Minimum cruising cat-size & cost

Discussion in 'Multihulls' started by Alex.A, Feb 24, 2010.

  1. marshmat
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    marshmat Senior Member

    The iPhone might be a useful aid in some places, but I would never trust my primary navigational needs to a device that can be remotely bricked by its manufacturer, without warning, at any time.

    As for chartplotters- there are more economical alternatives than the latest 3D networked gear, and that don't involve flying a technician from Germany to Trinidad if it breaks. A cheap laptop down below, for example, with a sunlight-viewable remote display in the cockpit.

    And from what I've seen of the fancy 3D plotters, they are probably worse for situational awareness than the more conventional 2D types. Look at the cockpit of an Airbus 380 (example: ). You don't see any fancy 3D graphics with multiple overlays: there are a lot of controls, but they're all simple 2D vector graphics, easy to interpret in a fraction of a second, once you know what they are.

    But that is getting off topic....

    Sage advice, as usual, Richard :)
  2. Fanie
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    Fanie Fanie

    Good grief ! On all 18 of them :eek:
    I must say I am impressed tho ;)

    Good posts and good reply's.
  3. Steve W
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    Steve W Senior Member

    You are kidding about the I phone right? Under the one breath you are talking about extras being added headachs and empty pockets and now you are suggesting paying a monthly phone bill
  4. isvflorin
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    isvflorin Junior Member

    don't get fired up for nothing. I gave it as an example of a gps handheld enabled device. First of all you don't need to have it on contract to use it for navigation, you can use maps allready available, for example :

    So don't use an Iphone, an HTC gps phone will do just fine or a netbook.

    I don't like the device myself but it is just an example of getting around with small handhelds, other software is available for Windows Mobile based devices like HTC gps phones etc. As others have said it before a small portable laptop (netbook) does the job very well also.

    I really don't think this is important at all, while you are building a cat for let's say 2-5 years on a small budget things change and gadgets will always be available, smarter, smaller, better (hopefully).
  5. Alex.A
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    Alex.A Senior Member

    OK guys - keep the electronics basic and each to their own..... i was hoping for more clever idea's during the build? What works on your boat/ ideal boat? What can be done without? What would you add? What would you remove? Keeping the simplicity "thing" in mind...... for 9m cruiser.
    Placement/convenience issues?
    Whats necessary and whats not?
  6. Fanie
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    Fanie Fanie

    The most reliable is probably a satphone, but expensive. Will work where no radio would. You need a VHF radio to communicate with the harbours and everyone within range, HF radio if you want more range. Get yourself two GPS's, one is a backup. If you have the money get a chart plotter and maps, they show you what is in the area you visit. A compass is a must have and you can also get marine maps for the area. You need nav lights and lighting so you can see, as well as preferably dimmable lighting so you don't night blind yourself. One or two spot lights, a horn or siren and an echo sounder or depth meter. A radio so you get the weather forecasts, a barometer and humidity meter to indicate weather trends. Make sure you have sustainable power and chargers and spare batteries.

    Should pretty much cover the basics.
  7. Richard Woods
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    Richard Woods Woods Designs

    I have just come back from a 6 month Bahamas cruise

    We used a small garmin chartplotter with built in N America charts. It showed every coral head. As a spare position finder we used Seaclear and downloadable charts on a USB gps antenna on our OLPC laptop. Antenna was USD30, we had the computer, the software and charts are free (opencptn is an alternative).

    We never used the compass, and in fact don't use it in the PNW either. We do carry paper charts "just in case" but never look at them except for passage planning (something that is hard to do on a small screened chartplotter). Certainly I have never "navigated" in the traditional sense for years

    We never used the horn or spotlight, and were one of few boats to have a barograph. We changed all our cabin lights to AA powered LEDs

    A handheld VHF usually has enough range. A fishfinder is a better echosounder than a digital yacht one.

    The computer was also used as a book reader (400 books stored on one SD card)and video (40 movies stored) and music player (400Cds). It uses less than 1Amp on 12v, so less than one conventional cabin light

    So fortunately these days you can save a lot of weight/space and cost by keeping stuff on a computer.

    Richard Woods of Woods Designs
  8. rob denney
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    rob denney Senior Member

    The curves do not have to be difficult. If you use a cored panel, with the core removed where you want to bend it (hull/deck join. rounded area below the waterline, cockpit seats, etc) it is by far the quickest and easiest way to build a hull. It does constrain you to shapes with straight sides and no rocker, but this is the ideal hull shape for the simplest, lightest, fastest and cheapest of all multihulls, the proa.

    It took less than 300 hours to build the two hulls, decks, bunks, galley, cockpit, bulkheads and rudders of the 15m weekend cruiser proa I am building. See Solitarry 2 in the Photos and Files sections at for step by step photos and a spreadsheet of weight, cost and time. I used foam/glass panels infused on a table, but you could easily use ply and hand lay up. Cost for the materials is under $Aus10,000. Rudders, beams and mast are all built using the same technique as the hulls.

    A few other points after a quick skim of this thread:
    1) An unstayed carbon mast is safer and easier to use than a stayed one. There is almost nothing to maintain, replace every few years or break. As Richard Woods said about balanced, unstayed rigs: "Easy sailing: The sails are always working correctly, whatever point of sail. Maybe it would be better to say the rig works to 95% efficiency all the time. A conventional rig may work to 100% if you're an expert, but only 70% if you're not." This is a huge difference for the cruiser who, even if he is an expert, seldom sails the boat to it's full potential all the time.

