help with 03 ultra cavation

[out of bounds]

need help. my ultra cavatates really bad when turning @ low speed . the jet is set back also has a loader grate in it. I do not have a ride plat and shoe set up in it but there is a place deverter. I can barley touch the gas when I drop a skier. I wonder if the suckition pice isn't sright or is there any body ealse had the same problem with there 21 open bow ultra

[Dan Lorenze]

John, Yes.... My boat cavitates too, pretty bad actually... My old jetboat that I had for 16 years never did this, the freakin thing turned on a dime, my Ultra's turning has me a little bummed. I would love to hear from some of the peeps about this. It cavitates more when there's 4 or 5 people on board. Also, if I have a few people in the bow area it doesn't want to turn at slower speeds just above plane, I have to pin it hard just to make it move a little bit..
Since my boat has a hydraulic place diverter it's hard for me to tell where I'm at with the trim but I've recently raised the pump on its most down position thinking it's been shooting down too much.. I'll see if this helps.
The set back Dominator feels drastic to me, the boat really sits on top of the water to the point of it feeling very loose to me. With the boat shooting anything over a foot it becomes a handful to keep it straight...
FYI, my boat is an 02 21' Stealth, 502 415hp Dominator 12s, I haven't done anything to it..

[BowTie Rick]

I have an 01 LX... it cavitates in reverse only. Gets a little loose around 55+ but I don't have a set back, just a droop and hydralic place diverter so it runs much wetter than yours. Most of the time I am not at high speed so its not a big deal.

[out of bounds]

I wonder if the bottom of the boat was designed to run stern drives. it almost sounds that the keel is way rounded and to far back . That could be why the boat feels loose. My buddy bought a shouckwave and that thing has a 502/ 502 hp with no set back and he does not have any problems. But my little 454 walks away from him . I have driven drag boats in my younger years and have been around boats for a long time and this thing almost feels like a drag blown fuel jet boat. Wild but @ a much slower pace. do you think that the pre-impeller would help? Do you know any body that has put one in and ran it?

[Dan Lorenze]

do you think that the pre-impeller would help? Do you know any body that has put one in and ran it?
I think the problem is that the pump is not in the water, regardless of what impeller is installed. (I could be wrong) Do you know what impeller you have? I'll check mine.
Curious, when this happens to you are there people in the bow? Have to tested the boat with just yourself and another?

[flat broke]

Something for you guys to think about... setting up a boat, be it for 100mph, or 10mph comes down to ballance and orrienting the hull to the water properly. When you throw a couple people ( and most guys are know are around 170-200lbs these days) in the front of a boat you are drasticly altering the ballance of the boat. When you're at either end of the speed spectrum, this change in ballance becomes more noticable. As an example, I weigh 250lbs, in my brothers boat, moving me from the front passenger seat to the rear bench is worth 2mph at WOT because the weight transfer allows a little more hull out of the water. Now imagine what moving 340-400lbs a lot further forward in the hull (as you do with putting people up front in a bow rider) can do to the handling of your boat. Complaining about handling when you're shifting your load around is kind of unfair to the boat mfg; When you change the boats ballance point, you as a driver need to be aware of how that will affect your job at the wheel. If it were me, the first thing i would do is call John at Ultra. It's his boat, give him first crack at helpin ya out. He's done more than a couple of jets and probably has tons of first hand customer and personal experience with different setups to point you to a possible solution based upon a very good apples to apples type comparison.
Good luck with it,
Chris

[sdpm]

Remove the loader grate and install a stock one and try it again. The ramps on the loader will block water off when turning and some loaders will actually slow some boats down. It's worth a shot.

[sleekcrafter]

Along the same lines if your not going for all out speed, you can afford to haved the loader hang down a little more to keep the pump fed.
Sleek

[TAYLORCHET]

Have you heard of DONS PUMP in columbus ohio he makes a cavitation reducer for jet boats and it does a super job. I recomend him highly. He advertises in HOT BOAT check the web sight for vendors. I was cavitating so bad I was going thru a impeler every season have not replaced one since I installed the reducer and oh what a hole shot! :220v:

[LGCDEVIL]

Have you heard of DONS PUMP in columbus ohio he makes a cavitation reducer for jet boats and it does a super job. I recomend him highly. He advertises in HOT BOAT check the web sight for vendors. I was cavitating so bad I was going thru a impeler every season have not replaced one since I installed the reducer and oh what a hole shot! :220v:
Inducer

[out of bounds]

has any 1 run an inducer on one of the bigger jet yet? and if so had did it work out. I spent the week end on the water with stock intake in and it did not help. I have to rember that I gave up my day of wrenching all day on my boat at the lake. I just want to know if i there is a fix to this ? has any body had the same problem and over come it??? love my boat and I think that ultra builds a top notch product and just trying to make mine better.

