CNC Plans not Included

I love them all )) ... What software did you use to draw that?

My sheer will improve when you see the whole boat. I couldn't get the back to not wrinkle, I think the taper is too abrupt and too much.

 

I don't personally use drawing or illustration software. The drawing is mine, I paid to have the illustration done.

 

That's the smart way to go )) ... I will eventually do that too but really feel like I should know how to draw it too.

The reverse bows are a look that grows on you but I love classic lines too. I think when I straighten up the taper aft a bit and depict the whole boat in won't look so bad ))

Edit: this is kind of interesting- http://www.livreayacht.com/
3D printing is soon to be a reality.

 

Can't get a smooth loft where chine tapers out. I'm starting to think that it's something you add in afterwards. Also the reverse bow isn't lofting too well and the transom has a strange pucker but it's a nice looking shape.

Don't really like Rhino that much, think I will try Delftship.

 

I had a cat with spray chines, my only complaint about the whole boat, the slap came from aft, most annoying at anchor but also sometimes at sea- it must therefore offer some greater resistance through the transition hrough waves.
If you look at a couple of the Simpson designs and Pescott designs they use like an inverted "bell" shape to increase living volume & will also blend it out at bow & stern.
At the size you're looking at I'd see no need for the complication & discontinuity, there's a couple designs out with inlaid/recessed panels to the outboard topsides, these break up the look but are a fluffy complication that can look good.
If I was to add anything it would simply be to add a timber or decent D rubber sponson/rubrail for the aft 8' or so at approx just below dinghy gunnel height.
Jeff.

 

I've been on this all day. Finally got the chine to loft and now I don't like it. Either the chine has to run all the way forward even if it tapers down to an inch ... or it needs to be removed. I will have a look at those designs you mention.

Going back to 2D to draw some new curves and try again.

 

Rubrails ...NOT

Why is it that so many new designs FORGET this very important item....a rubrail

Recently had some references to the special 'Dart style' keel of these Dazcats,...and when I went back to take a look, most all of them had NO rubrails !!
http://www.dazcat.com/dazcat-catamarans.html

 

I was wondering the same thing, didn't see any at the boat show.

couple more pics without a chine. Going to try with the chine running all the way forward and keep it smaller.

 

The simple things in life are often the best

 

I love Simple but Simple isn't simple

The only way I can see to not have super flared hulls is to have a chine unless you go really long. My education continues with a hull tapering up to a chine ) Need to round that bow off at the top for sure but it looks nice and fast and is scaled correctly.

 

CS hull form

Hi Jorge,
Hope you don't mind that I madea cross-refernce link with that latest hull illustrations you came up with and a discussion I was involved with suggesting a Tennant style CS (canoe stern) hull I wanted to adapt for a motorsailer

http://www.boatdesign.net/forums/motorsailers/cs-hull-sailing-performance-35387-2.html

I take it you are familiar with the CS hull shape?


You have done a much nicer job of taking away some of that very deep forefoot of the Tennant hull design.
Now if you can just give me some 'canoe' bottoms to mount my prop shafts or chain drive legs in, and some nice flat stern areas to assist with bigger power options,....wow, a great motorsailer hull

 

I have never seen that type of hull before. I think you need that forefoot otherwise you have a regular modified V hull.

I should have posted the underside view of the drawing, it's exactly the same as the other pic I posted, just have flattened out the flare on the sheer, thanks to the chine. Also it doesn't show it much but the hull above the waterline angles up to the chine to hopefully minimize that slapping.

I don't know anything about hull types actually, I laughed to myself at the boat show when I walked into one cat that had standing room on the bridgedeck cabin. I think it only had like 2'6" of clearance. A couple of friends with me were like, wow this is a good boat and I was raining on their parade lol

 

Here are a few more references to that Malcolm Tenannt CS hull type


http://www.webring.org/l/rd?ring=multihulls;id=1;url=http%3A%2F%2Fwww%2Ecatamarans%2Ecom%2Fnews%2F2006%2F04%2Fcatcomparison%2Easp

http://www.boatdesign.net/forums/multihulls/hull-shape-cruising-power-v-sail-cat-44023.html#post569957

And this was posted on another of those subject threads:

 

Very Interesting Stuff ... Wish I could do that all day long!!! Wish I had started 20 years ago )) I think I will have to settle for the co-co-pilot design specialist, aka back seat driver !

Here is how I do my testing. See the chine with the short 3" shelf that tapers up straight to the next hard chine. Works out pretty good because I get my floor shelf inside at the same time... Not that I am going to be flying the hull every day

It looks good from every position in the renders and I get the room I want plus will be close in speed to the SIG because we are longer and probably proportionally lighter, though my top will kill performance a bit.

EDIT: I think having that angle is going to reduce slap as well.

 

Brian - that article by noah thompson has to be taken with a grain of salt which is obviously written to suit his own agenda justifying his choice of the CS hull form.

There is no way a vessel with identical displacement to length ratio will have such a huge difference in powering requirements. My boat shares almost identical fuel consumption figures with many other catamrans of similar size and displacement regardless of its hull form. These include the CS hulls by schionning in the prowler series designs, the full transom stern of my own design, and the CS and full transom designs by Roger hill in the Argus 35 and outpost designs by NZpowercats. The powering requirements and fuel consunption is almost identical across all similar designs.

There is no magic bullet with hull efficiency. The well known facts pertaining to displacement to length ratio are not a mystery, and the facts show DLR is the single most influential design parameter on fuel consumption and resistance for ANY slender hull form operating above hull speed regardless of its shape, transom configuration, L/B ratio, or B/T ratio.