Small Cat Payload Numbers (Woods / Kohler)

Discussion in 'Multihulls' started by Owly, Nov 23, 2017.

  1. Owly
    Joined: Oct 2016
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    Owly Junior Member

    Looking at two catamarans, the Sagitta, and the KD 860, they have similar dimensions.... The KD is about 2' shorter, the empty weights and loaded weights are interesting. Both roughly 2 tons empty weight, with the Sagitta being as expected a little heavier due to the greater length. Payload for the Sagitta being 2000 lbs, and the KD is 640 lbs more. Presumably hull shape? What I can't help but wonder is exactly what is included in "empty weight". Presumably all the built in fixtures, perhaps with basic upholstry, but not mattresses and bedding and such, presumably a basic head.... like a C-Head, but not a fancy mascertor system, etc. Presumably basic minimal galley fixtures, a sink and a two burner stove, but probably not a full swinging range, and definitely not stone countertops and other fancy garbage, probably not a fridge or cooler, presumably not the engine. Presumably the mast, sails, standing rigging and running rigging............ and of course not consumables or human flesh and personal gear.
    That extra 640 pounds payload for a smaller boat begs answers, and suggests that perhaps Kohler counts up empty weight differently than Woods. I'd be very interested in knowing real world weights, and exactly what is included. Discovering that you had bought or built a boat and that it was not capable of carrying the payload necessary to it's mission without compromising bridge deck clearance would be more than just discouraging.

    H.W.
     
  2. Richard Woods
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    Richard Woods Woods Designs

    We built our own Sagitta and launched it in 1991. It weighed 1800kgs at launching. That was with cooker, oven, davits , fully finished, as you can see in various videos. It floated high when launched, the 2700kg loaded weight is for the boat floating on its marks. I remember that at one boatshow we took 12 people out sailing and did 16 knots. Or it might have been 16 people and we did 12. It was long ago but the numbers I do remember!

    I know some people will over build their boat, so the empty weight will be more. And when crossing an ocean, as several Sagittas have done, it will probably weigh more than 2700kgs and thus float deeper in the water than the DWL But that isn't a problem as I assumed some extra overloading when designing the structure

    We had our Sagitta for several years and won many races. It was actually designed as a fast coastal cruiser for two couples, but, as I just said, it has proven seaworthy enough for ocean crossings, both crewed and singlehanded. I believe the furthest sailed was Capetown - Panama - New Zealand

    For those who don't know the boat you can see more here
    Sailing Catamarans - Sagitta - 9m round bilge performance cruiser http://sailingcatamarans.com/index.php/designs-2/3-25ft-to-30ft-catamarans-designs/171-sagitta and a video here

    one of many from my Woods Designs youtube channel. The log reading doesn't show clearly in the clip, but we were doing over 12 knots, the longer Eric Lerouge catamaran was a lot slower

    I wrote a short article about how I define empty weight and displacement here Sailing Catamarans - Weight and Displacement http://sailingcatamarans.com/index.php/faqs/15-general-questions/467-weight-and-displacement

    Obviously the Sagitta and KD860 are very different boats, aimed at different markets (I would think my Gypsy design would be the nearest equivalent to the KD860) so deciding to build one or the other based purely on theoretical load carrying ability is probably not a good idea!

    In 1999 the Sagitta gained a big sister, the 9.9m Eclipse, while I recently designed a hard chine version, the Tamar 31

    I hope that helps

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
  3. DCockey
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    DCockey Senior Member

    I would not assume that Richard Woods and Bernd Kohler use the same critera or methodology or even definitions for determining "payload".
     
  4. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    Perhaps one of my biggest beefs about boat building is the uncertainties about displacement and 'empty' hull weight
    Important to note is that displacement and boat length are not linear
    I did a weight budget for my boat planning and working with the designer determined the vessel I thought I wanted (skoota 28) was going to miss the weight plans, so I went to the skoota 32.
    Designer is Richard Woods
    Make sure and do a weight budget of what you want onboard, engines, people, everything.

    I watched a video on youtube of this lovely woman trying to shed 10kg from her catamaran. At first, I thought she was nuts, but at the end of the video; she showed the rewards of her efforts were 10 bottles of wine stashed in a footlocker. Do a weight budget first, then discuss with the designers if the boat will work.
     
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  5. jamez
    Joined: Feb 2007
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    jamez Senior Member

    Owly, You are fortunate that many examples of both designs have been built and sailed. As well as talking to the designers re. suitability for your intended use you can get some very pertinent information from the people who build and sail them. Don't be shy about tracking down the owners and having a conversation. Most people I know who have built are happy to talk about their boats. Taking this approach some years ago saved me from building a design that I liked, but in reality would have been a bit of a lemon with regard to my intended use.
     
