Would this make a good coastal cruiser?

Discussion in 'Boat Design' started by boat fan, Sep 15, 2008.

  1. kengrome
    Joined: Jul 2006
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    kengrome Senior Member

    If by this you mean epoxy/glass taped seams and joints I agree. This is the way I build most of my boats anyways since I think it is the best low-cost, lightweight method available that employs plywood in the best possible manner.

    These hulls are very narrow, probably narrower than you're imagining, and this leaves precious little room inside for 'accommodations'. If you want wider you must go longer unless you change the hull form, but then you'd be reducing propulsion efficiency and increasing fuel consumption.

    Sure, if they are 4-5 feet off the floor.

    No way, not if you plan to use the same slim hull form the local builders use. Of course you can widen the hull but then you no longer have the efficiency advantage of these boats.

    I think you should come over here and take a look at some of these boats before you make any other assumptions about them. You seem to have the idea that they are much wider than they really are. Here are a couple pictures to help you put this into better perspective:

    [​IMG]

    [​IMG]

    I'm guessing that this second picture is a boat that's 40-50 feet long. I wish I had taken pictures of the inside of the hull of the one that was under construction on the beach in Argao last year so I could show you just how little space there actually is inside these hulls.

    Like I said you can widen the boat if your goal is interior accommodations. The only problem is the corresponding reduction in fel economy, that's all.
     
  2. boat fan
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    boat fan Senior Member

    Thank you Ken.

    You are right , I did not think that they were that narrow .
    If that is what a banca is , then I don`t think its what I want

    http://www.boatshop.com.ph/portfolio/mysteries.gif

    I guess its not surprising one gets confused , or " makes assumptions" : This boat above was described as a "liveaboard. "
    and , indeed as a " Banka ".

    Quote :
    Mysteries was designed to be a very basic but full sized cruising yacht with a minimal sail plan. When is the last time you saw a 50-foot cruising yacht launched for $25,000? The design has a generous stern cabin en-suite, pilot house/galley, and guest cabin forward also en-suite. This banka voyaged to an idyllic and remote bay and…. well, just stayed there.......

    Now , If its supposedly a " banca " ,or " banka " then there is no way it can be liveaboard. Its either Not a " Banca " by your description , or its some other , wider boat that can be fitted out and used as liveaboard.

    There is no way you could squeeze any kind of living space into a needle hull like this one , and why would you even try ;

    http://farm4.static.flickr.com/3126/2826316649_f29a372294.jpg


    It`s plain to me now that I`m barking up an entirely different tree here !


    Take an example here 50 ft loa x 4.5 ft waterline beam = 11: 1

    A bolger wyoming is 51 ft x 8ft 3 inches waterline = 6:1 That boat certainly is efficient also.

    If you build a better than 11:1 light hull , powered by a low powered (relatively) diesel you will travel at and exceed hull speed , easily.

    Now , that is efficient power boating , in my book anyway.
     
  3. boat fan
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    boat fan Senior Member

    Hello Zilver .

    It`s a beauty isn`t it.:)

    WAY , WAY too much boat for me too :(

    Could be scaled down a bit I`m sure.Easy dinghy launch too , strap it under the side deck ,you could just lower it with light tackle.:)

    I don`t understand why there are not more of them myself.Could be built with less material than a big powercat ,with similar performance :It`s probably not going very fast at all here , but there`s no wake either ......

    http://www.seakayakvacations.com/Mirage_with_kayaks_in_tow.jpg

    I like it . A lot !
     
  4. kengrome
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    kengrome Senior Member

    Some foreign builders like to modify the local boat designs and call them by the same name even though they end up being somewhat different.

    That live-aboard you mentioned may actually have the same underwater hull form as a local banca design, but if the sides are extended upward another foot or two it will end up having more internal space and therefore be more appealing to a western buyer.

    I think this is an example of a foreign builder redesigning a common local banca which really makes it into a different boat, but because it is 'similar' he still calls it a banca.

    I'm pretty sure it's been widened to appeal to foreign buyers.

