water-proof vents

Discussion in 'Boat Design' started by gregk, Jun 10, 2007.

  1. gregk
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    gregk GregK

    Is there such a thing as a vent that won't allow water to splash in? Also, something that would automatically plug upon a capsize?

    It's for my human powered ocean crossing boat:

    http://www.pedaltheocean.com

    I'm also looking for a few hatches that would do the same - ie: if they are kept slightly open, do any feature a mechanism that would auto shut upon a capsize?

    Thanks
    Greg K
    greg@pedaltheocean.com
     
  2. Trevlyns
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    Trevlyns Senior Citizen/Member

    Greg – What an amazing website and a worthwhile mission!
    I can’t answer your questions, but will be following your progress with keen interest. :p
     
  3. FAST FRED
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    FAST FRED Senior Member

    The usual system is a simple Dorade Box , with the inner pipe extended and carried low in the vessel.

    When capsized the pipe is above the inverted WL.

    FF
     
  4. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    A typical Dorade box with cowl vent will permit water to board. It will stop splashes and small pools of collected water, but a big wave will flood the box and get below before it can drain from the box.

    They do have a few different styles of "flapper" valves that can stop most of the water getting past the flange inside the Dorade box.

    Hatches are available that will completely seal an opening, but these aren't companionway hatches, they are deck hatches. In a craft like yours, you may consider these style of hatches compared to a traditional companionway slide, just to be on the safe side.

    All of these items are commercially available, check your local marine supply house.

    As far as a self closing feature or automatic operation, the flappers installed on vents will be, but hatches require good seamanship. I'd imagine you could engineer something to close a hatch that is partly opened, but his may prove more trouble then it's worth, considering the ease in which you can close and dog a hatch.
     
  5. gregk
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    gregk GregK

    venting

    thanks - good advice.

    Adequate ventilation is definitely going to be an issue for me. Since the human powered boat is more of a capsule than a typical ocean rowing boat with an open deck, fresh, cool air is a major concern for me. I like the idea of a solar vent - perhaps even something custom where the blower can really push through a decent volume of fresh air.

    Greg
     
  6. tom28571
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    tom28571 Senior Member

    I want to wish good fortune to Greg on his adventures. However, the current 24 hour record for human powered watercraft is well beyond his attempt of 173+ km/24hr mark. Carter Johnson of the USA set a record recently of 150 miles in 24 hours. This is about 240 km in 24 hours, far beyond Greg's number.

    He also paddled his Surfski XLXS in the 2007 Everglades Challenge from St Petersburg, FL to Key Largo, FL in 74.75 hours. This is a distance of 303 miles, partly in open ocean water and mostly in rough water. This equates to about 4.06mph or about 6.5km/h. His average for this race was 144 km/24 hours. His rest or off boat time was about 14 hours so the actual average per day for time spent paddling was about 177km/hr, which is also higher than Greg's number for one day.

    This sounds impossible but I was there at both the start and finish of his paddle and can attest that these facts are accurate. Carter is an unbelievable athlete and was totally spent at the finish. There is even more to the story but you can read and see it all at: http://race.fit2paddle.com/C741445042/E20070314202642/index.html

    Added to say that I just reread his account and it is even more amazing than I said above.
     
  7. gregk
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    gregk GregK

    24 hour record

    I know that Tom.

    My record was ratified, observed and officiated by the International Human Powered Vehicle Association and as such, is an HPVA record. For most, the general definition of a 'human powered boat' is a pedal boat. But, you are correct in that the ACTUAL definition of a true human powered boat would include kayaks, row boat and pedal boats, and Carter's surfski record of 240 kmfar exceeds what I was able to do in my HPB.

    My record is really a pedal boat distance record.

    However that said, I plan on returning next Spring to challenge the REAL human powered record with a better boat. WiTHiN was designed for the ocean, not for a 24 hour record. We figured it was just at the limit of being able to challenge the current HPVA record, so I gave it a shot. WiTHiN is based on a double sea kayak - very stable and pretty inefficient. I think I would have a shot at 240 or beyond.

    On that note - I am trying to contact Carter Johnson. Does anyone have his email address?

