Just a small fact check if you don't mind.




Right !
Like any good young happening individual. I need to clear a path through a jungle of old boy entrenched has-beens. All proper engineers are over the age of 50 are fat and have an air an unmistakenbly aristrocracy. You know like the old gits on the fench :"That contraption will never fly because when I ..." That kind of stuff.




I never knew that the Taipan was designed in 1982 ?

Besides where AHPC failed to market the Taipan with spinnaker we (I ?) succeeded.




Yes, I never said we were a development class not did I ever say that we pioneered these things so what is your point.

We do however offer carbon parts for less than halve the price of our competitors. We do offer cheap aluminium wingmasts as the only class. Stuff like that makes us unique I dare say. We also have a no-nonsense setup that works very well. We are a true formula class with 4 different builders offering 3 different designs. Try that with the F17.





Try doublehanding the Flyer with kite please, and after you have swam back to shore try singlehanding the Carpricorn F18 with kite. After you have reached the shore without boat for the second time YOU as well will learned to see the uniqueness of the F16 class. That is if you have not busted your old boy back first when getting the F18 in the water.

We are doing something that has only been done by a few Australian class like the Mosquito and Taipan and only 1 single EU class ; The dart 18, but were are doing it on a international scale with multiple builders and at a asking price well below F18's and even more below the price of A-cats. I imagine you would do it in an afternoon.




Why should I ? Did I ever claim that we were more innovative then other classes ? But if you want to hear one. We are fusing doublehander and singlehanded sailing into one single class while using spinnakers. This would qualify as an innovation. Not as an invention but as an innovation certainly.





Well it helped us survive all the attacks we have endured over the last years. One powerful guy actually threatened to do everything in his power to :"kill us off"; We are still here and he is nowhere to be found. We have a few inside attacks from OD sailors wanting to favour their own design with respect to others. The class rules are still open and favour NONE ! We started with NO true F16 boat builders in 2001 and now we have 3 builders who offer fully optimized F16 boats. We started with only a handful of sailors in USA, AUS and EU; after this februari we will have had inaugural F16 events on 5 different continents : America, Australia, Africa, Asia and Europe. All that in less than 4 years time and without the members paying membership fees. And more !

Maybe more classes should be run as somebodies "Own little club"





On the subject of catamaran design I know I am.




Why don't you ask me one more time where my "virtual" Typhoon F16 is ? The boat you claim was never build.

I'm sure you remember your statements of past about this.

Wouter

Seriously Wouter, why even bother with these type of individuals. He does not bring anything positive to the table, and only insults. Dont worry about him, people sometimes just crave attention.



Did I ever tell you im getting a Blade!

Wouter-
Just ignore Sam, he loves to argue, he can't help it! It's his way of getting attention. And Sam- if you want to personally argue with Wouter (he is Dutch after all and they are famous for being stubborn and argumentative, probably why you target him isn't it?) please do it personally rather than using our F 16 forum. If you have such a "thing" for Wouter - why didn't you take it up with him personally when he was at Spring Fever awhile ago?
As for criticizing how skillful another sailor is or how good a sailor Wouter is, why don't you tell everybody here your racing credentials?? Or your design, building or engineering credentials (compared to Phill for instance)?
If you want to contribute how about saying something positive and constructive and becoming a positive influence? I know you are capable of doing this.

Thanks-

Hi Wouter,

did the measument as suggested, 100mm. was the result. I never expected Altered to be stiff and as I said she doesn't feel stiff in the water. I have seen Hobie 16s that looked very flexible, wonder what they measure.
I would put it down to a number of factors.
Narrow decks = longer unsupported beams, allowing beam to flex.
Rear beam is fixed with a bolt at the outer end but has saddle riveted to beam bolted each end on inner edge.
Rear beam deck cut out is only about 1/3 depth of beam diameter.
A class beam mounts are built light.

All of the above I could expect when I went into this experiment and am happy to accept. The boat is a compromise and could never be as stiff as a purpose built F16 which would have the strength and stiffness where it matters.

Interesting thought though, when doing this measurement unless you picked up Altered from the bow, say 6" back it would prefer to lift the complete hull on one side before the other bow. Since the repair, the boat almost balances at the main beam, which is almost half way along hull.
Does this mean balance of hull weight effects this meausurement, ie. heavy bows puts more pressure on lifting just one bow. So is it a directly compareable measurement between boats of different centres of balance and beam positioning.

Still wonder if carbon beams would be stiffer. Not about to run out and buy some though. People forget this is still a low cost project despite the way it looks.

Regards Gary.

Can't say I can believe this one. How can you compress feathers to be smaller than Lead?
Can't believe I might actually think Sam has a valid point here.
I'm sure you were speaking rhetorically.
However, what I want to know about is the beams. I had the old style Strap Beams, they were a pain in the butt.
A Through bolt should be better, but I would think the Flat style beams Like the Nacras use would stiffen the boat's rotation around the beam better. I know I've never had mine slip, unlike the Strap-over-Round-Tube Design.
I understand the tube is far better from a strength compression standpoint than a flat surfaced beam, but at the amount of forces we're talking about, is that really significant?
Another advantage. It is a pain in the butt to mount hardware on a round tube as opposed to the flat style beams.
Cary

Quote:

a normal sized cube of 1 kg lead falls slower than a compressed smaller volume of 1 kg feathers.
Wouter
This is obviously a misprint??? every one knows that the law of gravity (or attraction of mass) applies equally to the weight of any mass regardless of the composition of that mass!

