Planning a workboat build

Discussion in 'Boat Design' started by Magnus W, Dec 1, 2017.

  1. Magnus W
    Joined: Nov 2017
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    Magnus W Junior Member

    I'm going to build a new boat. It's going to be a combined taxi and cargo boat with some ice capability.

    The general design is an open cargo deck with a hydraulic ramp and crane, a roomy cabin with seating for 12 passengers and an open rear deck for diving and salvage operations.
    Single engine with remote v-drive (FPT Cursor 9 and Twin Disc MGX 5136 RV). A smaller engine for ac power and hydraulics. Keel cooling. Material aluminum. Hydraulic bow and stern thrusters.

    Forward cargo deck about 6 meters, cabin about 3,5 meters and aft deck about 1,5 meters. With the deck about 0,5 meters above water that gives a waterline of slightly more than 11 meters. Beam tbd but about 3,5 meters.

    SOR:
    Forward cargo deck load capacity: 2500 kg.
    Cruise speed in taxi mode (12 pax plus luggage = 1200 kg): 25 knots
    Single engine with remote v-drive (for noise and maintenance reasons).

    I would like a moderate deadrise and a planing hull (coastal operations). Perhaps a pocket for the prop.
    I guesstimate that a weight of 8000 kg sans passengers/cargo is reasonable. That's based on a hull weight of 5000 kg, drivetrain 1500 kg, aux power and hydraulics 500 kg, fuel 500 kg and miscellaneous stuff 500 kg.

    What general hull design would you recommend?

    Oh, the pics are just 5 minute drawings to show you what I'm thinking about, they're not to scale or anything like that.
    IMG_5859.JPG IMG_5860.JPG IMG_5861.JPG
     
  2. Angélique
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    Angélique aka Angel (only by name)

    Godspeed on the design process Magnus, and I hope for some help and reviews here . . . :)

    P.S. - - Magnus' introduction can be found on the thread: - Hi all from Sweden
     
    Last edited: Dec 2, 2017
  3. Mr Efficiency
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    Mr Efficiency Senior Member

    There was a similar size and type of vessel depicted and mentioned on this site fairly recently, that was being used by Maritime Services Queensland for maintenance of channel markers and buoys, it was built at the Gold Coast south of Brisbane. Had the crane and what-not, and a good turn of speed. Naturally, not designed to encounter ice, the water temp here is usually over 20 degrees C. I will see what I can find.
     
  4. Angélique
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    Angélique aka Angel (only by name)

    Hi Mr E, maybe you mean the thread: Work Boat ? - - = - - www.everinghamboats.com.au - - I think.

    P.S. - Note: the last above link gives me a Hazardous Alert from my protection software, don't know if that's justified, but I've disabled the link for this reason !

    The site was OK though when I posted a link to it (on Jan 29, 2017) in post #2 of the Work Boat thread, of the first above link.​

    Anyway, here's a pic of the meant fast workboat from that site . . . .

    [​IMG]
     
    Last edited: Dec 1, 2017
  5. Mr Efficiency
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    Mr Efficiency Senior Member

    That was it, I could not find it ! Your sleuthing is top-class, as always. I forgot it was outboard powered, but it appears it is of a similar genre, if maybe larger than what he describes. No doubt the speed can be dialled back a bit. Gold Coast Waterways Authority, not Maritime Services Queensland, probably why my search missed it.
     
  6. Mr Efficiency
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    Mr Efficiency Senior Member

    It appears to be some kind of tri-hull, if it is being used as far away as Moreton Island, as was mentioned in that thread, it would need to be able to handle choppy waters, as that is more like open water. It may be of some interest to our Swedish friend.
     
  7. Angélique
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    Angélique aka Angel (only by name)

    I've posted a picture from another angle, showing the backside with the 3 × 250 Hp outboards of that 40 knots workboat on the thread: Repower Inboard Prop Pocket Hull with Outboards ? - see post #20 there . . . .

    Fast workboat with 3 x 250 Hp outboards pic2.jpg
     
    Last edited: Dec 1, 2017
  8. Mr Efficiency
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    Mr Efficiency Senior Member

    As you said, the govt is probably not that put off by big fuel bills, I would estimate that vessel would be getting around 1.25- 1.5 nmpg tops. But trundling around in a slow barge would result in low productivity, especially if the distance between jobs was well spaced.
     
  9. Mr Efficiency
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    Mr Efficiency Senior Member

    The inboard lean on turning suggests a fair bit of "meat" along the central portion, maybe enough room for inboard or sterndrive.
     
  10. Magnus W
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    Magnus W Junior Member

    Thank you for input.

    Maybe not so much a landing craft but I need to be able to load a car or an ATV from a jetty.

    The design I'm looking for is kinda like on the boat Vendela (pic) but I need a larger cabin. I also would like a flat deck all the way from the loading ramp to the open transom. I want to be able to walk besides the cabin on both sides.

