Help With Economical Semi-Planing Designs

Discussion in 'Powerboats' started by SAQuestor, Apr 5, 2007.

  1. tom28571
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    tom28571 Senior Member

    It occurs to me that if someone wants a boat that cannot be found in the mass market, that boat will necessarily not fit the usual profile of easy resale. If it did, then the search could be completed by a trip to local boat dealers. That is a deciding factor that all of us must face when trying to satisfy our personal tastes.

    If the desire is to have a boat with good resale value then it must meet what the market expects and favors. I know of more than one designer who must design boats that they don't particularly favor in order to eat and send the kids to school.

    Peace:)
     
  2. RonW
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    RonW Junior Member

    First of, what is graal??
    Interesting threads, will read.

    fcfc says.--And when you put a inboard in commuter 36, the layout become awkward.
    Of course if you only have around or less then a 7 ft. wide area and put a box 2ft wide by 3 or 4 ft. long in the middle of it, you layout kinda gets screwed up. That is why you consider other options such as stern drive or outboard, god forbid.

    As for market and resale value, then you need to find a 2nd hand boat of your specifications that the owner is in a bind and you can steal it for a song and dance. Enjoy it for years and then resale it and make money. GOOD LUCK..

    I think the saying is, if you want to play, then you gotta pay.
    Now the big decision of deciding what you want and what you can actually afford. And as they say in the boating world, all boats are a compromise..
     
  3. FAST FRED
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    FAST FRED Senior Member

    " The second issue is I doubt seriously about resale/real value of a custom designed custom built boat. Especially when the primary reason for custom design/building is that no other similar boat do exist. That simply means there is NO market."

    This would imply that,
    1, everything is already known and there is no such thing as progress.

    2, The market is so well informed that every buyer knows of the existance of every item for sale, worldwide.

    The containerable motor sailor on the Motor Sailor board shows an idea that may not be new , but is certainly unique.

    "Build it , they will come" is how the normal market forces work.

    It will be interesting to see of in 10 years they are still in business , and how many (if any) competition spring up to create a broader market.

    I'm interested in creating an outstanding cruising motor boat to be container shippable . Weather the world flocks to the designers door , or only one is ever built will depend on the market acceptance of the basic cruising concept.Cruise worldwide , with out ocean crossings.

    That a boat is not mass produced , does not mean there is not yet a market for a specialized design.

    FF
     
  4. RonW
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    RonW Junior Member

    Good post fred, and the needs and wants of the marketplace is a constant changing situation due to various reasons.
    On the pervious page the link that fcfc posted about pocket cruisers - with motors, not sail and under 30 ft. definitely trailerable has 21 pages of some interesting and very nice boats.
    And these come from all over the world, so the world seems ready for a economical, trailerable cruiser that is smoother riding and has as much room and as good a layout for comfort as possible in such a small space.
    Of course the consumer wants the best for the least amount possible.
    The point that I keep seeing is they want the smooth ride and rough water capability, but somehow they are in between the semi- hulls and the planning hull blend, as to actual speed capabilities.
    They want the cruise of 20, and are willing to drop the top end down to 25, but for a boat this size that still demands some form of planning hull.
    Where as a straight semi- hull of this size will basically cruise at 15 and have a top end of about 20. So somehow they want to blend the two together as for the ride of the semi- but a little more speed of the planning hull.
    Maybe some designer will be able to give the market place the best of both worlds and design a slightly altered, whatever we are going to call it.
     
  5. SAQuestor
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    SAQuestor Senior Member

    One of the positive attributes that Downeast semi-displacement hulls is their ability to go out into a seaway. See attached pics and the Yachtworld listing for this Duffy 31 Fisherman.

    But I can't help but question whether or not a pleasure cruiser would actually need this amount of seaworthyness? Would I go out in the conditions as pictured when on a pleasure cruise? Probably not. But... Is this sort of capability worth the extra cost and fuel burn if it's only a capability and not used except in an emergency?

    Hmmm... Something to ponder. What are your thoughts on whether this sort of seaworthyness is needed - Please comment TAD, PAR, fcfc, Tom28571 and Fast Fred?

    Best,

    Leo
     

    Attached Files:

  6. SAQuestor
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    SAQuestor Senior Member

    For reference only.

    The attached pic is from this Yachtworld listing.

    This picture exactly illustrates what I have always thought of as typical performance of a semi-displacement hull form.

    The listing says that this boat cruises at 14/17 knots and has a 320 hp Cat engine to do so. Fuel burn? Likely gallons per mile instead of miles per gallon.

    Now y'all know why I want to understand more about semi-planing/semi-displacement hull forms. And especially can they be efficient? As defined by a 12-14 knot cruise speed at a low fuel burn rate.

