Is the Razor Blade the Switch Blade for Surfing?

Looks like a foil for each side of the boat.

http://www.fatwakeco.com/

Anyone know how it works? It looks like it has more surface structure than just a trim tab.

Way too sketchy to tell. Looks like they mount like left and right trim tabs. Looks like a small set of fins on the bottom. The darned thing is so shiny you can't tell what it is.

Looks like a fixed plate to me.

I see a hinge.

I looks look it is something like double trim tabs. Engage one depending on which side you are surfing. Seems like a good idea in concept.

Larry Mann of Trickboardz has come up with a similar idea but it would require small gates on the bottom of each side of the boat to allow water to flow through tubes/channels in the hull itself. Maybe he'll post up about it...

I emailed Scott Adams at Pivotal Designs. He replied back and said that the Razor Blade is for the I/O market.

He also said that they have a surf specific Switch Blade modification in test. He said the modifications further increase wakesize, resolve the in your face spray, and resolve prop rotation issues. The modified device attaches to the original Switch Blade mounts.

However he said that the new option wouldn't be available until summer.

If they can resolve the firehose and one side only surf issues, that would make the Switch Blade a much better product for wakesurfing. Did Scott indicate what changes they were making to the blade?

Sounds like they've made and tested a prototype. Scott said something about a foil. At first I thought he was talking about the Razor Blade, but no he was talking about a Switch Blade with a foil or maybe some other structure that has foils. Either way the new Switch Blade will mount to the older transom hardware.

That puts the Switch Blade back on the Radar for Wakesurfing.

That would require some significant changes. We've surfed an Enzo without ballast, people or water, just the 'blade and I'd consider it marginal to crappy in that configuration. Without something to make the boat list the wake is neither well defined nor large. The wake was mostly created by changing the prop wash, as such it wasn't firm. It also tended to accentuate the Enzo's problem with the secondary lip.

The concept would be great, but...I'm rather skeptical.

I would really like to see a "push button" wakeshaping tool, hopefully these folks will have a viable product towards that end.

You add the switch blade to the Svfara SV3 and you will have a big wave for frontside or goofy side

Right, it sounds good but you have to see it first.

Notwithstanding the Svfara plug JL makes a good point and speaks to your concern, Ed. We ride regular and darkside in virtually every session. A device which allows an effortless transition between port and starboard would be a Godsend. We also do a little surfing with skimstyle boards and longboards. It would be nice to adjust the wake when switching boards or styles. For example, surf, longboard or skim.

So my wishlist is a device at the helm that allows shifting the wake from port to starboard. Even if it required the boat to be stopped - like when switching riders, that would be ok. Also, the ability to create a tall steep wake, or a less-tall rampier wake or a LONG short wake with a decided curl at the back of the pocket...all from a button.

i've always thought that the dual trim tabs would be the way to go, lower one port lift starboard and it seems like the boat would list more. As ed as shown us weight is important but getting the the v of the centurion hull to lay parrallel with the water is also important to making a long clean wake.

Jeff, you're asking a lot but whoever can do what you ask first, will probably sell a lot of boats!

Didn't wakesurfing mag's old Calabria have something like 5 trim tabs across the transom?

I hear you Bryan...it's probably NOT even feasible, but it would sure be "the answer" wouldn't it?

I'd think a Switch Blade with trim tabs might be a good combo. If however they've added a foil to the Switch blade it might not be needed.

So JL has a Switch Blade on a Svfara and that works on both sides?

You should ask for what you want. Otherwise no one will work toward giving you what you desire. Now, it may never happen, but you have to ask.

I was just saying the Svfara boat has a good wave on both sides , that could be made better with a switch blade, they do not offer that yet but it would make a good wave better .Any boat should have a better wave with a switch blade. The wakesurfmags 24' enzo with the switch blade still used a lot of ballast to make the wave huge .The Switch blade is worth adding to your boat it helps for shure

Ask for what you want, one of these boat companies should hire you two. This way you can play with boats, trim tabs, switchblades etc. and still keep your board development on the side! You want me to make a few calls?

