SoCal Jet Boats
Tech Talk => Hulls => Topic started by: UltraRed on May 09, 2012, 07:59:28 AM
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Not sure if this is in the right section but was hoping to get opinions and advice. I have been out testing this week and found I have a really bad bow to tail bounce (porpous) at around 75. The pump is a split bowl with a place diverter and set back aways. There is also a ride plate. What i am wondering is if the ride plate is at a bad angle. I have tried fixing it with the diverter but had no luck at any angle. Would take pictures but i am at work. Any ideas or suggestions???
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I have trim tabs on my boat and it stops any porpus issue on the spot. Not sure if your boat and my boat have the same characteristics though.
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try adjusting in small dosses. but write it down ( like a log book) so you have a reference to work from.
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full down on the diverter didnt stop it????
do you have a droop?
do you have a loader?
do you have a shoe and how far below the keel is it?
do you have any wedges installed?
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Correct full down didnt stop it. Yes there is a drop. No wedges. Not sure about loader or shoe. New to me boat. The ride plate is at an upward slope. Dont know by how many degrees
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Know the pictures isnt great but its what i have on my phone
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Correct full down didnt stop it. Yes there is a drop. No wedges. Not sure about loader or shoe. New to me boat. The ride plate is at an upward slope. Dont know by how many degrees
Drop the ride plate to about 2 degrees below even. If you don't have an angle finder but have an Android based smart phone (who don't these days?) use this badboy... :thumbup:
http://bubble.en.softonic.com/android (http://bubble.en.softonic.com/android)
For I-Phone
http://itunes.apple.com/us/app/ihandy-level-free/id299852753?mt=8 (http://itunes.apple.com/us/app/ihandy-level-free/id299852753?mt=8)
The upward angle of the ride plate takes away anything for the pump to push against, this the bouncy ride...
Without a ridiculous amount of HP (700+), the ride plate really needs to be even, or in a downward angle.
I believe this is where your issue may reside.
My little boat at over 80 will completely ruin a set of board shorts when it starts to fly, it bounces from tail to nose. The cure was a major reduction in HP. I believe a shoe and plate along with a droop and maybe even an override pedal for the Diverter would have cured it, but a 100 HP horsepower reduction was almost free.... ;)
After all, we're all just broke ass boaters.. :sly:
Be safe and have fun (hows that for an oxymoron? :screwy:
GT
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Glenn, i dissagree.. start at 2*and work from there it could get nasty on shut down if he goes below 0* depending on the depth of the shoe...
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Well the idea of HP reduction would be great if I had that 700 to start with...
I was thinking that the plate need to come down as well but wanted some opinions... Then again i will have to check just how far the upward angle is now. The boat sits nose high in the water and feels like it is nose high at speed. Havent seen it from the outside looking in though...
Here are a couple more pics...
Glenn, i dissagree.. start at 2*and work from there it could get nasty on shut down if he goes below 0* depending on the depth of the shoe...
So maybe start from the upward degree and start going to 0*
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Glenn, i dissagree.. start at 2*and work from there it could get nasty on shut down if he goes below 0* depending on the depth of the shoe...
Maybe..... :-\ The only reason I went with 2 below is because of the amount of setback and location of the nozzle...The pump has a buttload of leverage on the transom, betting it will want to ride up on the plate, as far as shutdown, not sure it will come into play depending on shoe depth and inlet location....If the inlet is where I think it is, a rapid shutdown should be "exciting" but probably not too dangerous, much above the 75 MPH mark and it Jetaway territory for sure...
OP, best to follow Ralph's lead here and "inch it down", but like previously said, GPS and logbook it...Also never hurts to have someone video from the shore...
Thanks Ralph! :thumbup:
GT
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glenn, the only reason i say that is because at level on the hornet (set back pump) the shut down was really nasty at 80.. raised the shoe and put plate to 2* up and walla 4mph faster...
another thing you can try is wedging the droop down. while you are under the boat with a straight edge check for rocker. you may not have enogh hp to stay on it if you do.. if there is a big rocker you may have to ditch the droop all together...
hope this helps
ralph
you need to check for the shoe and shoe depth, you have set back pump and ride plate you it should be there
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my Nordic has stationary cav plates that are adjustable like the ride plate. Although I have no ride plate, I have a P.D., river racer loader, mini droop, and 7* wedge. at full up it porpouses only sometimes, mainly on glass water. when I played with my plates, I adjusted them up a few degrees to free it up and I lost MPH and it bounced very badly, brought them back down and speed and smooth ride came back and improved. It has been brought to my attention that my loader is hanging down too far and could be the coulprit of my porpousing problem. I am going to trim it tomorrow, and see how it does in Laughlin this weekend
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Took me some pics when i got home. Although its ugly this is what it looks like
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WOW that shoe looks deep. :o
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The absolute first thing I need you to do before that boat sees the water again is re-bolt that damn loader.....That thing wants to kill you dead.
