designing a planing hull

[fede]

I'm trying to learn marine design sftwr, downloaded Maxsurf, autoyacht and some other demos, tutorials are always about sailboats, wasn't able to figure out how to obtain a planing hull shape, from what i understood a sailboat hull is easyly obteinable modeling 1 surface, (I was able to do that, following some tutorials), what are the basic steps involved in drawing a power craft hull shape? are 2 or more surfaces involved?
thanks
federico

[fede]

Ok, from what I see in the offshore hull that comes whith the maxsurf demo there are 3 surfaces involved, top, bottom and rail...I suppose that the process has to start from the bottom...

[guest12020101217]

Hi Fede

I use maxsurf to product planing boats and RIBs.
I use different surfaces for the hull (bottom), chine and topsides. Like the sample model l use surfaces for elements at the bow to get better bow shapes sometimes.
Spray rails can be produced in the bottom with time. The key is setting up a net with the right amount of control point so as you can get the shape you want but not get the net "twisted" and work along in one direction (I.e. stern to bow etc). The better you set up your net, grid spacing etc, the better the results l find.
Keep checking the shape by switching on and off render and parametrics (from the contours options).

Have fun.
Colin

[fede]

Thanks Colin, after a while I was able to figure out how to get a nice looking (nothing other than that for now!) hull...maxsurf is really a great software!

[BrettM]

Note that you can get chines/knuckles in maxsurf by grouping control points together on the same surface. Handy if you have one of the limited versions.

[fede]

Hi Brett, this interesting...I didn't really get the method though...can you describe a bit more?

[Dim]

fede,

It is all is described in Manual. I have the demo-version of "Maxsurf" and I know it from Manual.

Dim.

[fede]

Yes Brett just gave a read during wc time this morning :))) from what I got you justhave to use a double row of control points grouped toghether to obtain a corner...

[SailDesign]

fede,
In this business, the "wc" is often referred to as the "Research Department" ;-)
Steve

[BrettM]

Seems everybody answered their own questions before I could...

[Andrew Mason]

It is possible to design a hard chine hull in Maxsurf using either one surface for the whole hull and compacting multiple rows of control points together, or alternatively, by using a separate surface for each panel (e.g. bottom, chine flat, topsides, bow cone etc.).

There are pros and cons for both approaches.

Firstly, if you only have a limited number of surfaces to work with then it is quite reasonable to do the whole hull out of a single surface. The key here is to compact and group together only as many points as you need to get a hard corner and no more. The rule for this is -

number of compacted points = (surface order - 1)

for example, if you have an order 3 surface transversely (i.e. quadratic) you only need 2 control points comacted together to give a knuckle or chine. If you are using order 6 transversely, you will need to compact together 5 rows to get a hard corner.

The main reason for not using the single surface approach is that it prohibits you from using the developable surface rulings option in Maxsurf, which works by showing developable rulings betwen the longitudinal edges of a surface. Obviously if you have a chine in the middle of the surface the rulings are not going to be relevant.

My recommendation is that if you have the surfaces available, use them, you will find it easier to get the surfaces developable and have the option of being able to lock or make particular panels invisible during the design process.

[fede]

Thanks!