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Thread: Hospital Hop...how to stop it?

  1. #1
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    Default Hospital Hop...how to stop it?

    Newbie question for all you hydroplane guru's.

    My UL-1 starts a sponson to sponson wobble and sometimes gets worse and more violent until I have to let off. Some times it straightens itself out... but usually it doesn't.

    What is the cause and cure for this condition?

    Is this caused by being too light on the sponsons?

    Do I need more weight forward or more prop depth?

    BTW...I heard Darrel Waltrip (I think it was Darrel) talk about a car on the brakes too hard while getting into the corner too hot making the car hop up and out and hit the wall. He called this hop the "Hospital Hop" because that's where it lead too!

    I call the sponson to sponson wobble the same thing cause that's where your boat is going to end up if you don't let up.

    Thanks for the help guys...maybe I'll quit bugging ya someday....probably not though...cause we now have 3 of these new boats in the club and several more saying they are getting them....and nobody knows what there doing!

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    The first place on a Hydroplane that I suspect as being an issue is always the turn fin. Perhaps make yourself a STRAIGHT turn fin and give that a try. If the problem goes away, then you know where to start tweaking... Also make sure that it's aligned correctly, parallel to the centerline of the boat...

    I'm not a big fan of curved turn-fins... They can work great, but can also be a REAL headache until you get them just right...

    If that doesn't seem to cure it, then I'd look at the sponsons next... are they flat?? REALLY FLAT?? If you look at the pictures of my project boat, even though they appeared flat, a light sanding revealed some decent troughs down the center of the one sponson... This can cause the sponsons to suck down, then release, then such down, then release... Not good... MAKE THEM FLAT! Some block sanding and filler primer and block sanding again should take care of that for you... the other sponson on mine was REALLY flat, so just a little attention here needed... No need to go to the trouble of ride-pads if you don't mind taking the time to sand...

    Just my $0.02...
    Darin E. Jordan - Renton, WA
    "Self-proclaimed skill-less leader in the hobby."

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    It could also be caused by an incorrect angle on the prop. You want the prop to push the nose down (but not too far down). If the angle is wrong, it's going to lift the bow and force air under the hull. The air has to come out somewhere, so the boat rocks left and right to let it blow out the sides. An air dam prevents the air from getting under there in the first place.

    It could also be related to the design. If the air stays trapped under the hull too far back it will do the same thing. You need to allow the excess air to vent. This could be accomplished by removing the tunnel sides on the afterplane a little or by moving the sponson transom forward (that's the design solution, not the fix for something you already are driving).

    Another possibility is that the angle on the forward portion of the tunnel is too steep. This lifts the bow. On my designs I use a shallow angle and run it farther down the boat, resulting in a lower pressure gradient and smoother operation.

    Any chance you could get a video of it doing this? Some of it is normal - you might be seeing something normal and not realize it.

    Hope this helps.

    Andy
    Spektrum Development Team

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    There I go, ignoring basic setup tweaks again!

    I made the assumption that you had already tried various strut positions... Can't overlook the basics! (Like I seem to do from time to time... )
    Darin E. Jordan - Renton, WA
    "Self-proclaimed skill-less leader in the hobby."

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    Quote Originally Posted by AndyKunz View Post

    Any chance you could get a video of it doing this? Some of it is normal - you might be seeing something normal and not realize it.

    Hope this helps.

    Andy
    We don't normally have anyone taking pics except me and I don't have a way to take video.

    The "Hospital Hop" usually starts as a result of crossing my own wake from a previous pass. Once started...it usually, but not always, stays the same or gets more violent until I let off. When I ran with the air dam it still did it. The only difference I saw with the air dam was slightly slower speed...but this was a limited set of tests....3 runs with it on and 2 different props and strut settings. I will try it with the 40X57 prop 1/8" lower next run putting it at 1 1/8" from the bottom of the hull to the bottom of the strut measured with the boat on a flat surface, with out the dam.

    At what speed do we need the air damn with this boat?

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    Quote Originally Posted by Darin Jordan View Post
    There I go, ignoring basic setup tweaks again!

    I made the assumption that you had already tried various strut positions... Can't overlook the basics! (Like I seem to do from time to time... )
    Yes...that's one of my questions above...will more prop depth fix this?

