Thinking about building a Nightmare VIII from plans...help needed

MultiHulls General Discussions (MultiHull/MultiOne)
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Hello all. I am relatively new to RC Sailing, but not new to modeling. I am thinking about building a MultiHull from scratch and have downloaded several sets of free plans. The boat I really would like to construct is a Nighmare VIII, but I have a problem with the sections. In printing them from the PDF version and cross referencing them to the reference sheet, I struggle to produce the sections in the correct size.

Even what is supposed to be a full sized section 6 doesn’t print quite to the right dimension. It measures 138mm where the reference shows 144mm.

I have tried printing full size, not scaled to fit, but I can’t seem to get them to work out. Has anyone built from this particular set of plans?

Thanks,
James Vaello

2

James,

Printing exact scale from a PDF file can be problematic. Getting the plans in a different format that can be printed exactly to scale would be the best thing. But, if you can’t, as a work around, try printing at 105% then measuring the drawing. That may get you close enough. If not, add or subtract a few hundredths or thousandths of a percent until you are satisfied that the sections print as they should.

Good luck.

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I sent a note to Ernst Zeamann (AKA Disabled) about your problem. Please watch for his reply here.

Dick Lemke

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Hi,
the original drawings have been made to fit european standard A4 size -

  • 297 x 210 mm - paper sheets.
    If your printer is set up to use american standard sizes, this may be the reason for the corruption of the files.
    (Has happened before.)

Anyway - I´ll try again to upload my original zip.-files here.
Maybe this helps.

Ernst Zemann

I have now uploaded all Mini 40 datas I currently have + some other stuff that may be interesting/useful/challenging - have fun!

5

Thanks for all the replies thus far!

Dick Lemke:
Thanks for sending him a note. Nice to see him chime in on the subject. I wasn’t sure if he was still active in the forums.

keelhauled:
I have figured a factor of 230% on the smaller sections gets me pretty close to the ballpark. There is inherent distortion when blowing up pdf files in my experience as I have found, just as you mentioned. A different format would be great.

Ernst:
Is there someone that has plans for this boat in a dxf or other CAD format? Maybe CAD plans for one of the later generation boats?

My thoughts for this boat are to build it from some of the high density pink foam that I have, cover it in packing tape and pull a mold for a plug to be further refined. I would like to have a boat that I can experiment with traditional vs swing rigs, possible wingsails, and maybe a little foiling. There is no one in the area that races Mini40, but if I had a mold, there are several folks in my club that might want one for themselves. As much as I would like to buy a set of hulls ready made, I have a mountain of foam, fiberglass, carbon and resin that cries out to be made into something.

James

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Ernst:
Thanks for the additional information, The Artelio looks like great fun and a challenge! The file you have uploaded for the VIII is the same one that I am trying to work from. I’ll get it figured out and start cutting foam as soon as time allows.

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James,
for dxf.-files you could contact Siri at www.rcsails.com
Good luck!

Ernst

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Ernst - thanks for replies.

Siri is no longer with RCSails if I understood Rowland correctly. I might have misunderstood however.

James - a suggestion - print your PDF pages, and using a “graphics/proportional calculator” have copies made on a copier able to increase/decrease printing sizes.

here are several links - I used to have one that only required one dimension - either height or width but can’t find it - will keep looking

http://www.universalprinting.com/calculator.aspx

http://www.pixus.com/design-tools/proportion-calculator.html

This is one which I would recommend, as you only need one dimension of current size and one dimension of what you eventually want. When pressing “Calculate” it will give you the percent to change your copier (or printer if you can change percentages) So if you have a dimension of 5 inches on your printout, but you need 5-1/8 you would enter “5” as original size and “5.125” as desired size. Calculated you would need to increase your original print size 102.5% !!!

http://www.knightprinting.com/help/tools.php

if you search, you can purchase a heavyweight cardboard circular calculator - check printing supply houses and look for “Proportional Calculator” - Comes in handy for many things.

Good luck, Dick

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These are all great suggestions, but remember that for a hull shape any plan, especially on paper, is just an approximation, and the more reductions and enlargements it goes through the more approximate it is. What’s important is to make sure you get a fair hull, the process known as lofting. As the standard book on the topic puts it “A fair line trumps any given measurement.” Or, as a builder once asked a customer “Do you want it according to the plans or do you want it fair?” Computer design techniques can be a real trap in this regard; only the most expensive will do a decent job of fairing every time.

