SoCal Jet Boats
Discussion => The No Wake Zone => Topic started by: The Chaz on August 31, 2009, 11:35:22 PM
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I have been having problems with porpoising in my boat since I can remember. Seems to get worse the more weight that is in the boat.
The loader that is on it extends a long way beneath the bottom. I decided to take off the loader and see if this helps. Will I be able to get an accurate test result with nothing bolted up there, ie I replaced the bolts into the holes with silicone, but I dont have even a rock grate to bolt up to it right now? Could this even be the cause of the porpoising?
I also noticed when I removed it that one side is longer than the other...
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Im told my loader is diggin too deep although i did not porpoise , Im pulling it out and going back to a rock grate that im going to borrow..
you should atleast put something in the intake ? i would be worried running it wide open. But what do i know........
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No loader=bad idea. Won't help. Pump will unload too easily and could hurt the motor if you wing it too many times. First check the bottom, if it has a hook there's your problem. Other threads here can tell you the fix. Seeing in the pix you do not have a shoe and ride plate, my guess is your loader is too deep. About the one side being longer than the other, that's just one of the many variables you can have with a loader. Some one was just trying to load the impellor higher or lower for whatever reason they had at the time. Sounds like the loader might have been raced in the past. Which would make sence in a number of ways. First, racers try different loaders all the time doing unconventional things to them all the time. what doesn't work often gets sold, what does work often gets copied and sold. Second the loader would probably be deeper if it was in a race boat with a shoe and plate. They all work hand in hand. Finally you say it gets worse with more weight in the boat. I take that to mean more weight forward which when you think about it would help cause the nose to fall off at speed when the boat can no longer be supported at a higher angle of attack, hence porpoising.
SO... check the bottom for straightness. If not straight spend some time in the off season with your boat upside down, become one with a straight edge and put in a ride plate and shoe while your at it.
If not so bold and you think the loader is junk (might not be) cut back the leading edge 1/2" at a time and see if you notice a difference.
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Hay here you go! You two swap loaders and try it. It may lead to a solution for both of you. If not it adds to your knowledge of how your boat reacts to different setups.
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No loader=bad idea. Won't help. Pump will unload too easily and could hurt the motor if you wing it too many times. First check the bottom, if it has a hook there's your problem. Other threads here can tell you the fix. Seeing in the pix you do not have a shoe and ride plate, my guess is your loader is too deep. About the one side being longer than the other, that's just one of the many variables you can have with a loader. Some one was just trying to load the impellor higher or lower for whatever reason they had at the time. Sounds like the loader might have been raced in the past. Which would make sence in a number of ways. First, racers try different loaders all the time doing unconventional things to them all the time. what doesn't work often gets sold, what does work often gets copied and sold. Second the loader would probably be deeper if it was in a race boat with a shoe and plate. They all work hand in hand. Finally you say it gets worse with more weight in the boat. I take that to mean more weight forward which when you think about it would help cause the nose to fall off at speed when the boat can no longer be supported at a higher angle of attack, hence porpoising.
SO... check the bottom for straightness. If not straight spend some time in the off season with your boat upside down, become one with a straight edge and put in a ride plate and shoe while your at it.
If not so bold and you think the loader is junk (might not be) cut back the leading edge 1/2" at a time and see if you notice a difference.
I have to say I do not agree with some of this...
Not saying I'm right, but don't agree.
There are a lot of boats out there that do not respond well to loaders, that being said, there are about the same number that need them to run properly, it is a real hit and miss deal.
I almost always run a rock grate first just to get a baseline, then I have some "experimental" loaders to try and find a sweet spot...I have had two boats that overload the pum with any kind of loader at all..Three fingered rock grate worked killer. Can't explain it so wont try.
2Sav, I cannot tell from you bottom pic if that loader is deep or not, could very well be an optical illusion... :-\
A hook will never cause a boat to porpoise that I have seen, the pressure of a rocker can definately make things fun...
You may try to move some weight around and try a rock grate, your loader looks deep to me. They can be cut down quite easily and yes they should be the same from side to side.
More to come I'm sure.
GT
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I have to say I do not agree with some of this...
Not saying I'm right, but don't agree.
There are a lot of boats out there that do not respond well to loaders, that being said, there are about the same number that need them to run properly, it is a real hit and miss deal.
I almost always run a rock grate first just to get a baseline, then I have some "experimental" loaders to try and find a sweet spot...I have had two boats that overload the pum with any kind of loader at all..Three fingered rock grate worked killer. Can't explain it so wont try.
2Sav, I cannot tell from you bottom pic if that loader is deep or not, could very well be an optical illusion... :-\
A hook will never cause a boat to porpoise that I have seen, the pressure of a rocker can definately make things fun...
You may try to move some weight around and try a rock grate, your loader looks deep to me. They can be cut down quite easily and yes they should be the same from side to side.
