30" CAT, custom!

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  • d3lap
    Member
    • Aug 2011
    • 45

    #1

    30" CAT, custom!

    Hi guys/girls,

    I'm new here, the names Matt, and what better way to start off a first post then with an introduction to a build! This will be my first hobby grade boat, or an attempt at it. Been in the hobby for quite some time! But some time off has made me itching for a project...



    I have a cottage and the idea of a rc boat has always been a great idea for me... When I was a kid, I would shape styro-foam into a dual hull air powered boat to run around the shore, which was quite fun. I've been looking at boats online, and have been considering either a V hull or a Cat. I have also been playing around with the idea of building my own Cat.

    I found the plans online for it and built it in paper, although I need to upscale it 288% its original (to achieve the 30” span) I will make a mock up tomorrow in card board to see if it’s do-able.
    In terms of power plants, I like the idea of dual brushless, or jet drives, although I don’t want to be spending 300+ per system, so if I go dual it will be a 6s esc with a lower kv system, although those details will be worked out when the hull is completed/bought.
    I have 2 5s 5000mah 25c packs I use on my Truggy as well as 2 4s 4000/5000 30c/25c respectably.

    Some hulls I have taken interest in;

    Found a nice looking one at nitrorcx...

    As well as an off brand on eBay...
    http://cgi.ebay.com/32-3-EP-Fibregla...#ht_4353wt_905
    How hard would it be to make something like this achieve 50+ mph? Or something like this? 50+ mph on water, is it difficult?
    It’s just a hull, so brand should really matter right? RIGHT? My lake is really big and calm in the morning and at night, like glass (perfect for wakeboarding ) and I have a boat so I can retrieve it, if necessary. I’m up there almost every weekend (this summer at least) and like the idea of being on the water AND doing rc at the same time (both great love's of mine)
    Again, I have 4 and 5s packs, so hull that can run that would be perfect, basically, I’m just wondering what would be good for me as I have no idea on rc boats. They don’t have any gears or reduction so prop size, motor kV and voltage are probably the only factors to consider for speed"?? (Minus water drag, and weight... ECT)

    I’m only running this guy during the summer, and late spring early fall months so not looking to break the bank on this, kits would be better as I do have some brushless equipment here and radios so not really looking for the RTR electronics. Also, should I consider other hull types and other brands, like going to Wal-Mart and finding a nice sized plastic model and reinforcing it? Fibreglass is preferred but I don’t really see myself hitting anything so durability isn’t really an issue on water, but I’m a complete newbie when it comes to boats, so if I’m wrong let me know!
    Losi 8T-e 5s/1518/MMP/645mg
    Cat 30" build In progress...
  • siberianhusky
    Fast Electric Addict!
    • Dec 2009
    • 2184

    #2
    Take a look at Fightercat racing, he has some nice hulls for sale and all the hardware to set them up single or twin.
    The host store for this forum has some very nice stuff as well.
    50 mph isn't to hard to achieve with todays batteries and motors.
    Personally I'd stay away from anything with a metric driveline, not too many places in N.A. stock metric boat hardware. It's a real pain to have to wait weeks for a small part from Europe or Asia. Nothing wrong with it if you live in an area where it's the standard for the hobby.
    When you factor in shipping costs you're not coming out ahead by buying a cheap hull from overseas. Especially if it arrives damaged, some of those Asian places have a real "you bought it to bad" attitude towards customer service.
    If my boats upside down then who owns the one I thought I was driving the last two laps?

    Comment

    • d3lap
      Member
      • Aug 2011
      • 45

      #3
      OK, Appreciate the response. In terms of metric driveline, do you mean the screws, length and such, or something else? Also looked at that site and some very nice models, although I will only purchase a hull if i can not recreate my own. In in Ontario, Canada.
      Losi 8T-e 5s/1518/MMP/645mg
      Cat 30" build In progress...

      Comment

      • d3lap
        Member
        • Aug 2011
        • 45

        #4
        Here is todays progress, got it scaled up to just under the 30" mark. Going to get some balsa and start building the skeleton.



        And all cut out.

        Losi 8T-e 5s/1518/MMP/645mg
        Cat 30" build In progress...

        Comment

        • F1 madness
          Senior Member
          • Feb 2010
          • 788

          #5
          I strongly recommend using ply,use 1/8 or 3.2 ply then skin in lite ply 2mm or birch ply,also dont forget to make the transom 90* to the flat surface you build off.
          I not long help with the build of this design and to be truthfull its not the best.
          Check this link out of the build:http://www.rcgroups.com/forums/showthread.php?t=1429836
          http://s577.photobucket.com/albums/s...79/F1%20boats/
          Daz from sunny England

          Comment

          • d3lap
            Member
            • Aug 2011
            • 45

            #6
            Transom is the boats ass, so to speak correct? And man, you are amazing! Thats some work you did to take out the hull twist!
            Losi 8T-e 5s/1518/MMP/645mg
            Cat 30" build In progress...

