Mastercraft Experiment

[eleeski]

My 04 MC rocks for slalom! It is the victim of Leeski engineering. Sometimes (like in this case) the mods really work.

First, the stock 13.7 X 17 prop was replaced with a 13.7 X 17.5 prop. The boat is a little sluggish out of the hole but doesn't seem to hammer me as much.

Next, a 3/4 inch hole was drilled through the hull just in front of the prop. The hole was tapped so a 3/4 pipe could be threaded in to keep the opening above the waterline. This opening to air allowed air to get sucked into the prop. Adding some air into the prop is an established racing trick (surface piercing propellers) which added efficiency to the prop - as evidenced by 50 lbs less skier weight on PP Classic to make times with the bubbles.

The coolest side effect is the softening of the wake. It is noticeable and quite nice.

I had a bunch of Washington state skiers spend a few days with me. They drink the CC Koolaid (can you add some sugar with that 200 batch, Jim Jones?) and were really bummed when they broke the 97 Nautique. But the  modified MC did not offend their delicate sensibilities. All of them skied great! And raved about how nice the boat is.

Now MC builds an excellent slalom boat in its stock configuration. Great scores and feel are possible behind the boat. But there may be a psycological bias against the boat - especially on this forum. If the physical differences do exist they are very small. But this small tweak of the boat is a discernable real improvement. It has made my boat feel as good as any CC I've ever enjoyed for slalom. And the trick wake is still the best out there.

Now there are a couple of downsides. On startup the prop slips a bit - it feels like wrapping weeds or bumping bottom just as the boat takes off. Minor but annoying and I have a couple of ideas to fix that. Also, Mastercraft has not evaluated or adopted it yet (note that Mastercraft has a great track record of making improvements retroactive so there is hope). I have to talk Stan into letting me drill into his pretty 08 ZO MC to try it there...

Eric

[robscholl-OF]

Eric,

You will have a 2010 MC for the BOW camp up here.  Now all you have to do is convince RD that it is a good thing to leave you alone with his boat.....OF  

 

[ForrestGump]

Eric, Did you try the factory prop with your aerator mod? Just curious.

 

I will say this. I was VERY impressed with the 2010 MC TT we skied behind this weekend. Nice and soft pull and soft wake. I liked it as much as the 200. Which is surprising considering it was my least favorite boat in 08 and 09.

[DW]

Well Eric, I first have to razz you on the mod because in a different thread you called me out on my weight reduction items!

Very cool mod, did you do an A-B-A comparison, I assume you can cap the pipe if needed.  Also, what line lengths are most/least affected.  Does it just suck from surface P difference or is there some protrusion from the pipe (similar to the crank evacuation systems that install in headers).  How far in front of the prop is the hole?

What do you attribute the bump or slip to?  I would think you might get by the initial aeration rather than have it right out of the hole.  You could add a throttle position activated flapper to it, which I assume you have already thought of.  Or like in F1, make it a cockpit controlled bleed like the F duct.  Run the hose to the cockpit and you can block it with you knee/arm/hand on startup, then release.  The F duct basically bleeds air to the "wrong" side of the wing to reduce efficiency (downforce) and drag, resulting in higher top speed.

[RichardDoane]

Eric sent me some pictures of his modification, here they are.  DISCLAIMER - I assume no responsibility for anyone drilling holes in their boat, and have no plans of allowing Eric to modify my new 197TT in any way !

[RichardDoane]

http://lh3.ggpht.com/_I-Kt0bXum5I/TAb5C1KFHeI/AAAAAAAAAbI/0OPp_mgdDpQ/s800/inside%20hole%20%28Medium%29.JPGFrom SilverStrada

[RichardDoane]

http://lh4.ggpht.com/_I-Kt0bXum5I/TAb5DHuNOVI/AAAAAAAAAbM/qlgJoOUHats/s800/pipe%20%28Medium%29.JPGFrom SilverStrada

[RichardDoane]

http://lh3.ggpht.com/_I-Kt0bXum5I/TAb5DdHX9aI/AAAAAAAAAbQ/Kz1CIV2TsS0/s800/placement%20%28Medium%29.JPGFrom SilverStrada

[Jean B]

I don't know Doane, those youngsters seem to perfer my MC2000 for tricking. :)

[Roger]

While I'm all for a soft wake and soft pull, the last thing I want to do is make my practice boat softer than the tournament boats (much rather it was the other way around)...

