Would that catamaran ever sail?

I think you are a troll - though not a good one because you spend so many words of your own. Quality trolls keep their own input in very low ratio compared to the reactions they try to pull.

Or is there another reason why you always reply to carefully crafted explanations by totally ignoring the actual point? Or the fact that you went from easier to build arguments to not so inefficient argument once it was made clear that building curved hull is actually easier?

But unfortunately I will end your nonsense with one image. I recommend all the other posters top replying if you ignore this. It will very clearly point out that its not just that people haven't tried pulling boxes in water - this is done frequently.

trtrtrttrttrtrtrttrtrtrtrt (drumroll) rttrtrtrtrttrtrtrtrttrtrttr

ZZAAAHHHHH!!!!!














buuuyaaahhh

 

I don't know if its a special kind of crazy that we see frequently here - remember the guy who was building a submarine/sailboat to escape Turkey? or something like that.
Or if they are trolls similar to be found on more mainstream discussion forums (any more broadly popular topic from fitness to cars to politics).

Anyway - John from Brasil. How was the performance of your stand up board? Didn't that give you an idea of how the catamaran would work?
http://www.boatdesign.net/forums/bo...d-simplification-rectangular-kayak-33819.html

too bad you never made your box canoe. I am sure it would have performed beautifully.
http://www.boatdesign.net/forums/boat-design/case-square-rectangular-kayak-33745.html#post381760

 

That is because the only variable is shape, without considering displacement, draft or anything else. It is an isolated system.

Think about it this way, select the best curved hull of a sailboat with 17 feet, a monohull. Put some oars in it.

Next to that, a rectangle "kayak" without even the triangle for a bow, only a 17 feet rectangle made of a very lightweight composite material. Weight about 50 lbs or less and very narrow, the width of your normal kayak.

The monohull with a 2000 lbs weight, do you think it would be easier to row the fully loaded monohull only because it is curved?

 

Now next to those two, a curved kayak-shaped kayak made also of a lightweight material that is even lighter than the rectangular "kayak".
This third is even easier to paddle.

 

two boats of same weight one with rectangular hull, one with curved hull panels and a sharp prow. the clear winner is the one with curved hulls. I thought I made this clear. I have now lost my patients with you and your inane questions.

I have a question for you: are you being intentionally dense, or are you really that oblivious to what is being written? Could it be a language issue perhaps? Or is it you just do not know how to get along with others that are trying to help you?

I ask this because clearly the mass in my explanation is identified as the MASS OF THE WATER. than you ask me what I think about the mass of your "lightweight" boat?

I and many others have been kind to you, yet you continue to argue nonsense and refuse to respond directly to the postings.

Go try it, or you will get nothing more but belittling here. You must have some kind of antisocial mental illness to be so rude and obnoxious.

 

Absolutely, yes.


Now duplicate your properly designed kayak, put them together and form a catamaran. After that a sail is attached and it moves at 10 knots.

Duplicating my two rectangle kayaks and using the same sail of your catamaran with same wind and wave condition. It would move my catamaran at a lower speed, lets say 3 knots or less. Problem is that if I attach the same sail to a heavy monohull with 2000lbs, the same sail, it would move that monohull at a lower speed. It would always come in last position. Thus proving a rectangle catamaran would move through water better than a nice designed but heavy monohull with a lot of displacment but of the same length.

Any fault with that thinking or is that correct?

No, only talking about hydrodynamics. That what I have said above, it is right if you think about it.

That way proving a rectangular hull move through water better with a low displacement compared to a properly design but with a lot of displacement hull with the same length?

 

The fault is the reason for the constraint is missing. For example, why would the sail be the same between two very different boats?

You have three examples:
A - a larger, heavier monohull with keel. Advantages are more accommodation, storage, weight hauling capacity, shelter, availability on the used market.
B - this sqaure catamaran
C - a hydrodynamically superior catamaran

Provide some advantage of B over C and there is merit to analyzing how bad the hydrodynamics are in comparison.

Otherwise, there is no reason to choose B over C. Experience has shown that C is easier to build, has less drag, and it's lighter than B.

 

http://en.wikipedia.org/wiki/Non_sequitur_(logic)

It doesn't follow that, because your rectangle & triangle shaves a few hundred pounds off of a well designed monohull, that your rectangle and triangle cat will compare favorably to a real catamaran. Once you pile people and stuff into your square boat you will probably find that it does significantly less well than this heavy sailboat that you've chosen for comparison. No one can tell you how less well without doing the calculations, but again, your design isn't a revolutionary design poised to blow everyone away, it;s just a plain old poor design tried many times before.

 

An important consideration for those who respond at this point: The OP is bound and determined to ignore advice, or to ask for highly paid professionals to do a very in depth analysis of what will be a pig in the water. However, this forum will stick around long after he has given up on his poorly designed boat, or built it, sailed it, then left it to rot somewhere. Because the forum will stick around this will be a thread that we can use to link to when future John5346's show up, with their non-revolutionary ideas, expecting to change the world.

Next bit of response to the idea: It's important also to remember that a sailing boat isn't just pushed straight through the water. Drag as drag is not the only consideration. It's also a matter of drag moving forward versus drag moving sideways. You spend lots of time sailing with the wind places other than straight behind you. A streamlined hull moves very easily straight forward, and with great difficulty to the side, so path of least resistance is for the hull to move mostly forward when a force is applied at an angle. The catamaran shown will not be particularly more efficient moving straight forward than it will moving straight wideways, so a force at an angle will push it further to the side than it would a reasonably well built boat. This can be, to an extent, compensated for with larger daggerboards (come to think of it, did I see any daggerboards or keels on your design?) but those add additional drag.

 

Quit answering this ..... person.

 

I fail to understand why his rep is still in the positive.

 

The history of boats is full of flat bottoms. I didnt notice that until today and if you use the same arguments of "look at the waterline", like you did with that navy boat earlier, then it is only really a rectangle going through water.

http://en.wikipedia.org/wiki/Flat-bottomed_boat

The article of chine hulls says..
"The two chine hull (B), with a flat bottom and nearly vertical sides, was the first hard chine design to achieve widespread use. This design provides far more stability than the single chine hull, with minimum draft and a large cargo capacity. These characteristics make the two chine hull popular for punts, barges, and the scows."

http://en.wikipedia.org/wiki/Chine_(boating)

Only because I understand now that displacement and mass is a more important consideration than geometry of a hull in a sailboat.

 

A flat bottomed barge type boat legitimately is easier and cheaper to build, and has some advantages for a work boat (like beaching). However, most flat bottomed boats have curved sides. Again you trot out articles and arguments that don't actually support what you are actually proposing.

FALSE. Firstly, that is not universally true. Secondly you if you understood the importance of keeping weight down you wouldn't be suggesting such a heavy, poorly designed, catamaran.

You are relying on the weight savings of a catamaran to save you from your poor design choices, but the poor design choices squander those weight savings. You keep comparing to an overbuilt monohull, when what you should compare to is a well built multi.

Your design displaces significantly more water than a proper design.

Your design ALSO has really poor hydrodynamic properties.

You aren't exchanging the one for the other, you are choosing to give up both.

 

This thing is still going?

 

Waste of time isn't it!