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    It's not just depth, but also angle... I haven't run mine yet so I can't give you good answers... I've read to the effect that 1 1/6" of depth with a 3-degree downward angle works... I think that was Tony's setting (Properchopper)...
    Darin E. Jordan - Renton, WA
    "Self-proclaimed skill-less leader in the hobby."

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    Quote Originally Posted by Darin Jordan View Post
    It's not just depth, but also angle... I haven't run mine yet so I can't give you good answers... I've read to the effect that 1 1/6" of depth with a 3-degree downward angle works... I think that was Tony's setting (Properchopper)...
    Oh boy...I must have missed the angle setting part of this adventure!

    That poses new questions!

    Which way is down? Prop wash shooting down?

    What do you use to measure the angle?

    How do you orient the boat and take the measurement?

    Hey just how is this done?

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    Down means prop is thrusting downward... Front of strut is slightly higher that the back...

    The way I set a strut initially is to remove the rudder and turn fin, then set the boat on a flat surface. I set everything from there... Set your depth (1 1/16"???), then adjust your angle (raise the front of the strut slightly until you get 2 or 3 degrees??)

    To measure it... why not make yourself a shim from a piece of scrap wood... Sand it to the angle you want, then slid it up to the strut and set the angle...

    I usually just eyeball it... until I get it where it runs well... Then I measure it after that with a protractor...
    Darin E. Jordan - Renton, WA
    "Self-proclaimed skill-less leader in the hobby."

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    Thanks for all the great help here guys...one more question...if you had to guess...how far off the flat surface would the end of the strut (not propshaft) be @ 3 about degrees (in inches please)? or...how much air is there between the surface and the end of the strut....1/8" more...less?

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    .030" max (front of strut to table) is what I have read. Going over this setting may cause stern (rear) to hop...unless you bend your prop.

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    This is what fluid said to do and I have about the same setup but at maybe 2 degrees down and no hop. When I was at 1" and 3 degrees I had some hop.

    Fluid: My TP5000s weigh 9 ounces each, and I have no problems getting up on plane. Brian wasn't using light weight cells at the SAWs and his never subed. I suspect that the problem most guys are having is with the strut setting. Hydros are not like monos...
    The bottom of my strut came 7/8" below the hull and angled at most 1 degree down at the prop end. If you are having trouble getting on plane you can simply flatten the strut. You do not want to angle the strut any more or you'll never get on plane! A flat strut is the default setting; if the bow flies then angle it down a bit at the prop end. It won't take much. If the boat runs too hard on the water raise the strut 1/8". Several guys have e-mailed me about problems getting up on plane, and in every case a minor strut adjustment was all it took regardless of the packs used.
    Different props can cause trouble getting on plane too. Screw on a lifting prop combined with too much strut angle and you'll never get on plane. If you are using a lifting prop, flatten the strut. You may even need to run the strut up a degree at the prop end. "Best" all-around prop may be an m445 or K45. It will take some additional testing to find out for certain. The x442 is pretty small - doubt it has enough blade area to load the motor enough.
    BTW all strut adjustments must be done on a flat surface like a table. The hydro should rest on the sponsons and the strut. The strut angle will be between the bottom of the strut and the tabletop. Don't try to do it "by eye", it won't work.
    IMPBA 20481S D-12

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    Fealer gauge works great along with a flat piece of 3/4" MDF board. I attached three rubber non slip pads on the bottom of my 3/4 MDF setup board.

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    A feeler gauge I have...I must be getting tired...I dont know why I was thinking a gap at the back of the strut.

    Ok...now I think I'm ready to go to the barn!
    Last edited by Capt. Crash; 01-27-2009 at 03:58 PM.

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    Raptor has experimented with good success.

    Quote Originally Posted by raptor347 View Post
    Hey guys, I finally got my hands on a computer.

    The UL-1 really suprised me. I put an M445 on it for it's first pass, I flew it off and tumbled through the traps at 45mph. So I had a rough baseline. Next pass was with an M645 and 3/16" deeper on the strut, 52mph with a good ride attitude but still too light on the sponsons. 3rd pass was with a modified 2047 and a 1/2" deep tape air dam in the tunnel, 59mph pedaling it through the lights. Final pass was the same prop and air dam but 3/32" deeper on the strut, 65.7mph with a high 64mph return run. Temps on the final 2 passes were: motor 114F, ESC 126F, battery 109F (it had cooled down).

