Question?
+ Reply to Thread
Page 1 of 2 1 2 LastLast
Results 1 to 14 of 21

Thread:
Question?

  1. #1
    Senior Member
    Join Date
    Dec 2008
    Location
    Sacramento area
    Posts
    1,136

    Default Question?

    I have a question not sure where to post it. Because it has to do with my jet boat I will start here.
    I'm thinking to put some floatation jugs in the bow of my boat. The question I have is how much weight will a gallon of air float? I've done a web search, the math is way over my comprehension. To simplify my question, if you added weight to a gallon milk jug, how much weight would it take to make the jug start to sink?
    Thanks in advance, be safe. schick
    Half the people in the world are below average.

  2. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  3. #2
    Senior Member SuperJet's Avatar
    Join Date
    Oct 2010
    Location
    661 So. Cal.
    Posts
    501

    Default

    Quote Originally Posted by schick View Post
    I have a question not sure where to post it. Because it has to do with my jet boat I will start here.

    I'm thinking to put some floatation jugs in the bow of my boat. The question I have is how much weight will a gallon of air float? I've done a web search, the math is way over my comprehension. To simplify my question, if you added weight to a gallon milk jug, how much weight would it take to make the jug start to sink?

    Thanks in advance, be safe. schick

    IMHO you are overthinking this...... for starters what kind of boat is thins going in? if it is your standard 70's/80's jet then you are cramped for space from the get go.... For what it is worth I would just go to your local tire shop and get yourself a good truck innertube and push it as far up in the bow as possible. then inflate just as if it were on a rim. this is exactly what i have done in my 1978 18' Sanger Super Jet.

  4. #3
    Senior Member
    Join Date
    Dec 2007
    Location
    Iuka, Mississippi 38852
    Posts
    598

    Default

    X2 on the innertube. been doing it for 30 years.

  5. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  6. #4
    JRPM/e-PerformanceMarine Squirtin Thunder's Avatar
    Join Date
    Dec 2007
    Location
    Bullhead City, AZ
    Posts
    2,034

    Default

    Quote Originally Posted by Richard Till View Post
    X2 on the innertube. been doing it for 30 years.
    Do you know anyone that has tested it ? I know I have floated boats within a few feet of the surface with very little, 3 5gal bags. There are tons of sharpe edges under a bow.
    Jim & Amanda Rich
    CJ 72 & 53c

    JR Performance Motorsports

  7. #5
    Senior Member
    Join Date
    Dec 2008
    Location
    Sacramento area
    Posts
    1,136

    Default

    I've done the inner tube in the past, thanks for the suggestion. I'm looking for something a little more ridged, that will not be cut if the seam should split, or if the fiberglass should make a jagged edge.
    Maybe someone can tell me the buoyancy of a cubic foot of air, that would be easier, I can figure it out from there.

    Thanks again, be safe. schick
    Half the people in the world are below average.

  8. #6
    Senior Member ol guy's Avatar
    Join Date
    Mar 2008
    Location
    Lake Elsinore Ca
    Posts
    3,840

    Default

    Floatation specs, check the local search and rescue. Floatation device for under the deck-go to www.candoproducts.net. they sell excersize balls in various sizes. They are tough and they even come in various colors for that designer sh$t.

  9. #7
    Senior Member EVILFORCE's Avatar
    Join Date
    Oct 2009
    Posts
    5,180

    Default

    Fill the bow with Foam crack sealer. Only take 30-40 cans.
    No Fool Like A Old Fool is there?

  10. #8
    Senior Member
    Join Date
    Dec 2008
    Location
    Sacramento area
    Posts
    1,136

    Default

    There is the expanding foam for marine use, but that stuff will hold water like a sponge.

    Thanks again, be safe. schick
    Half the people in the world are below average.

  11. #9
    Senior Member coonass's Avatar
    Join Date
    Jan 2009
    Location
    Canyon Lake, TX
    Posts
    738

    Default

    All I know is that it takes 90lbs of weight to sink a tool in a gas well that has 1000psi 85 lbs will float

  12. #10
    Senior Member coonass's Avatar
    Join Date
    Jan 2009
    Location
    Canyon Lake, TX
    Posts
    738

    Default

    62.4 pounds per cubic foot

  13. #11
    Senior Member
    Join Date
    Sep 2008
    Location
    OC, CA
    Posts
    273

    Default

    There was a topic on here a couple of months ago where a few guys, Outlaw being one, bought up 60 to 100 of thoughs foam float tubes you can buy at any store to stuff in front of the boat. I like the idea of the truck tube.

  14. #12
    Senior Member
    Join Date
    Dec 2008
    Location
    Sacramento area
    Posts
    1,136

    Default

    I think I found it, anything that displaces water is buoyant by the factor it displaces, minus the weight of the container. 1 cubic foot of air is 1728 cu.in. There is 231 cu. in. in a gallon. equals 7.48 gallons per cubic foot. Water weights 8.35 lbs per gallon.
    7.48x8.35=62.45 is the weight of a cubic of water. If the container holding the water weights 5 pounds, the buoyancy of the container should be neutrally buoyant at 57.45lbs., (same as water)
    So, long story short. A gallon of air should float a weight less then 8.35lbs. not including the weight of the container holding the air.
    It's not the weight of your boat, but the amount of space it will
    displace under the water.
    This is my take, please post if I'm off.

    Thanks for looking, be safe. schick
    Half the people in the world are below average.

  15. #13
    Senior Member
    Join Date
    Sep 2008
    Location
    OC, CA
    Posts
    273

    Default

    I found the foam tube deal but now sure how to post the link. Search for Cheap Extra Insurance by Skippers WFOT

  16. #14
    Senior Member SuperJet's Avatar
    Join Date
    Oct 2010
    Location
    661 So. Cal.
    Posts
    501

    Default

    SchicK you are right, floatation for a non bouyant item ( ie a solid item like a boat) is all about water displacement. It is my opinion that I couldnt put enough "air" under the deck of my boat to keep it afloat for very long. I know everyone will give you an answer of "I don't plan on sinking my boat" but the reality is, no one does. So my best advise (for what its worth) is put as "air" under the deck as possible without sacraficing all of your storage space. Just my .02


    RC

+ Reply to Thread
Page 1 of 2 1 2 LastLast

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Please select your insurance company (Optional)

Log-in


Digg This Thread

Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
  •  
 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95