a bit of help

Discussion in 'Software' started by rastus, Sep 1, 2010.

  1. rastus
    Joined: Aug 2010
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    rastus Junior Member

    Hi, i'm currently trying to design a plate aluminium fishing boat around the 4.7m mark, I might take it out to 5.2m but 4.7 seems a good size for now.

    Skip to the bottom for short version.

    Most of my planning has been done in Autodesk inventor referencing different line plans I have come across. I have been revising my design from the original side console idea for a runabout setup and in doing so have managed to refine some of the practises I use with the modelling but am limited to the plate development side of it. Some of the shapes I want inventor just can't create them in the sheet metal part of the program. So I downloaded freeship+ to see if I could work out the design and export it and then thicken the material and go from there. the problem I face with that as a draftsman the control is not really there for the curvature and that what I am used to and as a surface modeller from back when I was using 3ds max there is not enough control, and I don’t want to model the hull in max as I don’t have the calculations that are in freeship+

    1st problem - is there a simple program that i can export a lofted part from inventor and then do the plate development. (I am not sure in the 3ds max unwrap tool will be accurate enough for me). I may upload some files here for people to have a look at when I get home

    2nd problem - trying to do the calculations in freeship+ tells me I have leaks, now I know that it is from my points that are on the centre line but the are on the 0 point and the hull is mirrored, do I have to model both sides to be able to use the built in calculations? Or is there a way to join the hull?

    And a question... should the bottom of the boat the boat the chine and the side all be separate layers for the plate development in freeship or is there a way to split the surface without changing layers.


    original thread here
    http://www.boatdesign.net/forums/boat-design/aluminium-4-6m-boat-34278.html
     
  2. lewisboats
    Joined: Oct 2002
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    lewisboats Obsessed Member

    Last first: You should separate into layers all different surfaces.

    Next...you should not mirror the hull. Freeship only shows 1 side of the hull but all calculations are done for a full hull. There is a button on the bar that will show the other side of the hull without control points. Therein lies most of your leak problems unless the centerline isn't at 0. The shear will have leak points unless you have fully decked the hull back to the centerline.

    Can't help you on the first one.
     
  3. daiquiri
    Joined: May 2004
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    daiquiri Engineering and Design

    Some neat CAD drawings in that thread. :)
    Maybe you could attach the Freeship file of your hull, so that we can see where the problem might be?

    Cheers!
     
  4. rastus
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    rastus Junior Member

    progress in inventor

    ok well i have been doing some thing and some testing i am now able to get complex bends with control out of inventor. but i will get to that later in the post.

    well i have attached the freeship+ model. i set a 300mm draft but am unsure if that is going to sit nice in the water, i have been working the parts i want cut from different plate in different layers and this seems to be working. tho i must say the modeling in freeship is very poor in how you have to go about creating faces etc... i can not even seem to be able to weld points together to form 1. may be just because i have limited knowledge but very primitive. i am not sure if this program will be any more use to me as i don't know how to calculate how the boat will sit in the water i think i have worked out the displacement but i think it is a bit high.

    I will be making the hull out of 5mm plate as that is what is available as a lower cost. and am planning to power it with a new 60hp 4 stroke (i hope this will be enough)

    now to the inventor part of thing i have attached a rar file of some parts i made the side is from a layout i made the other night and the chine test was made in 5 min very simple and flattens perfectly the only problem i have found is that you can not go to a pint as it wont allow you to create the sheet metal.

    im going to work on this some more in inventor tonight and see where i get to and leave the freeship for now.

    also i should ask if there is someone with hull design experience is able to help with calculations that would be appreciated and i am willing to put all the files for everyone to see if that would help i don't want to go down the track of making the boat and getting into trouble when i put it in the water.

    I would also bee keen to hear what other inventor used have to say about this method?

    and sorry is this post is all over the place long day at work my brain is not doing is best:confused:
     

    Attached Files:

  5. rastus
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    rastus Junior Member

    An update: have done more in inventor. am unable to get the base of the boat to work in sheet metal. i have to loft then thicken. i have attached a zip file with the parts in .ipt .stp and .igs some one may be able to help.
     

