Heeled Waterlines

Yes, I agree with gonzo, and that is yet another reason I would recomend hydromax, because you can combine wave form analysis with the large angle stability analysis, and observe the waterlines or any other contours behavior, with many, many different load cases and wave patterns in a very short amount of time. all the while tracking various centroids and there movement.

 

That is basically what I have heard. Unfortunately I don't have $750 for the program. I am hopeing they will make a student version soon. I really like the Maxsurf platform, but the academic portion is difficult since they only let you have three surfaces. That translates to a hull keel and bulb only. It is difficult but I have found a couple of ways around it. It is certainly better than the alternative, $$$$. Hydromax demo won't even let you import files.

 

Asymetrically because of a several reasons. The shape is different on each side when heeled. Also, the boat is not moving parallel to the centerline but has leeway. Another cause of asymetry is the turbulence caused by the appendages towards the windward side.

 

Sponberg Cross

Dear Eric,

About 5 years ago, our Naval architect was measuring the trim of our newly built boat. He was using a wooden cross fabricated by the carpentry shop. When i asked him what is that, he said it is a "Sponberg Cross".

Was it named after you? Did you invent it?

I have read many of your articles in Professional Boatbuilder Magazine and i must admit i am a fan of yours with regards to your knowledge in the boatbuilding industry. I just dont know where to post this thread.

regards,
Rx

 

RX,

Yes, I did invent the Sponberg Cross and published it some years ago in Professional Boatbuilder magazine in an article that had to do with weight management and stability tests. It is not a protected design, nor patented, so anybody can use it. Having it named after me was not necessarily planned, but it's nice nonetheless. Thanks.

Eric

 

Sponberg Cross

Thanks Eric.

Now i know. I kept my mouth shut then because i didn't want to be a dummy.
Now i have the bragging rights.

Rx

 

The scow is a double-ended boat in profile, rather than in plan view,
When the scow heels over, the waterlines develop well-balanced asymmetry.
The scow's waterlines are so well balanced that it develops no weather helm when it heels over.
The tiller is in the center of the boat until the mast hits the water.
The efficiency of the scow is best demonstrated by comparing a 20-foot C scow to a 20-foot Flying Dutchman ("the world's fastest monohull"). The Portsmouth Yardstick shows nearly identical ratings for both boats. The 650-Lbs C scow is a catboat with a rotating mast and no head sails at all. The 375-Lbs Flying Dutchman is a sophisticated sloop with a genoa jib and a spinnaker. . Currently-available scows leave plenty of room for design improvements that would make scows faster than they already are. The pram bow that smashes into oncoming waves, the large-radius chines that offer minimum lateral resistance, and the topsides that are curved in plan view, all offer opportunities for better performance.

 

The other trick is to run diagonals in Rhino, that way you can check for fairness of the form at any angle. Also out of trim ie bow down, stern down as well as heeled. As well as the waterlines, these sort of double check the curvature.

Looks good that hull.

 

Has anybody noticed that this thread started in year 2004 and stopped at 2005?