# low wake design

Discussion in 'Boat Design' started by halfrhovsquared, Jan 9, 2020.

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### gonzoSenior Member

As near to zero still needs to be quantified. He has constraints on loaded displacement, weight, size, speed and power. Without a maximum height, what is near to zero to me, could be too high. On the other hand, if near to zero is 1.5 feet (.45 m) then that would change the design a lot from what I am thinking.

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### halfrhovsquaredJunior Member

Not sure about wake height. Perhaps below 6"?

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### BlueBellAhhhhh...

Mariner 6" or scientist 6"?

That is: Peak to trough 6" or simply magnitude zero to peak 6"?

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### halfrhovsquaredJunior Member

Magnitude zero to peak 6".

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### BlueBellAhhhhh...

Ya, so mariners call that a one foot wave and that is certainly beyond the limit of a no wake zone.

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### halfrhovsquaredJunior Member

Ok, call it 3" then. Needs to be low wake.

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### BlueBellAhhhhh...

Oh, Gonzos gonna love this, it's subjective.

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### DCockeySenior Member

Gonzo, how can you or the original poster analyze a proposed design to determine if it meets a requirement of a maximum wake height at a specified distance? What analytical tools are available?

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### gonzoSenior Member

You don't necessarily need analytical tools. For example, there are existing hulls, like the chase boats for rowing shells, that make a very small wake. If they satisfy his requirements, that ends the discussion. Otherwise, model testing can also provide an acceptable design.

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### rxcompositeSenior Member

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### BlueBellAhhhhh...

halfrhovsquare,

Otherwise, good luck.

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### rxcompositeSenior Member

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### halfrhovsquaredJunior Member

The catamaran design is growing on me especially in light of this study. But wouldn't the catamaran hulls have to be planing to get to 15mph otherwise they would have to be crazy long? Or do they not meet the standard rules for displacement monohulls? Is a catamaran that is pointed on both ends significantly less drag that one with a squared off transom? (or is the squared off transom required to be planing)

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Depends upon the final length you select.

Well that is a can of worms.
Less drag is dependent upon the speed selected. At slower speeds, or rather Froude numbers, yes. But not at high Fn.

There are plenty of examples of catamaran hulls running way past prismatic hump, which is what may consider to be the onset of planning.
They simply have - as you called it - squared off transom.

Until you set your SOR, you'll be going around in endless circles.... and getting more and more confused, as you will be attracted by all things glittery.

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### DogCavalrySenior Member

The extremely high length to beam ratio allows a much higher hull speed. And a high prismatic coefficient is very desirable in those ranges.

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