[eleeski]

Shane, I haven't tried the stock prop yet. It is on the agenda. Actually a priority as the cotter key wasn't trimmed enough so I soon have to work on the prop anyhow (the long cotter key picks up weeds).

DW, if the experiment really gets carried away, I want to put a V6 with a 2 speed transmission. That will lose lots of weight. And I do believe in light boats.

22 off is where I noticed it most. The WA guys felt it was softer at all line lengths - well they wouldn't let me run capped at 38 so I don't have data points there. I am personally skiing great with the bubbles - but the new longboy Leeski slalom might be a factor.

The slip might be from the edges of the prop hitting air. As the boat speeds up the air may be drawn more to the center of the prop - or at least spread out smoothly. A strut injector which allows the air to be sucked into the center of the prop might cure the problem. An easier solution might to have a longer tube below the waterline so there will lots of water sucked in delaying the injection of air until the prop is moving fast enough to not jerk around as much.  Hand delaying opening of the air eliminated the slippage. There are lots of solutions. The slippage is noticeable but only a minor annoyance.

Roger, the old setup was so difficult to ski that I didn't get a chance to try the line lengths I need to work on. The new setup feels like a sweet tournament pull - not Dr Michaels buoys easy. And if MC adopts this or a similar change....

Richard, I know where there is a drill - better not leave me alone unsupervised with your boat!

Eric

[Thomas Wayne]

Lee,

Your little hull-hole experiment is interesting, but not the wildest MC modification I've ever seen.

Now, if you're looking for a lighter boat with a strong pull you might consider trying the wildest MC modification I HAVE seen:

http://i115.photobucket.com/albums/n293/ThomasWayne_2006/twinscrewMC.jpg

Based on the inventor's results, the dual props add so much towing power I'll bet you could run your V6 and get as much oomph as the CC 200 6L (or more).

TW

[DW]

Eric,

I noticed you asked about mufflers on the ZO thread, are you looking to make/buy some?  The slip ins are available from several suppliers, you just need a 4" tube ID (they might also make alternate sizes) and are available from a couple of west coast suppliers and are pretty inexpensive ($80/pr.).  Basically, a perforated ss pipe with a diverter in the center.  You can also make some easy and cheap.

[chris carter]

I am on the MC tournament team and I have a heavily cupped prop which is from 80 thousands to 130 thousands and I get a similar soft wake, but slow out of the hole. It b rings the rpm about 200 down from stock and makes the zero off beast tame.

 

I love the hole and aeration idea, .....got me thinking.

 

chris

crc.coach@yahoo.com

[Steven]

with all that "SCHMEG" on the bottom of your boat, you'd think that would create all of the aeration you'd need! I'm just sayin'

[Jody_Seal]

Any one ever hear of rudder stall???

In short rudder stall is when a rudder has a pocket of air introduced around it's surface. The result can be many un-wanted conditions that the boat can get in to when rudder stall happens.

Eric please be carefull as you experiment with your idea. And please let me know if ever I ski with you that you let me know that this apparatus is on the boat as I will then know not to get in it!!

 

From a designers point of view and from one that has spent over 20 years building boats I would highly recomend not following Erics Lead on this.

 

Jody Seal

Florida Inboards inc. 

[RichardDoane]

jody - most of us who know Eric have learned to not take him too seriously......

[Jody_Seal]

Hi Richard,

I have known Eric for nearly 30 years we go back to the 80's skiing in north West Montana and we get together at Nationals every year. Eric is very creative and has some great Ideas, I just have experiance in the realm of what he is doing at this time and would like to have him around and not see him get hurt or worse or anyone else for that matter.

