Affordable seaworthy cruiser

Discussion in 'Boat Design' started by goodwilltoall, Jul 31, 2010.

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  1. peterAustralia
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    peterAustralia Senior Member

    on little thing, I think your mast will need a vertical post underneath it to take the compression loads, much better than a ring frame IMHO. Access fore/aft can be via openings at either side of the mast support
     
  2. goodwilltoall
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    goodwilltoall Senior Member

    Yes I thought about connecting cabin to cabin but wanted room around the mast for sail handling and keeping everything to a min. with standing hdrm only where I find it absolutely necessary. If doing it your way I would not connect all the way thru as where you exit the hatch its designed to be about 64" below the boom and then a step down into sitting area or step up and around the cabin sides to access fwd.

    Forgot to mention the keel, there was no satisfactory way of dealing with large retractable foils for such a large boat so had to go with fixed appendages. Shallow draft was one of my main reasons for beginning to design and the bogomil is the closest I got to ultra shallow draft and not much a different hull idea than what Bolger already did.
     
  3. nzboy
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    nzboy Senior Member

    Moderation is the key in most things .Your fat duck might need a bit more Hp to push in to ahead sea or go against the tide .Are you really sure your flamingo 60 will float upright or on its side Did you know that beam width influences stability. Its no secret that the ocean class 65 and 70 in search of shallow draft have extremely wide after bodies
     
  4. peterAustralia
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    peterAustralia Senior Member

    In terms of ballast/stabilty, the NIS (Norwalk Island Sharpie) used a steel plate at the bottom of the hull. I think they protect it with a small layer of ply/fiberglass/epoxy to stop it rusting. This steel plate is external and follows the flat hull bottom.

    If you want shoal draught, have you thought about lee boards. Here is a setup that might work. The Zeigers in the Luna Sharpie use something a bit similar,,, leeboards that can only rotate on one axis.

    [​IMG]
     
  5. peterAustralia
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    peterAustralia Senior Member

    You could use a similar setup as the above image. Instead of having the axle at cain height, you could put the axle in a tube and put it under the floor of the new design, this would keep heavy weights down low which is a good thing
     
  6. goodwilltoall
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    goodwilltoall Senior Member

    Thought about leeboard but think they would be to big to easily handle. If putting a steel ballast bottom I would use strips of steel about 4-6" wide x the width of the hull x what ever thickness for the ballast weight your trying to achieve (1/2",3/4", 1", etc.) with screw holes in the middle 6" O.C. Sandblast each piece, prep hull then set n screw in a thickened epoxy. Glass over that. This is the only way I can think of satisfactorly attaching steel to a wood hull.

    nzboi, O65 wide sterns are more powerful shapes and not for shoal draft. Didn't calculate but would try to achieve .53-.55 cp and think the waterplane is average as drawn. Excluding keel, rudder, and minimal cutwater fwd. the hull is perfectly balanced (laying flat) since this would be more of a cruising boat with requisite for good handling. Speeds of VL.9 - 1.0 are the target range, the easy exit and narrow stern help in this regard and the long wl will still give it good speed (200mi daily). As far as higher HP, think it has more to do with your familiarity of how and where you plan to use it. Over here there are no strong tidal currents or dangerous inlets. We get short erratic waves and it should be able to handle these. Now if I was going to do extensive cruising and avoiding checking up on local waterways (with radio and internet you can get good info and should use it before arriving) or traveling often to known problem areas (I heard the entrance to Jacksonville is) I would be more apprehensive and maybe get a more powerful engine,

    In a 90 degree knockdown a hull with less freeboard will right itself quicker and is better overall as long as the deck does not dig in (boat should sail at max of 15 degree). A 180 degree inversion is different but all things being equal the longer hull is more unstable upside down. I look at other hulls as comparisons and used as39 which has over 2' less beam, almost same freeboard (4" less), n without ext. keel. So if that was seaworthy this should perform even better.
     
  7. goodwilltoall
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    goodwilltoall Senior Member

    On another matter I mentioned my displeasure with some things on the last drawing of 50'er such as the unprotected helm so I plan to have an inside steering station at where the chart table is drawn. The cabin would be raised about 6" and extended to the hull sides.

    Disadvantages are :
    1.) No access fwd. unless climbing over the top of cabin or another hatch fwd.
    2.) Mast locations are more problematic.

    Advantages:
    1.) Outside sitting area is unobstructed with eye view just above the cabin.
    2.) With helm out of way, bathroom entrance can be fwd. instead of aft., this gave me concern thinkin about going around the decks at night. This way u still go outside but its closer and more protected walking the footwell.
    3.) Dry exhaust can exit straight up where engine is and fits nicely at aft of cabin.

