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Boats built in flotation ratings?

Discussion in 'Boats, Blinds, & Gadgets Forum' started by meat hunter, Jun 10, 2019.

  1. meat hunter

    meat hunter New Member

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    SE Minnesota, near Preston
    Here's a question that no one at my work has been able to answer. The built in flotation on my boat, it is designed to keep the boat just below the surface in case things go bad, as I assume this is true for most boats.

    My question is, it that just for the weight of the bare bones hull. Does that include the weight of the outboard? How about 3 batteries and a trilling motor?

    See where I'm going with this? HOW do they, the manufacturers, determine at what point the boat will go all the way to the bottom.

    For what's it's worth, I have a 1860 roughneck.

    Curious to hear what you have to say.
     
  2. HaydenHunter

    HaydenHunter Elite Refuge Member

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    Weight on the plate is what will float at level when swamped. That includes hull, motor and other contents.
     
  3. Montauker

    Montauker Elite Refuge Member

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    It designed to float the hull, motor, and the weight limit of the boat (all identified on the plate).

    They put the boat in a tank and add weights to find the stability and limit. I am not sure if that is done for all but there is a video on here somewhere of that test being conducted
     
  4. lax

    lax Elite Refuge Member

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    Where that weight is distributed will play a factor also. Lets say you have 3 batteries along the transom and should only have two, the hull may take an attitude like a stick bobber.
     
  5. 1995 US1

    1995 US1 Moderator Sponsor Moderator

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    All of the above are correct. We are required to float test all our models. USCG gives weight specs for each size outboard. When float testing, we have to simulate the motor weight on the back, the max weight limit, and are required to have so many inches of the side of the boat above the water line when swamped. That is why you see such a variance in side height from manufacturer to manufacturer, to meet the level flotation regs.. Horsepower ratings have nothing to do with the strength of the hull, it is calculated using a USCG formula using the transom width, total length of the boat, and a factor provided by the USCG.
     
  6. Bob Johnson

    Bob Johnson Elite Refuge Member

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    so I have a Lowe Ultra roughneck 2070.... it is a 2008 I bought it new in 2009 and 4 years ago.....i had 55 lbs of air in my tires and they were looking like they had 10 lbs of air...***... the boat had "gained" some weight....... stripped it to the bare hull no decking no floor, and cut out the absolutely saturated flotation foam..... 1 cubic ft of that foam was weighing about 16 lbs.. it is supposed to weigh about 2 lbs....... I was carrying about 700 lbs of water, IN THE FOAM..... youve got a LOWE...so I just thought id pass that along. I replaced it all with known closed cell foam cut and fitting as tight as i could fit it , in as much area as i could fit it!.
     
    widgeon likes this.
  7. 1995 US1

    1995 US1 Moderator Sponsor Moderator

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    Best flotation I have ever seen was emptied water bottles stuffed below the floor so tight they could not rattle. They don't absorb water, are chemical proof, and if 1 breaks open you still have flotation. And just for good measure Bob, ALL foam will absorb water. Foam flotation is a material made of air bubbles surrounded by styrene, (plastic). The nature of the construction allows the flotation to absorb water. It makes no difference if it is poured foam or block foam, it will all eventually absorb water. We use GP foam under the floors of our boats. GP foam is blocks of foam with a barrier on top and bottom to render the foam gas proof. USCG regs dictate that the boat must float level with at least 2" of sidewalls above water when swamped and loaded to maximum capacity.
     
  8. Bob Johnson

    Bob Johnson Elite Refuge Member

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    i have always went out on Long Island Sound in late winter after waterfowl season and just scoured the island shores for "stuff"..... found a lot... and I have found hundreds of peices of DOCK FOAM...and its as light and dry as can be imagined... and most of it sat UNDERWATER for years!!!!!!!!!!!! and did not absorb water.....sooo thats what i tended to use, until i just went to Home depot and bought the 2" thick sheets of dow corning foam... you can cut it and it still doesnt significantly, if at all hold water.....
     
    Tuleman likes this.
  9. Bob Johnson

    Bob Johnson Elite Refuge Member

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    20160724_174644.jpg
     
  10. Fowler267

    Fowler267 Elite Refuge Member

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    I have an 03 WE that sits outside un covered. The foam has not soaked up water as of the last time I had the floor out which was probably four years ago.

    But if I ever replace the foam , it will be with quart oil jugs with the caps taped on.
     

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