Gravity determines the forces. The velocities will also be equal if you neglect drag. I think Wouter's point was that the drag is less for a smaller volume, leading to (what for some would be) the counterintuitive conclusion. Of course the illustration could also have been made without appealing to this subtlety.

M.

I see what your saying MARK, Wouter was giving an ilustration IN AIR and not as the attraction of mass (gravity) is generally assumed to be conducted, - without drag, friction etc, in a vacuum?

"a normal sized cube of 1 kg lead falls slower than a compressed smaller volume of 1 kg feathers."

You guys have had enough time to think about this one and Sam provide the right backdrop of the the example. While I'll admit their is a type in the example the basic underlying thought is not correct.

The example tries to show that :

-1- You can't reach a truthfull conclusions without specifying a multitude of conditions. (vacuum or air, both volumes of the same shape

-2- That something that is the case in in particular set of conditions may not at all be true in another set of conditions.


Typically if BOTH the lead and compressed feathers come in the shape of a cube and are examined in air than the lead will drop with a creater velocity.

If the same is done in vacuum then both will drop equally fast

Now when the feathers are compresses in to a volume that resembles an aerodynamic efficient arrow shape than it will drop at a greater speed than the lead with a cubuc shape.

It is the same with boat design. A certain setup may seem inefficient but when another aspect (compressibility) is taken into account it may proof more suited to what you want to achieve. This is thinking "multi-dimensionally"

With regard to same, he is right that you will have a very hard time compressing feathers to a density greater than lead. The placing of the word "smaller" is misleading indeed. I should have written "... compressed, smaller crossection, volume ...."

But even that is not complete as then I pretty much also need to define WHICH crossection I'm talking about and so on. I tried to keep the phrase simple and thus ended up making a misleading phrase.

Best would have been to choose something else than lead.

Best would probably have been.

"... a normal sized rectangular carton of milk. weighing 1 kg, falls slower than a compressed smaller volume of 1 kg feathers ...."

Wouter

All very true, although the magnitude of the difference may proof to be very little. Having said this; high quality ROUND tubes are fair easier to source than special extruded rectangular sections of the right strength/stiffness/weight. That is why the Blade homebuilding plans use the round beams.

But still I wish to underline that a homebuild Timber Blade with normal quality round beams (plain T5 alu instead of high strengh T7 or special allow) resulted in a stiffness that was a factor 2.7 stiffer than a young Tiger F18 that used oversized square beam sections. Something large opposite of what a quick look and gutt feelings may suggest.

So while in theory you say truthful things we must take care to not let such a single difference in potential colour our perception of the whole situation.

Wouter

Thank you Gary,

I appreciate you getting this measurement a lot !

Take a look in your catsailor-forum private mail inbox

Wouter

A good example of difference in falling weights Wouter would have been to compare a 1kg weight cube of lead (or any weighted cube of lead) to a peregrine falcon of much less than a kilogram falling from the same great height. The lead weight will reach a constant "terminal" velocity at a much, much lesser "speed" than the Peregrine falcon (not flying but simply "falling in a dive under its own weight") this comparison ilustrates "form" and "drag" over "grunt" quite dramatically

Darryl-
How about this even more obvious example-
Two 70Kg engineers, both with 5 kg parachute packs strapped on, jump out of an airplane. On the way down one of the engineers, to make himself lighter, takes the parachute pack off and tosses it away, so now it is just his 70kg being attracted to the earth while the other simply pulls the ripcord of his parachute, which opens, but his total mass is still 75kg being attracted to the earth.
Hopefully we all know which engineer takes longer to fall-
Hopefully we can all now move on from this issue-

By the way, it's believed one of the big advantages upwind of the Flyer/A2/XJ hull shape is the reduced aerodynamic drag of the reduced bows compared to more "conventional" shaped bows.

Kirt

I "love" the connotations of the engineer example KIRT (even though I am one myself), it is almost as good as the saying, "what the world needs is more lawyers".
We have a question in Australia about lawyers - what do you call 100 lawyers at the bottom of Sydney harbour (lawyers were responsible for a tax evasion scheme many years ago here that was known as sending your company "to the bottom of the harbour")
The answer to the question??
“A very good start”

What about boats that use a mast section for the main beam? Would this be a good compromise between round and rectangular shapes.
Are mast sections alot more expensive than round and Rectangular?

I'd have thought most boats would bed their beams in epoxy to give the best fit, is this not the case?

Cheers Phil

give CST in sydney a call.. Composite Spars and Tubes
he has a strikerless series of tubes available.. made on a round mandrel but with extra carbon on two sides, making it an elipse.
http://www.compositespars.com/
a pic of the strikerless vs the standard is here http://www.compositespars.com/images/A-class_beam_ends_web.jpg
I guess you could ask C-tech in NZ and composite spars in melbourne.