Boat Design Forums  |  Boat Design Directory  |  Boat Design Gallery  |  Boat Design Book Store  |  Thanks to Our Site Sponsors
  #1  
Old 03-28-2016, 10:18 AM
bscatam bscatam is offline
Junior Member
 
Join Date: Mar 2016
Rep: 16 Posts: 64
Location: Black Sea
40 ft cruising cat design. First steps.

I used Delft Ship for basic linesplan. After that continued with ACAD and Rhino.
Building method strip planked huls. Flat decks. Materials: huls 12 mm end grain balsa with 1,5 mm layer of okume veneer both sides. 19 mm for decks and BD roof. 25 mm for bulkheads.
Attached Thumbnails
40 ft cruising cat design. First steps.-linsplan.jpg  40 ft cruising cat design. First steps.-frames2.jpg  40 ft cruising cat design. First steps.-frames3.jpg  

Reply With Quote
  #2  
Old 03-28-2016, 10:32 AM
bscatam bscatam is offline
Junior Member
 
Join Date: Mar 2016
Rep: 16 Posts: 64
Location: Black Sea
40 ft cruising cat

Basic design idea was live a board single handed catamaran for Med.
Attached Thumbnails
40 ft cruising cat design. First steps.-cat-wr3.jpg  
Reply With Quote
  #3  
Old 03-28-2016, 12:16 PM
TANSL TANSL is offline
Senior Member
 
Join Date: Sep 2011
Rep: 300 Posts: 3,893
Location: Spain
A nice boat.
You probably already know but I would point out that you must take care with special attention on scantlings of the bow of the hulls, in the area between the two hulls, as well as the wet deck. These are areas that need to be strengthened. Similarly bending moments between hulls must be taken into account for dimensioning the deck beams.
Reply With Quote
  #4  
Old 03-28-2016, 01:12 PM
bscatam bscatam is offline
Junior Member
 
Join Date: Mar 2016
Rep: 16 Posts: 64
Location: Black Sea
Thanks. I know. Some additional drawings.
Attached Thumbnails
40 ft cruising cat design. First steps.-new.jpg  40 ft cruising cat design. First steps.-8.jpg  
Reply With Quote
  #5  
Old 03-28-2016, 01:23 PM
bscatam bscatam is offline
Junior Member
 
Join Date: Mar 2016
Rep: 16 Posts: 64
Location: Black Sea
Drawings.
Attached Thumbnails
40 ft cruising cat design. First steps.-i6.jpg  40 ft cruising cat design. First steps.-i7.jpg  
Reply With Quote
  #6  
Old 03-28-2016, 01:32 PM
TANSL TANSL is offline
Senior Member
 
Join Date: Sep 2011
Rep: 300 Posts: 3,893
Location: Spain
I supposed, but, of course, in the photos is not possible to see if you have scheduled additional laminate/reinforcement for those areas.
Reply With Quote
  #7  
Old 03-28-2016, 01:45 PM
bscatam bscatam is offline
Junior Member
 
Join Date: Mar 2016
Rep: 16 Posts: 64
Location: Black Sea
TANSL, I am calculating my lamnating schedule in separate table. So far I have for hulls, decks and bulkheads. Progressing construction drawings I will add all sensetive details. I think to put it in the forum. Probably somebody with more experience than I have, could correct me.
Reply With Quote
  #8  
Old 03-28-2016, 02:07 PM
TANSL TANSL is offline
Senior Member
 
Join Date: Sep 2011
Rep: 300 Posts: 3,893
Location: Spain
If you think I can help with something, just say so. Not take too long to define scantlings because you are interested to know the weight as soon as possible, in as much detail as possible. Good luck with your project.
Reply With Quote
  #9  
Old 03-28-2016, 03:34 PM
catsketcher catsketcher is offline
Senior Member
 
Join Date: Mar 2006
Rep: 790 Posts: 1,140
Location: Australia
Thanks for putting up something that shows thought and effort - looks good.

You haven't put up any hydrostatics - LCB and displacement are the big ones for me. Cats often go down at the stern or just sink too much. If I look closely I am thinking (guessing) the immersed volume is about 3600 litres. She looks too fine underwater to cope with the build and cruising load.

Be very careful and then more careful and then even more careful about your weight calcs. They are incredibly important. I would start with the built weight of a similar cat and use that as a base. Then work out if you would be heavier or lighter. EVERY first time designer gets this wrong. They ALL think their boats will be lighter than they end up. Only after a few boats do the underwater sections get filled out. Fixing this after the boat is built is expensive.