I've been playing with these



Fun

You play with 50 caliber machine guns?! That sent a shiver down my spine!

You know...I'm not convinced that the 'blade does anything useful in wakesurfing. It's techy as anything, but it doesn't add a foot of height or 10 feet of length. If you want to change sides - from regular to darkside you have to stick your boat on the trailer and remove the blade or the wake is awful. Also, there is that crazy spray issue that the manufacturer is attempting to fix in the wakesurf specific version.

IMO, from everything I've experienced it's a techy gadget that imposes more limitations than improving performance.

I think the proof really is in the pudding - go on the Inland Surfer website and those folks have been surfing Enzo's for ages. They don't use a 'blade. I don't think that you can find a picture of a WAKESURF wake that is substantially better due to the 'blade. Nor can you surf with the 'blade alone...so you're still having to supplant the 'blade with ballast.

I know nothing about the wakeboard wake and make no comment about that, but I have yet to see a wakesurf wake, on an Enzo, using the 'blade that was vastly improved over ballast alone. However, I do know that switching sides (e.g regular to darkside) is greatly hampered - you have to physically pull your boat out of the water and remove the blade. Also, the spray that eminates from the 'blade hits you in the face when you come up and hit the lip or start a surface 3 rotation.

It sounds like the manufacturer is making changes to address some of this, but at the moment it doesn't exist for consumers.

I've exchanged further email with Scott. The new device does not switch side to side. So, you still have to move ballast from side to side. It sounds like the three major advantages of the new device is increased wake size, with "Right Surf" good wake on both sides, and reduced fire hydrant effect.

Ed, could you clarify somrthing for me please. "Right surf" is Centurion's name for the reverse rotation prop. As I read your post I am interpreting it as:

'with "Right Surf" good wake on both sides' = folks would need to order the reverse rotation prop in order to get a decent wake on both sides with the new product. I know that I have heard the reverse rotation option does produce a more consistent wake on both sides than the regular rotation option from Centurion. Is that what you meant? If you'd be so kind as to clarify, please.

"Right Surf" = RH prop rotation.

First, I have never surfed behind an Enzo. Second, I have never surfed behind a RH prop Centurion.

The story I think I'm hearing is that the RH prop rotation is more balance than LH.

The new Switch Blade is reported to work well with both prop rotations. The Switch Blade setup with the most balanced wake might be with the Right Surf option.

This is coming from someone responsible for marketing a new product not from my first hand experience.

I’m trying to work through the cost of buying a new boat this week. I wanted to keep it simple and low cost. I already have 3,320 pounds of ballast. FAE runs about $350. If I make the SB leap that’s about $2,000 for Side Swipe exhaust and maybe $3,000 for the SB. Total that for about $5,000. That’s a cost difference that’s more than an order of magnitude.

Unlike the Wedge the SB can be an after market option. The decision could be postponed. Earning another $3,000 worth of husband points after buying a new boat might be difficult.

How much is the Rightsurf option on top of that?

Yeah...see FOAM is much cheaper and if I can just figure out how to NOT track it into the house, I'm golden.

Keep us posted on what you decide!

Anybody want to report on a Centurion that is listing for surfing and then engaging the switchblade?
I won't be able to report till late spring, and it's the standard rotation.

I will update everyone soon. I am riding for Switchblade and there are some cool things in the future. Can't say much now but the new switch blade is RAD and the other stuff they are working on is LEGIT...

Drew Danielo

Well...this thread is being read! So I'm going to state my wishlist in detail!

A device like this isn't going to be cheap, but I'd like to have the MAX cost be less than $5K installed.

The polished version of the 'blade is a sweet addition. I'd like the device to look good, either polished or maybe an adonized color to match the boat?

I want adjustments. Adjustments for height, adjustments for regular or darkside...I almost invision a joystick sort of control.

I want it to create a wake, similar to 1,300 pounds of ballast in the rear corner, without the need for any ballast. PERIOD. So surfing would be done strictly with the 'blade.

