Bow shape and keel arrangement

Both extremes, very hollow and bulbs, are hard to design. Also, they have a limited range of speed when they are effective. A moderately full bow has a better all around performance.

 

I'm sorry to insist but, Gonzo, you think all those words you've put one after another mean something ?. Please, and I'm talking seriously, if they mean something I would like to understand them to learn something else, someone could explain them?
For me they are words with technical aspect which, put one next to the other, make up meaningless phrases.
Why are they "hard to design"?.
What "limited range os speed" are we talking about : 4.56 knots to 12,34 knots?
Whar´s a "moderate full bow"?. How materializes "a better all around performance"?
Thanks in advance to anyone who manages to explain all that.

 

Many motor boats have hollow bows and I have to admit I don't like them but the speed range there are different. If cutter where fast ships it wasn't for their profile but for what was under the waterline, wich continued in the typical bow and bowsprit and a nice figurehead I am becoming a bildge keels supporter, TANSL please share your point of view on the matter, the speed range I'd like to go is under 1.34 r. Searching on the internet for SOR rule or something it came out with Slap Of Rightousness

 

SOR is a list of requirements to be met by boat. Nothing regulatory or mandatory, the list is made by the one who will design the boat or someone who wants someone else to design his boat. Among other things, the regulations must meet the ship, navigation type, propulsión type, number of passengers, maximum speed, range, etc., etc. ..
I recommend you read carefully the recommendations of PAR.
In ships you can´t generalize. As you define the SOR that it may be necessary or not a bulb. One type of bulb can be very good for a boat and very bad for another. That is, everything (and I mean everything) should be studied for the boat you want.

 

TANSL, both you and Gonzo are talking about the same thing, though Gonzo hasn't elaborated as much as you, about some of the details he's basically as correct as you, in regard to the observations on the images posted.

It is quite difficult to get hollow WL entries right for a specific project, though with some experience and possible testing, be that modeling or actual, not hard to narrow down to something close enough to satisfy the SOR, for all but the most insistent client. Lets face it, we're talking about basics and generalities in this thread, with nothing specific about the requirements of this hopefully hypothetical yacht. Given no idea of the SOR, further refinement past these generalities is folly.

I suspect the OP is playing with some software and thinks they've stumbled onto a clever setup, when in fact the software, does what all software does, which is to faithfully generate whatever good or bad ideas are inputted, regardless of suitability to an SOR in particular, let alone the realities of stability and hydrodynamics in general.

Lee, we're not trying to be pessimistic toward you or about your "design", it's just got so much wrong with it, to experienced eyes, these issues can't be taken seriously. Even in the very general sense the drawing has been evaluated, there are glaring errors and oversights in terms of the basics, so the recommendation of further study on your part is the usual retort. Once you get a better understanding of hydrodynamics, you'll look back at this particular hull model and have a good laugh, probably seeing much of what we see.

 

I think TANSL is going through the whole of Ashley's book of knots by now.

 

I cannot find any SOR related topic, what is this acronym for? PAR u don't see that i've only posted a sketch to express a concept here it isn't close to any actual design like not everyone seems to showoff their skills here, btw i'm not a sailing guru and I'm here to learn but I can send you more technical stuff in pvt when there is an occasion

 

I was hoping this was a hypothetical design study. Simply put, if you unfamiliar with what a SOR might be, you're a long way off in regard to the design decisions you need to make, for a reasonably viable design of any type. It might be advantageous to begin your post with "sailing concept ideas/keel and bow shape ideas", to keep the playing field level next time. This is a good place for answers to specific question, but a poor place to get a dissertation on yacht design and dynamics. I'd recommend a full review of the latest addition of "Principles of Yacht Design" as your first step.

 

There might be some useful stuff here Lee, especially regarding SOR

http://www.boatdesign.net/forums/boat-design/generic-advice-new-boat-designs-designers-51424.html

 

A look at actual Clipper Lines may be helpful to the discussion.

 

When the software created this bow every time I start to think it is a less forced shape also for the shellplate, the clipper linesplan posted was the same. If today it isn't mainstream for whatever reason doesn't make it useless, for example it can have a less bumpy ride; but I changed one model from hollow tu full bow and it looks a lot better one more point to the straight line against curved is that it has less surface, on power boats i prefer full sections also. Par, I have opened the book you suggest some time ago but it was too much technical and without photos maybe today i can try to read it again

 

If you are building a ship of the size of those clippers, the bow would still be close to a current design. However, on smaller boats they can make pitching uncomfortable. Design features don't scale up or down easily. SOR stands for specifications of requirements. It is what starts the design spiral. They get changed as conflicts or new requirements appear. The initial list is usually pretty broad and gets more detailed as you get along the design process. There can be some very detailed specifications from the start though. For example, that the stern must be round or that the master cabin must be on the port midship area.

 

Dont forget, Clippers were optimised for high load carry ability with as much sailing ability as they could considering they were square rigged. That was their SOR.

So many times, enthusiasts get "fall in love" with the aesthetics of a certain feature, and think it will suit what they can afford.

Gonzos' is stating the best way to get a desired performance result, but often aesthetics motivates customers wallets better than logic.

 

If he can't get through "Principles of Yacht Design" or something similar, well his likelihood of success is pretty low and drawing yachts at this stage, is simply doodling with computer graphics.

 

I think Lee01 has made a drawing with computer and then said: what a nice boat, let's see what it does.
All advice will be useless if the OP is not convinced that he has to do two things before proceeding:

• define its SOR
• Study about ship design.

For several days that PAR is saying the same thing. So, please Lee01, for your sake, start at the beginning.