Coastal house catamaran (EC cat. C or D) "kit"

Discussion in 'Powerboats' started by Sinclair D-R, Apr 1, 2014.

  1. Sinclair D-R
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    Sinclair D-R Junior Member

    Consumption figure i copied here must be taken with a grain of salt! as we have no idea how heavy were those vessels when -tested- nor how bumpy was the sea that day running with or against tide, etc.

    Minestrone of metric and imperial measures is a healthy brew: both brain hemispheres have to work. :)
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    Your options depend on how much money you have to devote to it, if it isn't much, you will be like Glen Campbell, suffering "a load of compromising, on the road to my horizon" :rolleyes:
     
  3. Skyak
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    Skyak Senior Member

    Sinclair,
    I don't know much but I think I have something to contribute.

    For a 15M hull I calculate displacement mode to be about 9 knots or less. 15 knots is well up the inflection of the drag curve. I make this distinction because the cost and performance drivers are very different in planing and displacement.

    Displacement
    max hull length
    minimal surface area (elliptical profile hulls)
    minimal thrust required/displacement and smallest engine is most efficient
    NOTE weight waves and windage are not as critical

    Planing
    hull length doesn't matter as much as hull lift
    Weight is critical, waves are critical, windage is critical
    structure required increases exponentially with velocity

    If you want to go 15+ knots and only need 10M of accommodations I don't think you want a 15M boat. You want something more compact and lighter and the right choice for every component will be "twice the cost and half the weight is worth it".

    If you want to carry big heavy cheap accommodations at the greatest efficiency then you should plan on a top speed in displacement mode ~9 to 10 knots.
     
  4. Sinclair D-R
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    Sinclair D-R Junior Member

    Thanks Skyak! Please do contribute!

    Coastal house cat

    She –must and will be- a displacement cat; LOA 14.98 m (LWL as close to LOA as possible) with 10 m accommodations plus 2 m fore deck ample safe area* for ground gear plus 3 m for covered aft terrace.

    *: Quote from Master Sid Fisher, by the way allow me to recommend reading: http://fishersurveys.wordpress.com/ When we think about ground gear it is in the context of terrible weather, an exposed anchorage in which we’re trapped, and poor holding (this from long experience). We want our everyday ground tackle system to be designed for these conditions. We once rode out a recorded Force 11, in sheltered water admittedly, but not in very good holding ground and never shifted an inch BECAUSE Zeemeeuw carries sensibly sized ground gear, at least double the ‘normal’ weight."

    Speeds:
    EU canal speed <20t vessel: 8 km or 4.3 kt

    The 15 kt speed I would like her to reach is waaaaaay far fetch for a 49’ displacement hull as it implies 2.14 time 7 -square root of 49’; yet I want her to be able to “run” in case of emergency as fast as possible without overpowering her at all.
    Narrow slim hulls: BWL 12/1 or more if needed as hulls will only carry –stuff- yet enough no to “shoe horn” engines and keep as small a shaft angle (<5º) as possible.

    Long range cruising: on one engine (alternatively), speed results from slightly over pitch* three bladed prop (maximum diameter* between half tunnel and rudder shoe) swinging from a tad below peak torque rpm of the 55-60 hp. avoiding glazing.
    See p. 24 attachement: Economies financières et de carburant dans la pêche artisanale - FAO 2003

    See drawing copied from F J Magnusson "Spice Too" sale web site.

    Weight is the enemy. Goal: light craft mass <9 t, performance craft mass <9.6 t, fully loaded mass: 15t. (Fuel 4 x 700 l)

    Could you elaborate a plenty on those elliptical hulls, please!thanks.

    FYI: Compu-Craft Qnsld. Australia: left text messages on 2 of their cellular phones in Australia, as of today no one answered neither e-mails nor text messages. Are they active, gone cruising?
     

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  5. Mr Efficiency
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    Mr Efficiency Senior Member

    15 metre cat seems big for just 2 people. Why that specification ? With hulls 12:1 L/B, going past the "hull speed" is not an issue, there will not be any real resistance hump to deal with. Seems to me you could come down to 11 metres and use 4-stroke outboards and cut the price in half, or more. If 15 knots flat-out, and only for emergency circumstances, those outboards won't need to be any bigger than around, say, 25hp high-thrust versions. And no smelly diesel wafting into your habitable space when the wind carries it that way.
     