Introducing Air by or near  into the water flow of the the rudder is not a good Idea especially with the barrel sided MasterCraft. I have been involved with many a experiment while at CC doing such experiments especially hull pressure points while under power. I have personally induced rudder stall and Chine lock in test boats Both CC and MC and also some Malibu's. It can be a wild ride when these boats decide to go in a unwanted direction or plane or even upside down.

Just do not want to see anyone get hurt..... Or Worse!

 Jody

[eleeski]

Steven, it's my 97 Nautique that has the dirty hull. The MC lives on a lift so it stays clean - the lift is dirty though...

DW, I don't like to re-invent (or re-weld) what others do well. Plus I only own a small share of Stan's boat so he might not let me build funky mufflers for it. Hopefully he will let me drill the air injector hole.

Jody, wow. 

I did not post this idea publicly until I had a plenty of sets to assure that there was merit and safety. My lake is very narow - the turning characteristics did not change. My lake has lots of weeds to load up the prop and rudder - no different response to weeds. The first ski sets were in a very strong crosswind - fine handling. Big Charlie ran deep into 38 off - tracks fine. The only thing I can't test is the response to big waves - but it handles the backwash fine. The startup shudder is a minor annoyance - not a safety issue.

While I'm not a marine engineer I am qualified to perform and evaluate this modification. I'm not sure I'm impressed with ski boat engineering. Correct Craft built a horrible boat in the 196. Only a boat company with so much clout in the industry could have gotten that boat approved for tricks. And the promised fixes were ineffective. Ask Marco how good the engineering and testing is on the 200. One of my members had an old Malibu which would lock out and couldn't make the turn in my lake - it was almost as bad as the IO and outboard using the lake.

Engineering is not magic - my boat will not go wildly unstable. The real issue is if the effect can be noticed enough to do anything for your buoy count.

My motivation for this is to improve the MC slalom reputation. I want to get a new boat and I want it to be current for a few years. Lots of hype has been generated by the CC 200. Mastercraft hasn't changed their hull since they dialed it in quite a few years ago (why mess with a good thing?). A modification like this might re-invigorate the slalom excitement for new Mastercrafts (with the added plus that it is retrofitable to old boats). I am posting in response to requests from this forum to see how my crazy experiments work.

Jody's ultra conservative approach might be appropriate. Mastercraft might refine this more and come up with something better. You are totally on your own if you modify your boat (I offer no responsibility for what you do). You won't be able to resell it to Jody.

But my old MC was a crappy slalom boat and now it is a great boat. For me the experimentation is a success.

Eric

[DW]

Chris,  I hope all is well with you!  If you need some holeshot back, reduce your pitch by .5 or 1 and keep the added cup but that would bump the rpm back up a bit.  I did that to mine and it works great.

Jody,  I would think that entrained air prior to the prop would be evenly distributed across the rudder in the form of cavitation not a sizeable air bubble as the prop would emulsify the air.  Should act no different than cavitation, I would think.  I agree that any changes should be thoroughly tested.

I have to agree with Eric that the tournament ski boat builders are not blessed with enough volume to allow the use of many expensive tools to evaluate many changes virtually and thus real life testing is a significant part of the development of a new product.  I have noticed that there are several boats that actually appear to be attempting to entrain air down the hull surface to improve wake characteristics via directional chines and hull steps.

[Guest]

The fact that Eric is willing to drill big holes in the bottom of his ski boat is an indication of his financial situation and why we (IRS) are always watching him.

[skibug]

Chris,

 Do you cup the prop yourself or do you have a pro shop do it?  I have heard of people doing it themselves.  I have an 09 MC 197 TT at it is a train.  I am probably going to go down the road of adding cup to the standard prop which has an .080 cup already.  How much more cup should be added to get that 150 to 200 rpm reduction?

 Thanks

[DW]

Skibug,  I cupped my prop, actually have done both a ss and a nibral.  I added  about .060" cup to drop 200+ rpm, so I would add .040" or go to .120" cup for your application.  My nibral prop is an Acme, so that might make a differnece if an alternate brand.  I used a piece of pipe and a hammer to get the desired results.  Make sure you measure the cup with a caliper or dial indicator as a reference and remeasure when you work it.  The stainless prop is a major PIA to work nibral is easy.  The Mercury Marine site has some good info on it along with the Acme site.

