New Aluminum CC design

Discussion in 'Metal Boat Building' started by EddieWeeks, Sep 9, 2009.

  1. EddieWeeks
    Joined: Sep 2009
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    Location: Baton Rouge, Louisiana

    EddieWeeks Junior Member

    My father owned a small ship yard till I was 18 and I have been around
    boats all my life but I never got a chance to build one.

    Now that I am over 40 (haha) I plan on building this boat from 5086 aluminum plate. I have used Solidworks for years and it has taken about a month to get to this point. But before I get to far along I need some advise.

    I think All boats are a compromise, and this boat will be around for over 30 years so who knows what it will be used for. I do know, I will not be taking it off shore, off Louisiana Coast, I will use it mostly in a large 10 foot deep bay
    that is always to rough for my 18' hull.

    Anyway the sides are 3/16 and everything else is 1/4 plate. The motors are
    2 x 250hp E-TEC.

    As its drawn with motors its 4200 lbs... I would guess it will be 4700 finished.

    As I look at other Fiberglass 27-32'.. They are 5000-7000 lbs without motors !!

    My father has been an a$$ lately, not wanting anything to do with this project, so any advise would be great, no matter how small...

    Also... I have been on lots of forums, so I have very thick skin... I take nothing personal.. Its just advise

    Eddie Weeks
    Baton Rouge, Louisiana
     

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  2. kmorin
    Joined: Apr 2005
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    Location: Alaska

    kmorin Senior Member

    Mass Versus "Ride"

    EddieWeeks,
    I would like to remind you that an old '59 Caddie had 'ride'. It would smooth out a gravel road, a potholed, rutted, old farm road between the corn fields. It did that by being heavy.

    It is not the end-all-be-all of boats to be light wt. Please take that from some one who's built a few hundred welded aluminum boats, none of them, even those with a very deep V that rode as well as their 'glass' boat counter parts.

    [Please] Don't forget that entry and power are related rates to momentum which is directly proportional to all-up mass [displacement]- so the light wt. boat may go faster with the same power as its heavier cousin, but the heavier boat will deliver less of the changes in movement to the crew. [A change in the movement of boats is often interpreted as impact.]

    I wonder if the after sections being concave in Body plan are a gain in any way to the hull's performance? None of the name open class 'cigarette-type' racers have bothered with concave sections aft, what do you propose to gain by that effort of form?

    it would help to post the lines as they show more [real] data in less space than 3D perspective views with shadows, which easily mislead. Another valid view that can be informative is a Plan view showing waterlines in 2-3" increments up to the LWL. Then; show that same set of lines with the hull pitched up by the bow in 2deg increments. I find these views helpful to envision the hull's planing surfaces at different angles of pitch and speeds.

    cheers,
    kmorin
     
  3. EddieWeeks
    Joined: Sep 2009
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    Location: Baton Rouge, Louisiana

    EddieWeeks Junior Member

    I agree 100%... Good point..


    My fathers company, LAFCO, Built all their boats this way...The bottom and sides all have 150 inch radius. I was told this increases the stiffness of the plate quite a bit, like a tape measure.

    One of the design goals is to run 23" or 24" pitch propellers... If it will run those props it should go 30 mph at 2500 rpm... Also I want to smash all the fiberglass boats miles per gallon. Witch seems to be around 1.9 - 2.1 mpg for the lightest FG boats.

    But like you said, it will get bumpy.

    Thanks for the input

    Eddie Weeks
     
  4. EddieWeeks
    Joined: Sep 2009
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    Location: Baton Rouge, Louisiana

    EddieWeeks Junior Member

    Here is my guess at water line while on plane.

    Also here is my other boat... 18 foot LAFCO hull... it was a 42 foot
    crew boat hull, but it was scaled down then built. It was built in the 70s.
    I blasted it and painted it, early 90s. It spent most of its life with a 200hp
    merc. A number of them... Did ~57mph... Has gone 62mph with tail wind.

    Today it has a 150 4stroke, witch is to heavy for that boat, but at 20 mph
    all you hear is spray, its really quiet.

