Adapting CC Hydrogate concept to 2004 ProStar 197

[swbca]

For years there have been discussions on trying to improve the large 30/32 mph wake on this boat. Talking about plates, trim-tabs, and hook-mods but I have never seen any results . . good or bad.

 

These results are preliminary, describing the first measured results before fully evaluating the net benefit to skiing.

 

See Image Below

The plate surface area is comparable to CC Hydrogate positioned across the width of the Power Slot indentation on the ProStar. The plate is shallower and longer than the Hydrogate . . the CC 196 has a straight-narrow tunnel down the center of the boat. The 2003 and later ProStar 190 has the hooked Power-Slot molded into the hull.

 

1/8" Stainless Steel plate projecting down 7/16" and 12" long. It looks un-even caused by photo perspective.

Measured Results

1. Top speed is reduced from 43 to 41mph

2. Requires additional 50 pounds of weight under the left side of love-seat to level the boat

3. Back of boat is 3.9" higher relative to bow at 32 mph (sine of delta degrees) x (20 feet)

4. Back of boat is 4.2" higher relative to bow at 30 mph

 

Can only guess that more than 50% of the hull attitude change is from lifting the rear, less than 50% dropping the bow.

 

Comments

Its the high pressure prop wash that is lifting the tail of the boat . . like the trim on an outboard motor or IO. Trim tabs that aren't behind the prop can change the shape of the wake at planing speeds but don't reduce the overall size of the wake. Must redirect the prop wash to create a net lifting affect on the boat.

 

Its apparent the affect of this plate would be different with different props and it could be tuned for the best affect with your prop.

 

Skiing first impression

The main wave is flatter than stock.

The "rooster tail" is wider, filling more of the trough behind the boat.

 

At 32mph 38 off, the wide rooster tail may create a larger bump but is still insignificant.

At 32mph 28 off, the wide rooster tail and the main wave are blended and less of a bump than stock.

 

More testing and adjusting of the plate will be done to draw a conclusion about the net slalom benefit.

Complete skiing results will follow in a week or so. I suggest you wait until then before drilling holes in your boat.

 

38 and 28 off skier position at wake - at 32mph

[GregHind]

VERY interested!

[BraceMaker]

How does the wake feel?

[SkiBadger]

@swbca - Enjoy reading your posts as I have the same hull. Could you post a pic showing how you attached the plate to the transom? Is the depth adjusable? WIll you try different shapes?

 

Thoughts on the effect at 22 off? Looking forward to read your thoughts about how it skis.

[swbca]

@BraceMaker It all depends on rope length. 38off is not an improvement because of the wide frothy rooster tail, but its no issue. 28off is an improvement. I suspect all longer rope lengths will be an improvement. I will provide an objective review when I find the best adjustment and have done good testing.

 

I am going to compare individual frames from skier videos at all rope lengths with and without the transom-plate to help make the best comparison.

[LeonL]

Top speed loss is to be expected as the Nautique HydroGate positions are: Slalom and Trick/Jump. Trick is self explanatory, jump helps to maintain jump speeds.

[swbca]

@SkiBadger I only have the picture taken before I rounded the bottom corners. Rounded for human contact safety and to get rid of the spray geysers that shot up from the square corners.

 

Used 1.25" #14 Stainless Screws. Was trying to get the screws close enough to the bottom of the boat so the entire screw length was in fiberglass. but the glass with thinner on the right than the left, so they are not fully imbedded on the right. (keep in mind the hull is cupped upward forward of the screws, so you don't want to get too low)

 

As you can see I first tried setting the plate lower (7/8" instead of 7/16"). It was way too much.

 

This is just an initial testing plate. If it works I will drill 1/2" holes and use thick SS body washers so I can fine tune the depth within the 1/2" hole. Will also start with a 3x12 plate instead of a 4x12 plate. #14 SS screws have a 1/4" outer diameter

 

Then when the final setting is determined I will set the screws in epoxy.

 

I ordered the steel plates from here because I don't know of any SS shops that want to screw around with hobby projects.

https://www.ebay.com/itm/322742802489

 

 

 

 

[klindy]

@swbca Do you have before/after pictures to see what the difference looks like?

[VermontSkier]

@swbca this is super interesting! I have a 2002 Malibu Sportster and while the wake is small, I would like to try this to soften it up. I know from your other threat you had a pretty big rooster tail and that seems to be flattening, but have you noticed the waken soften at all?

[swbca]

@klindy The before/after pictures will be done while testing before/after. Wait a week or so.

[DW]

@swbca - nice work. Slots work well for allowing quick vertical adjustments & allow some skew to balance the hull side to side, you could probably skew your plate side to side for balancing given oversize holes. Another thing to try would be to make the bottom edge serrated. Question - how were you measuring pitch angle?

