Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 28-01-2008, 18:12   #106
JCF
Registered User

Join Date: Jan 2008
Location: New York
Boat: 26' CATAMARAN
Posts: 36
Quote:
Originally Posted by Steven Prince View Post
Hi J.

I've been working on the current design for about 4 weeks, but I had been working on a different design before that but was not happy with the look. Before these boats I had been designing a 45ft monohull but I finally decided that I would look into a catamaran properly rather than just going of the magazine articles warning ppl away. Once I started looking into Cats I realised there many advantages and was sold.

I've read through part of your thread, haven't managed to read all of it yet. I have to admit that I haven't looked at the mathematics yet. I've mainly been trying to get a boat that I like the look of. The program I'm using to carry out the design allows for very easy manipulation. I believe that I currently need to move the Centre of Buoyancy slightly further forward by 300mm but I'll wait till I've finished the design so that I can apply the materials to the hull and check where the centre of gravity is in relation to the centre of buoyancy.

I've modelled my boat from a variety of designs but the biggest influence has been Darren Newton at Dazcats, particularily his D15R. I'm hoping to get in contact with him soon and see if he'll help with the design and eventual building of the boat.

I'm currently hoping to get a scale model made, although it'll be a lot smaller at 1:100. I hope to get a few made as the design progresses to show the different stages. The final model will be painted with the same paint as the main boat and will be used for carrying out test. The final model will be larger to show the details more clearly and to allow for some testing.

I was wondering what you have used to work out the hydrostatics.

Steven
Hello Steven,

Freeship works out the hydrostatics for you including CG and weights for all components. It is incredible and easy manipulation is the understatement. You can get it here. Try it...the worst that can happen is that you will fall in love with its ease and very satisfied with the result.

Freeship - Reviews and free Freeship downloads at Download.com

Four weeks? Well, you're doing excellent then. I don't think I had nice lines in place until way after my learning curve.

Unless you intend to have a qualified NA or NE do the work for you, it would be a good idea to get an understanding of the different design elements which include much math and pain to the noggin. If you have any intention on floating the design, it is imperative.

To start, learn the different design elements that assist you to understand how she will perform so you can design her well. For example. You mentioned that you will wait to move the CB.

Thats a no no. The CB on a cat should be at 50% of the LWL or dead center longitudinally. Therefore the CG of the design must at its final position be directly above it. If the CB is not centered and the CG of components are manipulated to be above the CB, not at the center, then the footprint changes as will stability, the LCF, increased pitch aft or forward, hobbyhorsing and other elements etc. That is ofcourse the ideal, but you should strive to always stay as close to center as possible right from the start.

If you like, I will look over your thread with more care and will offer my thoughts on her so that you have another "opinion" to keep you open about the design.

I don't understand the paint part of it or why? Can you elaborate some more?

Keep it going.

J
__________________

__________________
JCF is offline   Reply With Quote
Old 29-01-2008, 08:52   #107
Registered User

Join Date: Oct 2006
Location: Coventry or Chichester, UK
Boat: Currently an Achilles 24
Posts: 57
Hi J,

The CB of my current design is 300mm back of centre line. This of course will move slightly further forward with the addition of the rudder and a small keel running from the centre of the hull back to provide protection to the rudder / prop when beaching.

Can you import models into freeship from other programs do you know. I'm hoping to haval a NA look over the final design either way as I'll be spending alot of money to get the boat built although I'll be carrying out alot of analysis on the model and CAD model.

The boat is to be painted black but due to the temperature the boat would reach in the tropics it will be painted with a special paint that changes from black to white when it reaches a set temp.

Alsa Corp | Eclipse: Product Information
__________________

__________________
Steven Prince is offline   Reply With Quote
Old 29-01-2008, 18:04   #108
JCF
Registered User

Join Date: Jan 2008
Location: New York
Boat: 26' CATAMARAN
Posts: 36
Hello Steven,

Yes. Freeship will allow you to import different formats...DXF, Carlson.hul, fef, surface, chines, Carene xyz, vrml, polycad and michlet waves.

It is an excellent idea to have a NA or NE take a look at the design and call out the scantlings or at least confirm their integrity. I also did that with my design.

Black paint to white paint when temperature changes sounds koool. But if she will be in the sun in the lower lat's, why not just go with the thicker white gel coat with strong UV inhibitors? What is the purpose of having the colors change? I'm not being critical, and it's your pickle, but you should reconsider the colors and reject them.