    As far as propulsion goes the only alternative is a shaft. Even though efficiency might be lower than with an outdrive there are no outdrives (not even Konrad) that can take the ice. And maintenance is a pain with outdrives as I would need to put the boat on land every 200 hours (if I'd go with Volvo DPH but they're all the about the same). Outboards are out because of the maintenance issues and also the fuel. The only slightly interesting outboard is the Oxe diesel but it still hasn't got the ice part and it has a TBO of 2000 hours which makes for a very expensive option compared to the FPT I'm considering that in my application should last at least 15000 hours with no more than regular service (same, if not better, for the gearbox).

    As you can see in the two Capo pics they combine a "regular" monohull with a loading ramp. I'd like that too.

    Vendela.png Capo11JR.png Capo145.png
     
  11. Angélique
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    Angélique aka Angel (only by name)

    Hi Magnus,

    What about water jets for propulsion ?

    Check out Armstrong Marine for this, they build smaller than the here shown boat as well, but I've picked this 62' (18.9 m) Water Taxi as an example because the name Arctic Solution suggests some ice capability, as does her home bay Port Valdez in Alaska, 61°07'20.0"N 146°21'18.0"W.

    [​IMG]

    [​IMG]

    [​IMG]

    Good Luck !
     
    Last edited: Dec 5, 2017
  12. Angélique
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    Angélique aka Angel (only by name)

    I've just peeked into the specs of the above boat on the owner's website . . . .

    Arctic Marine Solutions Prudhoe Bay in Alaska - ---> - M/V Arctic Solution Specifications - ---> - PDF
    [​IMG]

    [​IMG]

    Maybe the below modular passenger pod concept could be interesting for you . . . ?

    [​IMG] - - - - [​IMG] - - - - [​IMG]

    [​IMG]

    [​IMG]
     
    Last edited: Dec 4, 2017
  13. Escwire
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    Escwire New Member

    Nice boat. But also being Swedish I guess that it might be a bit too big. I'm guessing that Magnus W is aiming to build a boat of under 20 gross tonnes and a top speed of under 35 knots (without cargo). Generally it's that if you keep it under 12m LOA there´s a low risk of being over 20GT. In reality 20GT could be pretty much anything between 10m and 15m depending on the construction. But when it's a doubtful case the risk increases that the authorities will want to measure the vessel, which is a cost of at least $2000.

    The limit of the gross tonnage controls what captains licence is needed and a boat of under 20GT is also subject to less frequent controls from the authorities. If the vessel is faster than 35kn the captain need to have special qualifications for handling high speed vessels. Bigger faster boats also requires bigger engines, which require an engineer.

    Personally I've been a bit curious about how close a landing craft like this 46' EagleCraft Landing Craft - EagleCraft Aluminum Boats, builders of commercial, pleasure and sport aluminum boats https://eaglecraft.bc.ca/photo-gallery/commercial-vessels/46-eaglecraft-landing-craft/ could come to the Swedish sub 20GT rule.

    But the hull shape of the EagleCraft (shallow deadrise with blunt front end) would not be very good for ice breaking. In general many landing craft boats tend to be similar to that, possibly a consequence of building a hull shape suitable for beach landings. The Arctic Solution looks a bit better at ice breaking judging from the last picture.

    When it comes to the propulsion a traditional fixed propeller and shaft is usually the most reliable option. Preferably with dual engines so that one is still operational if the other one gets stalled. A water jet could be used. But is not quite as reliable. It could also require a grate in front of the intake to the jet to further help prevent ice from becoming a problem. And such a device could reduce the efficiency of the water jet.

    Magnus W, read this if you haven't already: http://offshorevast.se/themencode-p...2016/04/lättvikt_vitbok_160530_enkel_digi.pdf
    (about light weight vessels in icy conditions, in Swedish
     
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  14. Angélique
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    Angélique aka Angel (only by name)

    Hi Escwire,

    Welcome to these forums, great post you started with . . . :)
    Here's a better view at the bow and bottom when she's in a crane herself, from the above specs link.

    [​IMG]
     
    Last edited: Dec 5, 2017

  15. Magnus W
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    Magnus W Junior Member

    Escwire, thanks for the link to the document. I hadn't read it before but it confirmed what I already suspected.

    About the 20 GWT limit I believe that it's about to be removed.

    And to clarify – I'm not building an ice breaker. The boats will be designed to operate at full efficiency during the three seasons. During winter I just need it to be operational, albeit at a degraded capacity, in the weather/ice span between when other boats stay at the dock and when the hovercrafts can take over in full.
    As far as construction goes this effects prop, rudder, transom (can't have sharp "corners") and weight that in turn could (will) have an impact on the three season performance.

    On a side note I think that the Arctic Solution is pretty non optimal in ice, partly because of the water jet tendency to clog up but also since the flat bottom won't make sure that most of the ice/slush doesn't reach the intakes to begin with.
     
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