[skibug]

DW, what size pipe did you use and where do you take the reference measurement from?  Is the ref measurement from the plane of the blade?  I understand what cup is; just not sure how it is actually measured.  the local prop shop said they would do it for $30.00 which seems pretty cheap and they are supposed to be the experts.  I might go that route.

[Jody_Seal]

If any that want to change the cup on their PS197 You might want to talk to Ray Crenshaw as he has been doing it to his promo boats for the last number of years. he can be reached thru the MasterCraft Promo program and is in GA. I am sure he will tell what cup he has been using.

[DW]

I recall it being about a 1/2" dia steel pipe or really double the radius you are looking for.  I used a straight edge across the blade and measured the trough from there using a dial caliper making sure the straight edge is perpendicular to the blade and 90 degrees to the center.  I also checked by going 2" from the trailing edge (Acme) since that is a straight line and having that point touch the surface of the prop and measure the trough, gives a double verification of consistency from blade to blade.  I marked the prop at all the points I wanted to measure to ensure consistency because the cup actually changes from root to tip of the blade.  Took me 2 shots to get what I wanted since I had no history to fall back on.  If you have a $30 local source, that is certainly a decent hourly rate, but in all reality it is not a difficult process if you like to learn or tinker!  I would certainly take up Jody's suggestion as Ray would certainly have the expertise and knowledge on how much to go or at a minimum give a great starting point.  The prop manufacturers, both of them, are also outstanding to discuss details with and will give great advice.  The Propeller Handbook by Dave Gerr is also excellent and worth having.

[eleeski]

I tricked last week with the bubbler open. Honestly, I couldn't feel the difference. Plus I learned a new (variation of a) trick. Cool.

Today, I changed the 3/4" PCV standpipe for a 2" standpipe. The air injector hole stayed at 3/4" and adapted up to 2". There was a lot more water in the standpipe so it took a bit longer to let air hit the prop. The significant rattle on startup turned into a little bump. Definite improvement but still not perfect. I didn't get a chance to ski it but everything else seemed the same driving.

Bill's 2010 MC at Paradise last weekend felt really nice - but the wake was a bit harder. (I had equipment problems or I would have won the BOS tournament - darn ski manufacturers.)  Strangely enough, Bill wouldn't let me near his boat with my drill. Actually, he wouldn't even let me wipe down the boat - "you can do the trailer". Maybe all that wax made the wake hard. Just a little hole in the bottom would take care of that pristine gelcoat...

Eric

[jipster43]

If you had a brand new 190/197 would you be performing this mod on it? How accurate do you have to be in your measurements to achieve the desired results? Do you think you would be seeing dramatically different results if you were up/back 1/16 of an inch?

 

I'm just curious, but it sure sounds like a pretty awesome modification. You have way more cajones than me!

 

JP :)

[eleeski]

I am looking to get a new boat soon. I will absolutely cup the prop of the new boat.

The only reason I wouldn't drill the bubbler hole is that Mastercraft might adopt the idea with some slight variations - I'd like to have the stock setup. If no factory specifications are available, I will definitely drill the hole as tested. I haven't played with any movement or resizing of the hole but since the effect is subtle, I can't imagine it being sensitive to small changes.

A lot of talk goes on here about how nice the CC pull and wakes are - especially compared th the MC. My old 2004 MC was a very unpleasant slalom boat - even with PP Classic. After the mods, this same boat is as friendly a pull as ANY boat I've ever slalomed behind! Well, maybe the 79 American skier...

There is no way fear of a tiny hole in the hull killing value of the boat would keep me from a modification that removes a slalom disadvantage. Just add the cost of the gelcoat repair to the cost of the bubbler.

Eric

[RichardDoane]

Eric - as soon as we make a deal for your 2010 MC, you can get the drill out !

[MCskiFreak]

All,

 

This is an absolutely crazy mod to make to your boat! As a Naval Architecture student/avid water skier I can categorically tell you to NOT make this modification to your own boat! This guy is introducing air in an area that you never want to, between the prop and rudder, there is a very valid safety concern with doing this. Not only is he aerating the prop (the slip and vibration is caused by this) which would reduce hole shot performance, and eventually damage the prop; he also risks rudder stall which on a tight lake could prove disastrous!

