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TOPIC: Show me your ships!

Show me your ships! 1 year 1 month ago #4931

  • cruzmayora
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And this one is similar to a RoRo Pax called Benchiguchuya or something like that
TrimaranRoRoPAXJCM-001.jpg
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Show me your ships! 1 year 3 weeks ago #4947

  • terrnz
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Attachment 11Mchineunderhungrudderreversetransom5h15heel.jpg not found



current project
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Show me your ships! 1 year 3 weeks ago #4952

  • Icare
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Congrats Terrnz!
You're a newbie on the forum, but I guess you're already quite experienced, aren't you? ;)
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Show me your ships! 1 year 3 weeks ago #4953

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been playing around with FreeShip for a couple of years and read up on Larsson and Eliasson Elements of Yacht Design plus a whole lot of stuff on the net.
I have a sailed for many years and built 2 boats.
This is my idea for a budget fast short handed 11m performance yacht using medium tech materials.
displacement is just under 3T in light ship mode.
The chines are at the 15 deg waterline for stability and ease of steering especially down wind under auto pilot as well as simplifying
construction.
the prismatic coefficient is high at .64
with a sail area to displacement of around 35 and a displacement to waterline length of 70 she should still go in the light
mast is alloy, sail plan is a self tacking jib backed up with a code 0 for the light and a roachy main, assymetric spinnaker downwind

ballast ratio of 55% in a bulb with 2.3m draft will make for a stiff yacht with strong upwind performance

other dimensions are
LOA 11 m
BMAX 3.3m
LWL 10.5 m
Bwl 2.2m

RM1deg 125 KgM
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Show me your ships! 1 year 3 weeks ago #4954

  • terrnz
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Suggestions welcome especially regarding stability calculations and VPP. I would also be interested in thoughts on merits of hard chine or soft chine especially down wind in planing conditions. I believe this boat will full plane in 20kts tws or less. with 160 m2 sail area.
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Show me your ships! 1 year 3 weeks ago #4955

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the picture fell off :(
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Show me your ships! 1 year 3 weeks ago #4956

  • Icare
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This can happen... depens on what picture hosting service you're using. Some of them erase the picture after a few of days/weeks... :S

Furthermore, as creator of this thread, I strongly suggest the users to limit their pictures' size to 100Kb (check for the parameters when saving the screenshot). This will leave HD space on the DS server for more important threads. :whistle:

I checked for the book you mentionned: Nice reading! It'd be delivered with our favourite software... B)

About the hard/soft chines question, I ain't a good judge, I never build a real ship. I just can report that a friend of mine told me long ago that soft chines were easier to build... on a RC scaled model. I assume it's true with real models, too. ;)
But, in another hand, the south-east asian traditional pirogue is called "sampang" that is "three planks"... :whistle:
I noticed, too, on the Vendee Globe Challenge sail racers they used both: soft chines on the fore part, hard chines on the aft part of the ship.
Maybe the answer is in the book you mentionned... :cheer:
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Show me your ships! 1 year 3 weeks ago #4957

  • terrnz
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1) I will post some more as you suggest 100Kb max
2) The book is available in PDF free online , message me direct and I'll send you the link or a copy
3) Chines are easier to build in my opinion, having a hard chine at the waterline sneaks a little more water line beam without much extra displacement and so increases righting moment. It is planing and surfing where I am concerned, Eliasson and Larsson refer to chines and planing strakes as a way avoiding increased wetted area by deflecting and disattaching the flow creeping up the hull sides in high speed conditions. A hard chine also seems to give directional stability at high speed.
4) I have been looking at the Vendee Callengers and Class 40s and aft chines may well be the way to go, just I havent mastered the transition on the software without getting an ugly bulge in the middle of the boat.
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Show me your ships! 1 year 2 weeks ago #4958

  • Icare
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About the last problem you mentionned:
Right now, I'm not using my computer (the one with FS installed on), but I think the solution is to draw three parallele lines (on the side view) from bow to stern. In the perspective view, on the bow, their origin will be lined up meanwhile on the stern their end won't be lined up at all.
Then set the middle line on "hard chine". I assume you'll get a pretty good result: on the fore part, the hard shine will look soft (all three lines being in the same plane).

I hope my english is understandable and my method will work. ;)
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Show me your ships! 1 year 2 weeks ago #4959

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I'm back with an example I quickly made!

The three lines I used to make an evolutive soft-hard chine are the two selected chines (yellow) and the concerned chine (enclosed between the two others).

As you can see, the "hard chine" option seems useless on the fore part: the three lines are on a same plane.

But on the aft part the "hard chine" option becomes more and more effective: the three lines are no longer on the same plane.

I annexed the FBM file, I hope this will help you.
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