Answers.Body: <p>With a few Power Functions elements and a pair of propellers, I was able to build a motorized boat similar to the alternate model.</p>
  <ul>
  <li><strong>1x:</strong> <a href="https://www.lego.com/en-us/product/lego-power-functions-battery-box-8881" rel="noreferrer">8881 Power Functions Battery Box</a></li>
  <li><strong>2x:</strong> <a href="https://www.lego.com/en-us/product/lego-power-functions-m-motor-8883" rel="noreferrer">8883 Power Functions M-Motor</a></li>
  <li><strong>1x:</strong> <a href="https://www.lego.com/en-us/product/lego-power-functions-ir-receiver-8884" rel="noreferrer">8884 Power Functions IR Receiver</a></li>
  <li><strong>1x:</strong> <a href="https://www.lego.com/en-us/product/lego-power-functions-ir-remote-control-8885" rel="noreferrer">8885 Power Functions IR Remote Control</a></li>
  <li><strong>2x:</strong> <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?id=961" rel="noreferrer">30332 Propeller 3 Blade 9 Diameter</a></li>
  </ul>
  <h1>See it in action!</h1>
  <p><a href="https://youtu.be/ZzDx8RgXrnY" rel="noreferrer"><img src="https://i.sstatic.net/v6p1U.jpg" alt="" /></a><br><sup>click to watch the video</sup></p>
  <h1>Pictures</h1>
  <p><a href="https://i.sstatic.net/zDOAr.jpg" rel="noreferrer"><img src="https://i.sstatic.net/zDOArl.jpg" alt="" /></a><br><sup>floating, side view</sup></p>
  <p><a href="https://i.sstatic.net/4yZFm.jpg" rel="noreferrer"><img src="https://i.sstatic.net/4yZFml.jpg" alt="" /></a><br><sup>floating, front view</sup></p>
  <h1>Close-up pictures on how it's built</h1>
  <p><a href="https://i.sstatic.net/pvReE.jpg" rel="noreferrer"><img src="https://i.sstatic.net/pvReEl.jpg" alt="" /></a><br><sup>propeller motor closeup</sup></p>
  <p><a href="https://i.sstatic.net/YKXhV.jpg" rel="noreferrer"><img src="https://i.sstatic.net/YKXhVl.jpg" alt="" /></a><br><sup>center structure closeup</sup></p>
  <h1>Conclusion</h1>
  <p>Overall it works pretty well, and the hulls are surprisingly resistant to water leaking inside of them. The only major issue is that direct sunlight can interfere with the IR receiver at a distance. As an alternative, the IR receiver and remote could be substituted with something third-party like an S-Brick (uses Bluetooth). I didn't have any of the smaller and lighter LEGO Powered UP controller and motors, but with some redesigning that could also be an option (also Bluetooth).</p>
  <p>I also hope that someday LEGO will make some propellers which are a better size/shape for use with water, and maybe this boat could go a little faster!</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-10-05T10:55:46.347Z
Answers.Text: Tons of proper propellers to choose from I’d say: https://www.bricklink.com/v2/search.page?q=Propeller. Part 6041 looks like your best match - though the blades are small they are properly tilted and it has an axle-hole. I’d think that running that one on high speed should work.
Answers.UserDisplayName: Phil B.
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-10-05T18:26:45.577Z
Answers.Text: Proper propeller does exist - lookup 2740c01 on BL. However it is 30 years old.
Answers.UserDisplayName: Alex
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-10-05T19:33:19.890Z
Answers.Text: Great answer, Alexander, though perhaps we shouldn't be surprised it's watertight as LEGO advertises the set as "For the first time ever, this LEGO Technic model toy floats on water!"
Answers.UserDisplayName: Kirk Woll
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-10-05T21:07:40.833Z
Answers.Text: I've tried most of the propellers, they've all been either too small or the blades are too long/thin/flat. The really small ones would have to spin really fast losing power to friction, and the really large ones would take much more power than these systems are made for.
Answers.UserDisplayName: Alexander O'Mara
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-10-06T00:52:21.797Z
Answers.Text: Have you tried changing gear ratios?
Answers.UserDisplayName: Davidw
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-10-06T03:46:44.140Z
Answers.Text: Could it help to stack several propellers on the same axle?
Answers.UserDisplayName: Matthew Jensen
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-10-06T06:17:19.087Z
Answers.Text: @AlexanderO'Mara IIRC the Brick Experiment channel on Youtube has made Lego submarines with only some minor aftermarket modifications. Maybe you could try the propellers they use?
Answers.UserDisplayName: nick012000
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2024-11-20T19:44:49.273Z
Answers.Text: I am new to this. I do not understand if the pieces already included are enough to mount the motors you mentioned in your list. Is there a guide?
  Thanks
Answers.UserDisplayName: Adrian
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2024-11-21T00:19:46.520Z
Answers.Text: @Adrian As I recall I was able to build it with just the parts in the set plus the extra pieces listed. I didn't make a full guide, but the build is kinda similar to the official alternate model.
Answers.UserDisplayName: Alexander O'Mara
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-10-05T03:34:15.810Z
Answers.LastActivityDate: 2020-10-05T03:34:15.810Z
Answers.UserDisplayName: Alexander O'Mara
Body: <p>The alternate model for the <a href="https://www.lego.com/en-us/product/catamaran-42105" rel="noreferrer">42105 Technic Catamaran</a> set looks a lot like a remote-controlled speedboat.</p>
  <p><a href="https://i.sstatic.net/5kgAq.jpg" rel="noreferrer"><img src="https://i.sstatic.net/5kgAq.jpg" alt="enter image description here" /></a></p>
  <p>This set doesn't actually come with any motors, or even propellers, so obviously this model isn't functional. So what would it take to make a motorized RC speedboat from this set?</p>
  
