, another thing I learned from Bolger who told me T squares are just for quickie diagrams. Don't believe Howard Chapelle used one either. We'll get into the subject of avoiding the T square later.

About three drafting triangles would be nice in different sizes. Get at least one that is quite large.

I use an ordinary three sided architect's scale for measuring. It has fine graduations and when working in 1/8 or 1/12 scales will give accuracy sufficient for boatbuilding from the scale drawings.

I use an aluminum yardstick meant for drywall workers as a long straightedge.

I use ordinary .5mm mechanical pencils that I get at the discount store. Last I saw him work Bolger was using very fine and hard drafting pencils that he kept to the sharpest edge. His preliminary lines were so fine that they were to me hardly visible. He has great eyes and hands and can work with accuracy in much smaller scales than I can.

For a compass I modified a discount store bow compass to hold a .5mm mechanical pencil on one arm by strapping the pencil to the metal compass arm with wire and then potting it into place with a blob of epoxy putty...

...If a design turns out to be a keeper I trace the lines on drafting mylar using ordinary .5mm lead pencil. It must be handled somewhat with care to avoid smearing. Bolger does his tracings with very fine ink pens but I make way too many mistakes for that.


..."

(http://marina.fortunecity.com/breakwater/274/2004/1115/index.htm#Drawing%20Toolsinteresting spiral metaphor used in there... Wharram uses a helix... Bolger used typewriter paper, and the mail or the bin)

I still have a recollection of Michalak mentioning that he didn't understand Bolger's method of conic projection. Not here then, but I'll bet it's in another Michalak essay... probably one to do with hull panels, sheet material limitations, and such.

--- Inbolger@yahoogroups.com, Mark Albanese <marka97203@...> wrote:
>
> My impression is that expanding straight sided boats was
> straightforward enough for him; somewhat more difficult to plot a
> multichine bilge, perhaps whether it twists or not. Some boats done
> with Harold Payson had those patterns fed back from a prototype to
> inform corrected drawings, IIRC.
>
> Two boats that couldn't be done.: Sea Hawk and Slicer.
>
> Where's the image of Bolger, drafting with a lapboard come from, please?
>

> > --- Inbolger@yahoogroups.com, "Christopher C. Wetherill"
> > <wetherillc@> wrote:
> > >
> > > [Snarky and sarcastic comments omitted}.
> >

On the couple of pages following is a method of plank expansion for flat bottom craft with parallel frames.

On Mon, Aug 22, 2011 at 11:12 AM, Peter <pvanderwaart@...> wrote:

> No matter how you do it, it's a tricky business because...

My belief is that it is primarily "tricky business" due to
inexperience. I bet that seasoned boatbuilders, (common a hundred
years ago), could mentally loft the shape of expanded panels using
their brains.

The reason I can say this is that personally I have used a computer to
loft expanded panels for a few hundred boats. (And, have built card
board paper models of most of these.)

After about the first hundred, I have found that I can visualize the
bend of the panels expanded to the flat with some accuracy.

Now that I have learned this skill, I would guess that if you took my
computer away, I still could make some pretty accurate guesses of
expanded panel shapes.

Phil Bolger designed more than 700 boats, and I bet that he could
visualize expanded panel shapes just fine. That said, it does still
make sense to make a model or two (scale size, or full size by
Dynamite) as insurance and for trouble shooting.

PCB was a skilled draftsman. I'm not sure he could be called a trained draftsman. He did work with a couple of NAs which formed a sort of apprenticeship. Also, in the time and in which he grew up, he might have had mechanical drawing in HS.

He referred in a couple of places to the fact that projecting panels added significantly to the cost of design, so whatever his method was, it apparently took hours at the drawing board. Just by the way, I read that he started out with the student-standard door blank resting on cinder blocks in his mother's house. I don't know if he ever moved up to a classier drawing board. Almost any kind of projection requires a lot of drawing board space, so I think you can be sure he didn't do it on a portable board.

He also wrote that he didn't sell designs with projected panels until they were proved out by Dynamite Payson.

No matter how you do it, it's a tricky business because the sheet material often does not take the anticipated curve due to internal stresses created by bending. It's often said that the designer pre-calculates the complex shape, but it's more true that the designer makes sure that something close to the desired shape is a feasible bend. Small variations in the actual hull can matter a lot. I gather that the forefoot of the Chebacco is an example, with the cheeks turning out fuller than anticipated. Just having the rabbet a half inch or so from the intended position could cause a problem to be dealt with.