The engineers and Naval Architect at MasterCraft are not stupid people, and without a doubt already have a much better solution figured out

[RichardDoane]

Eric just likes to tinker, what amazed me was how well his ski turned the day he let me ride it.  Although, it's bindings broke soon after, I guess it wasn't used to going that quickly from side to side with the shorter line lengths.

[eleeski]

I have a BSME from Stanford. I have sold ideas to industry. I have experience with high stakes modifications (aircraft modifications which got 337 certification) and low stakes modifications (the Fourvette and the Shrimp automobiles). I have reengined boats (2 liter BMW engine in an old Nautique) as well as significant maintenence of my ski boats. Oh yeah, I build my own National winning skis. I am uniquely qualified to design, test and develop innovative ideas.

I am not introducing air between the prop and rudder. I am introducing air in front of the prop. Since a ski boat prop is cavitating there is a significant amount of air (actually water vapor) already coming off the prop. Introducing air in front of the prop means that the introduced air replaces some of the cavitation generated air. There are no large bubbles evident in the propwash nor is there any buffeting of the rudder in my boat. Testing has proven the suitability in a tight lake. And the wake is a bit softer!

Race boats (that win) are using surface piercing propellers. Mixing air with the propellor is a proven, safe performance enhancement in a marine environment. Categorically ruling out established techniques is not the best way to improve performance.

Ski boat engineering leaves a lot to be desired. An old Malibu on my lake chine locked and wouldn't make the turns at speed. Correct Craft cannot seem to make a good trick wake. Mastercraft does have excellent designs. With my modifications the slalom pull is as sweet as CCs best - with a great trick wake!

Eric

[kdeupser]

MCskiFreak, as a MasterCraft owner I must side with Eric.  I have been reading his post's for awhile now and I like his logic.

You must have never skied behind the 98' MasterCraft 190's.  What a piece of crap of a boat.  You want to talk about crazy engineering, in 99' they put that stupid wing on the rudder to try and help the pathetic thing, that didn't work so well so they put jetski sponsoons in the spray relief's.  That didn't help much either.....would you call that "quality" engineering?

My boat is a 1995 ProStar 205.  This rudder stall you speak of, I know exactly how to cause it on my boat.  Unfortunately we found out the hard way.  We came within inches of beaching my boat with me skiing behind it.  If my driver hadn't reacted as quickly as he did the boat would have been a gonner.  All you do is simply put people in the open bow of the boat and drive it around a turn island while pulling a skier.  It will lockup every time.  Did MasterCraft own up to this design flaw?  Nope.  Did they do a recall?  Nope.  Does it still do it to this day?  Yep.  There have been articles where people have ran over there passengers from this design flaw.  Solution, don't use the open bow while skiing.  Amazing solution huh?  Don't use the boat as it's designed basically. 

I'm sorry, but the boat companies are in it to turn a profit period.  If they have a bad design, they just milk it till they can slowly design it back out.  It just cost's to much to really be proactive.  And as far back as I can remember, recalls are only for automobiles.

I am really curious of the bubbler idea, my 22' off bump is killer.  We have talked about putting more hook in the hull(bondo & gel coat), but the bubbler would be way easier.  Heck, I already had to drill a hole for the paddle wheel(thanks perfect pass).  

Eric, I have a tuning idea for the bubbler.  What if instead of just a hole you make a long slot if you will.  Then inside the boat have a plate with your hole that you could slide back and forth?  This would basically adjust/move/tune the hole to the optimum position.

Lastly, my 95's spray at 35' and shorter is killer as well.  Got any idea's?

Interesting ideas, Thanks all,

Ken D.

[ForrestGump]

Ken, Actually you can get just about any open bow inboard boat to chine lock with people in the front. When you weight the front like that you cause the boat to rotate around a position in front of the skegs. Which it does not do well. In effect, you have skeg stall, not rudder stall. You can make a SN206 do it too.