More to come I'm sure.
GT
This is why im taking YOUR advice and borrowing a rock grate to start with.. So far no porpoising (sp) for me but i really didnt run it hard.
I have alot of testing to do, Im going to try it with the rideplate/droop and rock grate then without the plate and if it seems to have better handling then im going to a snoot....... ;D Im probably way out on this thing but its mine and it dont hurt to try :)
I asked the owner before me about tunning the pump and he said he just ran it so he has no idea and said the bottom was "blueprinted" but has no info on it
sooo.........i disregard that info ;D
The Chaz ,
Sorry for the jack, but maybe you should pick up a rock grate.. hell you can always sell it again ??? Good starting point i think.
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2 Sav...did you put a straight edge on it like shown in chaz's photo? His is to far below keel IMO. Over on pb when someone said that to ya, I was thinking how the heck could you possibly tell from that photo.
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2 Sav...did you put a straight edge on it like shown in chaz's photo? His is to far below keel IMO. Over on pb when someone said that to ya, I was thinking how the heck could you possibly tell from that photo.
No i have not.... I have to get the boat out of the corner of the garage first :banghead:
I been working on my truck sooo i shoved her in a corner for now and i thinks she's mad at me :sly:
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as of right now i am running a loader similar to chaz's loader...so far "2sav" no porpoise with diverter all up and foot to the floor! however i think it is more loader then motor to push it...as you can see it only has a 2 inch opening on it and i think it is hindering my rpms...i got a rock grate loader similar to 2savs loader that i am going to try! i'll get some results once i get off my lazy ass and do it!
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How much intake pressure do you guys think is too much? I see no more than 10-15 at cruise and 25 at wot, and that's on the upper tap. The lower one I never see more than 10. Without a loader the were both so low I can't even see how the pump loaded at all.
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How much intake pressure do you guys think is too much? I see no more than 10-15 at cruise and 25 at wot, and that's on the upper tap. The lower one I never see more than 10. Without a loader the were both so low I can't even see how the pump loaded at all.
This almost sounds like a deep loader (or the need of a shoe)....It really depends on the location of the pressure readings location (garbage in garbage out)...
I like to see in the mid 20's with it "to the wood", but have gotten by with high teens and low 30's, the rock doger did not seem to care at all (the RPM's would change sometimes without affecting speed).. :screwy:
I really hate getting too specific, different strokes for different floats ;D
I have a good rock grate if anyone needs to give it a whirl... :thumbup: It has probably seen 15 different hulls ;)
GT
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Well, I guess my question is will there be any negative effect using nothing. I doubt I can get a rock grate before this weekend...
The porpoising starts at plane and worsens with speed. Once it starts it will get progressively worse at the same speed. The ONLY way to stop it is to slow down off plane, increasing speed makes it worse faster.
If I am alone in the boat I can get a good high speed run if the lake is calm, again, waves can start the bouncing and once it starts...
I like the loader as far as keeping the pump loaded, NEVER had it cavitate at any speed.
It just seems like having something dragging that deep below the bottom of the boat might be somehow pulling the bow down
The center of the weight distribution is almost exactly at the the tires on the trailer as I can lift the tongue with 1 finger with nothing under the bow.
As far as the bottom, It is not perfect, but it is much better than it was last season, as I redid the bottom before I painted it and straightened everything. The porpoising did not change.
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Your loader was hanging to low in the pic you put up ...if you haven't cut it back, you need to. I don't see how a loader an pourposing(sp?) can be related. I do see how having your loader that far below keel, and having I'll handling could be related...
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Well, I guess my question is will there be any negative effect using nothing. I doubt I can get a rock grate before this weekend...
Not unless you forget to plug the holes and run in shallow water ;)
The porpoising starts at plane and worsens with speed. Once it starts it will get progressively worse at the same speed. The ONLY way to stop it is to slow down off plane, increasing speed makes it worse faster.
Sounds transom heavy, bring some burlap sacs and fill them with rocks under the bow... :thumbup:
If I am alone in the boat I can get a good high speed run if the lake is calm, again, waves can start the bouncing and once it starts...
Do you have a Diverter?, is it down when it tries to dry hump you? ;D
I like the loader as far as keeping the pump loaded, NEVER had it cavitate at any speed.
It just seems like having something dragging that deep below the bottom of the boat might be somehow pulling the bow down
Maybe, I dunno. :-\
The center of the weight distribution is almost exactly at the the tires on the trailer as I can lift the tongue with 1 finger with nothing under the bow.
Get some boat forward, it'll tow betta O0
As far as the bottom, It is not perfect, but it is much better than it was last season, as I redid the bottom before I painted it and straightened everything. The porpoising did not change.
I do not think you have a bottom problem, I think it is more weight distribution. ;)
GT