    Attached Files:

  6. daiquiri
    Joined: May 2004
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    daiquiri Engineering and Design

    Just a short observation about geometrical proportions of your hull. If I were you, I would check the L/B ratio because you might have longitudinal stability problems (porpoising) with this one at higher speeds. I wouldn't go below L/B = 2.2 - 2.3.
    Cheers!
     
  7. alidesigner
    Joined: Nov 2006
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    alidesigner Senior Member

    I use a combination of maxsurf and inventor so I cant comment on freeship. I use Maxsurf/workshop for the surfaces with compound curvature (hull bottom, chine and sides) and inventor for everything else. The trick with inventor sheet metal is to only use lines and arcs - it cant handle splines.

    You can download some free drawings to see what can be done at
    http://www.cncmarine.com.au/FreeBoatPlans.htm
     
  8. rastus
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    rastus Junior Member

    i have visited your website and had a look at some of the posts about inventor you made prior to making this thread, and thanks for putting those plans available on you webpage they are good to study and i am keen to have a look at the 5m plans.

    i use inventor at work and have never gone in sheet metal as far as i do now with my own projects. its more of problem solving that i do at home and we have not upgraded at work to have the lofted flange so it limits what i am willing to spend work time on, though i do see the benefit given time to design in sheetmetal saving time in production.

    to me inventor is temperamental as to what it wants to develop, and most times i have to think of different ways to model something to get the same end result. The bottom of the model for example is no different to the chine as to the idea behind lofting it but inventor refuses to develop it. it may be worthwhile to go to a course to develop my skills further with the software, but the solid works training i received at my last employer was of no benefit to me as in the experimenting i had done at work have figured most of my issues out and the trainers were only knowledgeable of what was in the book (go figure), also considering studying engineering in NA as most of the analysis could be transferred into the field i am currently working and would give me the option to change direction if i feel the need.

    went a bit off track there.

    back the the boat, i would not mind having a look at maxsurf as i would hope it had more advanced work-flow.

    i will wok more on the hull design during the week and see what i come up with.
     
  9. alidesigner
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    alidesigner Senior Member

    The reason it wont develop the chine is because it cant handle splines. The 5m plans are just getting a final check so will be on the website soon.

    I dont do everything in sheet metal, just the bits I want to flatten (except hull)

    For training just buy the book Mastering Inventor by Waguespack. I got mine from amazon and it's all I have used. If you have done solidworks training then you shouldnt need any more. A loft is a loft and a sweep is a sweep, it doesnt matter which program you use, the workflow is the same. But learning how to model a bench vice wont help you much with boats.

    I have found the trainers here dont understand the workflow needed for boats so arent much help. They do their best though. Even the boat design videos on youtube are clearly done by people who have never designed a boat before. Ignore them.

    Do the hull in freeship or maxsurf then import it. Almost everything else can be done in inventor.
     
  10. rastus
    Joined: Aug 2010
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    rastus Junior Member

    thanks for coming back to the thread. i was hoping to get you input on this

    i am aware that you are unable to use splines in sheet metal. I have managed to get the sides and chine to be developed , did you download the file i attached in post number 4? there are 2 different parts in that zip that show the method i am currently working with. but its hit and miss thats my problem with it. and its more of inventor thinking it wont work rather than it not being practical i could work it out in a flat pattern then fold it but it would take far to long.

    edit: fixed some text that made no sense

    and also i'm curious as to you designs i believe you use foam for flotation, but i have also read mixed opinions to do with it corroding the aluminium.
     

  11. alidesigner
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    alidesigner Senior Member

    I havent had a chance to download your files yet but would discourage you from trying to do the hull in inventor for 2 reasons.

    1. To avoid buckling your plates should have some slight compound curvature, which you cant do with inventor sheet metal.

    2. The Aust builders plate requirements apply also to privately built boats so you will need to comply with parts of AS 1799.1 and you will need hydrostatic info for the calculations. Inventor wont give you this. You can read more about it at http://www.nmsc.gov.au/recreational_boating/index.php?MID=24&COMID=1&CID=24 and there is a free donwload of the standard on that site too. There is a new version out which has much higher requirements than the previous version.

    We use NMSC approved foam which is required by the standards. We install it so that the hull can drain and breathe. Some people coat their hulls with nyalac but we dont.
     
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