[kdeupser]

Shane, then this proves it truly is a design flaw.  The tournament boat design in the open bow flavor should be re-designed. Or at least the models that chin lock.  And experiencing this myself, it IS a rudder stall as well.  Since no matter what input you induce through the rudder the boat will not turn.  Yes, the skegs are slipping during this event, but the rudder is ineffective as well during the event.  The only solution I know to work is to back off the power, then the rudder will function again once speed decreases a bit. 

I am aware that many other brands do it as well, but I really didn't want to come off as all that.  I own one of these boats, and I am speaking from first hand experience.  Heck, come ski with me and we can duplicate this wonderful experience.

I applaud Eric's efforts and his willingness to share his experiences with us.

[ForrestGump]

Ken, I believe you. I've seen it before in a couple of boats. Have you ever driven an American Skier Elan, circa 2002-03? You don't go around a left hand island in THAT thing! it'll be interesting to see if the 200 will do it. 

[Horton]

http://lh6.ggpht.com/_4-6ay9R-bLE/StNCsqMUWYI/AAAAAAAACQ8/dFASOycrEK8/s400/DSC_8874.JPG

MCskiFreak,

Above is a photo of Eric explaining his slalom ski to Dave Goode. We all sort of love Eric like a crazy cousin. I no longer tell him he is crazy. He knows I think so.

[MattP]

Dave's facial expression looks like he is having a hard time wrapping his head around Eric's ski designs. (I bet Dave thinks he belongs in a crazy house)

[jipster43]

This has been my favorite interwebs thread ever.

 

JP :)

[Jody_Seal]

Thats what happens when you spend way to much time in the desert sun!! I do wonder what is going thru Daves mind. Great picture.

[eleeski]

After talking with Aarne Clow at Nationals, I had to drill another hole in my boat. According to Aarne, the cross member near the prop is not structurally critical. So he said to go ahead and drill through it. So I did. I drilled a new hole 8cm (3") forward of the last hole centered in the cross member. It wasn't easy as it was solid rubber (sound dampening?) inside the glass but I was able to get through. The biggest drill I had handy would only allow a 1/2" pvc pipe through it. So not quite as much air could pass. But enough to see an effect hopefully.

The slippage on startup went away. But so did the speed efficiency gain. Air was still getting sucked into the prop - there was suction on the pipe. I didn't get to ski behind it (no cracks from Jody about baking in the heat without being able to even get a ski ride) so the final verdict will have to wait. But I was surprised to lose the speed effect by the placement of the air injection. The other hole on top of the prop may have simulated a surface piercing propeller. It will be interesting to feel the wake...

Eric

[eleeski]

Got a couple of slalom sets with the forward bubbler. The wakes were OK - they didn't seem as soft as the over prop bubbler but a rock hard edge wasn't there either. I used the weights from the over prop bubbler for PP Classic and ended up in time but just a bit softer - so some of the efficiency effect was still there.

The wakes seemed smaller for tricks but we were skiing without a third. Despite the extra battery in back it was a bit small. Closing the air was barely discernable though.

The forward bubbler was a very subtle change. No issues with slippage on startup and fine handling. But I wonder how much of an effect it really made. I slalomed well - but I radically changed the setup of my ski. Needs more testing!

Eric

[DW]

The volume change from the hole size difference is actually quite a bit, I assume that would be part or all of the difference.  I wonder if the bubbler is actually reducing the negative pressure on the warped deadrise that these boats have when underway.  It would be interesting to see if you could measure any pitch attitude difference.

[eleeski]

The effect is very subtle. There is no change in boat attitude that I can see. Perhaps a careful measurement might reveal something but how I weight the boat makes a much bigger difference - one that I can see. I do change weighting a lot - removing the batteries for slalom and adding them for tricks. 

The wakes when aerated don't seem to change much in size or shape - they just get a bit softer. Maybe it's the rooster tail I'm feeling. Which makes sense if that is getting air added into the rooster tail, it will feel softer without showing much of a change.

The hole size idea might be a good place to experiment next. I'll keep you posted!

