Blueprinting hull and making it smooth and straight

[OnPad]

Need something to break water tension, sanded hull, golf ball boat, step hull, or wind riffle all work better than the glass smooth, or frosted cake camp.

[XstreamVking]

Blueprinted pad

[LakeFever]

Xstream is that the final surface finish?

[XstreamVking]

Yep, sanded with 360 grit. Notice where the hull rides in the pic? My bottom tune gave me the ability to not have to use any trim to lift the bow. Check the trim angle in the pic. Faster I go, the more I trim it down. All the thrust pushes the boat fwd and is not wasted. Picked up a few mph The 250 opti pushes the boat real well. 270 hp

[LakeFever]

I havent sanded mine yet but i was only going to do the pad. Now you got me wondering. I might try it in stages just to see the difference. 270hp i bet that thing moves out, wow

[r.c.]

I b.p.ed my pad, the factory g.c.finish was like dimples and i probably took .010+ off to get it flat. I left a 440 grit sand finish on it and have been running it for years with no lose of speed and have not resanded the pad, the water has taken that finish off. It runs at about 6 degrees on the water for best speed and packs the air best running that flat to the water. Gain right at 3 mph.

[CUDA]

Depends on how far from straight it is. I just had the bottom fixed on my 2022 Liberator. $2,500 worth. One side had so much hook in it, the shop used 3 layers of glass to fix it. The other side was fixed with faring compound. The boat was impossible to get past mid 90's without major porpoise/hop if the water was smooth. Was ok on a decent chop, but absolutely impossible on smooth water. Runs like it should have all along now that I had it fixed.

Wow , did you buy this new?
3 layers of glass wow, how the hey could that happen.

[CUDA]

I've always used a 48"x4" aluminum channel

Buy coils of 4 inch sand paper, more for first phase of getting the last 6-8 ft level

Then use 30" 4 inch wide3m hookit / https://www.industrialgeneralstore.c...BoCfHsQAvD_BwE

Sand with what ever makes you happy

[CUDA]

But researchers from UCLA have found that bumpiness can sometimes be better.
"A properly designed rough surface, contrary to our intuition, can reduce skin-friction drag," said John Kim, a professor in the mechanical and aerospace engineering department at UCLA. Kim and his colleagues modeled the fluid flow between two surfaces covered with tiny ridges. They found that even in turbulent conditions the rough surface reduced the drag created by the friction of flowing water. The researchers report their findings in the journal Physics of Fluids.
The idea of using a rough surface for reduced drag had been explored before, but resulted in limited success. More recently scientists have begun experimenting with rough surfaces that are also extremely difficult to wet, a property called superhydrophobicity. In theory this means that the surfaces can trap air bubbles, creating a hydrodynamic cushion, but in practice they often lose their air cushions in chaotic flows.
The ULCA team chose to model a superhydrophobic surface design that another group of researchers at UCLA had already observed could keep air pockets entrapped, even in turbulent conditions. The surface was covered with small ridges aligned in the direction of flow.
The researchers modeled both laminar and turbulent flows, and unexpectedly found that the drag-reduction was larger in turbulent conditions. The irregular fluctuations and swirling vortices in turbulent flows on smooth surfaces generally increase drag, Kim explained. However, the air cushion created by the superhydrophobic ridges altered the turbulent patterns near the surface, reducing their effect, he said.
The team expects insights gleaned from their numerical simulations to help further refine the design of rough, drag-reducing surfaces. Further down the line, such surfaces might cover the undersides of cargo vessels and passenger ships. "It could lead to sig

[CUDA]

Way back when...

[Mark Poole ModVP]

When a golf ball is hit it spins backwards. The dimples on the ball pushes a wedge of air under the ball as it flies and spins which makes it fly longer. There is probably a drag reduction factor because the top and rear of the flying ball is textured not smooth. But a round ball spinning through the air has no relation to a flat surface sliding across water. I can tell you from my own experience building RC race boats that a 400 to 600 grit sanded bottom makes a noticeable difference.
As far as air bubbles...remember the boat is supported by water. Even when the boat is on the pad there is a certain amount of water displacement that is constant as the pad pushes down into the water. You introduce a lot of air bubbles and guess what happens...less water, less support. A sanded surface reduces surface tension but the scratches are fine enough to not create drag.

[XstreamVking]

The balls dimples provide lift like an airplane wing. From my understanding, the sanded bottom carries water in the surface scratches providing a water to water interface. Which reduces friction. And the bubble theory has been proven by making intense bubbles under boats and it caused the boat to sink since air can't support it. JM2cts.

[Mark Poole ModVP]

Years ago I got into high performance surf skis...racing kayaks. A lot of things are different in making a displacement hull go fast vs a planing hull. The rudder on a racing kayak is shaped like an airplane wing equally on both sides, thick at the front and tapering to a point at the rear. The rudder on a high speed boat cannot be shaped like that as the sides of the rudder will lose pressure causing the rudder to shake left and right. It makes you think!