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Thread: Yes, another Catamaran Build!

  1. #1
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    Default Yes, another Catamaran Build!

    While waiting for my other projects to get painted, I deceided to start another build. It is a mini catamaran here are the specs
    Length = 16"
    Beam = 6"
    Motor = 2 300-400 brusless inrunner, water cooled motors (unsure of KV at this time thinking of 380 feiago, or similar)
    Batteries = thinking of 2s2p 1200-1500mah poss 3s2p, depending on room
    ESC = 2 25-35 amp
    Props =tbd
    hardware = tbd

    The plan is to make a offshore looking cat, with too much power that can easily leap out of the water, and be very fast in the straights as long as throttle is eased on to speed, and overall fun to drive and can turn left and right.

    I am open to suggestions, as nothing is set in stone except that it is a twin drive. Please feel free to comment good or bad. This is my first cat build, and as cats are very popular, there are only a few choices in mini sized ones. I am hoping this will spark interest, and maybe more hardware will become available at affordable prices that will fit small boats like this one. As it is going to be twin powered, I have a small area to work with on the transom.

    Here are some pics
    Nothing is glued yet, I have just mocked up the bulkheads for a general layout, and am making a little jig to align the main stringers to keep it straight. I probably won't work on it anymore till the weekend.


    Twin power =

  2. #2
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    They make really nice cats, I have made several in different sizes and powered them with elec and gas.... Check out my thread for ideas and mods..
    https://forums.offshoreelectrics.com/...ead.php?t=3413

  3. #3
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    Actually reading your threads got me interested in building a cat. I would like to make a rudder similar to yours, pull pull style.
    Twin power =

  4. #4
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    can't wait to build mine I already have the power plants. (a pair of 3550kv outrunner with 30a esc)
    The Manx has been sitting dormant, but I think I finally have my motivation back. I hope to see it float soon.

  5. #5
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    Wow, twin 3550kv, it will scream, and have some torque from the outrunner design. I may endup going with outrunners, not really sure yet. I think I can watercool the motor mount, and fan cool the end of the motor. I'm not sure yet. Can't wait to see pics of your progress when you start it.
    Twin power =

  6. #6
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    Check this out, it your gonna do a single motor, this looks like it would work well for a outrunner, if they have the same bolt patern
    http://cgi.ebay.com/alumium-water-co...QQcmdZViewItem
    Twin power =

  7. #7
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    I have 2 of those rudders for sale in the swapshop .... They are for cats set up with twins...
    Last edited by lonewolf; 08-15-2008 at 07:05 AM. Reason: forgot unfo typing too early lol

  8. #8
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    Ok I gotta learn to not respond to threads too early. Yes my rudders will work fine. The blade would be a bit long but easy to cut shorter.

  9. #9
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    i could save you guys so much time on these. i have a 31 inch version, which is not quite the same but it looks the same with the same bulk heads and such, setup for CAD to cut on a laser.
    because this is so popular .. lets make a build challenge out of it.
    EYEKANDYGRAPHICS

    www.rclipos.com

  10. #10
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    I have made some progress. I have glued all the bulkheads to the stringers. I have started to skin the sides. Everything needs to be sanded to be even with the stringers and bulkheads, so far it is very straight.

    In the pics you can see that I have basicly no room on the sponsons for a stinger, I may make it a fixed stinger, but well see when we get to that point.

    I am holding up the outrunner just for ideas, It will fit nicely in there, but getting it out will be a problem, I will have to make a trick mount or something. There is still a lot to be done.





    Twin power =

  11. #11
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    did you alter the #6 bulkhead?
    Peter Eells; Fun, and Helping others To Have Fun!!!
    http://rcboatsbypetere.blogspot.com/
    RC.Boats.by.Pete@gmail.com

  12. #12
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    None were altered.
    Twin power =

  13. #13
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    Those plans are real close but not the exact same as the ones I have. Could be a modded version????

    Running an outrunner in such a confined spaced will most likely cause the heat to rise above desired levels... Hmmmmm twins huh. Oh by the way my rudders would be too large, typing 5 minutes after getting out of bed a no no lol.
    Ammo motors might be a better choice. Remember you 2 esc's and packs for each esc... with the ammo moters you have a chance at cooling...

    Sorry Im not much help, this hull is quite a bit smaller than I am used too...
    My smallest is 26 inches..
    Last edited by lonewolf; 08-16-2008 at 01:45 AM. Reason: typo

  14. #14
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    looking good ace, the motor looks to have enough space, my 3550's have fans on the end bell. the transom will need some massaging to take twins. I can't wait to get mine going. It's going to be very interesting to see how fast I can get this little kitty.
    The Manx has been sitting dormant, but I think I finally have my motivation back. I hope to see it float soon.