Here is something for you to consider. Sunshowers that keep the temperature just below the color transition but the sun is beaming on deck. Given enough time you will be in an oven and although the heat build up may be slow, it will not dissipate as fast as you may think. Just some food for thought.

I know that exploring different things is always good (I have fighter sticks for steering in my design), but, sometimes it's good to stick to the tried and tested.

J
__________________
JCF is offline   Reply With Quote
Old 02-02-2008, 09:56   #109
Registered User

Join Date: Oct 2006
Location: Coventry or Chichester, UK
Boat: Currently an Achilles 24
Posts: 57
Progressed a bit more with the design this week. Here's a few pics. Will try and put into Free ship to do the Hydrostatistics sometime this week, if i can import the model into it.
Attached Thumbnails
Click image for larger version

Name:	top-03_02_08.jpg
Views:	89
Size:	54.9 KB
ID:	2572   Click image for larger version

Name:	side-03_02_08.jpg
Views:	97
Size:	49.6 KB
ID:	2573  

Click image for larger version

Name:	iso-03_02_08.jpg
Views:	107
Size:	59.6 KB
ID:	2574   Click image for larger version

Name:	Front-03_02_08.jpg
Views:	98
Size:	52.9 KB
ID:	2575  

Click image for larger version

Name:	bottom-03_02_08.jpg
Views:	89
Size:	52.8 KB
ID:	2576  
__________________
Steven Prince is offline   Reply With Quote
Old 02-02-2008, 10:16   #110
Registered User

Join Date: Oct 2006
Location: Coventry or Chichester, UK
Boat: Currently an Achilles 24
Posts: 57
Ok, I'm trying to import a wrl file into freeship but I just get a msg saying not a valid vrml 1.0 file. Has anyone got any ideas as to why i get this msg.
__________________
Steven Prince is offline   Reply With Quote
Old 02-02-2008, 12:53   #111
JCF
Registered User

Join Date: Jan 2008
Location: New York
Boat: 26' CATAMARAN
Posts: 36
Quote:
Originally Posted by Steven Prince View Post
Ok, I'm trying to import a wrl file into freeship but I just get a msg saying not a valid vrml 1.0 file. Has anyone got any ideas as to why i get this msg.
Hello Steven,

The only thing I can think of is that the file is not saving in vrml 1.0 format. It must be 1.0 for the import to occur. You will either need to save it as such or perhaps get one of those free converters from the net to convert it for you.

Have you tried importing in a different format? Are you able to do so?

J
__________________
JCF is offline   Reply With Quote
Old 02-02-2008, 13:07   #112
Senior Cruiser
 
44'cruisingcat's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 7,458
Images: 69
Quote:
Originally Posted by Steven Prince View Post
Hi J,



The boat is to be painted black but due to the temperature the boat would reach in the tropics it will be painted with a special paint that changes from black to white when it reaches a set temp.

Alsa Corp | Eclipse: Product Information
the boat will likely turn from white to black at sunset. Not the best safety feature I could think of.
__________________
44'cruisingcat is offline   Reply With Quote
Old 02-02-2008, 14:35   #113
CF Adviser

Cruisers Forum Supporter

Join Date: Dec 2007
Location: Wherever our boat is; Playa Zaragoza, Isla Margarita
Boat: 1994 Solaris Sunstream 40
Posts: 2,439
Steven, from a quick glance at your preliminary drawings it would seem that you would not have interior access from the bridgedeck accomodation into the hulls (or at least, not access permitting steps and headroom). And I tend to agree with the comments about black - especially for the decks and coachouse.

Further, I am not aware of any 2-part polyurethanes (or epoxies) that change colour as you describe. IMO no other paints are sufficiently durable and repainting any boat, let alone a cat of that size, is a VERY expensive proposition.

