Performance prediction methods review

[Alik]

Making review of performance prediction methods (systematic series and their modifications) suitable for small craft. Currently listed are these ones:

Sailboats:
- DSYHS

Displacement craft:
- Holtrop
- BSRA
- Oortmerssen (tugs and trawlers)

Semi-planning
- Nordstrom
- DeGroot
- NPL
- SSPA
- 63
- 64
- Compton
- Mercier-Savitsky

Planning
- 62
- 65
- Savitsky
- BK-series

Catamarans:
- Molland
- Muler-Graf

Please add, preferebly with references.

[HJS]

Has anyone out there used / checked this or / and produced a spreadsheet?

js

[valber]

Originally Posted by Alik

Making review of performance prediction methods (systematic series and their modifications) suitable for small craft...
....
...Please add, preferebly with references.

Sailboats:
- Systematic yacht hull series by L.Zaburdayev, Nikolayev Shipbuilding Institute, Ukraine, 1976-1977?
I have a copy of original dessertation paper... Do you need it? If so, I can ask permission of author to make copy for you...

[HJS]

Only shared knowledge can grow.
All information is valuable.
Send a copy to sass@sassdesign.net

js

[Alik]

Originally Posted by valber

Sailboats:
- Systematic yacht hull series by L.Zaburdayev, Nikolayev Shipbuilding Institute, Ukraine, 1976-1977?
I have a copy of original dessertation paper... Do you need it? If so, I can ask permission of author to make copy for you...

I have read this dissertation and even tried to use it for calculations 15 years ago...

Excellent research published before Delft Series. But the way they present the results (Davidson's polynom) does not allow to interpolate between models of series. They propose to interpolate coeffients - completely wrong method...

[valber]

Yes, it's so...

[MikeJohns]

I haven't had much success with any of the series the curves are often well off relative to the tank test results.

You need to be able to tie the prediction to some hard data to drag it into line.

Have you ever compared any series with a model smooth water resistance ? Once you have a few similar hulls they are useful but I'm skeptical as to their use for say; refining a new hull-form.

[Alik]

Originally Posted by MikeJohns

Have you ever compared any series with a model smooth water resistance ?

Yes I did, there was quite good match... if I use correction factors based on experience

Actually the task is not to give exact prediction. The task is to give exact OR slightly higher prediction of resistance, so the boat will deliver the speed.

[MikeJohns]

Yes its the experience game, not an absolute. No appendages in the prediction adds a lot of discrepancy particularly for vessels with a higher volume keel than a strut bulb.

They are no substitute for tank testing. Once you have some accumulated data of your own you just pull out an earlier curve for a similar hull and assess it from that. The rule of thumb method !

I often wonder just how useful a lot of the smooth water prediction methods are anyway for smaller sea going vessels.

[Alik]

Originally Posted by MikeJohns

They are no substitute for tank testing.

Even tank tests are not reliable for some types of craft. Say, planning powerboat with jet drives - pressure distribution in lift area will be very different between model and reality. Same problem with performance catamarans...

I used to 'anchor' calculations and tank tests with results of sea trials. I consider sea trials more valuable source of information than tank tests with usually limited program.

Now we are doing some RC model testing with model drives. But this is not for performance, this is for study of general behaviour.

[MikeJohns]

Albert

Yes sea keeping and maneuvering indication is very useful. And you can use quite small models for this. But sorry getting off the thread topic here.

[Alik]

OK, back to subject: who has ever heard about USSAM series of sailing yachts? I met brief mention of this series in F.Fossati's book, would like to know the details.

[DHMzip]

I have not.

However I am interested in learning more about catamaran design, and predicting catamaran resistance, especially for power catamarans with semi displacement hull forms, Fn around .7-.9.

Do you have any leads about bow shapes, hull forms (npl? series 63?) which is best?

I have read some of the AF Molland papers. I am a student trying to figure out the best way to approach the hull design.

cheers.

[Tad]

A study of a displacement hull series.......

A Resistance Study on a Systematic Series of Low L/B Vessels. By Sander M. Calisal and Dan McGreer, research done at UBC tank. Paper published in Marine Technology, Vol 30 #4, October 1993, pp 286-296

Data derived from a 13 hull series derived from a single parent by systematically varying L/B, B/T, and Cb. These are modern Westcoast (North America) fishing vessel hulls of developable (metal) form.

[Alik]

Tks, will check it