I do NOT care about wakeboarding or wakeskating. I'd prefer a purpose built device, not a "does everything" device that is marginal for wakesurfing.

I want to be able to back the boat up! My inboard is such a pain, I want the device to not exacerbate the backing issue.

No fire hydrant.

No secondary lip in any 'blade position.

Works on both regular and darkside without requiring special transmission options.

I'd prefer to be able to trailer my boat home without having to take the 'blade off. Maybe it swings up like an I/O?

I'd like it to have easy to understand markings on the controls. BIGGER, SMALLER, REGULAR, DARKSIDE

And all the normal stuff - warranty, local servicing etc.

I'd buy THAT product, or even something close.

So I was thinking about what the new Switch Blade (SB) was like and how it might be better than the existing SB. The new SB is the old SB with a foil, a kind of wing.







The old SB is a thrust diverter. That’s classic Newtonian Physics. Every action has an equal and opposite reaction. The diverter throws (diverts) water up. There has to be an equal and opposite response. That response forces the hull of the boat down.



The new SB has a foil and a diverter. The foil is an upside down wing. By way of Bernoulli's principle it provides lift (negative lift) as water passes over the foil surface. So the new SB leverages two effects thrust diversion and aerodynamic lift.



The fire hydrant effect is no doubt caused by diverting a stream of water up. The stream breaks the surface and gets in Jeff’s face. I’m guessing that since there are two properties in effect that the SB doesn’t need to be placed in as extreme an angle for the same downward force. Since the angle is less extreme water is not diverted in an extreme upward angle. Since the water isn’t diverted as strongly it doesn’t break the surface of the water with nearly as much force on maybe does not break the surface at all.

I have more hair than THAT! Ed, the Wedge tends to flatten the Bu's out, it pulls the middle of the transom down and affects the amount of ballast needed to maintain the list...how would this design increase wake height?

I couldn't find a Charlie Brown graphic with a respirator and a ski hat. Last night I re-applied the fat pin line. When I started out it was about 50 out side. This morning it was 13.

I'm not sure. The SB is really different from the wedge. The new SB is kind of a mix, a little of both wedge and diverter.

In the "Centurion: Not Wakesurf Ready" thread I said that I thought left and right trim tabs would be helpful. I think they would work with the Wedge, the SB, and good old ballast. Whatever flattening there system does to the boat I think that trim tabs should un-flatten.

Again I think one of the key objectives is slip. You want to present a more blunt bow to the water. You can do that by creating slip, that’s pushing the boat through the water sideways a little. I’ve seen that too much slip is bad though so it’s a tweaking kind of thing. The other idea to generate slip is another rudder offset from the primary rudder like the Centurion Tru Track. I think if a boat was flat but was made to dog track you'd build a bigger and better surf wake.

You need to build an oven for your pin line. I have the same issue, but not as cold. Build walls with insulation foam. Tape them together and cover with a 2 mil drop cloth. Place a small electric space heater with a fan or even a hair dryer...you'll get minimally 70 degrees.

RR epoxy is really prone to NOT STICKING well. It seems any number of things bug it and in particular temperature is right up there. Best is like Straight Trippin mentioned, a stable or dropping heat but not below 70 degrees.

The SB - old school just flopped with the thrust, does that act as a means to create the slip you talk about? I'm not familiar with Centurion's Tru Track is that the fins toward the bow?

Last two times I put black pin lines on I got a ton of zits on the board. Last night it started to open creators. I added some surfactant after the first brushing. That cleared up the creators, but I still had zits. I wipes the board down with DNA, don’t know what’s going on. I seem to have more trouble with RR than the cheap stuff.

The pitch of the “old school SB” is controlled but it floats relative to track or steering. You might be able to add another degree of control but I don’t think you want to do it at the transom. I think you’ll get spray or other undesired effects. If I were going to add another rudder I’d place it where the Tru Track (in front of the tracking fins) is at or on one or both outboard edges of the transom.

