Savitsky Power Prediction

[guest12020101217]

Thank you for posting your spreadsheet. Hope to have mine finished after new year and will post it here. It's been on back burn abit.

[Dingo]

Glad I could help. If anyone out there finds an error, let me know please.
Regarding the use of the spreadsheet, fill the boxes that are coloured yellow with your input; this includes the LCG's (LSP in the program), and velocities, as well as the various parameters regarding the vessel. Click on the 'Voortgaan' putton (proceed), and sit back and wait. The values of resistance and thrust will be calculated. Further on down are calculations for rollstability etc. using various theories from Lewandowski etc.
I am currently updating this spreadsheet to include planing catamarans based on the theory of Lee (republished by Insel) who builds upon the theory formulated by Savitsky and which takes into account the distance between hulls. If anyone out there has empirical formulas for cats that are as 'easy' to use as Savitsky (without going into triple integral formulas etc.!!) please let me know, otherwise I shall proceed with this one.

Hi Dingo much apreciated your spreadsheet, congratulation for the excellent work.

[Humberto Rodrìg]

Originally Posted by Guest

for Colin, I have already written an Excel spreadsheet to solve Savitsky's planing hulls. Give me your e-mail and I will send it to you. You can either use it, or see how I get Excel to solve Clo by itself.

Here is one: HumbertoR92@hotmail.com
I will appreciate your help

Dear Sir;

I was wondering if you were willing to divulge the Password for your resistance spreadsheet posted on boatdesign.net(Prestasie.xls). I want to unlock the remainder of spreadsheet for translation and use if for my senior design project at school(working on a high speed sportfish concept).

Thanks,

Brent

Email: wyy551@yahoo.com

Originally Posted by Dingo

Here is my spreadsheet on Savitsky and other methods. It contains various allowances for trim-tabs and shafts etc. Unfortunately, it was written by me in Dutch and Afrikaans, but the symbols and references should pose no problem. Any translation problems just e-mail me at: dingo at postmark dot net.

[Dingo]

Brent, I have written another spreadsheet for Savitsky/Hadler/Blount etc. (in English) that is cleaned up and easier to use. I will sent that to you if you desire. The calculations are hidden but I can give you the details to unlock it if you need to translate any Dutch/Afrikaans that I made notes or references in (old habit I picked up studying in South Africa).

Originally Posted by Brent

Dear Sir;

I was wondering if you were willing to divulge the Password for your resistance spreadsheet posted on boatdesign.net(Prestasie.xls). I want to unlock the remainder of spreadsheet for translation and use if for my senior design project at school(working on a high speed sportfish concept).

Thanks,

Brent

Email: wyy551@yahoo.com

[Humberto Rodrìg]

Please send a copy of your spreadsheet to HumbertoR92@hotmail.com

[stillgar]

Dingo:

Could you please email me a copy of your translated spreadsheet?

stillgar_@hotmail.com

Regards,

[albresco]

Please send me a copy of your English spread sheet as well.
Thank you
albresco@shaw.ca

[cgorton]

I'd love a copy of your English translation spreadsheet- thanks!

Craig

cg@zurnyachts.com

[Dingo]

Here is my spreadsheet. I've made it easier to use, translated it into English with a help file and hidden the calculations (password is Dingo to view it on a separate sheet). I've still yet to add catamaran resistance results, but will do so as soon as I have time. Any problems or errors, let me know please. By the way, be careful when predicting drag around the hump speed; there are other methods that can be used, but this is good for estimating.

Dingo

[albresco]

Thank you for the sreadsheet post. Looks great!!

[Dingo]

This reply is for Nev, but I will republish it here in case others have the same questions:
If you go to the Help tab in the spreadsheet, most of the definitions that you wrote in red are explained with diagrams. Regarding the sheet 'Berekenings' (Dutch for Calculations): the sheet is hidden but can be turned on and inspected (password is Dingo). All the background calculations are there. You ask why the thrust is more than the drag: it is because the drag is in the direction of motion (ie. horizontal), but the thrust acts at an angle slightly downward, so it has to be slightly higher in order to get the equal amount of horizontal force to counteract the drag. Regarding the Go button: press the button once you change a value. The trim will change to almost zero on the first run, then increment upwards until it reaches the equilbrium value for zero moment. If #VALUE appears, it means that the resistance can't be predicted for those particular given parameters.

[ars-technica]

Make 2 column
clo clb
0.1 value obtained with =clo-....
0.2 value obtained with =clo-....
make this for all number of clo you need
then use the function search to discover the value you need in that moment.
warning taht search function give you the value incorect if you do not impost an interpolation before...

