British Coastal Micro Cruiser

Discussion in 'Boat Design' started by stumando, Apr 14, 2008.

  1. stumando
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    stumando infant member

    Hi I am looking for someone to take the time to comment on my 2.7 Coastal micro cruiser. Any wise words or criticism would be gratefully taken into consideration before I build her this spring. I have attached a few pics, that should give you a good idea of my design and thoughts.

    The boat is designed to be easy to transport, store, launch and move, While resembling a very small flat bottomed, chine runner version of a beautiful yacht, the WESTERLEY GK29 . http://www.astonclinton.ndo.co.uk/GK29_Wicked_Lady.jpg Thanks. Stuart.

    (More pics coming. have to shrink them!)
     

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    Last edited: Apr 14, 2008
  2. alan white
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    alan white Senior Member

    It's difficult to make out the design details and of course you show one view only.
    So this is about nine feet long. Judging by the rudder pivot and color change being the waterline, there's a lot of boat under water. Plumb ends are a must, which I see you've done. I would imagine a 1000# displacement boat would have an underbody like that. Am I close?
    If so, I would say the boat is too heavy, as about half that displacement might perform well, and even 600# might, but at a certain point speed becomes so comprimised that one feels becalmed even when a decent breeze is blowing.
    It's windward sailing that will suffer first. Short waterlines are already challenged, but add great weight and the boat is too round and blunt to slide over and through waves coming forward of the beam.
    Nor is displacement of much value in terms of stability since the boat must be sailed upright to move well, meaning the sailor's weight is of far more value (and whatever else can be shifted if the rig is of any appreciable size).
    A shallower boat with (unfortunately) less interior volume with leeboard foils (!) or a daggerboard (though anything l;ike that will be in the way) would give more lateral plane, sorely needed I'm afraid. The full keel concept as you have it is just not efficient at windward sailing. Better to be able to remove the lateral plane in order to run downwind efficiently.
    I'll grant you, the space inside has value. It's too bad the premium you pay for it makes for such poor sailing characteristics.

    Alan
     
  3. rwatson
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    rwatson Senior Member

    It would make a great movie prop in a movie called 'Desparate Escape from Pirate Island'

    I dont want to pick on you only Stumando, but I roll my eyes at this and other "10ft wonders" in these forums who try to design a 'Cruiser' for the open oceans.

    The easiest and most economical way is to get a designsfor a proven 16ft -20ft trailerable day sailer, to get out on the water in the nice weather, and pull it up sleep on the beach when the weather turns rough.

    This configuration that you and many others toy with makes a fun 'mind game' but for all intents and purposes is just a ten ft wooden box to waste a lot of time and money on for an for a virtually unusable result. Too small and uncomfortable for real long distance travel, too heavy and enclosed for fun day sailing!

    Check out some of your local designers like Selway-Fisher for some more proven designs that may suit. Some of these have water ballast, which would help with the "light to transport" requirement.
    eg
    http://www.selway-fisher.com/PCup16.htm
    for the Lynx16 for example

    10 feet of enclosed box is no way to go out to deep sea in, especially one designed by an inexperienced architect.
     
  4. Manie B
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    Manie B Senior Member

    Stumando i agree with Rwatson.

    have a look at the Tideway14 of Selway Fisher on the link as per Rwatson that is also a very pretty boat with solid design behind it. Doing your own design might seem fun, rest assured you will only do it once.

    It seems easy - its not
     
  5. stumando
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    stumando infant member

    British Coastal Cruiser

    Thank you, very much, for your thought's on "Talisan" I appreciate them.

    Please accept my apologies for the lack of visual input, for you to gather before you replied. Unfortunately the picture above is only a peliminary drawing. I have shrunk down the other pics that belonged in my post. Again, really sorry about that.

    Just so everybody is aware that I am not mental or crazy and will not be venturing into the dark green ocean or crossing any passages with this design. Also that Talisan is very much suited for my height and weight which is 5' 7" 9 1/2 Stone. and would be uselessly small to someone larger. Therefore I will not be selling her on or encouraging other people to build one of this scale. This boat is not designed for deep sea or very rough weather. It will be suitable, however for sheltered waters, such as estuary's, lakes, and possibly coast hugging on calm sunny days. where the coastline and tides are familiar to the skipper. I am lucky to live half a mile from the river Medway, in Kent, which joins with the thames at its mouth. I should get plenty of use from this design. (Girlfriend permitting)

    Alan, pleased to meet you, I wish I had written on the sketch that the shaded area was indicating water tight areas, and not the waterline. I will be hoping, that including the 200kg - 250kg movable ballast, which is balanced out (by trial and error) and attached in place, under the flooring panels, that the draft will be around 350mm 13"1/4. and with me aboard (9 1/2 stones) it will be around 400mm 16". The construction will have as little weight as possible and is a big factor in the plan.