So here’s another idea to consider. Put trim tabs on a surf boat. Then mount a small set of rudders on the bottom of the trim tab. The rudders could be controlled or simply snapped into place by a swimmer. The trim rudders would alter slip. You could easily switch between settings that aid regular and goofy surfing.

I agree with you on RR, it's very persnickity. I'm ok with it for lamination work, but gloss and hotcoat work it's REALLY difficult to work with. Although I think you tripped over part of the issue of the separation. If you go too thin you get that separation, the gloss coat needs to be thicker to allow the flow - it's a surface tension issue. The zits are typically caused by dust contamination - literally you need a 'clean room' to avoid it with epoxy.

Check the nonsense that maxmercy goes through to get a gloss epoxy coat in this thread - find maxmercy 's NOVEL on how he does it.

I'm not completely following the slip idea. I can picture the effect as on the rooster tail i throw on my dirtbike powersliding or when I throw snow on my snowboard...but is the opposite orientation. When you have time, would you mind explain in more detail? Thanks!

ooops It would be nice if I included the referenced link, huh?

http://www.swaylocks.com/forum/gforum.cgi?post=278267;search_string=epoxy%20gloss%20coat;#278267

I have 300 hours on my blade now and I love the thing. My first season with it I was on the fence as it gave me some grief. But now that I have everything dialed it's great.

During one of the down times, I had the blade off the boat for about a month. We rode with ballast only. Everyone in my group was happy to have the blade back. On our lake we only have about 10-12ft of depth. On deeper water I can get a good wake without the blade but on our home turf, nothing beats the blade. I would prefer to run without it as the boat burns more fuel with it on.

Yes there is a roost on the "darkside" but only if you are right in the trough behind the boat. Trust me the wake is much better and more fun, further back.

Thanks to the Walker family for getting my buddy hooked on the "darkside", now we include that in our sets. We have been experimenting with and without the blade. We just pull up to the dock and take it off, not hard at all if the water is warm!

Even on the "darkside" we prefer to ride with the blade. If they are developing a better version, I am in line for one!

Anyone have a Blade with a RH prop? Care to comment?

I'm trying to see if I can pull off buying an Enzo. Many of my crew and family are goofy. I'd consider buying the RH prop if I knew that the regular wake would be pretty good too. I thought that I heard unofficially, on line some place maybe, that the RH prop might even produce a better regular wake than the LH prop.

Rich Seller's boat is a RH prop, with the blade. I'm sure that I have posted some pictures from wakefest. We also used that boat at the NorCal INT League up at gerber last year. Jason makes a good point about the shallow depth. The Gerber lake is on average 8 feet and the RH with a blade did a pretty good job.

Not sure I buy dragging an 80 pound blade off the back of a boat on a ramp as "easy". Here in CA you'd get sued. Plus for us, the switch would require a 20 minute motor back to the ramp and probably a 20 minute wait to get on the trailer. Figure another 30 minutes to switch ballast and 20 minutes back to ride that's 1.5 hours for us. Things are nicer in MN.

Jason do you folks still ride the darkside?! That's great! Doesn't look like Tom will be holding the contest this year, we'll miss the trip back to MN. That is truly God's country.

Jason's Enzo with a blade in 10 or so feet of water:

Not wakefest, sheesh. Surf Fest. Look for the red Enzo.

http://www.wakeworld.com/MB/Discus/messages/87668/469516.html?1183332674

http://www.wakeworld.com/MB/Discus/messages/87668/474874.html?1184333160

Sheesh that was TWO years ago.

http://www.wakeworld.com/MB/Discus/messages/87668/355203.html

All of the pictures of the darkside are the reverse rotation Enzo - again this is a man made lake - MAX 8 feet deep.

I forget that not everyone keeps there boat on the water. I just pull up to my dock and hop in and remove it, throw it on the dock and fill the other side. Takes us about half hour to make the switch.

That picture might not even be 10ft of depth. The boat was still new then and had some issues that held us back. I thought we had a much better wake at the 07 event. With more time on the boat we have it dialed in better now as well.