    Thanks,
    Greg K
    http://www.pedaltheocean.com
     
  8. tom28571
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    tom28571 Senior Member

    Thanks for clearing that up Greg. I don't have Carter's email handy but I expect you can get it by emailing the Chief at: Chief@WaterTribe.com

    I wish you well in your adventure. I could not even imagine such a thing in my best days and am well past them now.

    Propellers are supposed to be more efficient for energy-in vs energy-out than paddles, so you may well beat his record. I am not aware of just what monitoring was done on Carter's 24 hour record but am certain it is accurate. I do know that no allowance was made for the necessary turn around at the end of each leg. Based on what I observed over 300 miles in much more adverse conditions, I am surprised that the distance is not greater.

    Solar powered vents would be a great idea for your crossing. They are somewhat rain proof but are in no way waterproof for a dunking. A larger solar cell than they provide would allow charging a larger battery for night ventilation also which you will need. How can you carry the necessary water and other stores in your small craft I'm sure you have worked that out but the effort of paddling will require a lot of replenishment of both water and food. Speaking of food, how do you plan on taking care of the necessary elimination of used same?

    Oh yes, the Everglades challenge is welcome to all kinds of human or sail powered boats. There are no size restrictions but all must be capable of being muscled about by the crew on land as well as in water, under bridges and through narrow spaces. I helped build the winning boat this year. It is a 22' cat ketch with a highly variable sail compliment. All up weight with 2 crew and all stores and gear is about 1100lbs. Working sail area is about 237 ft sq and all up is about 550 sq ft or so. Catamarans are indeed faster but, so far, have not been able to contend with the conditions as well as monohulls.
     
  9. gregk
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    gregk GregK

    I am planing on doing the crossing with a support boat. We'll probably rendezvous once per week to hand off a resupply of food and water. They will be there for safety and also repairs, supplies and replacement parts, etc.

    gk
     
  10. naturewaterboy
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    naturewaterboy Steel Drum Tuner

    one thought for a self closing hatch is to rig up a spring loaded hatch that is propped open by an asprin. When water hits the asprin it disolves, allowing the spring to close the hatch. I've never seen one so you would have to design, test, redesign, (etc.)
     
  11. PAR
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    PAR Yacht Designer/Builder

    A faster method would be the "pill" that's used on self inflating PFD's. It would only tack a couple of seconds to trip the latch, once wet.
     
  12. alexlebrit
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    alexlebrit Senior Member

    Not waterprrof, but a thought

    Greg, I know you're still wondering about a large side hatch, and the tipping, and the fact you can't run with it open, so here's a quick animation of an idea I'd had for my HPB.

    [​IMG]

    It's basically a parallelogram arm set up - the two yellow lines. Obviously they're actually inside the cockpit. You can see that the hatch is lifted up as it moves forward and drops down as it moves back. This means it could be securely fastened closed with bolts or clips. I prefer this to a sliding system as the rails would have to be reasonably sturdy to resist wave pounding.

    Oh and yes, I'm sorry I stole your little men.
     
  13. innomare
    Joined: Jan 2005
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    innomare Naval Architect

    Greg,

    you could have a look at the deck vents at www.air-onlyventilators.com.

    Seems like what you are looking for. In general, to find stuff like that (hatches, etc.), it's useful to take a look www.nauticexpo.com or at www.metstrade.com (marketplace).

    I've never heard of a hatch that would auto-close during a capsize. But if it's kept only slightly opened and not fixed but kept open with a soft spring, the hydrostatic pressure will close it automatically.

    Another tip: consider taking a small sea-anchor. If it gets really rough, you'll want something trailing behind you so you can maintain a heading (head onto the waves). Without a sea-anchor, your boat can easily become a toy for the waves.

    Good luck with your expedition! Will be following your adventure with interest!

    Bruno
     

  14. mydauphin
    Joined: Apr 2007
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    mydauphin Senior Member

    How about a snorkel.

    A snorkel turned forward in good weather, backward in back. I don't know when and where you are going to be crossing, but I would be more worried about the cold and staying dry than cooling.
     
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