Aluminum Offshore Fishing Catamaran CNC Cost?

Discussion in 'Metal Boat Building' started by jwells11, Apr 1, 2020.

  1. Mr Efficiency
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    Mr Efficiency Senior Member

    What beam are you thinking ? Not ideal to be having towers on narrower beam cats, or at least much weight atop them when planing fast.
     
  2. jwells11
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    jwells11 Junior Member

    I will be going 11'6 or 12ft

    Dont think I will have that much more weight on top compared to this boat at 42ft 11'9 beam.

    My tower will be much shorter than this.
     

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  3. jwells11
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    jwells11 Junior Member

    The Fincat and the other aluminum cats I posted are built by Razorhead and Empire Boatworks(guy who works at Razorhead)

    This one was built with a much higher dead rise





     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    Well, I would say the cost of CNC files and cutting, would be minor compared to materials and fabrication and outfitting, not to mention engines. I don't think I could be talked into more than two engines, even if money was no object. Except perhaps if you were running a nasty inlet, and the loss of one engine would create a hazard.
     
  5. jwells11
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    jwells11 Junior Member

    Thats what I was thinking but I saw some crazy numbers flying around on CNC zone and other places.

    Hard for me to drop two extra engines but when you're running 140 miles one way it makes a difference of a 35mph cruise and a 50mph cruise.

    5052 .190 4ft by 12ft

    $350

    Plate | Aluminum | Buy Metal Online | No Minimum Order | Cut to Size | https://www.midweststeelsupply.com/store/aluminumplate

    At that rate I figured I would be at roughly $15k in aluminum. (no pilot house)

    Surely CNC wont put me over $25k total?


    That's what makes this so enticing, I could have a boat capable of doing what a $700k boat does for less than $150k

    $80k motors
    $25k CNC'ed aluminum
    $5k in hull design(I have a quote on that)
    40k-electronics, llebroc seats, bilge, livewell pumps, and miscellaneous
     
  6. jwells11
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    jwells11 Junior Member

    Go twins and im at 100k
     
  7. Mr Efficiency
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    Mr Efficiency Senior Member

    The fuel burn at 50 mph with 4 engines, off the chart. Probably 3 times your 2 x engines 35 mph. And that would be enough to buy a lot of fish ! But having said that, you don't need a boat that big to cruise at 35 mph, and with how many aboard ?
     
  8. Mr Efficiency
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    Mr Efficiency Senior Member

    Foil-assisted cats are probably the way to get speed without a blow-out in fuel use.
     
  9. jwells11
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    jwells11 Junior Member


    The guys running these boats say its not much difference.

    Maybe 1.4 twins @ 35mph and 1.0 50mph---That adds up but still 5.6 hours vs 8 hours is a big deal.

    I looked at doing smaller as well but I want a 4 jumpset pilot house.

    foil aluminum catamaran - Google Search https://www.google.com/search?q=foil+aluminum+catamaran&tbm=isch&ved=2ahUKEwi64q3vvsnoAhVNDq0KHTocDLYQ2-cCegQIABAA&oq=foil+aluminum+catamaran&gs_lcp=CgNpbWcQAzoECCMQJzoCCAA6BggAEAUQHjoGCAAQCBAeOgQIABAeULqVAViGugFg8LwBaABwAHgAgAFaiAH2CZIBAjE4mAEAoAEBqgELZ3dzLXdpei1pbWc&sclient=img&ei=ubiFXvqhGs2ctAW6uLCwCw&bih=645&biw=1261#imgrc=U4IXtPEAInOWRM&imgdii=iqrqJ_KSuiApPM


    Razorhead actually built a foil assisted boat for a charter captain in venice. Apparently he didnt like it.

    From what I have read.........

    Im scared of the engineering

    Without extending it down Im not sure there is much benefit. Extending it down would render trailering impossible.
     
  10. Mr Efficiency
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    Mr Efficiency Senior Member

  11. Barry
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    Barry Senior Member

    Or buy a couple of these 627 horsepower outboards. And owned by VolvoPenta
    mmm??? parts will be expensive
     
  12. jwells11
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    jwells11 Junior Member


    Na stick with cheap, lightweight, and reliable V6s
     
  13. jwells11
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    jwells11 Junior Member


    Whats your thoughts on 5052 vs 5086?


