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  #1  
Old 04-16-2012, 06:24 AM
SudorracMechEng SudorracMechEng is offline
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Propulsion for surfboard. Jet drive.

I am a final year Mechanical Engineering student. I am planning on spending the next twelve months researching and developing a propulsion system for a surfboard.

Essentially, i have the desire and the time to investigate methods of propulsion - however i want to be initially led in the right direction.

I wanted to investigate the viability of using impellers internally mounted on the bottom of fins - similar to a mini jet drive system.

I wanted to look at the effect of impeller dimension on thrust, and see if it was a plausable idea to run a direct flow nozzle.

I wanted to only run short bursts of accelerations, in order to get onto a wave. Would the back-pressure from the outlet of the jet drive, due to the density of water be a major issue? Am i better off running the outlet to the atmosphere.

It would be great if like minded people could have their input and colloraborate ideas.

Also - I was thinking about doing a Computation Fluid Dynamics study, and designing my own fin to encompass my propulsion unit that could potentially use small hydrofoils (simply to overcome the decrease bouyancy due to the increased weight, and allow for lower "planing" speeds)
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  #2  
Old 04-25-2012, 10:43 PM
Yellowjacket Yellowjacket is offline
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The idea of a surfboard that helps the surfer catch the wave sounds attractive, but in reality it doesn't work well at all. Once you are up on the wave, the weight of any propulsion system would make the board handle like a log unless it only weighed a few pounds. This is coming from someone who used to surf competivitely (a long time ago, but the dynamics of a surfboard haven't changed). A good board maximizes lift and minimzes weight. Shorter and lighter boards turn more easily than longer and heavier boards, so any added weight would really ruin the handling of the board.

If you wanted something for a tourist to help him catch a wave, it might be ok, but no serious surfer is going to want it. Also, any type of water jet would need a closed inlet once it got going or the drag from the water flowing through the jet would drag you right back out of the wave.

Not to throw cold water on the concept, and powered boards are out there, but they are used with the power on all the time, and not to just launch you into the wave.
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Old 04-25-2012, 11:04 PM
SudorracMechEng SudorracMechEng is offline
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Thanks for the reply.

Inherently, there are a lot of problems.

- impeller/propeller in the fins, creates severe drag.

- jet drive, inside the board - cavitation problems, also surface drag.

However, having a retractable system overcomes the cavitation problems and the problems to do with drag in the flow direction.

It doesnt overcome the additional weight.

Keep in mind, this is aimed at beginner to intermediate surfers - not professional.

Short bursts of acceleration in a retractable system, with the focus on minimising weight is definitely plausible.
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  #4  
Old 04-26-2012, 12:31 AM
Petros Petros is online now
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Interesting idea. I grew up in a surfing community on the southern California beaches, must have been almost 40 years since I have owned my own board!

How are you going to power it? Electric would be simple and compact, but batteries add a lot of weight and cost. Gasoline seems a bit complicated. How about a compressed air engine? You just need to bury a composite pressure vessel inside the board, you "recharge" with a bicycle tire pump! The "fuel" does not weigh a thing!

Any kind of prop or jet would add too much drag. You might use two oscillating skags (like the hobie drive system), that locks in place once you start surfing. That way you get double duty out of the drive. You would want to use a low speed piston drive, like a compressed air engine. A gear reduction drive would add weight and cost.

Also a ducted fan with blades that fully feather might work. the duct can act like the skag when the blades feather. Careful design of the duct will minimize drag. The feathering blades adds some complication.

Make it light and efficient enough it could even be used to power yourself out to the off shore breakers. You can even carry an extra "fuel cell" in a back pack perhaps, along with your lunch. I like it!

If you can get enough range you might even invent a whole new form of long distance adventure surfing that is not otherwise practical without a support boat.
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  #5  
Old 04-26-2012, 01:11 AM
Submarine Tom Submarine Tom is offline
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SME,

You mean like these?

http://www.youtube.com/watch?v=JpMe6...e_gdata_player

http://www.youtube.com/watch?v=5oQVg...e_gdata_player
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  #6  
Old 04-27-2012, 05:28 AM
SudorracMechEng SudorracMechEng is offline
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The compressible air is an interesting idea - however, encasing the compressed air with a composite material that is able to safely withstand all sorta of external pressure with the additional internal pressure - and be light weight will be a task in itself.

Definitely worth looking into though, has given me a few more ideas!

Have you got any ideas on how a retractable system could be devised, I have rough sketches of different designs that i need to start analysing soon.

Any input anyone has, i will definitely put it into my design proposal if it works out well and will be uploading constant data and results.
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  #7  
Old 04-27-2012, 05:36 AM
SudorracMechEng SudorracMechEng is offline
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If anyone has any links or recommendations of *research papers, articles, patents - that will be of use when writing a literature review for "retractable surfboard propulsion" please let me know, as it is a little tedious finding relevant data.
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  #8  
Old 04-27-2012, 07:11 AM
Aaron.Melvin Aaron.Melvin is offline
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I've looked at the idea before:
here's some ideas...
http://www.powerski.com/content/psi_index.php

http://wavejet.com/

http://www.deckjetwatercraft.com/sur...-powersurf.asp
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  #9  
Old 04-27-2012, 01:25 PM
Petros Petros is online now
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Composite compressed air tanks are not new at all, they are quite common and very light weight. They are filiment wound around a mandrel, so all of the strands are oriented in the load direction, simple to make and very strong and light. It can even be made intergral to the structure of the surf board.

I do not think I would complicate the design by making it retratable, unless you are talking something simple like the way an out board is lifted out of the water on the back of a transom.
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  #10  
Old 05-01-2012, 11:58 PM
SudorracMechEng SudorracMechEng is offline
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Hi Petros, my only concern would be the structural rigidity of the compressed air tanks, and the inherent safety precautions. With that being said, I think this is best idea I have heard of yet.
What type of composite tank do you think would be applicable to this?
What volume and pressure in the tank will i need?
What drive system will be most efficient driven by these air tanks?

If anyone has any ideas, let me know! i will be making weekly photo uploads, data and testing results.
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