Nowadays, there is software of the Hulls variety than can do the projections automatically.

Michalak wrote somewhere that he had to do bilge panels cut and fit at first but now can do them "on the computer". So maybe he read a sheetmetal book.

My impression is that expanding straight sided boats was straightforward enough for him; somewhat more difficult to plot a multichine bilge, perhaps whether it twists or not. Some boats done with Harold Payson had those patterns fed back from a prototype to inform corrected drawings, IIRC.

--- Inbolger@yahoogroups.com, "Christopher C. Wetherill" <wetherillc@...> wrote:

>
> [Snarky and sarcastic comments omitted}.

Apparently not. Come on now, don't hold back. Watchya got to add?

> He was a trained draftsman.

And Brad Story??

> Any good manual on sheet metal drafting has the techniques.

So why all the caveats, approximations, and trials? Michalak couldn't figure how PCB did it when drawing - especially conic projections - way off the small board on his lap...

>
> On 8/21/2011 8:14 PM, c.ruzer wrote:
> > How did PCB arrive at expanded dimensions before digital computation?
>

[Snarky and sarcastic comments omitted}. He was a trained draftsman.  Any good manual on sheet metal drafting has the techniques.

On 8/21/2011 8:14 PM, c.ruzer wrote:

How did PCB arrive at expanded dimensions before digital computation?

PCB's letters and periodical articles are really interesting for the additional light sometimes shone on various considerations. There's often additional information, including sense or context that is not conveyed by the altered language, or is ommitted altogether in the re-edited book versions.

In "Small Boat Journal" #54, April/May 1987, at page 30, in the Cartoon #30 ("Dart") Bolger article there are quite a few instances of these changes. Straight up, PCB wrote "Cartoon #30 is a design, not a cartoon. Nobody asked for it because nobody knew a boat like this was possible. I guessed that it might be possible and wanted to find out badly enough to pay Bradford Story to build it for me. The results broaden our options in small-boat design, particularly in the realm of devices to prevent leeway." This first paragraph is ommitted in the BWAOM version which commences from the second paragraph.

On reading the chapter in BWAOM I think I first formed the impression that Dart was not a plan for sale, but was perhaps some drawing for an experimental boat like Eeek! had been. However, corresponding to the eigth paragraph of the Dart chapter in "BWAOM", the tenth SBJ Cartoon #30 paragraph text reads "Dart was the cheapest boat I could work out that would give this idea a fair test. She was built of precalculated plywood panels, tack-and-tape in the fashion described in Harold Payson's Build the New Instant Boats.* All the plans Brad Story had to work from are printed here in case someone would like to repeat the experiment."

All the plans! And the same as shown in BWAOM.

Expanding on the plans, I expect that Brad Story would have built Dart similarly to the procedure demonstrated for Gypsy in "Build the New Instant Boats". Brad was an accomplished boatbuilder, so may have had a few tricks of his own in putting Dart together, but how did he, as PCB wrote in SBJ, "precalculate" the bilge panel when that expansion isn't in the plans? The approximate expanded bilge panel for Gypsy is shown by Bolger on those plans - the drawing approximation makes it a cut-and-fit affair for the builder as demonstrated by Dynamite. How did Brad story expand on Bolger? Did he loft the boat full size, and project the expanded full size panel from that? How's such a projection done? Perhaps he used a cheap sheet material template, doorskins or what have you, offered that up to the gap between bottom and topstrake on the partly completed hull, and gradually trimmed that to the correct lines before tracing onto the plywood?

The Cartoon #30 (Dart) topstrake panel expansion is shown in the plans. Is that one overall approximate, or exact? Presumably it would have to be exact lengthwise, and in width to mate well with the pre-cut, pre-assembled frames. How did PCB arrive at expanded dimensions before digital computation? (Think too of the twist in the Light Dory topsides and similar.) Were cardboard scale models used as a developmental aid in obtaining the flat plywood panel true dimensions? Can one of those wheeled drafting devices be run over the various 2D plans projections to take off the true lengths for drafting the expansion some how? Michalak uses his own computational method to define points along the panel edges by an algorithm repeating and building on many small triangulation steps. How did Brad Story expand from Bolger?

How about those many Bolger expansions from Bolger?