Sorry to hear that Tom is not doing it again, maybe we can find someone to pass the torch to?
I was looking for a better event this time around as I have a certified driver for my boat so I could compete and not worry about driving duties. We could have done a better job with it all but I suppose that comes with experience.

Or maybe I will have to road trip to Ohio? Ed, is that you?

Yup. The venue in Columbus is challenging to work with. I'm working on alternatives.

The venue in Dayton is Awesome!! I'm planning an Ohio NWL Championship in Dayton on July 12-13.

NWL Wakesurf Nationals is scheduled for Columbus on August 16-17. August 15 will be informal practice.

I'll be up by Traverse City in early August for about a week. At NE Indiana June 28-July 2 - but that's a family thing.

Hey Ed, what details do you have on the NWL Nationals in Aug? Will this take the place of Wakefest?

Roy, There will be no 2008 Wakefest for several reasons. Hold on this is going to be more than you expected.

First…After I asked what dates everyone was planning events for 2008 and after I found no conflicts I filed for a marine permit in Columbus for July 11-13. About a month later Chris Walker, the NWL chair, put a Pro-Am event in Dayton on the same date. Holding two events on the same weekend less than 1 hour a part doesn't make sense. The Dayton venue is so good, Chris invited me to run surfing at Dayton, and since Dayton is so supportive of these events I choose to run the Nationals Wakeboard League Ohio Championship in Dayton with Chris’ Pro Am event.

Second…The City of Columbus is insisting on a marine patrol for Wakefest. After last year I agree that a marine patrol may be necessary for Wakeboarding, Skiing, and Hydro foiling (but not for wakesurfing). No one but the city can provide marine patrol services. That means that the Scioto Boat Club, the Greater Columbus Rowing Association, the state, the Coast Guard, the Navy, and the Marines can not provide these services. The cost for the city marine patrol for two 8-hour days is about $1,400. That’s a huge amount of cash for a small event like the Scioto Wakefest. At the 2007 Wakefest we awarded $1,500 in cash. The Marine patrol would consume nearly all of the prize money.

With the same level of support I had last year I might be able to pull off Wakefest and still come out OK. I don’t pocket a dime of the event funds. However, I underwrite these events. If the event comes out in the black I buy more gear to improve the events or I buy prizes for the next event. Last year I made a contribution to the SBC Neighbors, the City of Columbus “Indian Village”, a day camp. If the event ends up in the red it comes out of my pocket. So far no event has come out in the red and I’m not going to run one might. For me there’s too much risk to run an event requiring a marine patrol in Columbus on Griggs Reservoir.

In an effort to save running events on Griggs I have modified my event plan and refiled my marine patrol event request. I have withdrawn wakeboarding, wakeskate, and hydrofoil. My reasoning is that tow boats must pull skiers at 20 to 26 mph and make hard turns on a narrow public waterway. For that kind of event a marine patrol is necessary. However, surfing tow boats only run about 10 mph. At the end of the Griggs course the tow boat stops, recovers the surfer, and gets set to pull in the opposite direction. There is absolutely no need for a marine patrol for a wakesurfing event on Griggs. I therefore refiled the permit as a surfing only event and changed the date so that it was later in the season but would occur before Worlds.

I’m not optimistic that the Wakesurf Nationals marine event permit will be granted in Columbus. The Greater Columbus Rowing Association would like to have Griggs reservoir exclusively for rowing. While that’s a not likely to happen the rowers are complaining heavily about wakesurfing. By allowing a national wakesurfing event on Griggs the city may be seen as endorsing wakesurfing to the dismay of the rowers. I am investigating other venues for Nationals. Hearing Jeff and Jason describe that a Switch Blade Enzo works reasonably well in relatively shallow water opens up a few more venues. I wrote off Lake Erie near Cedar Point as too shallow. I wrote of Grand Lake St. Mary’s, Buckeye Lake, and Indian Lake as too shallow as well. There’s a festival on Grand Lake St. Mary’s at about the right time frame and a spot near the festival with excellent access and somewhat deep water. The Cincinnati River front by the Serpentine Wall might also be a possibility.