Eric

[aguylikeshark]

Doesn't make sense to me to be adding mush to the prop when our IB's are high speed tug boats with a mission to pull and pull well. True, part of the wake reduction of the later CC's is getting the wakes all foamed & bubbled up - and shifting the weight around (tank, cockpit forward etc.). Now the 200 spread the girth over a wider area to reduce the dent in the water. That is one of the reasons I like the TSC1 wake it's a really clean, pure wake - not all junked up. Sweet hull for sure. CC's are typically lighter than MC's.

 

The biggest issue wake issue easiest to tackle is junk in the boat. The harder I am looking the more I see a lot of unnecessary weight. The deflection or dent the hull puts in the water = wake. Reduce weight - reduce wake it's that simple - one for one.

 

Here's my list so farBack seat (out complete) 50lbs (?)Floor Panel (Carbon) 25lbsSwim Platform (Carbon) 25lbsBattery - Smallest Size 15lbsGlove Box Lid (carbon) 8 lbsStuff (anchor, extra gas, tools etc.) 45 lbs Current Total =- 168 lbsDriver's seat - heavy sucker Passenger Seat (not too bad)Motor Box ??Heavy - (Carbon would be cool - but helluva project)I don't understand why small hydrofoils are not implemented to provide some lift and tracking improvement for the front and rear of the boat

[eleeski]

Shark, waterskiing is more than just slalom. Tricks and wakeboarding need big wakes, slalom needs a small wake and jump needs a ton of power to the skier. Reducing weight will improve a slalom wake and make the trick wake worse. Since ballast is easy to add, you are right - a light boat will be a better boat. But a good compromise onthe wake like the MC wake will not be the perfect wake for slalom. Softening the slalom wake is a worthy goal - especially if it doesn't hurt the trick wake (or is easily disabled).

The CC 196 wake was atrocious for tricks. That boat should not have ever gotten approval as a three event boat - the trick table was that bad! The 200 is better but a far cry from the MC trick wake (or even the trick wake on my old 97 CC).

Malibu has the wedge which is cool for tricks - oh wait, AWSA won't allow it. But the hydrogate is legal??! Your idea about trim tabs and foils is technically valid but politically random.

Mushing the slalom wakes was my exact intent with this experiment. The mush does seem to soften things up. But the efficiency gains with the air injection was very intriguing. Mushy but stronger.

Eric

[skibug]

Much like the hydrogate, if the experiments are successful and technically valid/justified; it wouldn't have to be a permanent situation.  It could be something that is just employed for slalom with the flip of a switch, to softem the wake; but disengaged for trick, jump, etc.  It seems as though this could be applicable to all boats in some sense. 

[aguylikeshark]

Mush to the wakes great. Mush to the propulsion unit i don't think is a good idea. If air under the hull is what you are after here is an idea i thought of last nite - using the exhaust manifold drain ports to pipe (stainless steel - two into one) some exhaust under the hull using the drain plug hole for the boat. Nothing permanent. The engine is a big air compressor anyway.

 

I had Bennett trim tabs on my SN 2001 to reduce the wake. That boat was too narrow but the tabs helped a lot. I had two switches by the throttle could adjust level etc. it was pretty cool but purists had a problem with it. Cost me about $1000 shipped/installed

[eleeski]

Skibug, I was going to quote the rule that prohibits trim devices - but I couldn't find it! Maybe boats can now have movable trim devices - which would be a great thing for all skiing disciplines. Maybe I didn't find the stupid rule. It used to be a rule.

Shark, you're backwards. For slalom, once the rope shortens a bit, you are inside the wakes. Propwash becomes a bigger factor. Soften the propwash and the slalom gets better. It is the rooster tail that draws the biggest complaints.  Mushy wakes makes tricking bad. Tricks just bounce in the propwash - a softer propwash should give a better table.

The holes I drilled require no moving parts. The aeration is sucked in from the low pressure generated by the prop. Clean and simple. It gives some of the benefits of a surface piercing propellor (proven advantages for race boats) without many of the drawbacks. And we can feel an improvement in slalom. The experiment isn't over - the experiment is part of the fun!

Eric