    Last edited: Nov 25, 2017
  6. Owly
    Joined: Oct 2016
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    Owly Junior Member


    Richard:
    Thanks for your prompt and very clear and to the point response. I'm looking for a boat for a specific mission, as a mostly solo live aboard voyaging boat that will on occasion make long ocean crossings, presumably in the optimal season. I used the two examples I chose based on payload versus boat size, as an example of the challenge of choosing a suitable boat. Keeping the overall size down is important to me. I often hear people suggest going to ever larger boats, something I would like to avoid. I'd like to keep things down in the 9M range, and Sagitta appears to fill the bill. I'm not a packrat, and I'm primarily a single hander, and don't have family. I do not demand a bunch of luxuries, and fancy trimmings. I will however carry a larger complement of tools than some folks. Being able to repair and fabricate things myself is a habit of a lifetime. I'm not the guy who calls the tow truck or tow boat when something goes wrong, but I can do a lot with very little.
    Payload is a bit ambiguous until one has a boat sitting in the water in a known state of equipage. At that point, weight could be added in the form of sand bags or drums filled with water, etc, or something else of known weight until the DWL is reached. That is the only way a meaningful baseline working payload could be determined for a given boat in my opinion, short of hanging the boat on a crane and weighing it, and then keeping track of everything taken on board.
    It's an unfortunate fact of life that the time when light weight is potentially of greatest importance is when a boat is most likely to be overloaded. On a passage. On an ocean passage, one is most likely to want to have one or two crew aboard, and supplies sufficient for a minimum of 4 weeks. Each human and his basic gear is going to account for at least 250 lbs, probably closer to 300, as one has to include bedding, foulies, and various other things per person. Food and water, conservatively adds up to about 7 pounds per person per day including half a gallon of water. For two people, lets say realistically a bit over 1000 lbs in addition to the fuel load & cooking fuel, spares, tools, anchors and rodes, fenders, dinghy, nav equipment, radios, batteries and wiring, solar panels and windcharger, and countless other items. That extra 980 pounds beyond people, personal gear, food and water, is something one can burn through incredibly fast............ But I'm not telling you anything you don't already know.
     
  7. Richard Woods
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    Richard Woods Woods Designs

    Scrumpy was probably the latest Sagitta to make an Atlantic circuit. I went on that boat, it was very heavily built, in part because the original builders modified the build process without discussing it with me. But it still sailed thousands of miles without problems.

    and that is the real point. Figures don't matter, what does is that a boat does "what it says on the tin" A Sagitta has proven by several owners to be a safe ocean passage maker with 1-3 crew. Fast and comfortable. I sailed the slightly larger Eclipse over 10,000 miles. We had three people on board for the Atlantic crossing, yet still did over 16 knots on the 18 day passage. Definitely not stripped out race boat (even though we won the UK's Round the Island race). Solid fuel stove, sailing dinghy, sewing machine, big oven, water cooled freezer, bicycle....

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
  8. guzzis3
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    guzzis3 Senior Member

    Maybe. In open ocean deep water you don't have sharp chop and lee shores to worry about. Obviously there are other problems, but controlling weight on a multi is an issue all the time.

    If you want to know roughly how much your boat will weight empty then build to the plans, and be meticulous. The actual variation will be small.

    If this is a big concern to you then before you do anything else you should sit down write a detailed list of stuff you will have on board and weigh each item. When you have an accurate payload you can work back from there. A rough guess probably isn't good enough.

    If it's a woods design you like but payload is marginal Mr Woods offers various build methods for many of his boats, there is weight to be saved there.

    A smaller boat is sensible for a single hander, and a finished 9 meter cat sails much better than a 12 meter boat that never gets finished. This one was already in that shed 20 years ago when I moved here:

    Catamaran 45ft unfinished project | Sail Boats | Gumtree Australia Brisbane North West - Mount Crosby | 1167696511 https://www.gumtree.com.au/s-ad/mount-crosby/sail-boats/catamaran-45ft-unfinished-project/1167696511
     
  9. Owly
    Joined: Oct 2016
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    Owly Junior Member

    I've drafted several replies......... but not sent any of them....... I tend to do that.
    Good points all:

    On passage one quickly sails beyond the weather report you put to sea under. Hopefully if you sail during the optimal season for the area. You make a good point about chop in the vicinity of land. It's important NOT to sail on a schedule, and hopefully if overloaded one has the good sense to take things easy. In any case overloading is far more likely when making a passage, unless you make a point to leave a lot of stuff ashore. In my case as a live aboard voyager without a land base, I'm looking at an ongoing battle with weight.