If the plans present any kind of puzzle the best thing to do is to get off of paper and into three dimensions real quick by carving a half-hull. Nat Herreshoff started all his designs that way. Trust me, it’ll save you a lot of time and produce a better sailing hull than trying to get measurements on a plan to match to the gnat’s eyebrow. Your fingers will tell you more about fairness than any ruler.

One final saying: “Carpenters work to the nearest sixteenth, cabinetmakers work to the nearest sixty-fourth, and boatbuilders work to the nearest boat.”

Cheers,

Earl

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Hi Earl,
I tend to agree with the above.

Sorry to be a little OT.

Personally I give the most important part of my design time to get the best lines to obtain a “fair and fluid” hull.

This is why I refuse to use 3D software linked to predefined algorithms but rather a 2D software where I can play with all “splines” until the technical intent meet the eyes judgement.

See Water Plan, Rocker line, Curve of Areas and the Prismatic Coefficient.

The right mix can produce a boat that can be faster then another.

“Fairing in the wrong place is not good either”

Cheers
ClaudioD

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@ James Vaello,
Where are you located?
I´m from Vienna/Austria - in the middle of Europe with no sea nearby.

Anyway -
You may need to know that I´m one of these ´Old School`- shipwrights…-
means, I don´t know how to use Auto-CAD… still working with the old method of drawing everything on millimeter papersheets.
Then doing the calculations with a simple pocket ruler, then redrawing on another sheet of millimeter paper if necessary.

All the designs shown here where originally done that way.
Only then - via the internet - I found several guys capable of CAD-design and interested to help me out, who then transformed the datas I sent them into dxf.-files.
These persons where - Eric Edel from Germany and Umut Korkmaz from Turkey both for the Nightmare Mk.VII - and Phanchita Supasirithanawat from Thailand for the Nightmare Mk.VIII. - Siri later on then also asked me to do two trimarans for the 65cm size. -
There even have been some students in the past who provided me with 3D-renderings of some of these trimarans. (can be found at www.rcuniverse.com - sailboatsection somewhere.)

I myself never needed them - this was just to present my design ideas online.

As Im European, I´m used to the metric system -
If you are working with inches normally, this could cause some difficulties.

But please note, that each curve I´m using is a parabolic curve,
which is self fairing and can be (re-) calculated with the biggest ease.

The sequences are simply: 0 + 1 + 2 + 3 + 4 + 5 and so forth.
Which add up to: 0,1,3,6,10,15 - and up to eternity, if needed…
or - 0,0.5,1.5,3.0,5.0,7.5…
0 - Zero - are the two mainframes - and from there curves can and will be different fore and aft.
So if you want to redraw the plans, you just need to use the reference sheets with it´s numbers and go from there.
And you´ll know very fast, what I mean!

I myself - by the way - have learned ´lofting-the-lines´ the old-fashioned way. But this has never stopped me from designing modern trimarans. :slight_smile:

Ernst

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All, thank you for the replies. I started working on an IOM years ago from plans, so I understand the sentiments regarding lofting and visually creating a fair hull. Likely I was getting too caught up in the technical details as I often do with things.

Years ago I worked on converting a set of plans, a friend in the UK drew up, of an F-14 Tomcat. I did all the CAD work to convert it to the model from a propeller driven aircraft to a Electric Ducted Fan. After releasing a set of laser cut parts for two different sizes of the aircraft, and shipping them all over the world, I was inundated with questions. My love for the actual building process waned as I got wrapped up in the questions, with the building thread swelling to 258 pages and 3000+ posts. Only a few of the kits ever stretched their wings for the sky of the 75 or so sent out.

So, I guess what I’m rambling on about is that in order to not suffer the same fate, I will get the sections as close as possible. From that point on, I’ll use the adage, “Carpenters work to the nearest sixteenth, cabinetmakers work to the nearest sixty-fourth, and boatbuilders work to the nearest boat.” I really enjoy that saying…I’ll run from there.

Thanks for all the information, from everyone. As I get started on the project, I’ll be happy to put up a build thread. Maybe you guys can chime in and keep me motivated :wink:

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I’m located in San Antonio Texas. I am a new member of the Woodlawn Sailing Club, http://www.woodlawnsailingclub.com/

I just competed in my first Victoria Regatta this weekend at our pond and had a lot of fun.

James

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And I had been trained - from 1977 to 1980 -
to work as carpenter, cabinetmaker AND boatbuilder/shipwright at the same time…- so guess what I was aiming for all the time? :smiley:

Please start your build thread - I´ll be watching!

Ernst