[ultra tweaker]

I have a 2000 21 xt open bow, love the boat but it cavitated on me also when it was new. I had Jack at mpd in Costa Mesa Ca. put an inducer on it and I love it. It really improved the hole shot but the boat from Ultra had a lot of hook in it and the hook was uneven, made the boat pull violently to the left. Talked to John and he said I was putting to much horse power to it, it was a family boat? I had Jeff Bennet work the bottom and it rides awsome. Right after I had the bottom repaired I had a flat loader grate and it almost completely blocked the flow so I had Jack make me a custom loader which works great also.

[jbone]

I wonder if the bottom of the boat was designed to run stern drives. it almost sounds that the keel is way rounded and to far back . That could be why the boat feels loose. My buddy bought a shouckwave and that thing has a 502/ 502 hp with no set back and he does not have any problems. But my little 454 walks away from him . I have driven drag boats in my younger years and have been around boats for a long time and this thing almost feels like a drag blown fuel jet boat. Wild but @ a much slower pace. do you think that the pre-impeller would help? Do you know any body that has put one in and ran it?
I've got a 2005 21 ft Shockwave with the 502/502 package with a fully set back jet. I do have the Dominator 12S Pro pump. Absolutely no cavitation at any point, that I can notice anyway. I also have the inducer, but that came with the boat, so I don't know if it helps or not.
I'm curious what speed you and your buddy are getting for you to walk away from him with much less hp.
By myself, down river, with the bimini up, 40 gals of gas, I get 67 mph on GPS. That took me a lot of playing around with the set up though.
J

[ultra tweaker]

My boat is the XT hull and I am running a 509 solid roller motor with pro topline 320 heads a berkeley 12jg pump with a droop loader and hyd. place diverter. It ran 65 up river with 40 gallons, full ice chest, bimini up and a roll away worth of tools under the engine cover. I am going to play with some wedges to make the boat launch harder. My boat will shoot a huge rooster but the down trim is minimal and I think a down wedge would help.

[RandyH]

Don Bowers RIP
Fully loaded (5+ people) the rev limiter will hit from a dead stop. But with just a few people, cooler and full tanks, the inducer works. No Cav. B cut SS, MPD, loader, droop, 540 solid roller motor, NA.
RandyH

[out of bounds]

my buddies shockwave doesn't have the set back jet or any thrills as far as that goes and he can only get 62 max with his wife and min load. I keep telling him that some thing is wrong with it. I want to change the carb and try to wake it up a little. my boat runs 67 on gps with an A impeller and very little work done to the motor. Also how bad is the flow on these hardan marine mainifolds???? I am going with that inducer this winter because we use our boat 2 to 3 times a week and can't go with out going to the lake.Also how do post photos on this site it's killing me to see all of bitchen boat out there.

[SmokinLowriderSS]

my buddies shockwave doesn't have the set back jet or any thrills as far as that goes and he can only get 62 max with his wife and min load. I keep telling him that some thing is wrong with it. I want to change the carb and try to wake it up a little. my boat runs 67 on gps with an A impeller and very little work done to the motor. Also how bad is the flow on these hardan marine mainifolds???? I am going with that inducer this winter because we use our boat 2 to 3 times a week and can't go with out going to the lake.Also how do post photos on this site it's killing me to see all of bitchen boat out there.
If he's running a roughly 300 HP engine, no diverter, 62 is pretty good. A carb change ... maybe 10 HP, maybe 20RPM, maybe .5mph. Much better off with some real engine work, Manifold, well-chosen cam, thru-transom headers. Logs suk for flow.

[out of bounds]

He is actually running a 502/502 hp with a diverter. I think that the ultra may be about 200 pounds lighter than his shockwave???? That is if he is correct on his weight. He is not 100% sure on what they told him when he bought his boat. I was looking at the bottom of his boat and found that about 22'' in front of the intake, the bottom gets flat in the kell area . I still think that's where the problem is. Also does anybody know what the flow #s are on the harden manifolds?? How bad are they??