    That said, I have experience with packing light. In my teens and 20's, I often took long backpack trips in the Cascade Mountains of Oregon and Washington. 50 miles being a relatively short trip. The most I ever packed for was 11 days, and my pack was just over 30 pounds including my stove and cookware food, first aid items, water, repair items, spare socks, rain gear, sleeping bag, and tent. I always carried the tent, as my pack was always the lightest, and we each carried our own stove and fuel and packed our own meals.

    I totally agree with your point about a 9M boat versus an unfinished 12M boat........ for that reason I do not plan on building a voyaging boat. I've built enough boats and other things to know the magnitude of such a project. Boats are plentiful for numerous reasons, and I will acquire a multihull... cat or tri, that may require some work, but hopefully not a lot. I don't need a large boat....... just large enough. The size / cost relationship is anything but "linear"...more like parabolic, and my budget is small. The result is that I'm looking at smaller boats, and naturally come up against the "payload squeeze".

    Richard took offense when I mentioned the KD 860 and Sagitta as two "contenders" in my list of cats, and compared payload, and absurdly equated the Gypsy with the KD 860........ a comparison based ONLY on length. In all other respects the two designs are not at all similar, and reflect an entirely different design philosophy, and different choices by the designers......... and a vastly different payload. Both are attractive for different reasons in different ways, and to different people.

    In reality it is unlikely that I will ever own any of these boats, and if I were to build one of them, it would probably be the KD 860, for numerous reasons that are specific to me, my needs, priorities, abilities, time, etc. No reflection at all on Richard, and his excellent designs. But at 62, I'm not interested in starting a big building project......... I know better. I want to sail, not build at this point. I have two small boat projects in the works as I write, and don't want a big one. That leaves me assessing the relative merits of boats that may or may not be available within my budget. Cheap is, I've found, not always cheap in the end. I've bought a lot of bargains that turned out not to be bargains. When I look at a boat, I want to know all about the design BEFORE. I do not like surprises.

    H.W.
     
  10. guzzis3
    Joined: Nov 2009
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    guzzis3 Senior Member

    The weather can change long before you have a chance to get to a safe anchorage here even if you're only a couple of miles off shore.

    People have sailed around the world in tiny boats, the smallest cat I know of was a tiki 21, 18' waterline. The cost is proportional to weight and that is usually the square to the cube of the length depending on the design.

    Could you show me exactly where Mr Woods took offense ? All I can see is a calm and extremely well informed answer to your questions.

    As for the comparison the KD860:

    LOA/LWL: 8.60m
    Beam: 5.60m
    Draft hull/rudder: 0.4/0.7m
    Weight empty: 1800 kg
    Weight cwl: 3000 kg
    Sail area
    Main: 27 m2
    Jib 10 m2
    Reacher: 26 m2
    L/B ratio: 1:2
    L/B ratio hulls: 1:11
    Prismatic coefficient: 0.569
    Righting moment max.: 5600 kgm
    Optimum speed: 21.5 kn
    Outboard engines 2x 6 HP

    LENGTH O.A. 8.5m
    LENGTH W.L. 8.1m
    BEAM OA 5.4m
    DISPL (empty) 1.8T
    DISPL (loaded) 2.4T
    HEADROOM 1.85m
    DRAFT 0.7m
    SAIL AREA 38 sq m

    They look pretty similar to me ? The KD has a full width cabin while gypsy is divided into cuddy and hulls, that's probably the biggest difference. Sagitta is a MUCH bigger boat. The quoted payload for the KD is bigger I suppose....but at 3 ton it will sail about as well as a gypsy at 3 ton.



    If you aren't going to build or buy any of these then why are you asking about them ?

    I am sure everyone on this forum has owned boats that turned out to be more trouble than they are worth, but building is absolutely not the cheapest way to get a boat that suits your needs. The cheapest path is to buy something second hand where you are able to assess properly what you are buying and pay a good price. Abandoned projects are often the best bargains, you can pick them up for a fraction of the materials cost, but the key phrase there is "assess properly what you are buying".
     

  11. Richard Woods
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    Richard Woods Woods Designs

    I was also puzzled why you said comparing the hard chine sheet plywood simple to build Gypsy with the KD860 is absurd. Especially when the Sagitta has round bilge hulls and is a much faster, bigger and more sophisticated boat

    Both Gypsy and Sagitta have made ocean passages. If you want more speed than a Gypsy check out the Saturn. Faster offwind than a Santa Cruz 52 (video to prove it) and similar to Fboats to windward

    Richard Woods

    Www.sailingcatamarans.com
     
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