BMoto Desktop Surfer - with Radio Control??

Haha you're dedicated. I was just joking but I guess a gram here and there makes a difference for you. Keep up the good work


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Weight is very important for the entire project. The weight needs to be approximately 450g or else it won't work as expected. The battery weighs 70g (or 15% of the total weight). That 15% needs to be placed where the center of mass is neutral. All things need to be considered. Consider a situation where the center of mass is 1cm to the right of the center of buoyancy.. It will want to rotate to the right. Even a real jet ski is very close to being neutral.. They lean slightly to the right when water fills the exhaust tube, but when underway that water evacuates and it becomes neutral. Think how much that thing wants to roll if you are traveling 10mph and you place your weight on the bondrail. This kind of puts everything into perspective at this scale. Offset the weight towards the front some and it will submarine. I added rocker just in case.

I looked up titanium and it needs to bent at high temperature. At room temperature it has a ton of springback and it weakens considerably if tried to be bent.
 
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Bottom deck needed some fixing. Added some tubbies, some rocker, and chines that reach to the front. Working my way into the bilge. It will probably have a half bulkhead so the batteries can be shoved underneath the tray. Maybe have some stringers that intersect the bulkhead and mounts the motor.

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I have been getting better at modeling organic shapes. It is a very interesting concept. It is all mathematical expressions that form curves. The curves are classified as G0, G1, or G2 curvature. In which G0 touches, G1 is tangent, and G2 maintains acceleration along the curve. I used many cross sections that ran longitudinally that represented the taper from chine to smooth rocker surface. Guide rails were used to define the profile perpendicular to the cross sections. The air foil tubbies were added later by projecting curves to the surface of the bottom deck.. In other words this maintains a perfect air foil for production.

For scale, the bore of the pump tunnel is 20mm.

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I forsee a lot of people having fun with @Balduccimoto 's creation once it's done.

I saw that video earlier today. I really hope this will work out like that little RC surfer.

I have been bashing my head against the wall with this project. I am fighting with pump fitment and the reason why it's difficult is because the tray is low and I don't want to increase the depth of the bottom deck. There is many options and all of them have some kind of compromise somewhere. Compromise is cost/hull proportion/ease of assembly/etc.. It seems like I have exhausted all my options and tried everything.

One thing I ended up doing was making the bottom deck deeper in the center. It adds a bit of deadrise (more V shaped). That will make it slice through the water a little more rather than glide above the surface. It was either that or increase the size of the ski. Now I can just about fit an off-the-shelf pump which really brings the cost down. The problem is the driveshaft is not accessible without separable decks or access cover. Both are doable but that increases cost/labor. The driveshaft can be extended, but that is even more money. Ideally I could fit the off-the-shelf pump and make it accessible.. The other problem with that is settling on a driveline angle that complements the hull. There is constraints with that as well.. :mad: Lets not forget about ensuring there is no negative draft angles!
 
Any updates?!?!?

College started back up so I have been very busy - I am taking 6 classes with a total of 18 credits. That is the equivalent of academic suicide, sacrifice of social life, and mass anxiety all wrapped up into a semester. Just to add to the mix is some personal time invested into learning programming in Visual Studio (which will make me more employable) and off time invested into being a Shaman in World of Warcraft. (It is more epic than it sounds)

I am still thinking very much about this project though. I feel as if the original top deck model is subpar so I was in the progress of making it again from scratch. I am lacking progress due to my own limitations in modeling smooth continuous surfaces in CAD. I began using T-Splines to model the top deck. It is a very intuitive method of solid modeling, but the popular methods really require a defined set of geometry. (Such that the curves are defined in each plane, much like a blueprint) and my artistic skills are lacking to go at it freehand. It's not impossible to achieve, it just requires some experimenting to find a striking design.

One method I tried was to find blueprints of a stand up jet ski and then redefine the curvature to stray from being an exact replica of the subject's hull. One reason to alter the geometry is to be polite and not rip off other people's designs .. I am not opposed to copying a Yamaha Superjet or Kawasaki SXR since I think the amount of sales won't upset anyone in corporate. The problem with either method is that there is no existing blueprints and I don't know how to do it without some kind of expensive process of reverse engineering (laser scanners generating 3D point cloud data).

My vision is that there will be two different versions of the RC jet ski. One is a RTR version with a brushed motor/nimh batteries. That configuration is more user friendly since lipoly have been known to have certain issues. It is also a bit cheaper for people that aren't in the category of "enthusiast".

The second version would have a brushless motor/lipoly battery and would be sold as a kit. This configuration would probably be in the "enthusiast" category since the customer would be interested in the performance of the hull and enjoys the tinkering/building process. I think the enthusiasts are evident if you just look at the other builds in this forum.
 
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