    I originally wanted the boat to look beautiful (like a GK) but to have the same benefits as a dory, pram or dinghy. such as fitting it in the back of a van such as the ford transit. or car topping. To be easily moved around by one person. Low building cost. . Maximum bouancy I thought, also comes with the large flat bottomed shape of the hull. which in effect, should raise the boat out of the water, more than a V shaped hull does. I understand the need of a reasonable rocker. Also I had been looking allot at all the micro cruisers out there, and love the PARADOX and LITTLE CRUISER concept, also some of the ocean crossing designs fascinated me. so the Chine runners and large rudder seemed like a proven slightly lighter and space saving way to fit my design requirements. Also, leeboard can be added for extra lateral plane.

    The tideway 14 is a beauty, and definately appeals to my eye. I would enjoy building and owning one I think. The plans are very cheap also. However I will only draw inspiration from it until I have built my own design. So please if you would take the time to look through the pic's and comment some more I will be indebted to you all.

    Stuart.
     

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  6. rwatson
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    rwatson Senior Member

    Oh - I forgot to mention - on that Selway-Fisher link, there are two "mini cruisers" called the Micro 10, and god forbid, the "micro 8", which are along the lines of your concept.
    You might get some 'inspiration' from those designs.
    They look as if they will actually sail a bit, while these latest pictures go close to the "Clog Boat" in "Wynken,Blinken and Nod". I gather you have very little sailing experience ?

    As a design exercise, cut out a full scale frame and mock up the cockpit of that boat in heavy cardboard - then try to get in and out of the cabin 4 or 5 times in a row - with wet weather gear on.

    I dont want to be overly critical (again), but why would anyone want a ten foot boat with 250 kilo of ballast?

    If, as you say "will not be venturing into the dark green ocean or crossing any passages ", and "The construction will have as little weight as possible", then the whole design concept doesnt make a lot of logical sense.

    By adopting a "slowpoke" hullform, you do away with the manouvaribility and speed that when "sheltered waters, such as estuary's, lakes, and possibly coast hugging on calm sunny days" turn unpleasant, you are stuck out in the waves and tides instead of sitting on a beach out of harms way. (You will never get that boat above the waterline without a winch.) You would be better off in a 12ft Mirror Dinghy with a deck tent.

    At the very least, I would suggest water ballast rather than fixed. (My current project plans even have collapsible fresh water bags inside the saltwater ballast tank, so you can also drink and wash with the stuff that keeps you upright.)

    As I say, no insults to you intended - more power to your inquiring mind - but hopefully you will benefit from your very wise and brave action of submitting your ideas to public scutiny. Keep up the dream, but if we can save you money,time and frustration - thats why the forum is here.
     
  7. alan white
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    alan white Senior Member

    Stuart, what is the displacement? Do you know how to estimate it?

    A.
     
  8. tinhorn
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    tinhorn Senior Member

    Looks like the Bugeye Sprite of boats. Impractical as hell, but gobs of fun in just the right conditions. Otherwise, well, we just slog through until the next "right conditions".
     
  9. stumando
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    stumando infant member

    British Coastal Cruiser

    Firstly, thanks again for your time on this.

    I agree with what you said. Although I am still thinking of my original concept as the next boat project. I thought:
    The cabin can be built, simply, with more headroom. Not a problem.
    I am young and nimble and the cabin size is just big enough for me to pop in and out the door (with sliding hatch fully open.
    The whole reason for it to have removable ballast is so the boat becomes lighter for moving or launching and pulling on to the shore. By the sounds of it, I have overestimated the exact weight of the ballast needed for good stabilizing. I figured that sand bags or concrete blocks would be a more compact way of getting the same weight of ballast as a larger salt water ballast. I understand that the heavier the object, the less impact waves will have on stability. So am a little confused by what you said about the ballast. apart from it being too heavy of coarse.

    Would you recommend a more streamline shape to the boat (less beam) so that it won't have such a 'slow poke'.

    Also my design is very close to some of the boats that have achieved ocean crossings, long trips through the bahamas and even circumnavigation. So I am still fixed on the idea. All be it that with a little guidance from gentlemen such as yourselves, I will have to put some changes to these early plans of mine. before I commit to build.
    Here are a few boats like talisan:
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]

    Surely I won't have to scrap my plans. just adjust them.
    If you have the inclination, please list what you might change and how it will help her to be a more efficiant boat. I still would love to keep the GK look, and need the flat bottom so I can pull her about easily.