  6. Richard Woods
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    Richard Woods Woods Designs

    Yes I could, maybe my Skoota 36 would suit you?? But I would suggest you email me direct rather than discuss your plans in a public forum

    I don't think the single mounted engine is a good idea. Top speed will be limited, damage from flotsam is likely and you won't get very good manouverability

    BTW, unlike most here, I have actually sailed to Nicaragua, and also been out to Ometepe

    see here

    http://sailingcatamarans.com/index....rticles/30-cruising-on-eclipse-the-final-days

    and scroll well down

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
  7. Sinclair D-R
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    Sinclair D-R Junior Member

    Coastal -- house -- cat

    Mr. Efficiency,

    M2:
    Why <15 m (14.98 m) + <20 t?
    Because at that LOA and tonnage your vessel is a pleasure craft; category that Brussels's bureaucrats do not scrutinize -that much!-and the captain does not need higher professional licences!

    46 m2 as living accommodations plus aft & fore deck, total: 67 m2 (737 ft2). Well no doubt Admiralty and i do want all those square meters for our -home- afloat. Especially the aft deck.
    Pics and drawing belong to Spice Too web site, FJ Manusson

    Outboard versus inboard: EC (regulations) makes it tough to carry petrol gas versus diesel. :rolleyes:
    Besides, in my early 60' i feel comfortable with those -ever- lasting simple diesel engines.
     
  8. Mr Efficiency
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    Mr Efficiency Senior Member

    Sounds like you have the champagne tastes, but on the beer budget ! I doubt your dream is compatible with your budget.
     
  9. Sinclair D-R
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    Sinclair D-R Junior Member

    Forgoten pictures

    Her they are, sorry!
     

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  10. Sinclair D-R
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    Sinclair D-R Junior Member

    Richard Woods,

    Thanks for answering.

    Allow me to remind you: this coastal house cat has 2 inboard diesel 50-60 hp engines as stated on my first post.


    Did drop a short message at your site-mail-box.

    Eclipse: sad story, you are both alive and well. All my thoughts.
     
  11. Mr Efficiency
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    Mr Efficiency Senior Member

    "Spice Too" wasn't styled by Pininfarina by the looks of it. Does it pass EU ugliness restrictions ? :p
     
  12. Richard Woods
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    Richard Woods Woods Designs

    I didn't get your message, maybe you should PM me on this site to see if that works (maybe Compu-craft didn't get your messages either)

    I apolgise, I thought, since you published photos of Spice Too and asked "Could you elaborate", that you were now considering a central engine.

    I have not been through the French canals, but have, on several occasions, and in several different boats, made canal trips in outboard powered craft from Kiel down through Germany and Holland to Flushing. I hadn't realised outboard engines were banned from European canals.

    I agree with Mr Efficiency's comments. The boat you are thinking of is bigger than I would use for your planned trip. However, if you took my Skoota 36 and lengthened the hulls you would then have space for the diesel engines, tanks, shafts and rudders. Of course you'd also have a more expensive and complicated boat

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
  13. Sinclair D-R
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    Sinclair D-R Junior Member

    Mr. Efficiency,

    Thanks for making me laugh! :p:D:p


    Sure enough Spice Too is not Concorde!
    she is efficient at what she was designed and built for: (canal) transport and shelter a couple on a one level, flat surface with all the amenities from a land-home.
    All the while optimizing every m2 of a small foot print in length, in width, in height, in power, in operation and maintenance cost and that is what i like from her.
    She could look very different. My coastal house cat will!

    Can you do some thing for me: try to get in touch with Compucraft:
    http://ccplans.com/index.php?pag_id=30
    would like to know if they are a active or not. And if they are not active any more, who if any body did get their plans as i am interested in their 47/50' model.
    I e-mailed them and left two messages on each cel number i found on their site: Colin Clifford and Brian Forbes
    http://ccplans.com/index.php?pag_id=28
    scroll way down.
    Thanks!
    Will e-mail them, again!
     
  14. Sinclair D-R
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    Sinclair D-R Junior Member

    Greetings Richard Woods,

    About CompuCraft: I wrote them twice, left messages on both their mobile phone and nothing.
    The model I like from them is: 47/50’, scroll down: http://ccplans.com/index.php?pag_id=51

    EC: never did I say that Out-boards are banned; there are special regulations and rules for carrying petrol gas on a boat due to its high flammability.

    This coastal house cat is our full time retirement home not just a day boat or summer live aboard.
    LOA 14.98 m
    BOA 4.50 m
    Draft: < 0.80 m
    Air draft < 3.00 m
    Engines 2 x 50-60 hp

    All living accommodations 45 m2 + aft deck 15 m2 on one flat and level bridge deck on coastal displacement cat hulls with 2 diesel inboard.


    Read my first post if you have a minute.
    Questions? Please.

    Cheers.
     

  15. Sinclair D-R
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    Sinclair D-R Junior Member

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