Orca3D News

Tuesday, December 8, 2009

Multihull resistance prediction

We are sometimes asked about resistance calculations for multihulls in Orca3D. Orca3D doesn't have a resistance method that is specifically for multihulls; however, the planing hull and displacement hull analysis can be used to predict the resistance of a single hull, assuming it fits within the valid parameters of the method (which is shown on the report along with the resistance data). Obviously you need to enter the parameters for a single hull (e.g. half of the total displacement), and then double the predicted resistance to get the total resistance (for a catamaran). Depending on the type of multihull, you may want to add some margin for interference drag between the hulls.

If you try to run a prediction for your multihull and get an error, you may want to consider these common sources of error:
  • not selecting only half of the hull (and only up to the chine for planing hulls)
  • incorrect model orientation (positive X should be in the aft direction, positive Z in the up direction)
  • incorrect outward normal direction on the surface(s). When you select Direction in the Analyze menu, the arrows should point into the water.
  • not positioning the centerline of the hull surface (even if it's a multihull) on the Y=0 plane
Note that the current release (1.0.14) has an issue where once you get an error while in the dialog (for example, you enter an invalid speed value), you need to save your file, exit Rhino, and re-start it. This has been fixed in the next release. The next release will also allow you to orient the model in any direction in the coordinate system (i.e.,doesn't require that positive X be in the aft direction).

Also, we sometimes see that people have not set the units as they expect; you may want to go into Orca3D roperties, and in the Units section, be sure that the speed is set to knots and the power unit to HP.

If you feel that you need a prediction method that is specifically designed for multihulls, you may want to consider the NavCad software from HydroComp, Inc. (HydroComp supplies the resistance library that is used in Orca3D). You can read about NavCad at www.hydrocompinc.com. We'd also recommend reading the technical paper "Predicting Catamaran Resistance with NavCad" from HydroComp on multihull resistance prediction, at http://www.hydrocompinc.com/knowledge/whitepapers/HC105-NavCadCatResistance.pdf.

Monday, November 30, 2009

Selecting Control Points

Selecting control points (whether Orca3D control points, or the standard Rhino control points), is normally done by simply clicking on the point. This method is usually very effective, but what happens when control points are stacked on top of one another, or are very close? How do you make sure that you've selected the correct control point?

Rhino has a set of functions that make this very easy, by allowing you to select a control point, and then select the next or previous control point in either the U or V direction. These functions are located on the Select Points toolbar, which can be enabled using Toolbar Layout in the Tools menu. For example, in the image above, selecting NextV will select the point on the same column, at the sheerline. NextU will select the next point forward on the same row. There are also "add" versions of these functions, so for example you can add the NextU to your current selection.

If you have multiple points that are stacked, start by selecting a control point that is outside of the stack, on the side next to the control point that you want. Then just "step into" the stacked points with NextU, NextV, PrevU, or PrevV to get the control point that you want.

Tuesday, November 3, 2009

See Orca3D at METS in Amsterdam

Orca3D will be demonstrated at METS in Amsterdam, November 17-19. We will be in the stand of our European Master Reseller, Design Systems & Technologies (Stand 04.408, in the French pavilion). We will be joined by representatives from Robert McNeel & Associates (the developers of Rhino) and HydroComp (the developer of the drag prediction library that is used in Orca3D). This is a great opportunity to get an in-depth demonstration of the software, and speak with experts. We always enjoy seeing current users as well as those who are evaluating the software.

Complete information on METS is available at http://www.mets.metstrade.com/mets2009/e/home. We look forward to seeing you there!

Tuesday, September 1, 2009

Running Orca3D on a Mac

While we haven't done any testing and don't officially support Orca3D on a Mac, there was an interesting post on the Orca3D forum recently by Victor Soto, a Rhino and Orca3D reseller in Peru. He used Sun Microsystems' VirtualBox software to create a virtual XP computer on his Mac, and is running Rhino and Orca3D successfully. Click here to see his post on the forum. A reply to his original post shows a screen capture of the settings that he used.

RhinoMarine announcement

As of September 1st, 2009, Alion Science and Technology has suspended sales, maintenance, and support for RhinoMarine. Click here to view the announcement letter that Alion sent yesterday to their users. As a courtesy to RhinoMarine users, DRS Defense Solutions Advanced Technology Center (ATC) is available to provide limited technical support for RhinoMarine through the end of 2010, as well as replacement Site Keys. Because we won't have access to the RhinoMarine source code, we will not be able to make changes or fixes to the program, and there will surely be some questions that we won't be able to answer. But with our experience in naval architecture and with this type of Rhino plug-in software, we hope to be able to answer most questions. Alion has authorized us to provide replacement Site Keys for existing RhinoMarine users, so if you lose your license due to a hard disk crash, a new computer, etc. we can generate a new Site Key for you. With these resources, you should be able to confidently continue the use of your copy of RhinoMarine.

If you are a user of RhinoMarine, please click here for information on technical support and discounted pricing on Orca3D.

Thursday, May 14, 2009

Attend an introductory Orca3D webinar on May 21st and save 20%!

We will be holding an introductory webinar entitled "Extending Rhino's capabilities for the naval architect" on Thursday, May 21st at 0900 Eastern Daylight Time (1300 UTC, 1500 Central European Time). The webinar will feature a live presentation of the four functional areas of Orca3D: Hull Design & Fairing, Intact Hydrostatics & Stability, Resistance & Power Prediction, and Weight & Cost Tracking, and will last for approximately 40 minutes.

Attendees will receive a coupon code good for a 20% discount on Orca3D purchases made within 30 days of the webinar. To register for the webinar, visit the webinar page on our website, where you'll also find links to recorded versions of previous webinars: http://www.orca3d.com/support/support_webinars.htm

See you there!

Tuesday, April 21, 2009

Interesting capsize and flotation study using Orca3D

Scott Graham of Graham Marine, Inc. is restoring a wooden Lightning class sailboat, and wanted to look at various options for adding flotation to make it easier to recover from a capsize. After building a detailed model in Rhino that accounts for the thickness of all of the parts, he looked at adding watertight bulkheads, airbags in various locations, and foam under the gunwales. Using Orca3D, he computed righting arm curves that include the effect of the crew and the buoyant mast for each configuration. Click here to see his results, as presented on the Lightning Class website.

Thursday, April 9, 2009

Webinar "Speed/Power Analysis with Orca3D" available on Orca3D.com

We've added a webinar to our website, entitled "Speed/Power Analysis with Orca3D". This 30-minute recording of a recent live presentation provides background on the resistance methods in Orca3D, and demonstrates their use. Click here to go to the webinar page on Orca3D.com.

Wednesday, March 4, 2009

Webinar "Extending Rhino's capabilities for the naval architect" available on Orca3D.com

We've added a webinar to our website, entitled "Extending Rhino's capabilities for the naval architect". This 35-minute recording of a recent live presentation demonstrates the main features of each of the four functional areas of Orca3D: Hull Design & Fairing, Intact Hydrostatics & Stability, Resistance & Power Prediction, and Weight & Cost Tracking. Click here to go to the webinar page on Orca3D.com.

Monday, February 16, 2009

Special discounts for Westlawn and Landing School Students

We've just announced special discounts on Orca3D/Rhino bundles for Westlawn and Landing School students. Active students from either school receive a 10% discount when purchasing Orca3D together with Rhino or the Rhino/Flamingo/Penguin/Bongo bundle. Click here for details.