Hi all

I am writing a savitsky planing power prediction porgram in Mircosoft excel at the moment. Well in fact l am writing two! One using the thoery in principles of yacht design and the other from copies of savitsky's and others papers.

Can anybody tell me how l can get Excel to solve equations like the one below. I need to solve for CLo.

CLb = CLo - 0.0065*B*CLo^0.6

CLb = Deadrise Lift Coefficient
CLo = Flat Plate lift Coefficient
B = deadrise angle.

I can do it by getting excel to plots graphs and me having to pick the value off and enter it in, but l really want excel to solve it.

I want to do the same when solving for the wetted length/wetted beam ratio (L).

CLo =t^1.1 x {0.012L^0.5 + (0.0055L^(5/2))/Cv^2}

t=running trim
L=wetted length/wetted beam ratio
Cv= Speed coefficient

Plan to develop the programs over time and use Maxsurf's Hullspeed as base data. May but the program on net when happy with it.

Any help or comments are very welcome.

[Danielsan]

Hi,
I did use the last version (English) of Dingos spreadsheet

Any one thinks this can be a correct result? I should need 160HP to get my boat planning at 50kts

Any advice on this design? (my boat)

THX in advance,

Daniel Peeters

Inputs

Hull Beam B 9.18 feet
VCG VCG 1.02 feet = 0.311 metres
Displacement D 6,800 lbf = 3,084 kg
Deadrise @ Transom b T 27 °
Deadrise @ Amidships b )0( 27 °
Distance to Amidships L )0( 12.160 feet = 3.706 metres
f 1.00 feet = 0.305 metres
e 15.00 °
q 0.000 °

Minimum Speed Vmin 6.1 kn = 10.3 feet/s This is the minimum speed valid for this analysis
Maximum Speed Vmax 132.4 kn = 223.4 feet/s This is the maximum speed valid for this analysis

Number Number of Propellers N 1

Trim Tab Chord cF 1 feet = 0.305 metres
Span Ratio s 0.333 ( <= 1 )
Deflection Angle d 0 °

Rudder Chord crudder 0.00 feet = 0.000 metres
Thickness t 0.00 feet = 0.000 metres
Area Arudder 3.60 feet2 = 0.334 m2
Centrepoint xc -0.80 feet from transom = -0.243 metres (+ve fwd)
yc -0.60 feet from baseline = -0.183 metres (+ve up)

Shaft Diameter of Shaft Fshaft 0.00 feet = 0.000 metres
Length of Shaft & Hub l 0.00 feet = 0.000 metres
Centrepoint xc 5.50 feet from transom = 1.676 metres (+ve fwd)
yc 0.00 feet from baseline = 0.000 metres (+ve up)

Strut Chord cstrut 0.00 feet = 0.000 metres
Thickness t 8.00 feet = 2.438 metres
Area Astrut 0.75 feet2 = 0.070 m2 ****
Centrepoint xc 3.50 feet from transom = 1.067 metres (+ve fwd)
yc 2.00 feet from baseline = 0.610 metres (+ve up)

Output V LCG t D T Peffective h
[kn] [ft] [metres] [°] [lbf] [kN] [lbf] [kN] [ehp] [ekW] [ft] [metres]
6 10.5 3.2 10.3662 595 2.6 659 2.9 11 8 3.51 1.070
7.5 10.5 3.2 11.5474 1,087 4.8 1,215 5.4 25 19 3.51 1.070
10 10.5 3.2 14.2537 1,665 7.4 1,909 8.5 51 38 3.29 1.003
12.5 10.5 3.2 > 15° #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE!
13 10.5 3.2 > 15° #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE!
14 10.5 3.2 > 15° #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE!
15 10.5 3.2 > 15° #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE!
17.5 10.5 3.2 > 15° #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE!
20 10.5 3.2 14.0987 1,583 7.0 1,812 8.1 97 73 1.38 0.421
25 10.5 3.2 11.0293 1,318 5.9 1,467 6.5 101 75 1.18 0.360
30 10.5 3.2 8.7581 1,151 5.1 1,257 5.6 106 79 1.09 0.332
35 10.5 3.2 7.1278 1,065 4.7 1,149 5.1 114 85 1.04 0.317
40 10.5 3.2 5.9385 1,045 4.6 1,118 5.0 128 96 1.01 0.308
45 10.5 3.2 5.0493 1,081 4.8 1,151 5.1 149 111 0.99 0.302
50 10.5 3.2 4.368 1,169 5.2 1,239 5.5 179 134 0.97 0.296