BAOW Performance Number

MultiHulls General Discussions (MultiHull/MultiOne)
21

I know a good deal about numbers and modeling things, and with all do respect to both professional and amateur designers most of the simple imperial formulas are nothing more than numbers to throw around, that have no value whatsoever.

We can sit here and debate the value of numbers until where all blue in the face, but it isn?t going to do anything to promote the image, or the number of boats in a class.

When it comes to getting a class going you need three basic things,

  1. Boats on the water
  2. Cheap boats, because no one is going to spend an extravagant amount of money for a model boat they might never get to race with.
  3. Designers with proven race winning designs.

Everything else doesn?t mean crap.

-Dan

22

Remember these quotes from a differnt topic … ???

A “Bruce number” is used by multihull designers to compare the power to weight ratio of multihulls.

The Bruce Number is a DESIGN comparison

There are some limitations on using the Bruce Number

<font color=“red”>Further, BN’s don’t reflect the intangible’s that show up on a race course</font id=“red”>

Model multihull’s, under both the mini 40 rule and the Formula 48 rule, are allowed to vary displacement as well as sail area further clouding the BN picture

My point in saying what I did was to caution people not to draw too many conclusions, at this point, regarding the application of Bruce numbers

Perhaps some correlation between BN and performance will be shown as time goes by

You can create BN’s for any size boat but their major value is in comparing similar boats

The fact that the X3’s BN with a spin is higher than an 18sq. has absolutely nothing to do with the X3 being able to beat such a large boat;

By compiling data such as Bruce numbers and working toward other methods of evaluating multihulls, perhaps thru a wider set of parameters, we are making a start on building an information base that will be added to over time. It may help us all see the relationships involved more clearly

BN numbers are just a start

This again reinforces the fact that collecting data such as BN numbers for rc multihulls with a perspective of using the data to help develop accurate ways of assesing an rc multihulls’ potential across the board including it’s proclivity to capsize/pitchpole (or lack thereof) is important. Going about promoting multihulls in the same old way just won’t cut it; there are solutions that can be developed.
BN numbers are a start…

I’m sorry it’s hard for you to understand the way Bruce numbers work; they have some limitations as pointed out several times in earlier posts. They appear to be accurate when comparing rc multihulls in light air and based on European race results maybe in heavier air as well.

In point of fact Bruce numbers are relevant for rc multihulls in light air when length (wave making resistance) and RM(righting moment) are not factors.
<hr noshade size=“1”>
All of the above are quotes and show a move away from a pure post to one that includes righting moment, water line lengths, sail area, wind speed and a whole host of other intangibles ? see the red post above. Notice how Doug kept adding in other “qualifiers”?

I suggest that my post is just as valid ? if not more so - than all of Doug?s quoted posts above: My post said ? ?The BAOW Performance Number (rating from 0 to 10) can provide a quick, effective and easy to understand guide number for determining which boat should be selected for your immediate, pending multihull purchase.?
I further went on to point out that?.

<font color=“red”>If the boat isn’t on the water - it’s rating is Zero ! You can’t buy one or sail one.</font id=“red”>

<font color=“orange”>If the boat is under construction - it’s rating will be around 5 depending on the level of construction! You can sit around and wait for it to be completed if you want to - your choice!</font id=“orange”>

<font color=“green”>If the boat is actually on the water and sailing, it rates a 10 ! If it is for sale you can buy it, take it home and go sailing!</font id=“green”>

Please explain why this set of ratings should any more confusing, be less useful, or do any more damage than those ratings posted by Doug. My ratings are based on actual boats that are either on the water or they aren?t. I?m not sure what part of my post is difficult for you to understand.

In the end ? performance is judged <font size=“3”><u>on the water</u></font id=“size3”> ? not by a bunch of databases and tables and numbers. If my boat (monohull OR multihull) finishes first ? that is the only number to which I care to relate or understand.

And Matthew ? we can compare my boat against your boat to no end by numbers and databases, until they actually do meet in the water. THen there is a factual outcome - not an outcome of theory! Remember, Doug is the one who indicated the Aussie multihulls couldn?t possibly be any good, - without seeing or sailing against them. Talk about confusing people!

Cheers - try sailing instead of analyizing - it is more healthy and more enjoyable.

23

Found more infos:

the BAOW is always linked with the NFB number, the NFB was created by a French guy (Professor), named:
Jean Aimare de Louis…

I hope it helped

Wis

if it isn’t broken, don’t fix it!

http://wismerhell.esmartdesign.com/index.htm

24

So it sounds like people have worked out that this is crap. Well you are all wrong. This is an actual equation that does work.

Dick, I have no idea what you are on about(maybe trying to playdown the fact you released something you weren’t supposed to). The numbers that you posted make sense, but you now have everybody believing that this formula is rubbish.

The formula does work. It was designed to rate the performance of a “platform”.

If you build a slow hull shape, there is no point in continuing on with the sails etc. This formula allows the builder to know whether the shape of the boat will be quick.

If your boat rates low(1-3) it would be better to be used as a pontoon.

What you are obviously looking for is a boat design “platform” that rates 10 or higher.

Dick you know the formula works. Doug is after formulas that help and as you are well aware this one does what it was meant to do.

This formula is not a worldwide known formula. It was worked out not by a university professor, but by someone who sails r/c multihull’s and is good at maths.

Yes cougar, this is a formula that works for multihull’s. It will not work for monohull’s, it wasn’t designed to.

Peter

25

WOO HOO!

So do I actually get a smart kid point for figuring it out!!! Im kinda proud of myself. One of those step back and look at the big picture thing.

I must say though. . . its somewhat a valuable scale. Right now my new us one meter would only rate a 5. . . and that is ok in my book. I wouldnt want anyone to think that its actually on the water and doing anything great (yet). . . .nor will it ever be available to anyone else as I will not be building or selling or anything like that. . . . but as a consumer, knowing if the boat is actually on the water, is valuable information, also, how many of them are on the water.

Alright, Ill shut up now. Good stuff, and worth the read.

I dont know if anyone noticed, but doug posted right after my post, and its now gone. . . why? ? ? where? ? ? Doug???