    An unstayed carbon mast can be built by you for considerably less money than buying an alloy section, and all it's rigging.

    Look at other threads and you will see that this sort of comment usually triggers a host of 2nd order reasons why stayed aluminium masts are better, but no one disputes the safety (instant depower on any point of sail) or the ease of use (single lightly loaded sheet).

    2) The shorter the boat, the slower it will go, and the lower the speed at which you will have to slow down for comfort. A longer boat will not only go faster, it will be, and feel, safer. Most crew abandon boats because they are scared. The boat often turns up months later, unharmed. The longer the boat, the less scared they will feel. Notice I use long, not big. Big boats are expensive, heavy and end up full of unnecessary stuff. Long, low and narrow hulls with no accommodation or storage have far less surface area than short hulls with wnough height and width room for people to move around in them.

    3) Windows are a necessity for light and vision without leaving the cabin. Mine cost $180 plus $120 for adhesive. Took me 4 hours to prep and install them yesterday. Helps a lot if the cut out is built as part of the infusion and if the cabin side is straight and flat. Straight and flat also makes it a lot easier to install bulkheads, shelves, frames, furniture, etc. Easier still if you include the landings for the frames, etc in the infusion.

    4) Bridgedecks add weight, windage and cost a to a minimalist cruiser. Far better to have everything in, or cantilevered off, one hull, including a comfortable, covered when required cockpit. Obviously, this hull should always be to windward, as in the proa. Not just for crew comfort, but to get the weight in the most useful place.

    To get an idea of what a big, heavy (3 tonnes) 15m cruising proa looks and performs like, check out the video at Then scale it down to whatever your requirements are.

  9. Alex.A
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    Alex.A Senior Member

    Hi - thanx Rob D - intrigued by proa's but dont think i'd go that route..... maybe a tacking outrigger, with almost = hulls. Get a bigger boat for less - say 30'/40'. That way i could do away with the bridgedeck and get headroom below.
    Prefer to build in ply.....
    Still interested in unstayed masts though......
  10. DarthCluin
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    DarthCluin Senior Member

  11. Alex.A
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    Alex.A Senior Member

    Yes - seen it but if i was to go this route - it'd be more like Ontong Java - Hans Klaars tacking outrigger.More like an "uneven" cat. Doesn't look too extreme, like the proa's - shunting seems too odd if you can tack? Proa's are cool as out and out speed machines but a cat wins for cruising........
    With say a 30'/40' - you get a bigger cat for less costs? Live in the large hull - headroom etc and use the small hull for storage and tanks etc?
    The proa and tacking outrigger fraternity does seem to be growing though - along with people using crab claws......
  12. rob denney
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    rob denney Senior Member

    Shunting is safer, easier and more reliable than tacking.
    Proa hull shapes are far easier to build than cat hull shapes. They are also far lighter (see previous post). Half the weight is half the materials and considerably less labour.
    Living in the large hull will be wet in a breeze, there is nowhere comfortable to sit as you are under the sails and you will need a lot of stuff in the other hull to balance the weight of crew and accommodation. To handle this weight and still work as the leeward hull, the small hull ends up pretty large. The live in hull also has to be much larger than on a proa. More material, more labour, more cost.
    A 70'/51' set up like Ontong Java may not be much affected by the smaller hull, but on a 40/30 it will be very noticable when the small hull is to leeward, particularly broad reaching in waves.
  13. Alex.A
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    Alex.A Senior Member

    Hmmm. Was thinking of rig in middle(ketch) or bi masted? Noticed in the petroglyph on easter island - or at least the impression of - that the cat was bi masted - not an original thought.....
    Wouldn't water,fuel stores etc etc balance the weight sufficiently? I was thinking more voyaging canoe type hulls -straight sided and reasonably flat along keel....
  14. DocScience
    Joined: Apr 2010
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    DocScience Wishful builder


    This is what I want for a MINIMUM COST CRUISING CAT.
    I put what I would consider minimum sizes on the drawing.
    Although it looks like a racing cat, it would weigh more with heavier material for strength, and have the purpose of cruising cat.
    This is somewhat the type of cat that I would like to build to sail.

    I have studied engineering and like trusses.
    Trusses are stronger then most other shapes for the amount of weight.
    To me, I think trusses look like a work of art whereas I think many other people see it as unfinished architecture, and to some, a floating piece of junk.
    The trusses make it much cheaper to make a somewhat small pod craft act like a larger size craft.
    It does vaguely resemble Team Philips structure.
    I intend to make it plenty strong to handle any weather conditions.
    The living area is relatively small which makes it cheaper to construct.
    Please comment if you think that it is not a good way to proceed.

    My main problem is that it would probably be too large or too expensive to dock in boat yards, and probably have to be anchored outside of boat yards.
    What are my problems with anchoring outside most boat yards ??
    If I go on a land tour for a day, What is the possibility the boat be there when I return ??
    The 2 main problems are will anchors hold good , and what about thieves.

    P.S. how do people get those Rep points ??

    Attached Files:

    Last edited: May 1, 2010

  15. redreuben
    Joined: Jan 2009
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    redreuben redreuben

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