 

@VermontSkier - adding chine along the sides will soften up your wake, not as easy a project as a gurney lip project.

[Windsurfnut]

Not specific to this project, but along the same lines...I wonder if you can further enhance this or any other hull with creating your own "wake tuners" or changing the shape of your plate, to help fill in the trough like the newer Nautiques. It got me thinking, on my SN196 that was originally equipped with 2 Pitot tubes for the speedo, that were folded up out of the way when Stargazer was installed, did the spray created from them change any of the wake patterns? The wake tuners on the SN's are not very intrusive.

Just thinking out loud..

[swbca]

@DW What would the serrated bottom edge do ?

 

 

The pitch was measure with a phone app. I taped the phone to the side window with the edge of the phone tight to the bottom edge of the glass frame. There was constant jitter of +- .3 degrees from the boat's mechanical vibration. I just recorded the middle of the jitter. Some accelerometer based apps have a jitter dampening setting but not the one I used. I repeated each measurement by stopping and restarting the boat and the readings were consistent. The pitch change with plate and no plate was 4.6 to 5.6 degrees at 32mph. A 4" change between stern and bow.

 

Sine of 1 degree = .01745 x 236" hull = 4.1" change in end-to-end boat attitude.

There could be an error of .1 degree in measurements or .4"

[ETskier]

So you manage to get your wake near perfect. That's great! Then you go to a tournament and get "surprised " by any of the new boats, particularly at 30/32 mph 22 off. May as well learn to get used to it.

[swbca]

@ETskier I don't care about the wake in tournaments. But I need a small wake for training because of double knee surgery caused by too much pounding behind one my earlier Correct Crafts. Don't want to take a year off again.

[dbutcher]

Do you need to consider the possibility that Correct Craft has a patent on the hydrogate? I don't know (or care) if it does, and I doubt that it would matter unless you go into commercial production. ????

[chrislandy]

@dbutcher I suspect this would not infringe any patents, it's just a (semi) permanent hull modification. The hydrogate is a moveable, "on the fly" wake adjusting device.

 

If they do have a patent on it, similar to the "other" issue with surf tabs - not sure how any of them got a patent on it when both are just trim tabs (the hydrogate is an interceptor type trim tab) which have been in boating for decades - they do the same thing and use the same parts either way but where the results are observed is different.

[DW]

@swbca - I assumed you might have used a phone app for that, thx. The serrated edge should be a less draggy option to lift the back of the hull. It gives more edge effect with a decrease in surface area. There may be tip vorticies that could cause some froth although it may also create an even flatter table surface. It will depend on water tip velocity. The interesting thing about fluid flow testing, one can always expect the unexpected...

[swbca]

@DW The plate is adding a small amount of lateral pressure on rear of the boat because its redirecting pressure downward from the top of the spinning prop wash cone. Would a small lateral offset in the plate position make any difference ?

[KRoundy]

Why wouldn’t you try something more like a trim tab?

[DW]

@swbca - yes, it simply moves the lift force laterally thus creating a moment around the center to rotate the hull a bit. Same as when a little hook is added on one side of the hull, a common practice when hull tuning was more common. There are examples I recall on this site although I can't remember under what threads.

[MISkier]

@KRoundy, I think the surface area of a trim tab may be larger than desired and may affect the boat attitude or wake more than just a simple shaving of the roostertail that is the goal. Nautique didn't do one and the success of the Hydrogate seems to bear out their design. But, it would be interesting to see what a trim tab would do.

[Ed_Johnson]

Interesting that the New Ski Nautique not only has the Hydrogate but the Diffuser Teeth that come down for different line lengths.

 

Surprised no one has added a fix plate with the diffuser teeth they can adjust for depth with screw slots to find the optimum position.

 

 

[DW]

@Ed_Johnson - I wouldn’t say ‘no one’ has added … ?

[Ed_Johnson]

@DW...Well if you know of "someone" who has added a diffuser plate could you have them share the results of their endeavor. Inquiring minds want to know !!!

 

 

[swbca]

CC Diffuser Plate Photo ??

Can anyone take a picture of the Correct Craft Diffuser Plate ? Tuning and Testing has always been the most interesting and time consuming part of competitive skiing.

[swbca]

@DW There is more pressure on the port end of the plate. I am going to try sloping the plate reducing area on the port end to center the effect the plate has on the hull. Then re-adjust height for best effect.

 

With the current position, there is more lift on the port side and the hull is ejecting the high-velocity wash left of center. The current asymmetry affects how the wash and wave blend back at the rooster tail. And/Or maybe this can eliminate the extra 50 pounds of steel shot under the passenger bench seat the plate requires to re-level the boat.