    I named it Isobar because I am a meteorologist at LSU.

    This dam boat has beat the crap out of me and I am done with it.
    That is my fat a$$ father picking up before hurricane Gustav.

    Eddie
     

    Attached Files:

  5. mark775

    mark775 Guest

    Eddy, I don't know enough to comment yet but am a good critic as ideas come forth. Good luck with the relationship with your father.
     
  6. FishFleet
    Joined: Sep 2009
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    Location: Alaska

    FishFleet New Member

    hey eddy, I happened to...happen, upon your boat that you've designed up and i was just wondering what the general size of the boat was. Length? Width and the widest point?

    Thanks, looks like you've got a nice little project ahead of you!
     
  7. EddieWeeks
    Joined: Sep 2009
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    Location: Baton Rouge, Louisiana

    EddieWeeks Junior Member

    The boat is 30 feet long and 8' 4" wide.

    Right now I am making the 1/4 scale model of it.

    The scale model will be 4 times smaller in every respect. (not motors)
    it will be made from 1/16 plywood instead of 1/4" plate and will be 7'6" long.

    I plan on putting an electric motor in it and getting it on a plane to see how
    it runs. (did the RC thing for 25 years)

    1/4 scale version cost so far has been 2 months on the computer and ~$500 for plywood and water jet.

    About the full size... Can't decide on engine. I am stuck back and forth from
    a Yamaha 350hp 4stroke or
    2 x 250hp ETEC

    Fuel mileage with the 350 is about 2.7 mpg (for similar size boats)
    Fuel mileage with 2 x 250 ETEC is about 2.0 but 7-12 mph faster (guess)

    but full size is on hold until my father gets his head out of his a$$....hahaa

    Eddie Weeks
     
  8. EddieWeeks
    Joined: Sep 2009
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    Location: Baton Rouge, Louisiana

    EddieWeeks Junior Member

    Parts going to water jet this week... This is the 8 foot version
    that will be cut from Formica

    Eddie Weeks
     

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  9. sabahcat
    Joined: Dec 2008
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    Location: australia

    sabahcat Senior Member

  10. alidesigner
    Joined: Nov 2006
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    Location: Australia

    alidesigner Senior Member

    Nice boat Eddie.

    Concave hull shape might be difficult to plate as you will have to break its back to pull up at the bow. Convex will be easier (try it with a piece of paper).

    You can donwload Freeship (its free) at use it to check that the hull shape floats properly for its estimated weight.

    What software did you use to flatten the hull bottom? You need to make sure its developable.
     
  11. 21ftcc
    Joined: Jul 2009
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    Location: USA, Beantown

    21ftcc New Member

  12. mark775

    mark775 Guest

    Okay, I have enough to comment now...
    The aqua cat I like but those little lights forward suck, the cabin is (subjectively) ugly, the word "Aqua", I think symmetric hulls are better, displacement is best for a small cat. That Rocksalt thing is wonderful looking but what are center console boats for - fishing? How do people STAND having an outboard where they need to fish? Forget having a tiny pooper, or whatever, under the console and put the engine there!
     
  13. 21ftcc
    Joined: Jul 2009
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    21ftcc New Member

    Well out in New England with a cc like that, it runs to the canyons and is fishing for tuna.
     
  14. FishFleet
    Joined: Sep 2009
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    Location: Alaska

    FishFleet New Member

    hey Eddie one more quick question, what kind of depth you design in?

    reason I'm asking sizes by the way is that the boat your looking to build is pretty much identical to the boat that I'm trying to design up to build this winter. About a 32' by 8' cigarette style boat. Dual outboards...basically fast rigid and something that can move 13,000 pounds of fish at 40mph.
     

  15. EddieWeeks
    Joined: Sep 2009
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    Location: Baton Rouge, Louisiana

    EddieWeeks Junior Member

    13,000 lbs.. that is a lot... I don't know if this can do it... I guess with the right props and power it could..

    What depth are you talking about... how much water it draws or depth of the sides.. ?

    Eddie
     
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