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Thread: Wave Energy

  1. #1
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    Default Wave Energy

    I'm aware that some boaters believe that their 22' inboards put out less wake than smaller outboard Jon boats. Here's the question. If Sir Isaac Newton was correct in that "for every action there is an equal and opposite reaction", how does a 3000# boat travelling at 40 miles an hour make less wake than a 1000# boat travelling at half the speed. Total wake isn't necessarily the height of the wave left behind, but the TOTAL WAVE ENERGY. Actually, Newton's theory states that the reaction will be equal and opposite UNTIL ACTED UPON BY AN OUTSIDE FORCE. An outside force? Like a wave hitting a bank?

    This isn't intended to be a contentious issue, but rather a scientific one. Any physicists want to chime in? If not, I'll find one and ask. I believe I know the answer.

  2. #2
    Member chriso's Avatar
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    Default On step or off?

    Well, one thing that can be a variable is that the whole equation changes when you plow water versus run on clean step. Most guys I hear make comments about less wake than the smaller boats are referring to smaller boats with less horsepower as in the kenai river 35's trying to still carry as heavy loads as possible, plowing and making larger wakes than a larger boat running clean on step probably would. That's part of the real life results of what is seen by many as the flawed thinking behind limiting horsepower as a means of minimizing wake.

  3. #3

    Default Not a Physicist but

    Quote Originally Posted by Mr. Pid
    I'm aware that some boaters believe that their 22' inboards put out less wake than smaller outboard Jon boats. Here's the question. If Sir Isaac Newton was correct in that "for every action there is an equal and opposite reaction", how does a 3000# boat travelling at 40 miles an hour make less wake than a 1000# boat travelling at half the speed. Total wake isn't necessarily the height of the wave left behind, but the TOTAL WAVE ENERGY. Actually, Newton's theory states that the reaction will be equal and opposite UNTIL ACTED UPON BY AN OUTSIDE FORCE. An outside force? Like a wave hitting a bank?

    This isn't intended to be a contentious issue, but rather a scientific one. Any physicists want to chime in? If not, I'll find one and ask. I believe I know the answer.
    I have designed and built a few boats in my time. I have also invested a lot of time in researching how more knowledgeable boat builders have perfected boat designs. It is entirely possible to design the bottom of the transom to increase or lessen the wake. It is possible to design the boat to create a wake on only one side. Wake turbulence is the same, whether it be on water or in the air. Bottom line is, the more disturbance, the greater the propulsion. That said, it does not mean the greater disturbance, the greater the wake turbulence. It can be minimized or increased at will, through design configuration and choice. A vortex design will create accelerated propulsion, with little outward disturbance, concentrated wake, in a very tight area. Take a look at some of the competition ski boats. They actually have adjustable transoms, that can produce the type of wake they desire at will. Most boat builders, have no knowledge of how the keel and transom affect wake. They are more concerned about boat handling, speed and an overall compromise for most conditions. It is a little more complicated than size, weight, power and speed. I would love to hear of your more simplistic answer, because the entire marine and aviation industries have been waiting for someone to address this matter in a way we morons can relate to it.

  4. #4
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    Default Grizzly 1

    Quote Originally Posted by Mr. Pid View Post
    I'm aware that some boaters believe that their 22' inboards put out less wake than smaller outboard Jon boats. Here's the question. If Sir Isaac Newton was correct in that "for every action there is an equal and opposite reaction", how does a 3000# boat travelling at 40 miles an hour make less wake than a 1000# boat travelling at half the speed. Total wake isn't necessarily the height of the wave left behind, but the TOTAL WAVE ENERGY. Actually, Newton's theory states that the reaction will be equal and opposite UNTIL ACTED UPON BY AN OUTSIDE FORCE. An outside force? Like a wave hitting a bank?

    This isn't intended to be a contentious issue, but rather a scientific one. Any physicists want to chime in? If not, I'll find one and ask. I believe I know the answer.
    Still sounds a little like hull displacement vs velocity, to me. For example: your aircraft on floats exibits a smaller hull displacement when on the step, as opposed to the displacement when plowing ahead at 1200 rpms.

    But, what do I know ..... ?

    Mort

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    Default

    Mort,

    You make an interesting example. Remember the take-off/landing channel between Lake Hood and Lake Spenard? Almost every airplane that goes through that channel is on the step. Most overfly it. A few years ago the State found it necessary to install concrete erosion mats on both banks of the take-off channel. There is no need for such erosion control on the slow channel side, even though lots of guys plow through.

  6. #6
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    Default More to thinkk about

    If a big boat is barely in the water and running on step, then his displacement in the water is also barely leaving a wake. However, the small boat chugging along leaving a larger "footprint" in the water is going to displace more water creating a larger wave too.
    Ie, if your 20' hull, while on step, penetrates the water only 3" deep and 2-3' long (it's footprint) then it creates a smaller wake vs. the 14' boat penetrating the water 6" deep and 14'. (More Cubic feet of boat under water = displacing more cubic feet of water out of the way to pass by.)
    This is why I promote the idea of limiting your guests on the boat to what the boat/motor is rated for, not how many people you can cram in it. It does not "push" a large wake if it can get on top of the water and plane out, as most of the hull is out of the water.
    BK

  7. #7

    Default 22' hewescraft pacific sport

    am thinking of getting this boat , mainly for in the salt ,, but a few times a year i want the ability to go to the lake with the kids and grand kids and go for a ski--- any thoughts on what it would be like to ski behind--i wonder what the wake is like --- anyone done it ? looks like a similar hull to the searunner ocean pro ---the kids like wakeboarding the most 18-23 mph bigger wake the get more airborne --- only old guys ski

    poor guy on the west coast can only afford one boat

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    Member bkmail's Avatar
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    Default ballast tank

    If you want a bigger wake, put 100 gal's of water in a tank in the rear of the boat and keep the motor trimmed up and she will plow giving them a nice big 'ol wake to jump off.

  9. #9
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    Default

    My question is what is more damaging, a 3" wave traveling @ 40 mph or a 6" wave traveling @ 20 mph?

  10. #10

    Default

    i would say the 6' high one it must have more weight--but then again i got kicked out of school in grade 11

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