 

The shorter/deeper CC Hydrogate confines the lift closer to the center of the hull.

[DW]

@swbca - If I am reading correctly, appears you may have a conflicting issue to solve. Reducing the height of the lip on the port side will reduce lift as you note, which unfortunately will require more port side weight to balance the hull. You want more lift and less disturbance given your description, perhaps serrating the port side of the plate may help both. Prop rotation is not helping you in this case so maybe moving the plate a bit laterally could even things out. Have you checked the center of plate relative to rudder and prop cone?

@Ed_Johnson - version #1 still needs some tuning ...

[Ed_Johnson]

@swbca ... If you go to nautique.com, click on Ski Nautique, then click on Performance, and scroll down to Micro Tuners, there is a complete explanation.

@DW...Excited to hear that..Let us know the results of your progress. What worked and what didn't. Thanks

 

 

[swbca]

@DW I left a message for you. Thanks for your help

[swbca]

@Ed_Johnson

You mentioned adding a plate with the pointed diffusers like the Correct Craft. On the Correct Craft, I doubt if the plate supporting the pointed diffusers actually drops down into the water flow. I tried a pair of pointed diffusers on the center plate I have installed on my ProStar 197. They didn't do much because the plate, similar to CC Hydrogate, deflects the water flow downward, so the pointed "tabs" were not directly facing the horizontal flow off of the bottom of the boat or the prop. That's why I think the CC diffuser plate only acts as an adjustable mount structure for the pointed diffusers but doesn't get down into the water flow. I would be interested if someone knows if that's true.

 

It would be easy to add 2 pairs of the pointed diffusers to a boat with a single bolt through the transom for each diffuser. A slot in each diffuser could permit a manual vertical adjustment. A single #14 stainless steel screw (1/4" outer diameter) would probably work as well. Testing I did shows that the threads formed in the fiberglass transom by a large stainless sheetmetal screw don't deteriorate with repeated loosening and tightening a couple of turns to position a plate milled with an adjustment slot. Without testing, I have no idea if this would improve the slalom wake.

 

 

 

 

[DW]

@swbca - I believe you are correct, it is simply the two tabs or teeth that go in the water to trip the flow. Also, the CC micro tuners as they are called, are designed to trip flow in the dish hence no effect on the table. The center mounted hydrogate impacts the table.

[GregHind]

@swbca do you have an update for us?

[jjackkrash]

The "tuners" are basically 4 metal triangles that are on the sides (2 each on port and starboard side) and froth the trough on the side of the table. They make the transition between and the table and the trough smoother at certain speeds and line lengths. The hydrogate is a plate in the middle that goes up and down to cover two small rails on each side of the running gear. It is lifted up for trick and jump and down for slalom and will radically change the wake when deployed or not deployed and needs to be fairly precisely placed to get good results for the slalom wake.

 

https://nautique.com/models/ski-nautique/performance

[swbca]

@GregHind @klindy @DW

An update on the effect of adapting something similar to the CC Hydrogate to a Prostar 197.

The results are with a 110 pound driver and 100 pounds of shot under passenger seat.

 

The plate improves the slalom wake at 32mph - the only speed tested. The impact or dual impact at some rope lengths is reduced to a single impact and its a softer impact than stock.

 

The only skier testing to date is at 28off and shorter. The impact is softer but not dramatically softer. Its worth the effort to me because my purpose is to avoid a repeat of double knee surgery caused by endless training with early Correct Crafts with a large wake.

 

The best depth for the plate is 3/8" on the left and 3/16" on the right. The difference is due to the lateral pressure from the prop wash rotation that is partially deflected downward. The unequal left/right plate depth eliminates a ridge that forms on the right edge of rooster tail if left and right are at equal depth. The narrow tunnel on the CC196 hull inhibits the lateral pressure from the propwash when its deflected by the Hydrogate.

 

At 32mph there is a 4" change in the front to back attitude of the boat. The tail of the boat is lifted 2" by the plate and bow is dropped 2". At top speed the affect is greater causing the boat to plow with irregular spray and water noise coming off the front of the boat.

Top speed is dropped by 3 mph.

 

The blend of prop-wash and rooster tail is the same height (relative to lake surface) as the original triple rooster tail but is now a single, wide frothy rooster tail. The triple rooster tail without the plate is a double hit at 22 and 28 off. With the plate its a single bump that is softer because the left and right troughs are shallower so the drop from the lake surface is less and the impact face of the rooster tail is smaller. At 35 off and shorter, there is no wake problem to fix and no significant difference with the plate.

 

Tomorrow I will be spending time with a 2008 CC196 with a Hydrogate to see if there is more to learn and see if the plates have similar affects between the CC196 and ProStar.