Beebe Power Calculation

The lasts piece in the jigsaw

There is no article on the Beebe power formula. It will be several weeks before I am home. I could then send you a scan of the graphs and info on. how to use them. If you have a particular boat in mind I could work out the power for you as the Nordhaven 46, then you could make the graph of power vs speed. Boats are limited to 95 tons and SL 0.7 to 1.65
Thank you for the info you sent, I considered the reason the Diesel duck was way off was either there was a more accurate WSA formula and/or some allowance for wind/weather. MikeD's post gave the answer. AV^3/50000 gives HP to overcome wind with the reduction (boatspeed/combined wind &boat speed)^3.
At the low end of a force 5 (26kts combined speed) 38hp is used up. The formula you put into the spreadsheet you gave me says 40hp gives 8.17kts. The Diesel Duck has 80hp therefore should be able to maintain 8kts into an 18kt headwind. And MikeD says larger boats require a much smaller percentage of power to overcome weather. Thats why a battleship's predicted power requirement is very close to the published figures and the Diesel duck is not.
mik the stick

 

No hurry. Anytime you are able to. I work on it during my spare time for professional advancement.

Workboats and Warships have very different ratios and coefficients. Deviations will be large if you use standard powering program. Most of Taylor's work was on military naval vessels.

 

I am home sooner than expected. I have attached scans from voyaging under power.
1. On the F1 graph a 30 ton boat has a value of 52.
2. on the F2 graph an SL of 1.35 has a value of 2 .375
3 multiply F1 and F2 together 2.375 x 52 = 122BHP.
It.s as easy as that. My maths training was specific to my job therefore I am unable to work out the maths behind these graphs.
mik the stick

 

This should be the scans now

 

Do you have something much clearer and not distorted? Hardly readable when I downloaded it.

 

Do you have something much clearer and not distorted? Hardly readable when I downloaded it.

Just buy Da Book, it has lots of useful info for an ocean going cruiser.

 

Fast Fred. I have lots of books and plenty of resistance-powering formula. I just want to set the formula for Mik using the trendline function of Excel. In order to be accurate, I need a clear copy.

 

Sorry Ive tried to improve the scan without success. I don't understand how they are unreadable. The only part difficult to read is F1 0 to 5.5 in 0.5 steps. it might not print out very good I don't know.
I take for granted that you are an expert in naval architecture, certainly good with spreadsheets so I thought what is the problem if it is unreadable on your screen. So I changed the scans to make them sharper, didn't make a lot of difference. I think the problem may be windows doesn't come with a dedicated picture viewer (I use irfanview) Windows picture viewer zooms in on the scans and is quite clear on my computer but you have to drag the scan down to read the top line.
If that is not the problem let me know and I will sit down and tabulate the graph lines.
Mik the stick.

 

You can try scanning it with a higher resolution. You can see how it is coming out in my end.

The procedure is;

1. Create an Excel spreadsheet.
2. Adjust the cell size
3. Insert the graph as image. Adjust image to align with excel lines.
4. Input values from graph in yellow boxes.
5. Create a graph using the inputted values.
6. Insert a trendline in the graph using trendline function of Excel. Pick a trendline that will approximate the curve of values (linear, exponential, polynomial, ect.). Click the trendline box to show values in the chart.
7. Plot the correct values using the formula derived from the trendline.
8. This is the iterative steps. The more accurate the inputs, the closer the trendline tracks. The closer the values deviate, the simpler the trendline.
9. Once the trendline and the input values are corrected, it is time to interpolate to get values "in betwen". I did not do it as my input values are still far from accurate but I can show you how,
10. When completed, I can either use the trendline formula to arrive at a Y value given an x value, or use the Excel Lookup and Reference function formula (Hlookup, Vlookup, Match/Index) to "walk and find values from the database".

Of course, I have other tricks that I use to make things easier such as adjusting the inserted image contrast, superimposing the graph values and making it transparent so that as I input the values, I am seeing the correct graph and can fine tune the inputs "on the fly". The graph shows how it was done.

 

Now I see the problem, but as we know I'm not great with spreadsheets.I struggle with microsoft software I use open office and microsoft office on my computer makes sure I can read xl etc. It seems unless I buy it and it keeps trying to make me I get the watered down version with nag screens. I feel I have a better chance of becoming a fully fledged Naval Architect than ever living long enough to learn how to use this software.
Sorry for the rant. I deleted the F2 scan and inserted my scan as a background and now it is much clearer I then tried to make the blue lines converge over the scan but can,t do it. I have attached my rather poor effort and will continue to try and improve the scan.
mik the stick.

 

Hahaha. That is why I am planning to automate it for you, Just input the values and and the Excel gives you the result. Plus you can evaluate maybe two configuration at the same time to see which one is better.

Now that is a good copy. I can work from there.

 

Variations

 

bit, you beat me to it. How did you get the F1 value so quicjky. It is spot on. I am getting a 4th order polynomial to make it fit.

By the way, you used Tonne, Mik says the values are for long ton.

 

Rxcomposite: download-> Engauge.com->Import image->Export As...->Open Excel->Text in Columns->Diagr->Trend Line =
F1 = 0.9344*L9^1.1784; power
F2 = -12.54*L12^4 + 59.073*L12^3 - 96.102*L12^2 + 67.569*L12 - 17.392; poli

 

Mik, can you post a scanned copy of Bebee's formula and some of the explanation. It seems it is not a resistance based formula given the equation. It is a displacement based formula to find BHP. Can't find the formula you posted and need to find the application of the graphs. It seems the graph is "zoned" for different types of ship as you have mentioned.

I looked up E Sponberg article on design ratios and the reference was "SL ratio = 1.34 = 9.966(BHP/Displ)^0.333
Solve the equation for BHP, the only unknown:
BHP = 1.34^3 x Displ/9.966^3 = 2.406 x 115,745 / 989.835 = 281 HP" and

"Well, this is all very well and good, but then two years ago, Dave Gerr changed his
formula. In the June 2008 issue of The Masthead, the design newsletter from
Westlawn, Dave published this version:
SL ratio = 2.3 – (((Displ/SHP)^0.333)/8.11)
(and so we’ll call this “Version B”)
And, solving for speed:
V = Lwl^0.5 x [ 2.3 – (((Displ/SHP)^0.333)/8.11) ]"

Referring to D Gerr's A anf B formula.

The nearest I can relate to is "which is the Bp-d method (pronounced “Bee-Pee-Delta”) of propeller specifications,
which is found in The Propeller Handbook and is also covered in other major
professional naval architectural texts."

I have D Gerr's Propeller Handbook and have programmed the Bp method before but it is about prop sizing.