            Comment

            • F1 madness
              Senior Member
              • Feb 2010
              • 788

              #7
              Yes bud the transom is where everything is mounted.
              LOL thank you took some doing aswell
              http://s577.photobucket.com/albums/s...79/F1%20boats/
              Daz from sunny England

              Comment

              • d3lap
                Member
                • Aug 2011
                • 45

                #8
                And when you say this hull isnt the best design, in what terms does it limit the boat? Speed and hydrodynamics? am i going to have to add "tracking" plates to the underside like rotorkilla did with his? Also, dual vs single engine, whats your opinion?

                can i obtain the wood from hardware stores, or is it better to "special order it?" ....
                Losi 8T-e 5s/1518/MMP/645mg
                Cat 30" build In progress...

                Comment

                • F1 madness
                  Senior Member
                  • Feb 2010
                  • 788

                  #9
                  power wise is up to you but theres not much room so single would best,also make the opening wider for easier access and add some strengtheners across the top before skinning.
                  The problem is the aero of the hull,the original design is 72" for gas and scaled down is doesnt really work at high fe speeds and doesnt turn very well being narrow with narrow sponson.
                  JMO but dont wanna see you dissapointed

                  and somthing else,make the stringers full length of the sponsons for added support, skin the sides then skin the sponson bottoms
                  http://s577.photobucket.com/albums/s...79/F1%20boats/
                  Daz from sunny England

                  Comment

                  • d3lap
                    Member
                    • Aug 2011
                    • 45

                    #10
                    I guess i should note that i have no idea what sponsors are nor stingers... I guess single engine would be best.. As a first boat, especially being homemade if it works and can do 40mph i would be extravagant!
                    Losi 8T-e 5s/1518/MMP/645mg
                    Cat 30" build In progress...

                    Comment

                    • F1 madness
                      Senior Member
                      • Feb 2010
                      • 788

                      #11
                      Good luck,if you need any advise just ask,ill be watching your progress LOL
                      http://s577.photobucket.com/albums/s...79/F1%20boats/
                      Daz from sunny England

                      Comment

                      • d3lap
                        Member
                        • Aug 2011
                        • 45

                        #12
                        Thanks, going to get some material tonite!

                        any recommendation on rudders, shafts motor mounts...?
                        Losi 8T-e 5s/1518/MMP/645mg
                        Cat 30" build In progress...

                        Comment

                        • siberianhusky
                          Fast Electric Addict!
                          • Dec 2009
                          • 2184

                          #13
                          By metric I meant a 4mm drive shaft setup, very common overseas not so much over here, the "standard" here is 3/16 drive shaft, easy to find props, bearings and such.
                          Big boats use 1/4 shaft and small ones 1/8. Most of the higher quality hardware over hear will be imperial sized.
                          If my boats upside down then who owns the one I thought I was driving the last two laps?

                          Comment

                          • d3lap
                            Member
                            • Aug 2011
                            • 45

                            #14
                            ahh i see, im going to go the most common route then, as i dont want to be messing about with stuff im not to knowledgeable in. Ill go with 3/16th shaft size. Could you guys suggest some good hardware..? ie motor mounts, rudders, water cooling...
                            Losi 8T-e 5s/1518/MMP/645mg
                            Cat 30" build In progress...

                            Comment

                            • d3lap
                              Member
                              • Aug 2011
                              • 45

                              #15
                              OK guys, looking around some, and tell me what you think of the hardware ive picked out..
                              rudder
                              Motor mount
                              or this one...
                              Cooling esc
                              water nipple
                              water seperator
                              high flow 1/4 hose
                              1/4" clamps

                              I need a 5mm motor coupler, but i'm unsure of which type of flex cable to go with..?

                              booties:)

                              http://www.hobbypartz.com/77p-lbp367...5d-1900kv.html motor
                              http://www.hobbypartz.com/96m215-3674-1900kv-9t.html or this one
                              http://www.hobbypartz.com/07e-c-seaking-120a.html esc

                              5s lipo!


                              probly going to go with a 6s capable esc, about 120A and a 1600-1800kv motor..
                              Losi 8T-e 5s/1518/MMP/645mg
                              Cat 30" build In progress...

                              Comment

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