flatbottom conversion

Discussion in 'Boat Design' started by stribman, Apr 7, 2007.

  1. stribman
    Joined: Apr 2007
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    Location: georgia

    stribman New Member

    Hello all, new here so please understand. I have an old flat bottom "holiday" houseboat that was an outboard, it has trailer wheels built into it that lower and raise. A square keel on front. With removable hitch for towing, about a 1952 I think. I need help putting some type of v hull on front, and incorporate a permanent hitch. The top speed will eventually be less than 20 mph probably more like 15 max. Use will be in a inland lake, fresh water; calm average winds not over 30 mph. I am thinking some type of triangle will work with a slight curve in. adding about 5 to 6 feet to an already 22’ boat. Advice needed.
     
  2. messabout
    Joined: Jan 2006
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    Location: Lakeland Fl USA

    messabout Senior Member

    Why do you want to put a vee bow on your houseboat?

    A 22 foot houseboat is probably going to be pretty heavy. If so it will take a lot of power to get 20MPH. Houseboats are generally designed to go very slowly, maybe 6 MPH. If you drive it too hard, the boat will suffer. Especially a 52 model. Speed will rattle everything aboard including the people, it'll break dishes in the cabinet, etc... Speed will cost big money on a boat like that. An engine big enough to go as suggested will cost a bundle and use enough fuel to make the arabs smile.

    The retractable wheel feature may prevent or at the very least complicate any speed above hull speed which will be somewhere in the region of 6 or 7 MPH. Attempts to drive it faster will result in monster wakes which will make you unpopular with other boaters.

    Best advice: enjoy your boat for what it is. It is a boat that is to be used languidly, to enjoy the comfort, to go slow enough to take in all those wonders of nature that you'll miss while going fast.
     
  3. Poida
    Joined: Apr 2006
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    Location: Australia

    Poida Senior Member

    languidly

    Best advice: enjoy your boat for what it is. It is a boat that is to be used languidly, to enjoy the comfort, to go slow enough to take in all those wonders of nature that you'll miss while going fast.

    Languidly - had to look that one up. The wife new what it meant but she does crossword puzzles.
     
  4. ted655
    Joined: May 2003
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    Location: Butte La Rose, LA.

    ted655 Senior Member

    :) . Man, in some peoples eyes, you have a treasure. Join this group. They will want to ask questions about the design and measurements. PLEASE!
    shantyboat@yahoogroups.com
    Now... Do you want a V bow or a total V bottom? For inland calm waters, don't fix what ain't broke. You didn't say, is this a scow *barge) hull with a rake "up" at the bow?
    I'd like pictures! Soundslike a neat boat
    Like all above, it can be done but should it be done. That same amount of $$$ will get you a nice used runabout (to come & go to your cool vintage HB).
     
  5. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Assuming you have about a 20' LWL on your 22' houseboat, the best you can do is about 5 MPH. Her general dimensions being intend around life aboard, with little regard for efficiency while moving through the water, she is limited to a speed governed by her waterline length. To exceed this speed limit, you'll need many hundreds of HP and other contrivances (tabs, etc.) to control her manners at speeds she was never designed to produce. Unfortunately, this is the case with the vast majority of houseboats. Compromises in hull shape and volume have conspired to make her next to imposable to propel even moderately quickly. Newer designs have attempted to address this issue, using lighter construction methods and better hull shapes, but even these have limits.

    A pointy bow will help, but only a very small improvement will be noticed, though this improvement will not register on your speedo or GPS. Frictional drag, windage, weight and total available HP, need addressing to improve your top speed.

    30 MPH winds are well after small craft advisories have been issued. It wouldn't be a wise thing to have any boat, with power and shape limitations, particularly with the top hamper your boat carries, out in these conditions, for any reason. Gale force winds (30 MPH) are not a place for any houseboat to be puttering along. In 30 MPH winds the waves will be quite high, some bigger than the boat is long, the sea will be whipped up into a frenzy, with wind blown foam in long streaks and wave tops sheered off completely.

    Having a vintage boat of any type is a wonderful thing. I'm sure you can find a seemly endless list of things to fix, improve, modify and upgrade, before you jump into hull design alterations and repowering options that require quadrupling the HP just to get 3 more MPH out of the old girl's top speed.
     