    I do not know how to estimate the displacement, until the boat is fully built.
    How is this done Alan?

    regards stuart.


    Also I am interested in the boat's that you both have designed. I would love to see a few pictures. and talk some more.
     
  10. rwatson
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    rwatson Senior Member

    The confusion comes from your contradictory statements -
    "You are only going in calm waters ."

    but in your last statement

    "have achieved ocean crossings, long trips through the bahamas and even circumnavigation"

    If you are secretly picturing yourself doing big ocean trips in a ten foot barrel, then you need the ballast - and several sessions with a phsychiatrist who specialises in curing masochistic tendencies, and a wealthy sponsor to make it all worthwhile.

    If, as you say, you are doing calm, coastal trips, then loading and unloading 200 kilos of ballast is completely a waste of time, and the "cosy" confines of the design will drive you mad ,no matter how small you are.

    You state that you want a light load to transport - how do you think the ballast will get to the ocean with the boat? Follow you on horseback? You will have to cart it with you in or out of the boat - generally you will leave it in the boat, or else spend an hour at busy launching ramps packing it back in.

    Now lets imagine you have 200 kilos of concrete or whatever in the bilge. You arrive at the lonely beach, pull the boat up as far as you can out of the surf, and then spend 30 minutes scrabblling around in the bilges, chucking out bricks through that tiny door, into the sand and the surf. Then, you spend another 30 minutes carrying the bricks up the beach before they get buried in the sand, then you go back and manhandle the 10ft boat above the tideline. Lets not consider the problem of getting it back in to the water - that gets really hard.

    Why all the trouble? The average unballasted 12 ft dinghy will sail 4 times faster and 50 times better, be 100% more comfortable to camp in, and be a fraction of the weight to transport and launch, and pull up at a nice little beach.

    If you still want to build a trans-atlantic dog box, then get one of the professional designs to build so at least they will pay out on your life insurance.

    But thats just what I think.
    It has been great fun waxing lyrical. Have fun :)
     
  11. messabout
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    messabout Senior Member

    Another design worth looking at is the Bolger Micro. It is as mentioned above, a sea going dog box. However the micro does sail pretty well. Micro has ballast and is not one that you pull up on the beach easily. I have sailed in/on one of them and was quite amazed that it sailed as well as it did. Bolgers boat is about as simple as it gets, so building is not a challenging exercise.

    That said,I have to wonder why anyone would want to build such a boat. RWatson has gotten it spot on. Get a small dinghy such as the mirror and use a cockpit tent. I suggest that it might be a good plan to get hold of a book called "Beachcruising". Some very good advice is contained there. I cannot remember the authors name but he has done a good reference for people who are inclined toward self flagellation.
     
  12. alan white
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    alan white Senior Member

    The Micro has an amazingly large interior for a small boat. Incidentally, Micros and long Micros, and a lot of Bolger's designs incorporate identical curves stem to stern along the keel and also the sheer as viewed from above----- so there are overhangs and a difficulty beaching.
    Then when the boat heels it actually becomes symmetrical again. Here is where the good sailing qualities come from.
    No, I wouldn't own one cause I think it looks like a box. For me, half of the joy of sailing is the way the boat looks.
    Bolger boldly omits a chine just because he knows it isn't necessary and he likes to prove it.
    I would add a chine, like a simplified Swampscott dory, just because it looks good.

    Alan
     
  13. alan white
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    alan white Senior Member

    I do not know how to estimate the displacement, until the boat is fully built.
    How is this done Alan?

    regards stuart.


    Hi Stuart,

    To estimate the displacement take your midsection drawing and measure the area of the proposed submerged area.
    Multiply this times the waterline length (in your case, same as the overall length).
    Again, multiply by .52 (in your case because your boat is short for its beam... low prismatic coefficient).
    Now you have the cubic displacemrnt of the submerged volume.
    Multiply the displacement in cubic feet times 64 (salt water per cu ft).
    Bingo.
     
  14. lewisboats
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    lewisboats Obsessed Member

    Alan...shouldn't that be a higher prismatic coefficient? Long and slim =low and short and fat = high (er)?
     

  15. alan white
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    alan white Senior Member

    Actually, in order to form a decent bow on a very short fat boat, one is likely to straighten out the lines coming up to the stem. What's wanted is a sharp enough entry to tell the water where the front of the boat is.
    Length shouldn't have to do with prismatic coefficient anyway. A large ship is parallel-sided and so has a very high prismatic. So do a lot of small catamarans.
    A boat like the one were discussing, in order to have a high prismatic, would be very apple-cheeked.
    I'm not a super-expert in this area. I'd welcome comments. In any case, at least Stuart now knows how to get an estimate of displacement from the midsection.

    Alan
     
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