    I looked at a picture of the M65 with inside steering station and it doesn't show a wheel helm. Can something else be used rather than a wheel and is it a good idea? Like the looks and will most likely go with this arrangement but would like to keep the chart table if possible.

    Peace.
     
  8. goodwilltoall
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    goodwilltoall Senior Member

    Drew this up last night showing changes. Moving the helm inside made a big difference with small changes overall.

    1.) Is sail plan feasible? Would like to keep just single mast aft.
    2.) Access fwd ontop of cabin with short lanyard opposite of which side you walk on.
    3.) Or fwd hatch & ladder intruding into berths area.
    4.) Undecided if fwd facing seats are best, could possibly turn 90 degree with sliding foot rest to allow passage.
    5.) Might need to make AS15 to fit within the hull aft.
    6.) Side cabin window 15" rather than 18" (shorten at bottom).
    7.) Prefer doors instead of drop boards but cabin would need to be higher preventing view fwd while sitting.
    8.) Even if keeping the chart table is possible it would put the helmsman back 24-30" causing a less favorable location for viewing. Hope is electronics are better than chart papers anyways and can fit them somewhere near helm, although still like a table for reading n drawing.
     

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  9. goodwilltoall
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    goodwilltoall Senior Member

    Greetings,

    Able to fit in steering station and chart table, corrected keel size, added hatch, and tabernacle. This should work as it has mostly everything i want -sor- in a boat this size so shouldnt have to continue making changes other than to perfect whats there. Will have to learn to deal with fwd berths.

    Peace.
     

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  10. nzboy
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    nzboy Senior Member

    Had a few hours to spare so I put design for 20m yacht into freeship approximation anyway .Then using the same parameters waterline beam,
    draft, essentially waterplane is 20 % less and displacement also .I allowed freeship to invent the 2nd model .Question is what model would be more seaworthy? goodwill5_Linesplan.jpg

    goodwill5.jpg

    goodwill6_Linesplanjpeg.jpg

    goodwill6jpeg.jpg
     
  11. SamSam
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    SamSam Senior Member

    What a cluster ****. Knock this boat down, roll it over or have a wave sweep it...

    [​IMG]

    and this could be you...

    [​IMG]
     
    Last edited: Jan 31, 2014
  12. peterAustralia
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    peterAustralia Senior Member

    ahem

    that boat was built in Bangladesh, by a local builder for two Frenchmen, they sailed it back to France. the vessel was made out of Jute and fiberglass and cost 10K, round section tubing, cheap labour, cheap steel, galvanised wire stays. So they had an adventure. I think they had sponsors.

    http://www.dawn.com/news/934430/frenchman-in-jute-boat-sets-sail-from-bangladesh

    http://www.friendship-bd.org/news/v...ngladesh-to-france-on-jute-fibreglass-boat-29

    http://www.reuters.com/article/2010/02/17/us-bangladesh-france-sailor-idUSTRE61G13G20100217

    Boat was built to trial jute fiber as an eco friendly alternative to fiberglass
     
  13. peterAustralia
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    peterAustralia Senior Member

  14. SamSam
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    SamSam Senior Member

    No, that's Ahab. Ahem must be a brother or cousin. ;)

    Well, luckily, it seems..

    [​IMG]

    At least he stowed the lines a little better.

    I don't know, it just seems like one of those personal self promotion schemes.

    They've used burlap and resin for decades making corrugated roofing, the idea is not new and I wonder how useful it actually is when it comes to strength and longevity. It must soak up wonderful amounts of expensive resin.


    [​IMG]
     

  15. Sailor Alan
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    Sailor Alan Senior Member

    Haven't we all dreamed of setting off on our own boat for parts overseas, and wondered how we could do it at the least possible cost? I know I have.

    Nearly all boats are a “Beam”. We might not think of them as such, or even really design and analyze them as such, but they are. For instance, the very large cruise ships designed and built in Finland are a box beam. Four vertical webs extend continuously from the bottom plating (the bottom flange) to the 12th? deck (the highest contiguous deck) as the upper flange. These webs are the port and starboard sides, and the vertical sides of their “Main Street”. All openings in all these elements have either rounded corners, or “Micky Mouse” ears to reduce corner stress risers. These latter boing covered with trim.
    “Floors’ Decks, or as i would cal them, intercostals tie these ‘webs’ horizontally.
    Similar French designed and built cruise ships, have a matrix of vertical webs and bulkheads making a sort of steel ‘barge’ up to the ‘main deck’, and a basically non-load bearing aluminum superstructure above that. (This is a gross over simplification I might add). These “Beams’ are to allow the ship to be suspended at each end and suffer no damage. Bulkheads, or more probably diagonal braces provide torque resistance in the “box beam”.