  6. stribman
    Joined: Apr 2007
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    Location: georgia

    stribman New Member

    Thanks for the replies; I didn’t really expect to get much. I will try and get some pictures up and on as I proceed, looking at regulations is going to have to keep it less than 22 ft. to get registration. Your right about not getting in a hurry with it , when we had it running bout 5 years back, top speed was probably about 6 mph. some times we just start it off and check direction every half hr. another point made was I do need to lighten it a good bit . Although sitting low in water has some advantage. I notice you don’t get the cork effect some pontoons have, it is a lot more stable in rough water, and 1ft. waves that is. Although once in a storm where we had about 6 big v8 speed boats in tow, during the rain , we caught a cross wind that caused some concern by all aboard, While she rolled to about a 30 deg tilt , until we got back facing wind.
    Over all it has some good features flotation tanks fore and aft. She draws about 8 inches loaded but has 26 inch side walls before you take on any water. If it did ever roll over would float on tanks.
    But I’m still convinced, I need something up front to break the water, you do get some splash when trying to plow that flat nose up to speeds of 5 mph or more.
    But again thanks, and I will touch back in as work begins, really enjoying this site for the information here.
     
  7. ted655
    Joined: May 2003
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    Location: Butte La Rose, LA.

    ted655 Senior Member

    :confused: . Here is a pointed bow, off of a flat bottom. Which is why I asked if your boat had a rake. A version of this should be easy enough to add, but then keeping the registration lengyh down complicated what you want to do.
    As has been stated, Ving your bow will not get you speed. More (a LOT more) horsepower is whats needed.
    If V your bow you must, then here is how it might look.:D
     

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  8. stribman
    Joined: Apr 2007
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    Location: georgia

    stribman New Member

    pointing the shoebox

    Ted, thanks for the pictures , that’s somewhat like I was thinking , if you could picture it on a 8 ft wide shoe box, I have questions about how much lift I want / need . That is the boat is not ever going to be up on a plane, as some have pointed out, too much hp required. I have a question about the length factor that is right at 19’ tip to tail. The outboard mounts on the rear on a transom that protrudes about 20” of the back of boat , I am thinking could shorten rear and get about 3 feet / little more to work with on front and still come in under 22’.
     
  9. ted655
    Joined: May 2003
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    Location: Butte La Rose, LA.

    ted655 Senior Member

    Here are a few more pics of how a rake bow was fastened to my shoebox barge. Not the same I realize, but ithey may help. You can't tell but the bow rake is narrower than the hull. I suppose you could just continue to a pointed bow.
    Another solution would be to add a "pod" (sponcin) to what is already there. Your length concerns might prevent doibg anything really useful. In order for a bow to part water, it should have some length to it.
    Your bow is 80 deg. to the water now? No rake at all? I question how much speed you'll gain by narrowing the bow rather than just a simple rake as I have. Will 2,3,5 mph be added by pointing it?
     

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  10. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    There will be no speed increase with a sloped, pointy, narrowed or otherwise altered bow shape. Additional LWL length and/or additional HP are the only realistic options, both with considerable limits.
     
  11. sal's Dad
    Joined: Apr 2005
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    Location: New England

    sal's Dad Atkin/Bolger fan

    Please post pictures? Especially of the wheels/suspension! I always thought this would be a great modification to a Bolger Watervan, for cross-country trips! no need to deal with a separate trailer...

    Sal's Dad

    Watervan:
     

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  12. ted655
    Joined: May 2003
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    Location: Butte La Rose, LA.

    ted655 Senior Member

    Gosh, I'd forgotten that one. With the popularity of homebuilt aircraft, the basics should be pretty much off the shelf components.:)
     
  13. harry tams
    Joined: Mar 2006
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    Location: tasmania

    harry tams Junior Member

    Bolger Water Van

    I'm very interested in purchasing the plans for the 22' Bolger Water Van design.
    I too think that some 'swing up down wheels' could make for a very versatile land and water craft. Would any of you have interest in progressing discussion on sourcing the design and progressing the thought of a light weight houseboat/RV trailer/caravan that utilizes the Bolger Water Van plan?

    Apparently you can ski behind it with 90hp. Using Foam sandwich or polypropylene honeycomb sheeting for everything but the underwater portions of the craft could significantly reduce the weight, possibly power requirements, a make it easier to tow with a smaller car.

    Any thoughts other than 'this thing is butt ugly'?

    Harry Tams
    Tasmania
     

  14. jg451
    Joined: Jul 2010
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    Location: portland,oregon,usa

    jg451 Junior Member

    Getting your brick to plane is certainly ano go. Altho...maybe with an Alison craned in...I find the idea of watersking behind a giant shoebox mildly hilarious. BUT. If length is an issue and you still wish to lessen the bow curl you might take a page from the Marines and ad a hinged bow plate (with triangular sides) that would fold up to vertical when trailering may be a possibility. It would flood, of course, at rest, but w/ 8" draft, so? You'd have to play with the length and angle and perhaps some adjustable bracing, but it would allow you to keep the water going under rather than over and that's the idea now isn't it?
    It must be a stone B___h maneuvering that thing in a crosswind. my Pop's was longer and a headache in a blow. Perhaps two motors spaced apart aft would give more of a moment arm for ease of handling.

    Good Luck, Jon
     
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