Lastly, even though I enjoy running completions and I appreciate the help that I get from my family, regular crew, the SBC, Jeff, the ASWA, and Roy’s family, I don’t want to run three competitions. I enjoy Surf and Turf events much more. They are easy fun and I get to surf more.

Ed, am I following your idea correctly on sliding the boat, kinda like cars with quad-steering? The rudder and the front fins are slightly angled and cockeye the boat?

Being able to move the switchblade not just up and down, but side to side would be key (by side to side I mean from 90 degrees to 105/75 degrees). I think this is the only modification needed. Think about it, if you rotate the mounting point on the blade to one side, it will do both pull the boat down and list it to one side. It wants to evenly thrust the water upwards and pull the hull down, this mod would just pull the hull down on one side. Well, that's my theory. I'll leave better designs up to engineers.

Back to our regularly scheduled program…

Jeff asked about slip. Take a look half way down this web page. Read the prop rotation discussion. http://www.boatfix.com/how/props.html

Here’s what uncorrected prop rotation does.



If there is slip the boat isn’t traveling straight the bow wake in front of one side of the boat is larger than the other side.

Here's a little hardware that I experimented with. I replaced my tracking fins with offset tracking fins.

I can set these tracking fins to a fixed +/-5 or +/-10 degree angle.

The result is.


Speed in MPH is shown in the upper right hand corner. There are no tracking fins in the RB figures. The C8 figures have a 5 degree angle

Joe, I’ve thought about your idea before. I don't think that you want to add another control to the SB. It would apply torque like the tracking fin experiment, but torque where the prop thrust is at might produce a geyser. Plus it would make a complicated device even more complicated.

One way to test your idea would be attach an adjustable arm from the swim platform transom mount to the SB. You could use hardware that is similar to manually adjustable wakeplate adjusters. Set the angle to just a few degrees off of straight. Then the diverter will steer in one direction the rudder in another the result would be torque on the boat altering the slip angle.

Edward, I have to say I am always impressed by your graphics. I'm far to lazy to put that much effort into it.
Oh, and useful information as a bonus.

Wow, Ed that offset fin really cleaned up your wake from 10 mph+ In wakesurf fin terms, you've changed just the toe-in? Interesting. I'd buy that product too!

Thanks Art. I've become a MS Power Point Engineer. I don't do any real work any more I just tell the story to get the work in the door. Telling stories with pictures is easier for me.

Jeff, I think a little slip control is good. I think the amount of slip needed differs with speed. My slip device is rather crude and not readily adjustable. Also, I think you can change weight placement given different slip. I think you can put more weight in the back with the right slip.

At the lower speed a large plume developed. I think there was too much slip. Again my device didn’t have any ruin time control.

I don’t tink I’d call this toe in. On your WP boards both fins are aligned to meet an imaginary point just in front of the board. The fin set up in the experiment above all point in the same direction off to the side of the bow.

One difference that a reader might have missed is that normally I run with out tracking fins. My hull has a lot of structure that helps it track straight. That’s great for skiing, not so good for surfing. The tracking fins straighten out the boat even more, so I removed them. DON’T REMOVE YOUR TRACKING FINS WITHOUT PLUGGING THE TRACKING FIN HOLES; YOU’LL SINK YOUR BOAT. My goofy wake is OK, with tracking fins in its impossible.

Ed- wow! You blow me away with some of the stuff you are doing. Just incredible! How cool would it be to be able to adjust the tracking fin angle from your dashboard? If you could license that technology I'm sure you would be able to afford that new boat you are eyeing.

I talked with Larry Mann yesterday again about his "Flow Rider" boat idea. You guys should get together on this and incorporate your adjustable tracking fins idea into the Flow Rider and that could be then next level of total innovation in wakesurfing boat design.

My working agreement with my employer prevents me from patenting any of my ideas. They are far afield of my work and so they are not interested in taking them any further.

I think it would be hard to patent over the Centurion Tru Tack patent. To my knowledge Centurion has not attempted to use the Tru Track as a slip angle control.

