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  • Stock PVC and Other Materials Division

    Certain things are clear: PVC division requires the frame materials to be of only PVC, CPVC, Pex, etc.

    How about some of the more gray area components?

    I assume these are allowed in Stock PVC:
    - Zip ties
    - Tape like electrical tape or duct tape
    - Glues like superglue or hot glue
    - Electrical connectors/insulators like heat shrink or liquid electrical tape

    I'm not sure on these items
    - Non-PVC material to build a hook to life challenge elements like a pencil, chopstick, wire, etc
    - Non-PVC material for something to coral the floating challenge elements
    - Different motor waterproofing items like a different type of wax, etc

    And only pool noodle material can be used for flotation?

  • #2
    brian_c The class information has been updated to clarify these areas.
    Please see the matrix and PDF document at https://www.seaperch.org/2020challenge.
    "Attachments and non-frame parts made from various materials but may not include 3D printed or additive manufactured parts."
    Yes, all the items you listed are allowed in the Stock PVC class.

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    • #3
      “Additive manufactured parts” does this mean something premanufactured and purchased? Understand not buying a gripper but if they use a syringe for hydraulics and make a gripper themselves is that okay for the PVC class? Also is is laser cutting flat materials for auxiliaries or attachments allowed in the PVC class? Thanks.

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      • #4
        Shanklincj Buying parts and modifying is allowed in PVC Class. Laser cutting or other fabrication technologies that use automated machinery is not allowed in the PVC class.

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        • #5
          Last question, are there any restrictions on the pvc pipe size? Specifically diameter.

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          • #6
            Shanklincj There are no restrictions on the size of the pipe used.

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            • #7
              In regards to flotation, is the pool noodle the only material that can be used?

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              • #8
                brian_c "Attachments and non-frame parts made from various materials but may not include 3D printed or additive manufactured parts."
                The flotation may be any material as long as it not 3D printed as follows the other guidelines.

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                • #9
                  We have a team that is trying to use a gutter (I think it’s vinyl) for the shell of the ROV and they only use cpvc pipe to mount the vertical motor. If they don’t have any 3D or automated machined parts would this still qualify for pvc division?

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                  • #10
                    Shanklincj The PVC class is for standard pipe and fittings only. Anything other than standard pipe and fittings falls under the Other Materials Division.

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                    • #11
                      A few questions:
                      1. Are boost/buck converters considered power conditioning?
                      2. The rules say I can't power auxiliary equipment (like a servo and microcontroller) from the ROV propulsion battery, but do we need to account for the cost of the secondary power source in our $25 limit? If so, the battery cost could use a significant portion of my limit.
                      3. Are shipping costs, taxes, duties, etc. included in the cost, or just the actual cost of the item? If so, how should the other costs be allocated when multiple items are purchased? Do actual receipts need to be provided or can we find the best price of the component online and use it whether or not it was purchased there or not? Is so, what prevents all the extra material from being donated so that no receipts are needed and the best price can be found? If only a portion of the material is used, do we divide the cost of the item by the portion of the total that was used? Does anything prevent us from buying in bulk to reduce the cost? Are any materials excluded from the cost calculation (like glues, tape, zip-ties that are not included in the kit)? It seems like determining the cost could be prone to cheating. In the regional competition I attended last year the inspection was very casual and many teams used non-stock motors for propulsion. Do all regional competitions need to follow the class and design rules? Can students challenge teams not following the rules?

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                      • #12
                        hillmr3141
                        1. Buck converters are allowed to reduce voltage and therefore reduce the speed of the motor. This is not considered power conditioning. Keep in mind that if you are trying to boost the voltage to speed up the motor that they may burn up pretty quickly.
                        2. If you are controlling an additional motor, servo, or microcontroller that attaches through the controller than you can power it with the ROV battery (please reference the rule you are referring to). However, if you have auxiliary equipment that is separated from the controller then you need an additional battery. Yes, additional batteries count toward the $25 stock class limit. The open class does not have a budgetary limit.
                        3. Shipping costs, taxes, etc. do not count toward the budget. Excerpt from the rules: "*Budget Guidelines include: Donated material will be assessed at what the cost would be to procure the material." Yes, you need to keep receipts. Yes, you may buy in bulk and account only for the portion of materials and supplies used in the final ROV. Use reasonable accounting for supplies.
                        Regionals may not follow the International rules exactly.
                        You should check with the local coordinator of the regional event that you are planning to participate in.
                        Teams using non-stock motors at the International Challenge will be disqualified.

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                        • #13
                          In the pool event rules is says, "...power connection is for the ROV only, no auxiliary equipment may be connected to this power connection" and "auxiliary equipment such as cameras, advanced controllers, and electromechanical ROV attachments". I assumed that any electromechanical attachment to the ROV (i.e., a servo motor) would require a separate power supply even if it went through the same ROV controller but you have clarified for me. It sounds like I can power a microcontroller and servo motor through my console with the ROV propulsion battery. It sounds like as long as everything goes through the same console/controller that powers the ROV, then a single battery can be used.

                          The specifications for the motor say it is rated up to 18VDC and last year I operated my motors at 20VDC without failure. It was good clarification for me the a boost/buck circuit would not be considered power conditioning.

                          Thanks

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                          • #14
                            Sorry, clarification please. The rules say we can’t use the power connection that is provided for the auxiliary equipment. It doesn’t say we can’t use the battery for the auxiliaries. If the servo and controller are not connected to the motor controller can the auxiliaries be connected to same battery so both the motors and auxiliaries are powered off one battery. We already have been doing this and would be a major shift in plans because a second battery kicks them into open class because of the budget.

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                            • #15
                              "Buck converters" are allowed to reduce the voltage. We will have to discuss an official rule for boosting in the competition. We have allowed resistors in the past and teams have used buck converters, but we are starting to get into a grey area here.
                              Teams are not allowed to connect auxiliary equipment to the power connection provided at the International Challenge. Teams may use the power connection for the ROV and use a standard SeaPerch battery or equivalent without this battery counting against the budget. Teams can power the ROV and auxiliary equipment from a single battery that they provide without counting against the budget.

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