    Yes, but it's not very well suited to anything but relatively calm waters in my opinion. I would much rather have a banca than a Wyoming in offshore conditions.

    Maybe you'll go 1.5 - 2.0 times the calculated "hull speed". These local Filipino boats are exceptionally fuel efficient, and now that you've seen what their shape is in a couple of almost head-on views I think you can understand why ... :)
     
  5. boat fan
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    boat fan Senior Member


    The Bolger Wyoming is a great boat , but I would not even consider it for my use.
    Its just a 50 ft power sharpie with a 8 ft wide flat bottom , after all. Keep that for canals , lakes or sheltered rivers and bays.....

    I mentioned the Wyo because it underlines that even a 6:1 l/b ratio can produce good power/fuel efficiency. You could do a lot better with ratios above 6:1. Since I don`t want to push into wasteful planing speed anyway , there`s no need to have it flat bottomed , or wide either.Add just enough rocker so you don`t drag the stern along .A modest sponson /outrigger / log would take care of the roll, and provide other obvious benefits.At sensible speeds it would add only modest drag. With a little thought at around 50 ft you could easily expect 12 knots with modest power.
     
  6. masalai
    Joined: Oct 2007
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    masalai masalai

    Several boats have l/b ratios around 20:1, The chamberlin C10 in my gallery is about 15, John Hitch "XIT" would be close to 30, "Foreign Affair" which has demonstrated ocean passage-making capability voyaging from Bris to Hobart, thence? and recently across to New Caledonia and cruised that region before returning back to Brisbane, A Schoenning design also went across to NC and worked around Vanuatu and is now working around the Whitsundays I think?

    So there seems merit in slender hulls....
     
  7. boat fan
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    boat fan Senior Member

    G`day Mas !

    Yes I think its the way to go.Why push all that water in front of you?
    If you want to keep usable space in the hulls though , then I think 20 : 1
    is too extreme.

    What I mean by that is this :

    1 : The hulls become really weight sensitive , unless very long.:(

    2 : If you want usable accommodation IN the hull , rather than ON the hull,
    you need to flare them out above the LWL.:( The build becomes more complex , and possibly heavier.

    3 : If you use sheet material such as plywood , its a lot harder to integrate
    that flare into the topsides and still have it look " nice ":D
    I guess that`s personal taste though.....

    4 : You could strip plank all or some of the flared sections.Lots of fairing ...
    YUK !:(

    Having "whinged" about the flare thing , I concede that those ratios you give above are more than efficient.They are super nice for economy.

    I like the idea of keeping the bows above water rather than piercing waves with a needle hull. That`s an entirely different subject altogether :confused:

    What do you think of that " power proa " as I call it ?

    http://www.seakayakvacations.com/Mirage_-_65_Power_Outrigger_Yacht.jpg

    A 40 - 50 footer would be really nice to park at Shute Harbour ...:cool:

    I like most of what John Hitch has done.Every now and then one of his boats comes up for sale .There was one of his cats
    in a pen at Manly in Brisbane two years ago , may still be there ,I used to look at it often over my morning coffee at the Fish Cafe .. It had dory hulls and twin forestays , one to each bow on furlers.
     

  8. masalai
    Joined: Oct 2007
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    Location: cruising, Australia

    masalai masalai

    On the C10 the "false floor" was above the waterline and was only needed to access the forard double cabins, and midships in one hull was the w/c and the other the shower... Aft of these was the engine rooms and services (hws, batteries bilge pumps, fuel tank transfer RO water etc and below the "false Floor" was tankage for water (bows) & fuel.....

    Have you read ALL the website on "Foreign Affair" a 14m power cat - a 12 m is being built in Bris now/soon.... http://www.icecat.com.au/objectives.htm also have a look at Bob Oram website especially the "40ft Pearl Bay" & 39C http://www.boboramdesign.com.au/ and not to forget John Hitch who is also in Bris? designing/building his next - a power-cat for his retirement home....

    These guys are at the fore-front of this style of design and use slab & strip plank and have a following that will almost guarantee a buyer (for a quality build), when one becomes too old, (Dementia nursing home), for continuing life at sea....
     
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