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 Boat Design Forums How to calculate materials list

#1
03-04-2017, 08:54 PM
 scott2640 Join Date: Dec 2016 Rep: 10 Posts: 4 Location: Rochester, NY
How to calculate materials list

I purchased a set of boat plans that include CAD renderings of the vessel in addition to the printed version.

Is there a way to calculate a materials list?

For example: how many board feet of planking? Board feet for the chine log? Gallons of epoxy for wet out?

Preferably an online calculator?

I know it's not as simple as LxWx2 to calculate the planking. With all the curves and sweeps and what not.

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#2
03-06-2017, 03:05 AM
 ludesign Senior Member Join Date: Aug 2003 Rep: 60 Posts: 209 Location: Sweden
Not an easy task unless the design program used supplied such data for you.

I get a full set of specs directly and with minimal effort, including nested flat panels optimized for the given material dimensions, surface areas, weights, center of gravity, edge lengths, and center of gravity for each panel, and all compiled in an integrated spreadsheet that dynamically interacts with the 3D model as it changes throughout the design process.
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Claes Lundstrom
#3
03-06-2017, 03:18 AM
 TANSL Senior Member Join Date: Sep 2011 Rep: 300 Posts: 3,893 Location: Spain
Quote:
 Originally Posted by ludesign an integrated spreadsheet that dynamically interacts with the 3D model as it changes throughout the design process.
A really interesting idea. Do you know how it could be put into practice?
#4
03-06-2017, 08:35 AM
 ludesign Senior Member Join Date: Aug 2003 Rep: 60 Posts: 209 Location: Sweden
In this case, it's an integrated standard feature in the program I use. The point is that it requires very little work beyond specifying a weight per area unit for each panel. In most other cases, you essentially get all the data by simply drawing something in 3D. The rest is more or less self propelling.

If I like, I can associate a help text to the panel, which can be visible in 3D as well. Quite handy when reading the spreadsheet. Other useful identifiers include colors associated (colors have readable and meaningful names in the program) to the object and in which layer it's located in. May not matter much on simple models, but it helps if you have say five hundred or a thousand panels to deal with.

I can (and often do) use the spreadsheet to "debug" the 3D model, that is, if I find a panel with an unexpected setting or value, I can select it in 3D from inside the spreadsheet, and the program automatically goes to the relevant layer and selects it in 3D or in the "Unfold view", if you happened to be there. The spreadsheet is also dual acting, that is, it does not only extract data from the 3D model, it can also return data updates back to the 3D model to correct mistakes.
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Claes Lundstrom
#5
03-06-2017, 11:03 AM
 TANSL Senior Member Join Date: Sep 2011 Rep: 300 Posts: 3,893 Location: Spain
Could we know what program/s is/are involved? I would like to try it.
In addition to the weight of the hull, can it calculate the weight of the equipment, of the accommodation, etc. ?
Is it valid also for GRP hulls?
#6
03-07-2017, 03:42 AM
 ludesign Senior Member Join Date: Aug 2003 Rep: 60 Posts: 209 Location: Sweden
Quote:
 Originally Posted by TANSL Could we know what program/s is/are involved? I would like to try it. In addition to the weight of the hull, can it calculate the weight of the equipment, of the accommodation, etc. ? Is it valid also for GRP hulls?
TouchCAD only ( www.touchcad.com ). All described features are standard features in the program.

Normally, I would say that I extract about 85% of the total project weight in this way. The rest can be described as nuts and bolts or other smaller parts that for sure has a weight but would simply be too expensive to specify in a normal design project, not having the budget of say a Formula 1 team.

There are three basic ways to add weights to objects:

1/ As a weight per area unit, where you figure out the weight of for example per square meter. On solid materials, such as for example aluminium, you simply multiply the density of the material 2,7 kilos per liter, by the thickness (1 square meter times a thickness of 1 mm equals one liter of volume). For materials being a combination of materials, such as GRP, sandwich panels, etc., it may be a good idea to measure the actual weight of a sample panel, and extract a weight per square meter weight from that. This method works well for all parts that can be described as real surfaces, for example hull and outer skin, glass panels, sails, tubing and rails, bulkheads and frames, etc.

2/ In some cases, it's more practical to define the weight and location as a given point weight, not being associated with their object area, say a stove, an engine, or a radar unit, which consists of many parts, but where you only have access to the total weight. I then draw a reasonable representation of that unit, being good enough so that you can see what it is, and to make sure that it fits well into the given space. I then specify that the panels are to be ignored by the spreadsheet, and add a simple point at the estimated center of gravity in the 3D model, having the true weight of the object. In this way, I can include almost all major parts of any significant weight, and can move them around if required to adjust the floating balance of the boat. Point weights can be associated to surfaces, curves of points, where the center of gravity is based on the given graphical properties of the respective object.

3/ Curves and polylines (as opposed to surfaces or points) can also be used for weight calculations, for example of rigging. In this case a weight per length unit is applied (unless it's specified as a point weight of course). Also worth noting is that any 2D or 3D lines can be used as measurement lines, showing either segment lengths or accumulated total true 3D length. Quite handy for rigging.
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Claes Lundstrom
#7
03-07-2017, 04:28 AM
 TANSL Senior Member Join Date: Sep 2011 Rep: 300 Posts: 3,893 Location: Spain
From what you tell me, this program does nothing that can not be done with any other CAD program. I use autoCAD to get lengths, areas or volumes of the various elements as well as the exact position of its center of gravity. There are a large number of elements whose weight can not give TouchCAD or AutoCAD, but that gives, with total accuracy the supplier of the equipment. AutoCAD gives me its center of gravity.
I think that, even if it takes a little more work, to define as accurately as possible the weight of that 15% of the items you are talking about is worth it, even if one is in the first steps of the project. Although I believe that what can not be directly obtained from the CAD program is much more than 15% of the total.
After all this conversation, regarding the questions posed by scott2640, I would answer that no, that there is not a program that does, not even 50%, what he asks.

Last edited by TANSL : 03-09-2017 at 11:22 AM.

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