If you add too many wake enhancement systems it will be too complicated and expensive for a consumer. I'm guessing that the current Switch Blade is a $3,000 option. Add Side Swipe to that and now your at $5,000 in surfing options. These boats are already expensive.

I reviewed Larry's concept last year. I believe he's working with someone on it and so I'd prefer not to discuss it in an open forum.

Hey Ed,

Yes, all these options tend to add up!

I was only half joking when I mentioned you guys should get together as I know you and he keep in touch...

Anyway, I spoke with him about FlowRider again today. He said he's brewing up a website to showcase it soon.... stay tuned...

Does anyone know what Side Swipe runs?

Larry's a great guy and the FAE is really a great product. I love how quite the boat is with it.

Unfortunately FAE and the Switch Blade won't work together.

It was only an $875 upgrade, when I got my boat. I believe they will sell it but only to manufacturers for install in new applications.

That's not as bad as I thought.

Ed, backing up the truck for a minute. There is a constant debate in surfboard construction about the generation of lift by fins. Some argue Newton's third law, some argue Bernoulli.

http://home.comcast.net/~clipper-108/lift.htm

and NASA says - when you factor in viscosity you need to be familiar with Navier-Stokes Equations.

http://www.grc.nasa.gov/WWW/K-12/airplane/bernnew.html

I get to the second paragraph on these things and my eyes gloss over.

In the instance of the theorized "wedge" component of the new SB or as Drew is calling it the Surf Blade, is there a component of Newton AND Bernoulli in the function of the wedge? I do not understand Navier-Stokes at ALL.

In fin shaping, the argument goes - THICKER foils in small'ish waves produces more lift...which seems true.

Clearly the Malibu Wedge is Bernoulli. Clearly the old Switch Blade is a thrust diverter.

My guess is the Surf Blade is half Newton - every action has an equal and opposite reaction - and half Bernoulli - submerged air plane wing.

I'm off to take my 15.5 year old daughter for more driving practice. If I don't reply again it didn't go well.

I survived. I just read the two links. I've always thought that air plane lift was the Bernoulli phenomenon. Since the authors say that equal transport isn't accurate then the scooping Newtonian theory holds more water.

I'm not a mechanical engineer and I haven't formally studied fluid dynamics. I've looked at Navier-Stokes but as an electrical engineer I'd be more comfortable with Fourier and LaPlace. Unfortunately an understanding of Fourier and LaPlace methods don’t apply to lift.

So, if we say the Wedge and Switch Blade are both diverters, then the Surf Blade is the bi-plane wing of diverters.

However I have a new wake enhancement idea now

OK, Thanks to Jeff's post I think I just figured out what the Razor Blade is about. I also realized that guys at Pivotal have already done my new idea, dang it.

So why is the Razo Blade curved, anyone? I think they are taking advantage of the Coanda effect. Look half way down the page on the first link that Jeff posted.

I think they are using the Coanda effect to divert water up. Every drop of water that gets diverted up pushes the stern of the boat down. Hydraulic flow wants to follow a surface that it has been traveling along. If you take the flat surface at the end of a boar and gradually transition the surface upward the water will follow. All the water that flows the Razor Blade upward pushes the hull down. I think the Pivotal guys might be what we've needed for some time.

I’ve seen a number of Tige’ threads on the WW boats forum bashing the whole convex hull-TAPS system. The convex hull-TAPS system doesn’t get a lot of respect. Tige’ claims that other boats have a slight downward lip at the very end of the hull. The Tige’ hull is curved up. The Tige’ claim is that the downward curve makes other boats plane easier and stay one plane even though that not what wakeboarders want. Whether or not Tige’ knows it the advantage that the convex hull provides must be the Coanda effect.

does w when you don’t want it upward curve helps sink the hull in the water or at l. Considering the Coanda effect I think that’s an accurate claim. However, I think that the amount of the curve is quite small and mostly likely not as effective as the razorblade. That curve should

I think a hull that if a hull had a stronger curve than the Tige’, that hull would require less ballast. However that hull would always work as a wake hull and would not work well as a regular ol’ boat as well, i.e. high gas costs. I suspect that’s why the Tige’ hull has a small curve. The Razor Blade gives a more dynamic range of effect than a permanent hull curve. Again I’m really impressed with the idea. I can’t wait to see how the surf foil works.

