Request your input on my design

Before I got into the design business a very well known Naval Architect here in the PNW told me that design was 60% art, 35% engineering, and 5% luck. His designs are classics in the industry.
I have used the Rabl method on over 50 metal hulls from 16' to 70'. It is not quite as accurate as the "mathematicians system" but is more user (and boat) friendly, gives better control, and has certainly been satisfactory for any of the many builders (professional and amateur) I have worked with.
I can post the article if interested.

 

Please post the article.
Richard

 

Hey from northern Great lakes area Ontario!

- I would love to see exactly what you mean when you say "used the Rabl method..."
I know of Rabl's backyard books but never heard of it.
I guess it off to "google" then

cheers!

 

MultiConic Development

Here is the article - low res. & hi-res . After you have done a few designs and built the hulls you will get a feel for the process and how each material (steel, aluminum, plywood, etc) behaves..... and how good you are!
On some planing hulls there is often a transition from 'cylindrical' (aft) to 'conic' (for'd) and one area to watch out for is the bottom plate around station 3 (30% of LWL from the stem/LWL intersection). If the plate is laid down and there is a butt joint to be made in this area, the plate may want to take over and 'oilcan' and make life 'interesting'.

 

I just ordered Gerr's books from Amazon. Look out for more questions once I get into them. Thanks for a lot of good information coming from this thread (for me, anyway).
Richard

 

Nice work,Wayne.
And I like the bowls too!

 

that's some serous pony's on the back !!!
Wonder when the next lot of even bigger motors will be rolled out and hit the water !!
Gas turbine oooooooooh ! now that's a scary thought !!

 

Years ago I made two models ( 1.2 metres maybe) of planing hulls, both were 20 degrees at the transom, the difference between the them was basically that one was a developed bottom shaped with thin ply, the other straight vee throughout made with thin strips. Other than that, basically the same dimensions and weight. Towing them behind a boat on a slight chop, the most noticeable difference was the developed bottom bucked and leapt rather more the other. I realise dynamic forces are amplified in a small model, but it made an impression on me, and convinced me the limitations imposed by having to be developable makes a difference in this type of boat, in a non-planing design probably not so much, or very little..

 

The one who told you that was not a naval architect, or was pulling your leg and you are so gullible that you wrote the quote here.

 

Are you a naval architect? Fron what college did you receive your degree?

 

richardf, `don't get testy when your challenged on this forum. It is really not meant to be personal so do not let the hair on your back stand up. We all need the knowledge of our various members to get our questions answered and were happy when those questions generate answers for us. Many here are much more knowledgable then I am in their fields but I can always hold my own in my field of knowledge. Relax and enjoy the learning experience. Stan Rasor

 

Would you explain the basics of the math involved?

Or what would be a one sentence statement of what the goal is? Are we moving from a flat keel to a rounded keel? for example.

Once I have a picture of where the math is supposed to go, it is easier for me to read someone else's numbers.

Wayne

 

I would agree that you are limited in possible shapes.
But that does not mean that it is an inferiour type of shape; I read that as an implication in your post.
Look at the 'Fireball' class (as only one example) and see how they outperform many other 'undevelopped' boats.

 

You can go trigonometry if you need to involve mathematics.
But actually it is a method to AVOID maths.

 

Hakim, I understand that.

That is why I need a 'bridge' to help me see what they are saying. If it was straight trig, I would see that immediately.

It is just they way my brain is wired ....