Get some hardened hardware and through bolt it......There is one bolt missing and the others are just stainless steel machine screw...
Ever seen what happens when one of those breaks loose? Look up "ugly" in the dictionary and there should be pictures..... :thumbdown:
With that being said.... WOW that shoe looks deep. :o
Uhm, yeah. :screwy:
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Ok change the screws to bolts and replace the missing. (guess i should have looked under there earlier :banghead:)
What about the shoe being deep. I dont quite understand
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Ok change the screws to bolts and replace the missing. (guess i should have looked under there earlier :banghead:)
What about the shoe being deep. I dont quite understand
use grade 8 allen head bolts with lots of anti-seize and run them all the way through the intake and put nylock nuts on them..
dont worry about the shoe just yet, lets try the free/cheep stuff first ;)
what angle is the ride plate at?
do you have rocker in the hull?
you can remove the droop and try it, all this stuff is free :thumbup: and you get to go to the lake and test wich is another plus ;)
take a gps with you and make one change at a time...
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No idea the actual angle just yet. Just climbed under last night after getting home from work and snapped pictures. It is however an upward angle. Going to be changing the screws to Grade 8 allens as said. Then i will get the degrees figured out...
Thanks for all the advice already everybody :thumbup:
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http://www.fastenal.com/web/products/detail.ex?sku=1124258 (http://www.fastenal.com/web/products/detail.ex?sku=1124258)
;) :thumbup:
IMHO, and this may require lifting the engine up, drill the threaded holes all the way through the intake, put a dab of marine sealer around the bolts near the head and through bolt the whole ball of wax. I would use Ny-Locks (AKA aircraft nuts) but if you have the room (seldom do) put them in with standard nuts and then run an aircraft nut down on top as a jamb nut. It makes it easier to do...You will probably need an assistant either way.
The ramifications cannot be expressed enough if that dealio comes loose at speed. :sly:
Another little test to do when your out tinkering with the boat is to put a straight edge along the bottom of the boat from just in front of the intake preferably on the fiberglass and all the way back to the ride plate and note where there is contact, or how far things are from the edge (i.e. the intake just before the opening, the loader edges, the shoe, rideplate etc.). Put these in your notebook and keep them for reference.
That boat has had a major amount of mods done from when it rolled out of the factory, I would not be at all surprised if you need to "undo" some of those mods.
Good luck, in all honesty, I think you may be really close to having a badass running boat. :thumbup: :thumbup:
GT
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I believe you about the danger of what could possibly happen if it were to let loose at any speed but dont want to even imagine at faster speeds. I took Saturday off so maybe I can get started on everything then. Think im going to get the loader rebolted (correctly) and set the ride plate at 2* degrees. Maybe test monday and go from there. It has definately been modded since the factory. But i kind of wonder after seeing the few receipts he did have if the orginal owner started tinkering after the mods for no reason. What he did have was a couple Tom Papp, a GS marine, and a westec dyno sheet. Figured they would have had that thing perfect. Oh well thats what i get for thinking :banghead:
Hopefully soon this little red monster will go fast >:D
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when you have the loader out inspect it for cracks. maybe sand blast it and paint it white so if it crackes you will be able to see it
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So leveled the boat out and took a starting measurement. The ride plate was at 3*. Set it at 1*. Hopefully i can see what that adjustmet was worth come Monday or Tuesday. That is of course after fixing the loader issue :-[
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For shits and giggles I downloaded the leveler app and found my plate was 4* up. Adjustment prob not so critical on mine, but hopefully on yours you'll see a difference.
Sent from my ADR6400L using Tapatalk 2
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Well finally got the remaning screws out of the loader. Lots of :beer: quite a bit of swearing a few drill bits and eventually a torch :mad:. My buddy took it to work today to sand blast it for for me. Told him if they have any light colored equipment paint to shoot it for me. Drilled the holes. Think i can get it back together with the thru bolts without pulling the motor. Only time will tell.
Started out with only a ride plate adjustment to fix the porpous and get a couple more mph and quickly became a damn chore... Worst part is no water this week have to wait till next week to retest.
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Loader is now thru bolted in the hull... ^-^