Help SAVITSKY power prediction

[BOATMIK]

Originally Posted by Willallison

Ah - ok - this is a 'school' question - thats different. You must go look at as many similar boats as possible and note down as much info about them as possible - displacement, deadrise, CG etc etc. Many things you wont be able to get info on - like CG for instance, so you will have to make an educated guess about its position

If it is a school question and they have only given length then they can't be expecting an accurate answer.

However it does open the opportunity for the student to look at savitsky and to make a presentation about what other information is needed and discuss why his/her particular educated guess for each factor (deadrise CG etc) is reasonable. Then use all the reasonable values to come up with a figure.

Then state something like ... the more accurate the inputs the more accurate the outputs, so if more information comes available it can be used for a more accurate projection.

That would be a reasonable response to the question and would show an intelligent response to a question with clearly too little data.

Michael Storer

[pacoblasco]

If you are in a Spanish naval architect University (UPM-ETSIN or UPCT-ETSINO) they have Hullspeed (maxsurf range) with Savitsky method

[Guillermo]

Chocomono:
Have a look at these interesting pages:
http://www.jbmarine.biz/Web/JBReviews.html

At: http://www.well.com/user/pk/SPApower.html you'll find a downloadable program that uses Savitky's method (Surface piercing propellers).

At: http://www.hawaii-marine.com/templat...escription.htm you can buy for 50USD an Excel spreadsheet working with Savitsky's equations.

Also an spreadsheet within these forums:
http://boatdesign.net/forums/showthr...?t=2187&page=4


Paco Blasco, is it you?

[pacoblasco]

Guillermo
Yes it's me.
Nice to see you here in this other forum.

See you

[Guillermo]

Paco,
World is small.
Have you tried the AINE's Forum? I've discovered it only yesterday (!!) Needs a lot of improvements, but it is a first tool....

[akuamare]

Allo,

I was looking for the Savitsky's power prediction method to use it in a patrol of 40m in length and..... i think this is my good luck day !!!

My more sincere thanks

PS, Sometimes we think what we do is like a drop of water in the sea, but the sea won't be the SEA without that drop

[CDBarry]

Get the paper by Blount and Fox (1976 or so) that was published in Marine Technology. You can order it from SNAME.