  15. #15
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    you can get it real fast I am betting, and Ace, #6 is not supposed to have the diagonal brace and you will need the space for your motor shaft to run through. John I have just about finished the mods to the plans and have to lay them out like we discussed, should have them ready today.
    Peter Eells; Fun, and Helping others To Have Fun!!!
    http://rcboatsbypetere.blogspot.com/
    RC.Boats.by.Pete@gmail.com

  16. #16
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    good stuff peter
    The Manx has been sitting dormant, but I think I finally have my motivation back. I hope to see it float soon.

  17. #17
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    I see you are hard at it this morning John, Thanks
    Peter Eells; Fun, and Helping others To Have Fun!!!
    http://rcboatsbypetere.blogspot.com/
    RC.Boats.by.Pete@gmail.com

  18. #18
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    #6 should probably be made out of ply, or basswood. The balsa is really flimsy right there because it is super thin.

    I forgot to put the stringers on the sides of the bulkheads where the skin sides go. So I will get some small strips today, and put them inbetween the bulkheads.

    This boat builds really fast. I think the mini cat strut can be modified to fit under the transom overhang, but I'll mess with that more when I get that far. I would like a stinger, but I may have to make my own.
    Twin power =

  19. #19
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    Here is a little more progress. I have some more sanding to do before I put the sponson bottoms on.

    Twin power =

  20. #20
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    I may try a out runner where it was in the pic, with a fan blowing in the side of the sponson with duct work to it for cooling, and line the insides with aluminum foil to keep the heat from warping the paint on the outside. I think I am going to try it, if It don't work, I'll have to take it out, or build another one lol. Its a little hard to explain, but once you see it you will know what I am talking about.
    Twin power =

  21. #21
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    I have added fillers in the bottom of the front sponsons to keep their shape in the pics above, here I have cut out the center sections, to save weight (not even close to notice though) and to make use of less glue, and because I felt like it, and it looks better. Now I need to go to michaels to get some balsa strips, and do some final sanding before the sponson bottoms and center bottom go on. I also added support bulkheads for the center skins where they meet at the front.
    Twin power =

  22. #22
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    I didn't make it to michaels, so I will go tomorrow, but I was able to make some progress in the sponsons. I have covered the front part up to the first step. Everything looks straight, in the pic there is a pen line at the end of the sponson sheeting, in the pic it makes it look uneven, but it is not.

    Also here is another pic, I held up the parts for cooling just so you might be able to see what I was talking about with making a duct for the fan to blow on the motor. I still may change to inrunners, but out runners are looking to be the ones due to cost factor.

    Twin power =

  23. #23
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    here is my power plant, notice the fan on the end bell, they should throw some serious air around the hull. the e-fan is a good idea, but if you keep your run times down heat should not be a real issue. are you going to duct the fan toward the motor so the air is forced over the can and not forward into the sponson?
    The Manx has been sitting dormant, but I think I finally have my motivation back. I hope to see it float soon.

  24. #24
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    Here are some of my thoughts on fan-cooled motors: They work! I am using a fan-cooled 1107 NeuMotor (helicopter version) in my MHZ Miss Madison and even though I am "pushing things" the motor remains at about 110º. Now, if only I could keep the 40amp ESC that cool.

  25. #25
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    Well I do not know what esc DR Jet uses but I run a computer fan on mine and it works great!! if you do not want water cooling in there, or the esc is not equipped for water cooling, and has an heat sink on it a fan will do the job,
    Ace good Job on the sponson covers!!
    Dr Jet, What rudders do you use on these little guys?
    Peter Eells; Fun, and Helping others To Have Fun!!!
    http://rcboatsbypetere.blogspot.com/
    RC.Boats.by.Pete@gmail.com

  26. #26
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    Ace, I would mount that fan on the other side of the stringer since you are going to extend your hatch over the sponson and it would keep all your room inside the battery area real clean and Neat, Then I would cap off that bulkhead just forward of where you are holding the fan.
    Peter Eells; Fun, and Helping others To Have Fun!!!
    http://rcboatsbypetere.blogspot.com/
    RC.Boats.by.Pete@gmail.com

  27. #27
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    Quote Originally Posted by peells View Post
    Dr Jet, What rudders do you use on these little guys?
    On the MHZ boats, I use the supplied MHZ hardware. Very nice stuff. On the BBY hull, I am using the "New" Solinger micro rudder. Very nice stuff from Joe.

    With regards to cooling the ESC, I just don't have the room in the tiny hull for a fan. It has been coming in at about 145º or so after a long run, and that is about the limit. I have a similar-in-size Schulze 18.97FW that may go in that hull if (or when) the Chinese ESC fails.

  28. #28
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    Default water motor cooler for out runner

    Hey look what I just found Now I have to figure out where to get it
    Attached Images Attached Images
    Peter Eells; Fun, and Helping others To Have Fun!!!
    http://rcboatsbypetere.blogspot.com/
    RC.Boats.by.Pete@gmail.com

  29. #29
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    And just so you know I only want the cooler and that mount and the mount is not a big deal or maybe it is!
    Peter Eells; Fun, and Helping others To Have Fun!!!
    http://rcboatsbypetere.blogspot.com/
    RC.Boats.by.Pete@gmail.com

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