Brad
__________________
Southern Star is offline   Reply With Quote
Old 02-02-2008, 15:37   #114
Registered User

Join Date: Jan 2007
Location: Malborough Sounds N.Z.
Posts: 93
Have a look at Pelin designs, He is a NZ designer and would be one of the best known designers in NZ , I have seen one of his cats a 40ft and even though I am not a cat person I was impressed this one was home built and the owner did a amazing job, I was also impressed with the bridge deck to water clearance of about 4 ft , He has a 40ft and a 45 ft in the cat designs and can be built out of ether cold molded marine ply or FG
Pelin Boat Plans - Build Your Own Boat

Graham
__________________
KIWI is offline   Reply With Quote
Old 02-02-2008, 18:48   #115
JCF
Registered User

Join Date: Jan 2008
Location: New York
Boat: 26' CATAMARAN
Posts: 36
Quote:
Originally Posted by Southern Star View Post
IMO no other paints are sufficiently durable and repainting any boat, let alone a cat of that size, is a VERY expensive proposition.Brad
From my calculations, with paint, clear coat and uv inhibitors... thinned 2:1 with 3 coats recommended, minimum of $3,200.00 per gallon of coverage, whatever that coverage may be. Primer and special base coats not included. That is a prohibitively expensive yacht R & D venture.

Do a pro job and it will last 10 years in the tropics and then it's time to do it all again.

J
__________________
JCF is offline   Reply With Quote
Old 06-02-2008, 07:12   #116
Registered User

Join Date: Oct 2006
Location: Coventry or Chichester, UK
Boat: Currently an Achilles 24
Posts: 57
Well I've finally managed to get the model convert to a wrl. 1.0 format so will look at running some of the hydrostatistics on it tonight or tomorrow.
__________________
Steven Prince is offline   Reply With Quote
Old 11-02-2008, 10:54   #117
JCF
Registered User

Join Date: Jan 2008
Location: New York
Boat: 26' CATAMARAN
Posts: 36
Hello Steven,

How is it going with Freeship? Make sure all the layers contain accurate data and that all required fields in project settings and layer boxes are accurate and complete or the hydro may not run or be accurate.

Keep it going...I want to see more.

J
__________________
JCF is offline   Reply With Quote
Old 11-02-2008, 11:32   #118
Registered User

Join Date: Oct 2006
Location: Coventry or Chichester, UK
Boat: Currently an Achilles 24
Posts: 57
Hi J,

Managed to get it converted but it comes up with an error message and won't load it. I think the model all though converted is to complex for the program.

I'll have another go soon but rather busy at mo, got a few uni assignments to get done. Bit of a juggling act between work, uni and designing the boat.

Got a bit stuck on the back of the bridgedeck, not to sure howi want it.

Steve
__________________
Steven Prince is offline   Reply With Quote
Old 03-04-2008, 07:45   #119
Registered User

Join Date: Oct 2006
Location: Coventry or Chichester, UK
Boat: Currently an Achilles 24
Posts: 57
Ok. I've finally managed to get some time free to do some more work on the design. I've also finally managed to get the model into Freeship using VRMl. Could any1 now give me some pointers on how to run the various hydro calcs.
__________________
Steven Prince is offline   Reply With Quote
Old 03-04-2008, 11:39   #120
Registered User

Join Date: Jan 2008
Location: Fort Lauderdale, FL
Posts: 310
Steven,

Here is a design for a 55 footer that you may find interesting. The design incorporates a small forward cockpit for handling all the sail control systems and an inside steering station like the Gunboat. The design was a joint effort between Dudley Dix and Phil Harvey. Phil Harvey was involved in the building of some of the early Gunboats and designed this boat for him and his family to live on and cruise.
Attached Thumbnails
Click image for larger version

Name:	DH550.jpg
Views:	174
Size:	119.3 KB
ID:	3161   Click image for larger version

Name:	Cat Top View.jpg
Views:	140
Size:	144.6 KB
ID:	3162  

Click image for larger version

Name:	Cat Layout.jpg
Views:	291
Size:	93.7 KB
ID:	3163  
__________________

__________________
Abaco is offline   Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Hydronic Heating System Design ldrumond Construction, Maintenance & Refit 4 13-11-2010 20:48
Wanted: Yacht WANTED in Australia ribbony Classifieds Archive 6 23-07-2007 16:41
Info on Garmin 498 C Sounder. Opinions? Transome mounted Transducer? Opinions? chuck711 Marine Electronics 0 14-01-2007 17:06
Sailboat Design Ratios GordMay The Library 3 28-11-2006 21:41
Increasing Sail Plan and / or efficiency - Ideas? David_Old_Jersey Construction, Maintenance & Refit 15 26-11-2006 13:13



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 01:26.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.