Where do I begin for mono hull design

Discussion in 'Boat Design' started by aaronhl, Dec 3, 2013.

  1. aaronhl
    Joined: Aug 2012
    Posts: 204
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: Central Connecticut

    aaronhl Senior Member

    New to boat design, looking to build a mono hull that is about 48 inches long for a remote control boat. Not a toy- a boat that will go 60mph with a 5hp engine. So where do I BEGIN reading about mono hull design?
     
  2. Doug Lord
    Joined: May 2009
    Posts: 16,651
    Likes: 322, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    Go to the members list and "PM" Lohring who is very knowledgeable about small fast rc powerboat design. I'm sure he can help you.
     
  3. Mr Efficiency
    Joined: Oct 2010
    Posts: 8,572
    Likes: 505, Points: 113, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Seems to me models would have different criteria to full size craft, especially since there are no occupants and their comfort and safety to worry about !
     
  4. aaronhl
    Joined: Aug 2012
    Posts: 204
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: Central Connecticut

    aaronhl Senior Member

    Yes I know Lohring, he's a great guy does a lot for the rc boat community.

    I've also heard if you scale a large size hull down to a smaller size it might not drive the same. Maybe just the basics would help. I don't want to start building a plug without a design or game plan...what are some main design topics I could search for? For example, I've had rc boats where the chine is sharp and some have round. And what about the v degree..I know how a boat should look but the little things will help with design
     
  5. messabout
    Joined: Jan 2006
    Posts: 3,051
    Likes: 237, Points: 63, Legacy Rep: 1279
    Location: Lakeland Fl USA

    messabout Senior Member

    There is an existing class of RC racing boats that fit the general description that you posted. I would suspect that careful examination of those boats will get you on the best route to a successful build. Do some research on the net. You will find that class somewhere and perhaps a lot of good information. I have attended a couple of RC racing regattas here in Florida and that class is popular and fun to watch.

    Scaling down a full sized boat is not the best way to start if ultimate performance is your aim. You can make the model similar but maybe not quite with scaled dimensions. Your first consideration is the weight of the finished model boat. If you want to compare it to a full sized boat then you can use the following arithmetic as a rough guide.

    Say that you like the looks of a 24 foot hot rod... a Donzi, Riva, or whatever. You want a 4 foot model. Your scale will be 4/24 or one sixth scale. That happens to be a convenient 2 inches to the foot. Take the cube of 6 which is 216. Now lets say that the Riva weighs 2400 pounds. Divide 2400 by 216 and you get 11.1 pounds for the scale weight of your model.

    You will need to fight every ounce of weight in your model to get to that displacement. The Zenoah engine that you will probably use will use up a lot of the allotted weight. You can probably build the model lighter and stronger with wood than with glass. Quicker too.

    One caveat. Be prepared to spend some signifigant money for the whole mess of props that you will need for experimentation. I have more than once thought of building such a boat but the total cost has given me pause. Somewhere around two grand if quality components are anticipated.

    This kind of boat makes sense to me because you can start the engine. put the boat in the water, press the throttle and go. Not so with nitro powerd boats that need a helper who must sling the boat into the water while you handle the controller. The boats that use weed eater type engines with their centrifugal clutches make life much easier.

    Good luck with your project, and keep the bottom side facing downward.
     
  6. aaronhl
    Joined: Aug 2012
    Posts: 204
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: Central Connecticut

    aaronhl Senior Member

    I don't mess around with nitro, I have Zenoah engines (no clutches) only in several rc boats, mostly monos so I do have some models to inspire my design.


    Is there a resource on here that provides info on the different aspects of the design? The boats I see have one strake on each side, one has a rounded keel, one has a sharp keel. And different V angles. Where can I read more about each?

    Not in the game to copy an existing design..or scale down a full size boat. It should be too difficult to design the boat (not build plug) because all it seems to be is a simple shallow vee..
     
  7. aaronhl
    Joined: Aug 2012
    Posts: 204
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: Central Connecticut

    aaronhl Senior Member

  8. aaronhl
    Joined: Aug 2012
    Posts: 204
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: Central Connecticut

    aaronhl Senior Member

    What is the part of the vee hull design where the keel connects to the bow? Where the keel starts curving upwards to the bow tip, referring to a side view of the keel. The part under your feet if you were driving the boat with a steering wheel towards the middle. Hope that makes sense?? And how do the different curve angles affect performance??
     
  9. Mr Efficiency
    Joined: Oct 2010
    Posts: 8,572
    Likes: 505, Points: 113, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    The forefoot ? Boats are three dimensional objects, and one line taken in isolation may not be enough to be categorical about.
     
  10. aaronhl
    Joined: Aug 2012
    Posts: 204
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: Central Connecticut

    aaronhl Senior Member

    Not sure if it's forefoot- do you have examples? Any good articles how deadrise slopes upwards the keel to the bow? I'm referring to the keel curve right under his feet below. There could be a gradual upwards curve, or a curve that is "lower" than the keel towards the transom, or even a very abrupt upwards curve..

    [​IMG]
     
  11. Mr Efficiency
    Joined: Oct 2010
    Posts: 8,572
    Likes: 505, Points: 113, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Not following you I'm afraid. I would be fairly confident that if you want to go 60 mph, you will require a hull that the aft third of the bottom is pretty well constant in shape, that is lengthways slices of the bottom will be parallel in that area. Forward of that you can steadily increase the steepness of your bottom, but normally the keel wouldn't turn upward till roughly 2/3 of the way forward, but that varies. You should study existing model RC boats that are successful, and benefit from the trial and error of others, what is best may differ from full size boats.
     
  12. kerosene
    Joined: Jul 2006
    Posts: 1,048
    Likes: 62, Points: 48, Legacy Rep: 358
    Location: finland

    kerosene Senior Member

  13. Mr Efficiency
    Joined: Oct 2010
    Posts: 8,572
    Likes: 505, Points: 113, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Key thing with a model is the ratio of lifting area/kg of weight is much greater for a model, and at a given speed the model should sit proud of the water, compared to full size being more settled in it. That's assuming they settle on the same static waterline. I'd be looking at what is proved to work best, and not worry about how full scaled boats are designed.
     

  14. aaronhl
    Joined: Aug 2012
    Posts: 204
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: Central Connecticut

    aaronhl Senior Member

    That's pretty good information, the boats have have now are pretty much designed that way.

    So far what I'm thinking of is two extended strakes all the way back to transom and a small pad.

    When you talk about lift...that is a new concept to me...are you saying the rc boats probably don't need as much lift as big boats to get them to run hot?
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.