Dang lot's of typos, sorry about that...

OK, Thanks to Jeff's post I think I just figured out what the Razor Blade is about. I also realized that guys at Pivotal have already done my new idea, dang it.

So why is the Razo Blade curved, anyone? I think they are taking advantage of the Coanda effect. Look half way down the page on the first link that Jeff posted.

I think they are using the Coanda effect to divert water up. Every drop of water that gets diverted up pushes the stern of the boat down. Hydraulic flow wants to follow a surface that it has been traveling along. If you take the flat surface at the end of a boat and gradually transition the surface upward the water will follow. All the water that follows the Razor Blade upward pushes the hull down. I think the Pivotal guys might be what we've needed for some time.

I’ve seen a number of Tige’ threads on the WW boats forum bashing the whole convex hull-TAPS system. The convex hull-TAPS system doesn’t get a lot of respect. Tige’ claims that other boats have a slight downward lip at the very end of the hull. The Tige’ hull is curved up. The Tige’ claim is that the downward curve makes other boats plane easier and stay one plane even though that not what wakeboarders want. Whether or not Tige’ knows it the advantage that the convex hull provides must be the Coanda effect. Considering the Coanda effect I think that’s an accurate claim. However, I think that the amount of the curve on the Tige’ hull is quite small and mostly likely not as effective as the Razor Blade will probably have.

I think if another hull had a stronger curve than the Tige’ hull has, that hull would require less ballast. However, that hull would always work as a wake hull and would not work well as a regular ol’ boat as well, i.e. high gas costs. I suspect that’s why the Tige’ hull has a small curve. The Razor Blade gives a more dynamic range of effect than a permanent hull curve. Again I’m really impressed with the idea. I can’t wait to see how the surf foil works.

That's interesting. In designing or shaping a board, you put "sharp edges" where you want the board to release. I would presume that water will wrap "around" gradual or soft curves, but will release on sharp edges.

Ed, my eyesight isn't what it used to be, but in the picture of the Razor Blade at the start of this thread, there appears to be a series of small tabs just before the apex of the curve. I can't remember the name of these things - Dennis would know, but I've seen them on the wings of modern day jets. What is their purpose here?

I’m only a few years younger and those pictures are darned shiny, so I know what you mean. It’s kind of hard to see what the shape is. One thing that Scott Adams mentioned is that the Razor Blade is controlled or actuated by Leno rams. The rams aren’t shown in the picture. I’m sure most readers figured that out.

On a modern airplane wing there are "winglets at the far ends of the wing. According to the first of your links the winglets improve efficiency by extending the effective length of the wing. The winglets prevent pressure from escaping around the end of the wing tip. I don't think that's what's going on with the Razor Blade tabs.

I don't have a good idea of what those tabs are doing. The important surface on a wing is the top surface. You never see anything attached to the top of the wing. Only one surface of the Razor Blade is in contact with water and it isn't really a wing. Also water isn’t compressible and as you pointed out above the viscosity is a lot higher. Air plane wing analogies might not be informative.

Your not always wakeboarding when your boating. It would be helpful to have a way to turn the Razor Blade off. Maybe those tabs help break the flow of water when the Razor Blade is fully retracted.

I think the Pivotal guys have a good understanding of hydro dynamics and I suspect the tabs are there for a good reason. Maybe Drew can get one to post online and enlighten us, or maybe they’ll want to keep things under wraps a bit longer.

Vortex generators They put them on top of the wings and on the fuselage.

Hey ED, just went to the National Arizona boat show and the centurion rep said the new blade will move left to right giving you the ability to sink one side more than the other. Not sure how reliable this info is.

I don't know. Sounds different than what I heard. The SB floats left and right. I guess we'll see more when it's released.