    I thought the sides was standard 5052 on 30-40ft boats
     
  14. Barry
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    Barry Senior Member

    We always used 5086 H32. on the sides and bottom, 5052 for stringers as we they were a bit more ductile for bending. Upper decks etc were 5052 I think H112

    There is a difference of opinion on using hardened alloys. The discussion being is why choose a hardened alloy that when welded the aluminum becomes almost a Zero hardened alloy due to the property changes in the Heat Affected Zone
    My own view was that while the weld zone hardness and hence strength will be reduced in the HAZ, there are areas away from the HAZ that may become under a high level of stress, say due to impact. As our almost all of our boats were meant to run boulder strewn waters and impacts were expected, and the price between the hardened alloys were not significant when compared to the price of a completed boat, we wanted any factor of safety that we believed that we gained.
    Our area of concern was mainly between stringers where permanent bending could occur upon impact. You will not have this issue.
    If you google the aluminum boat builders, the manufacturers often will include the alloy that they use.

    I am not sure what the cost of 5086 is these days and certainly not at a one shot buy price. You really want to buy sheets as large as you can handle and as wide so you do not have to spend time joining sheets. Additionally, using large single sheets reduce the chance of inflections in the hull at joints. Say you take 3 12 foot pieces to make 36, but install each 12 foot ends on the framing. You can ruin the fair curve and if you end the sheets on a frame, you cannot properly weld the inside of the joint. . It is extremely difficult in curved sections of the hull, developable bend, to carry the same curve with joints on frames or welded in position. The best procedure
    is to pre-join the sheets on a flat area, and install a large section at a time.

    In an earlier post you mentioned a 4 x 12 sheet. Often smaller aluminum suppliers
    will offer stock sizes as it is easier for them to handle. For a 21 foot hull, we bought 20 feet by 5 foot in 1/4 and 3/16. We had to join just a bit on the front, tack one side, 1/2 inch tacks, flip it, tack the other side, , sand the tacks smooth, flip it, sand the tacks smooth, make up the weld on one side. Back cutting every start and stop, to eliminate the potential voids due to crater cracks or cold bead stoppages, Flip it, back cut the weld to the first weld, weld the side, grind and sand the weld, flip it grind and sand. Then on a perfectly flat
    surface, use a body hammer and tap out any discontinuity

    If your aluminum source distributor has a coil line, ie they by hundreds of feet on a coil, and unroll, straighten and cut to length, they you are buying from a large aluminum distributor. I would make up a list of what you need and email it around for a one time quote, and you may find different prices varying signifantly

    The $40k that you suggest to finish seems a little light. By the time you buy and anchoring system, head components, fuel tanks, lighting, hatches, dipped wired,
    batteries, cleats, and a good quality Radar, gps, a couple of vhf's, fish finder, and the list seems never to end, you will easily burn through this.

    You should also discuss with a marine insurer as your boat will be "home built"
    Some insurers will require a complete survey and if the vessel is large, they may want a surveyor to do periodic inspections during construction. Something to keep in mind
     
    Last edited: Apr 4, 2020
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  15. Rumars
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    Rumars Senior Member

    I am looking at those numbers and wondering.
    5 000$ for a custom design of a high speed boat and at least two building licenses (yours and the one you want to trade with your buddy for work)? Absolute bargain.

    15 000$ for Al I can not comment about, it depends on how much you actually need (total surface, nesting), local prices plus transport and discounts available to you. As had been said a high volume customer dealing with a producer has different prices. A specialised Al fab shop could possibly deliver the already cut plates on your doorstep for less then you can buy the raw materials and still make a profit. Only quoting helps here, but you need the plans for that.

    10 000$ for CNC cutting the boat? Crazy. You could own the machine for less. Remember you don't actually need CNC cutting. Print the plans on adhesive backed vinyl, buy a good jigsaw with new blades and spend some quality time cutting. A small angle grinder and a dremel for fine tuning and beveling. Under 1000$ and some elbow grease all in. The saved 9000$ you can spend on things you actually need like renting a professional welding machine, buying supplies for said machine and paying a pro to weld the thing up after you tack it together.

    40 000$ for a complete fitout? I suppose you will not paint the boat, do the wiring yourself, and be spartan everywhere else.
     
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