    Stock motor/esc/hull. I didn't even touch the sponson bottoms. Total mods from out of the box: remove turn fin and vertical fins, tape air dam, strut adjustment and a fairly trick octura 2047. I did run my Futaba FASST 2.4G radio.

    Then I put the turnfin back on with a 38x55 grimracer prop and ran 41mph for 8 minutes in rough water. I LIKE IT!!!

    After the SAW passes

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    Another thought is the CG a little too far back. I assume if you were to let it go it would blow over? Sounds like you are running on the ragged edge?
    Jim
    "Our society strives to avoid any possibility of offending anyone except God.
    Billy Graham

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    I've not had it try to lift.

    Here is the set up. 1 1/16" from hull to bottom of strut (table). Where do I measure the angle....at the end of the taper (yellow dot) fore or where the taper starts (red dot) aft. How does this angle look?
    Attached Images Attached Images

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    wow.. that’s a ton of strut angle..

    I use a digital level and a rod in place of the stub shaft the check the shaft.

    The hull over all is very solid and the numbers are good..

    Remember the boat had to work for all pilots..

    Andy.. just so you know.. and im sure you do.. to low or flat a break angle and the boat can blow off with 0 warning. .. personally I hate that.. I would rather have the boat wiggle or something to let me know something bad is about to happen. Gives one time to get her back on the water and FINISH THAT HEAT… very important.

    What I was going for was a 40 to 50 mph heat race boat.. Bottom line..

    Grim

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    o yea.. Capt. just so you know its called Chine Walk.

    ROCK ON and keep testing!

    Grim

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    Measure at the red dot using fealer gauge, but like Grim said...that is probably too much angle.

    Why do you have wire in the rudder adjustment hole? Do you run the boat with wire in that location?

  21. #21
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    racers,

    every time we start talking handling Brians post comes back regarding his SAW run..

    DO NOT EXPECT YOUR BOAT TO HEAT RACE AT THAT SET UP.. and please do not START THERE. I personly have NEVER ran the strut that deep.. as I go faster I might but to set the boat.. never..

    Start with the strut set where its at from the factory.. if you want to change it (and I recomend it depending on the prop) do it after the first few runs.

    Starters.

    Set the strut at 15/16"
    Set the strut flat on the setup board, I see you have the L40x57/3. Better yet lets start with the 40x52/3.. Just a note.. the L38x55 - 63 and the new L40x57/3 were designed around 0 strut angle.. having said this you MIGHT? have to cup slighty to remove some lift.
    Round or shapren the bottom of the rudder
    Set the turn fin so the top break is parrell to the foot print with your 15/16" strut height. My setup board has marker lines on the side of it for this.

    Test and report.

    As a side not.. I do not like turn fins that enter the water at an angle.. and.. truth is that is why the fin is the way it is. its a smaller version of my US-1 Ninja fin with a slight change to the LE..

    Grim

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    I should be able to report on the before & after results of Darin's ride-pad installation. Both to flatten out the surface & help re-inforce my turn-fin fix I did the G-10 thing today. I'll leave all other settings the same & should get some runs in Sunday & post.
    2008 NAMBA P-Mono & P-Offshore Nat'l 2-Lap Record Holder; '15 P-Cat, P-Ltd Cat 2-Lap
    2009/2010 NAMBA P-Sport Hydro Nat'l 2-Lap Record Holder, '13 SCSTA P-Ltd Cat High Points
    '11 NAMBA [P-Ltd] : Mono, Offshore, OPC, Sport Hydro; '06 LSO, '12,'13,'14 P Ltd Cat /Mono

  23. #23
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    Quote Originally Posted by detox View Post
    Measure at the red dot using fealer gauge, but like Grim said...that is probably too much angle.

    Why do you have wire in the rudder adjustment hole? Do you run the boat with wire in that location?
    My boat came with an almost flat thrust setting and it runs pretty nicely with the 40X52/3 prop at that setting (43mph)...but I couldn't get on plane with the 40X57/3 until I lowered the prop to 1"....now it "Chine Walks" a little too much for my liking.