Go visit a boatyard and see how many cats are floating on their lines. Then work out what type of interior you want. My cats' sistership floats 8cm lower because they have a beautiful interior and heavy stainless fuel and water tanks. Bit of a dog.

I am guessing 3600 litres - Am I too far off? I think it needs to be closer to 6000 litres for a forty footer but then again you could get away with 4200 if you are very weight conscious.
Reply With Quote
  #10  
Old 03-29-2016, 04:43 AM
bscatam bscatam is offline
Junior Member
 
Join Date: Mar 2016
Rep: 16 Posts: 64
Location: Black Sea
Thanks, CATSCATCHER. This is what I got from design parameters and calculations (in meters):
LOA 12,21
LWL 12,18
BWL 1,12
BH 7,08
BCB 5,35
Bridge Deck Clearance min 0,75
Draft 0,58
Light boat aprox 6000 kg
Loaded aprox 7400 kg.
LBRC 2,32

I have very clear ideas for weight. As I am a furniture maker (factory) design of light, stiff and still nicely veneered panels for furniture is no secret for me. Of course it's still work in progress so I will apreciate any advices. My idea is to post regulary my work progress in the forum.
Reply With Quote
  #11  
Old 03-29-2016, 05:29 AM
catsketcher catsketcher is offline
Senior Member
 
Join Date: Mar 2006
Rep: 790 Posts: 1,140
Location: Australia
That weight is very achievable. Looking at the renderings it looks to me that there is not enough volume there. So does each hull have about 3000 litres volume at designed waterline? (the grey part of the render).

As to special scantlings for the bow areas and "wet deck" (I don't know what this is) - I don't think this is normal. Most of the boats I know just use a similar laminate all over with extra around the keel. Of course beams are very interesting and you need to copy someone's similar and well proven boat or do really good engineering based on something. Almost all the cats I know are based on simple rules of thumb - the one like this didn't break last time.

cheers

Phil
Reply With Quote
  #12  
Old 03-29-2016, 05:52 AM
bscatam bscatam is offline
Junior Member
 
Join Date: Mar 2016
Rep: 16 Posts: 64
Location: Black Sea
Actualy - 3,4 m3. I think cross beam is not as big issue as bridge deck roof. As I have to reinforce it because of mast and mast post.
Reply With Quote
  #13  
Old 03-29-2016, 08:19 AM
Richard Woods's Avatar
Richard Woods Richard Woods is offline
Woods Designs
 
Join Date: Jun 2006
Rep: 1244 Posts: 2,004
Location: UK, USA and Canada
I would try to slope the bridgedeck front more to reduce slamming. I am found that a slight Vee in the bridegdeck helps a lot. See my Transit 38 for more details. You will have to be very careful with the build to keep under 6T

Richard Woods of Woods Designs

www.sailingcatamarans.com
Reply With Quote
  #14  
Old 03-29-2016, 09:42 AM
TANSL TANSL is offline
Senior Member
 
Join Date: Sep 2011
Rep: 300 Posts: 3,893
Location: Spain
Following the line of what advises Richard Woods, I recommend reconsidering the shapes of the forward part of the wet deck. In this area the sea produces huge hits and forms in "V" are a "very adequate" solution.
Reply With Quote


  #15  
Old 03-29-2016, 10:17 AM
bscatam bscatam is offline
Junior Member
 
Join Date: Mar 2016
Rep: 16 Posts: 64
Location: Black Sea
This is how BD front actually looks like. Do you think that I should add some kind of nossele? I still hope that the minimum BD clearence of 750 mm will be enough. Originally its 780 mm.
Attached Thumbnails
40 ft cruising cat design. First steps.-tw1.jpg  
Reply With Quote
Reply



Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Crowther design 226A (42 foot cruising cat) DennisRB Multihulls 12 02-07-2016
05:50 AM 
Help with design first steps? voodoo92 Boat Design 12 05-27-2014
02:21 AM 
22m cruising cat design concept Becaris Multihulls 114 09-07-2009
09:34 AM 
What are the steps to getting a patent on a design? AlaskaFisherman Boat Design 13 07-23-2005
05:02 PM 
Summary of Power & Propeller Design Steps JohnHeart Boat Design 8 07-08-2003
04:01 PM 

Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.

All times are GMT -5. The time now is 01:13 AM.


Powered by: vBulletin Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Web Site Design and Content Copyright ©1999 - 2017 Boat Design Net