Tags: <piece-information><technic><moc><activity-support>
Title: Motorized speedboat from Technic Catamaran alternate model?
UserDisplayName: Alexander O'Mara
ThreadText: # Motorized speedboat from Technic Catamaran alternate model?
  
  (Asked by: username_0 on 2020-10-05)
  
  The alternate model for the [42105 Technic Catamaran](https://www.lego.com/en-us/product/catamaran-42105) set looks a lot like a remote-controlled speedboat.
  
  [![enter image description here](https://i.sstatic.net/5kgAq.jpg)](https://i.sstatic.net/5kgAq.jpg)
  
  This set doesn't actually come with any motors, or even propellers, so obviously this model isn't functional. So what would it take to make a motorized RC speedboat from this set?
  
  **Tags:** piece-information, technic, moc, activity-support
  
  ---
  
  ## 1 answers
  
  ### Answer by username_0 on 2020-10-05. Score: 18
  
  With a few Power Functions elements and a pair of propellers, I was able to build a motorized boat similar to the alternate model.
  
  * **1x:** [8881 Power Functions Battery Box](https://www.lego.com/en-us/product/lego-power-functions-battery-box-8881)
  * **2x:** [8883 Power Functions M-Motor](https://www.lego.com/en-us/product/lego-power-functions-m-motor-8883)
  * **1x:** [8884 Power Functions IR Receiver](https://www.lego.com/en-us/product/lego-power-functions-ir-receiver-8884)
  * **1x:** [8885 Power Functions IR Remote Control](https://www.lego.com/en-us/product/lego-power-functions-ir-remote-control-8885)
  * **2x:** [30332 Propeller 3 Blade 9 Diameter](https://www.bricklink.com/v2/catalog/catalogitem.page?id=961)
  
  # See it in action!
  
  [![](https://i.sstatic.net/v6p1U.jpg)](https://youtu.be/ZzDx8RgXrnY)  
  click to watch the video
  
  # Pictures
  
  [![](https://i.sstatic.net/zDOArl.jpg)](https://i.sstatic.net/zDOAr.jpg)  
  floating, side view
  
  [![](https://i.sstatic.net/4yZFml.jpg)](https://i.sstatic.net/4yZFm.jpg)  
  floating, front view
  
  # Close-up pictures on how it's built
  
  [![](https://i.sstatic.net/pvReEl.jpg)](https://i.sstatic.net/pvReE.jpg)  
  propeller motor closeup
  
  [![](https://i.sstatic.net/YKXhVl.jpg)](https://i.sstatic.net/YKXhV.jpg)  
  center structure closeup
  
  # Conclusion
  
  Overall it works pretty well, and the hulls are surprisingly resistant to water leaking inside of them. The only major issue is that direct sunlight can interfere with the IR receiver at a distance. As an alternative, the IR receiver and remote could be substituted with something third-party like an S-Brick (uses Bluetooth). I didn't have any of the smaller and lighter LEGO Powered UP controller and motors, but with some redesigning that could also be an option (also Bluetooth).
  
  I also hope that someday LEGO will make some propellers which are a better size/shape for use with water, and maybe this boat could go a little faster!
  
  > **Comments:**
  > **username_1**: Tons of proper propellers to choose from I’d say: https://www.bricklink.com/v2/search.page?q=Propeller. Part 6041 looks like your best match - though the blades are small they are properly tilted and it has an axle-hole. I’d think that running that one on high speed should work.  
  > **username_2**: Proper propeller does exist - lookup 2740c01 on BL. However it is 30 years old.  
  > **username_3**: Great answer, Alexander, though perhaps we shouldn't be surprised it's watertight as LEGO advertises the set as "For the first time ever, this LEGO Technic model toy floats on water!"  
  > **username_0**: I've tried most of the propellers, they've all been either too small or the blades are too long/thin/flat. The really small ones would have to spin really fast losing power to friction, and the really large ones would take much more power than these systems are made for.  
  > **username_4**: Have you tried changing gear ratios?  
  > **username_5**: Could it help to stack several propellers on the same axle?  
  > **username_6**: @AlexanderO'Mara IIRC the Brick Experiment channel on Youtube has made Lego submarines with only some minor aftermarket modifications. Maybe you could try the propellers they use?  
  > **username_7**: I am new to this. I do not understand if the pieces already included are enough to mount the motors you mentioned in your list. Is there a guide? Thanks  
  > **username_0**: @Adrian As I recall I was able to build it with just the parts in the set plus the extra pieces listed. I didn't make a full guide, but the build is kinda similar to the official alternate model.  
  
  ---
  
  