Tow Tank Model Build?

[freeski27]

I am a Naval Architecture student here in NYC, USA and I plan on building a tow tank model of a small sailboat design that I have done. I tried to find some decent info or literature on model builds, but didn't come across much.

The scale model will be just over 3 feet long. How do you recommend going about the build? Carve foam? Cut sections from wood and try to glass? etc. Any advice would be very helpful.

-Noble

[Submarine Tom]

Glass or epoxy over carved foam.

-Tom

[Crag Cay]

Saw or slice up thin 'flexy ply' into 'strips' as appropriate for the curvature of the model.

Strip plank over frames cut from regular ply. Use epoxy thickened with West Microlight.

Skin with glass tissue and epoxy.

[wardd]

here's another way cut out the station outlines out of anything mount them to a board and fill the voids anything, crumpled paper.

layer modeling clay over it and fair with a spline

build a box around the base and coat with a good release agent such as simonize..

pour plaster in to make a female mold.

after its cleaned up a model can be made of paper mache and sealed

[mydauphin]

OK, so I have tank and models then what? What else do I have build to get a working idea of which hull is better. Sorry for my ignorance, I am building dingy and would like to try a few models.

[wardd]

do you have a swimming pool?

[mydauphin]

No, I was going to build RC boats and try in pond....

[mydauphin]

Or could borrow pool..

[wardd]

use the filter out flow and a mail scale for drag readings

a simple way would be a line over a pulley to a weight on the scale, read how much the weight weighs as the model pulls on it

a mod on on the mold, if you cut out half hull shapes you can make a mold that splits down the keel, turn the shapes around for the other half

the nice thing about this method is common cheap materials

These are made of cnc milled poplar wood.

http://www.hsva.de/

[Crag Cay]

The test tank world is highly competitive, in the scope of the facilities offered, the quality of the analysis and the cost of running a program.

A major part of this, is the quality and cost of the model. There are loads of different techniques for their construction, but not all are even applicable to high tech yachts models. The CNC poplar models above are not going to mimic the moments of an AC90.

In my experience the best quality models and the most cost effective are made in wood strip by a skilled model maker. Luckily a view shared by most of the leading designers, AC / Volvo campaigns and even ferry companies.

I doubt there are better model makers in the world than the guys at HSVA.
But of course, the smaller the vessel a model has to mimic, the more effort has to be made.

The most cost effective are still CNC milled, not handmade.
two of them:



Regards
Richard

[gonzo]

To make a significant comparison between a model and what you plan to build, the displacement and moment of inertia have to be proportional. Whatever method you use, should give you the same numbers as the calculations for the full size boat.

[wardd]

Originally Posted by gonzo

To make a significant comparison between a model and what you plan to build, the displacement and moment of inertia have to be proportional. Whatever method you use, should give you the same numbers as the calculations for the full size boat.

but couldn't you compare 2 or more models against each other for the better performance and extrapolate that to the full size, saying this one will perform better than that one?

[Crag Cay]

I doubt there are better model makers in the world than the guys at HSVA.

The most cost effective are still CNC milled, not handmade.

I'm sure the guys at HSVA are perfectly good ship modellers, but they're not a big player in the yacht test tank world.

CNC has been touted as 'the answer' for years now, but unfortunately has yet to make an impact except where there isn't the skill base for using an alternative.

As I say, the tank testing world is highly competitive and I know exactly how the cost and accuracy of various methods compare. The various methods are constantly evaluated and so far, with yachts up to 200ft the model maker still rules on price and accuracy. If it didn't, we'd use the alternative.