    Your boat is exactly similar. The sides are the web, and the deck and bottom the flanges of a simple box beam. You need at least some bulkhead like elements to stop torque twisting. These can be partial bulkheads joining part of a side to a deck or bottom, and there should be several of them toward the middle and at mast placements.

    I am supposed to be some kind of expert on composite fiber structures, (airplanes and satellites, not boats) so I know Jute fibers will not help much. There have been a lot of talk at conferences i attend about ‘natural’ substitutes for carbon and glass fiber in structures. Most of it is useless, and merely a publicity stunt, though Basalt fiber, rock wool, is not, and could be used for building etc. Glass fiber is merely sand and heat (energy) and is pretty benign even if it is forever. It is the resin systems that worry me. They usually use oil as the basis, simply because it is the cheapest form of hydrocarbon. Again, resins are forever, but it is not a nice, or a benign substance. Unfortunately we are kind of stuck with it, at least for the foreseeable future in boats. Even if we didn't ‘fiber glass’ our boats, the best paints are fairly similar chemically.

    Now if you could arrange to heat the jute in the complete absence of air, you would get carbon fiber. Admittedly, a poor, low modulus, short fiber version of it, and one that could not be “handled” or moved, but carbon fiber nonetheless. I would use one of the polyesters as a cloth. Kevlar and the nylons are all hydroscopic, and do not “grip’ to the resin very (long explanation needed, very technical), so basically not a good choice.

    As to the boat design. I notice the boat is evolving? into something like the Dashewes Wind Horse, not necessarily a bad thing. I am a big convert to Bebe’s book (and principles) and have noticed even my delivery trips tend to be under power, not sail at all.
    I would personally try to add a bit of displacement to it, so its inertia (heft) was greater, and the movement at sea a bit slower and less tiring. Perhaps a ballasted box keel.

    Someone much wiser then me once said, you bolt a lead keel to a wooden boat, but you bolt a wooden boat to a steel or reinforced concrete keel. Sound words. don’t use small pieces of steel for ballast, it is very hard to support them. Remember, plywood, like all composites, does not like point loads, and separate pieces of ballast steel look like a lot of ‘point loads’ to the supporting plywood.

    I once made a ‘box’ keel like this. I laid 3/8th steel plate flat on the ground (sand) butted to the length of the necessary keel. I then took more 3/8th plate about 18” high and placed it edgewise along this base. At the ‘bow’ i used a 6” diameter half pipe for the ‘bow’ of the keel, and welded the sides to it. I used just 2 ‘bulkheads’ about 3’ long (wide) to spring the keel sides into place, then welded these side pieces in a “V” at the stern. These 3/8” thick sheets naturally took the proper curve, no distortion. After welding the sides to the bottom inside and out, i cut off the bottom scrap off flush to the sides. Now i took a 1” diameter pipe, and laid it from center bow to stern “V”. A weight in the middle produced a fair curve, and i projected this sideways onto the vertical sides. This curve is cut, and I welded on a ‘flange’ to the outside of the sides. This flange bolted directly to the plywood skin, frames etc, using several hundred 1/2” galvanized bolts. The motor was mounted by welding mounts in the stern of the ‘box’, the stern tube welded through a hole in the stern “V” and all the scrap cut small, a lot more added, and secured inside with concrete slurry. I think we poured oil in after the concrete was set, but cannot now remember. The welded in “bulkheads” were extended up using plywood to make a completely sealed ‘engine room’ at the back.

    In this case i would put such a keel from under the forward mast (see more anon) to the rudder/propeller position. As we did, add floor boards to the top of the concrete ‘ballast, and walk in the keel trench, increasing headroom, and avoiding the deck cutout for the deckhouse(s).

    With a low cost boat like this i think i would go with multiple masts. Being very long and slender, perhaps 3 masts would be best. My personal preference now (i am getting older too) would be free standing masts with either Bolger type “Leg o Mutton” sails, or my favorite, Bahama Sloop type “leg o mutton” (shoulder o mutton?) sail with a short club and a loose foot.
    Free standing masts do not necessarily need a ‘pole’ from the deck to the keel, but they do need to be mounted substantially. Bolger taught us that they did not necessarily need to be on the centerline either.
    Classically, they are keel stepped, and supported at the partners, which means they penetrate the cabin, and some of these free standing masts have quite thick heels. My personal preference, especially when we are dealing with a “box” like plywood boat is to have the freestanding mast ‘deck’ mounted, like a flagpole, and take the loads out through adjacent deck, bulkhead, and/or web structure(s).
    Alternatively, deck stepped hollow square wooden masts are vary cheap and easy to make, not pretty, and can be braced with galvanized power pole cables. Completely satisfactory, and you will replace the cables for cosmetic reasons long before they become actually weak. Unlike SS cables i might add.
     
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