    The brass rod is a thin shear pin. I keep the rudder bolt tight enough that the rudder does not move unless I hit something. I've had the rudder swing up to the shear pin after hitting sticks, buoys and a probable turtle but there wasn't enough force to shear the pin. The pin stops the rudder deep enough in this situation to allow enough control to get the boat back in. It's worked great so far. REMEMBER...I'm only sport racing here....and have among other things big mean Aligator Snapping Turtles to contend with.

    As for the thrust angle...I was thinking that the angle I set in the pic was not going to be enough based on the 40X57/3 prop with the 1 1/16" setting. Ya'll think it's too much?

    With it set here and no air dam it what should it handle like?

    oh...and exactly where should my CG be?

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    Quote Originally Posted by Grimracer View Post
    Round or shapren the bottom of the rudder

    So you don't want a factory fresh squared off rudder?


    Set the turn fin so the top break is parrell to the foot print with your 15/16" strut height. My setup board has marker lines on the side of it for this.

    Grim

    Can ya elaborate on this some more with a illustration?

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    Quote Originally Posted by Grimracer View Post
    Andy.. just so you know.. and im sure you do.. to low or flat a break angle and the boat can blow off with 0 warning. .. personally I hate that.. I would rather have the boat wiggle or something to let me know something bad is about to happen. Gives one time to get her back on the water and FINISH THAT HEAT… very important.
    Mike,

    There's a solution to that, too. Get yourself an original UL-1 and you'll see it. You end up with a MORE stable boat.

    Andy
    Spektrum Development Team

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    Andy..

    What?

    Grim

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    Wait wait wait.. i get it I get it i get it...

    Andy... How does that post help Capt. Crash.. Well.. it doesn’t.. It does not help him in anyway..

    So Andy what are you really saying with that post?

    Sounds again like just spuing info for the good of Andy and his master design the "Original UL-1"…. I detect a sore spot in there..

    Capt. Please just read through that stuff bud.. we will get your boat rocken. Yea.. its best to Always round or sharpen the bottom of your rudders.. just standard issue on my race boats.. ya buyem square and sharpen..

    Andy.. play this game the way you see fit.. I can tell you now however.. Im not the kind that’s going to comment on how your designs for Proboat work. Its just tacky and not all that professional.. especially when you work for a company (Horzion) that makes products that are in direct competition with ours. Im not going to do that to your boats.. but again its your head.. do as you please.

    ROCK ON UL-1 Drivers.. lets get some heat wins.

    Grimracer

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    Default ok......

    ....ummmm.....back to my questions at the end of post #23 please. And can ya show me what you mean about the turn fin setting with a pic or drawing.

    Thanks


    (I didn't know Andy is affiliated with Pro Boats)

    Youz guz need to duke it out with your products on the field of battle...not this thread please!

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    Quote Originally Posted by Grimracer View Post

    ROCK ON UL-1 Drivers.. lets get some heat wins.

    Grimracer
    Mike, there's EIGHT LSH entries so far at WW V [which allows UL-1's].
    Besides myself, only one other racer reports using a 2.4 radio so I'm assuming one or two UL-1's in the class. I'm pretty focused on doing the deal, testing & tuning my a** off . The driver lineup is all totally top notch excluding myself, but
    anything can happen
    [ BTW my VS-1 is poised & ready as well. 7 OPC entries so far also ]

    Tony
    2008 NAMBA P-Mono & P-Offshore Nat'l 2-Lap Record Holder; '15 P-Cat, P-Ltd Cat 2-Lap
    2009/2010 NAMBA P-Sport Hydro Nat'l 2-Lap Record Holder, '13 SCSTA P-Ltd Cat High Points
    '11 NAMBA [P-Ltd] : Mono, Offshore, OPC, Sport Hydro; '06 LSO, '12,'13,'14 P Ltd Cat /Mono

  30. #30
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    Quote Originally Posted by Grimracer View Post
    Yea.. its best to Always round or sharpen the bottom of your rudders.. just standard issue on my race boats.. ya buyem square and sharpen..
    Mike,

    That's so the bottom of the rudder doesn't become a planing surface, right??


    I should have noted above... I almost ALWAYS start out with my struts... all of my struts (monos and Hydros) flat... then tune from there... Otherwise, you can end up fighting a self-induced problem... Plus, it puts all of the thrust pointing in the direction it needs to be pointed!!
    Darin E. Jordan - Renton, WA
    "Self-proclaimed skill-less leader in the hobby."

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