    Best,

    Leo
     

    Attached Files:

  7. longliner45
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    longliner45 Senior Member

    ya might not go out into it intentionaly,,,,but sooner or later the odds will catch up to you,longliner
     
  8. RonW
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    RonW Junior Member

    Your post is very missleading leo.

    You fail to mention that your example boat above is 35 ft. long with a 12 ft. beam and dissplaces 7 tons. It also has a top speed of 23 knots or 26.45 m.p.h.
     
  9. SAQuestor
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    SAQuestor Senior Member

    Misleading how ron? I said:

    What part of these two simple statements is misleading? I said it is for reference and it's what I think of when a semi- hull form is mentioned.

    It is NOT misleading at all - the actual size and tonnage of the boat is irrelevant. Stop creating strawman arguments that are based on a misrepresentation of my statements.
     
  10. RonW
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    RonW Junior Member

    It is simple leo, as we have disscussed before on the wooden boat forum, the merits of a semi- hull versus those of the planning hull. You took the position that the planning hull is more fuel efficent then the semi-hull and that is not so, as long as you compare apples to apples. Speed is the great consumer of fuel. You used the example of the horsepower, but neglected to specify the weight and the correct maximum speed that actually required that much horsepower. So the actual tonnage, size, speed and horsepower are all relevant in determing what is what.

    The actual mileage at the cruise rate of 14-17 should be about 1 & 1/2 miles per gallon, not gallons per mile.
    I thought earlier of the lobster boat, probably the hull form that has already combined the merits of the semi-hull with a low speed planning hull. Maybe we need to look no further for the do it all hull..
     
  11. longliner45
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    longliner45 Senior Member

    what is amasing to me is that ,,designers,and na/s not only have disregarded,the statements I have made of 31 ft jc boat ,,but not even looked into it ,,if that was my bread a butter,you can rest asured I would have at least looked into it,,,this tells me that this field will be controlled by others,,in other lands ,,,,,,longliner
     
  12. SAQuestor
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    SAQuestor Senior Member

    Please, provide some links of exactly what boat and design you are writing about. I've Googled, but all I saw were commercial boats. Are commerical fishing boats what you meant?

    Best,

    Leo
     
  13. Frosty

    Frosty Previous Member

    A 320Hp cat This is the 3208 I should immagine will use 16 gallons per hour at max.

    16Kts at 16gallper hour =1 gall per nautical mile.
     
  14. RonW
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    RonW Junior Member

    Jack frost says--A 320Hp cat This is the 3208 I should immagine will use 16 gallons per hour at max.
    16Kts at 16gallper hour =1 gall per nautical mile.--

    Not to be argumental, but that is not correct. If you are going to try and compare performance, especially fuel economy, then you need to get the actual figures as close as possible for a fair comparison.
    The example above of the lobster boat actually has a top speed of 23 knots or 26.45 m.p.h. So don't take a lower speed and then use the maximum fuel useage and try and make a comparison.
    Besides I thought diesels where pretty much in the fuel useage range of using 1 gal per 16 horses, so max. fuel useage on a 320 horse diesel should be closer to 20 gals. But it is gonna take no where near that to cruise in the mid teens.
     

  15. longliner45
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    longliner45 Senior Member

    the boat was a 31 ft jc hull we custom built for commercial longlining ,,,bottom and sword,,I did try national fisherman mag ,but they only go back 3 or 4 yrs,,and I tried to contact jc boat ,at least tried to find a web site..all you guys are more savvy at that than I,,but I will try to explain,,,,we took the 31 ftr,,placed the volvos on the stearn ,duoprpop outdrives,this does 2 things we felt were advantageous,,most lobster boats ,and other commercial fishingboats must mount the iceboxes (on )deck,,since we had no engine and shaft to contend with ,,we could sink the 6000lb icebox in the center of gravity,,allowing the boat to travel more stable and even,,,in calm seas we could get 20 knots at about a gallon a hr,,in rough seas we could get 8 or 10 knots depending on conditions,, we had 375 gallons of fuel and 150 gallon of water for drinking we estimated about a 900 mile fuel range,I know you guys arent calling me a liar ,,I m just a little frustrated that I cant find any meaningfull documation,,but I can give you names,,nikis seafood in orange beach alabama owned one(miss lila),paul pence and steve perdicaro of penco tackel destin fla ownd the broadbill,and broadbill2,, the touch` was owned by sanders mfg in destin fla,and pauls brother ron ownd the kantoo ,,thats the best I can do ya ,now if I were going to make a substantial investment for a boat ,,I would try to contact jc boat in newengland,,oh yea the boat hull itself wieght was 11.000lbs empty.longliner45
     
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