Jetboat operating (driving) and setup questions

S

shimp

New member
Now that i have had my boat out a few times, I got a few questions:

1.  How should I setup the manual control on my diverter?  Should the nozzle hang down a little (point down) at the bottom most position to help get on plane easier?  I think it's set just straight back (I guess called "neutral position"?) I have to gas the fawk out of my boat to get it on plane, but it does fairly quickly get on plane, then once on plane I pop the control up to about midway and it seems to ride best that way, little roost just barely above the water while I am going, at least as far as I can see from inside the boat looking back while driving.... 

1a.  Would you guys recommend to get a hydraulic diverter setup or should I just leave the manual?

2.  Turning and gasing it hard...  I did that Saturday, and the pump unloaded (maybe I needed to put the nozzle down first and forgot? I don't remember really) I had to gas the boat a few times to get the pump to load back up and go, in the process a big A$$ splash of water came over the back of my boat, I don't know how many gallons, but after about half way across the cove when I finally let off the gas pretty hard all the water came by my feet!  I was like WTF? and kinda like oh shat, but since the boat didn't seem to be sinking I just got over to the shore quickly to check things and run the bilge pump for about 2 minutes or maybe it was like 5 minutes, and then all the water was gone and no leaks, just got the water in the boat from the big splash over the back.... Is this normal?  Is there a limit to how sharp you can turn and then gas it or is something possibly not setup right and could be corrected? Or just operator error (yeah, im a jet noob for sure, LOL)

3.  Typical cruising and top speeds...  My boat is 19' fairly heavy I would say, dominator mb-12s with stainless impeller, not sure if it's abc, aa, whatever, don't know, wish I did, with ride plate, shoe, and loader, and Droop Snoot, motor is 10.5:1 or so 454 mild marine cam, big oval heads, dual plane with Edelbrock 850 carb.  I got good GPS readings on cruising speeds, seems to be nice and comfortable and only on the primaries of the carb at 34mph, seems like if I go much slower the back of the boat starts to sag and nose comes up a little, it's just noticable anyway...  Is that about a normal cruise speed?  This is about 2800-3300rpm, It was hard to get exact readings, my friend was holding the GPS (I don't have a mount for it, just handheld deal) and the water was rough.  Top speed I got was about 58mph, this at about 5000 rpm, and then my rev limiter kicks in, I finally adjusted it so now it's set to 5900 or so RPM, will test again when I go out next time.  With the motor/pump/boat setup I have not knowing what the impeller is, just that it's stainless, what should be the top speed on it (roughly of course) and if it's not up to par, then where should I start looking to adjust things so I get a little more out of it?  Not that it's not fast enough for me, it is, but the rev limiter thing was very annoying while trying to top out the boat, the motor has way more in it with the current setup than 5000rpm, it's all new crank, standard, no undersize, rods were all resized and ARP bolt kits, and the engine guy told me I could probably spin it to 6500 without it coming apart, or stacking a bearing, though I'm not interested in that, but am interested in 5500 or so.  Maybe I need a different impeller, I don't think the impeller to wear ring gap clearance is a problem, it was recently redone by the Snowman before I got the boat and don't have many hours on it after the install of the stainless impeller and new bronze (i think) wear ring...  Could be wrong on that one, it's whatever the expensive shiz is.

Sorry for the long A$$ post, just trying to figure all this stuff out, the boat has been a blast so far, just trying to learn a little more about it and make sure it's setup right.  Thanks in advance for help!
 
Devilman

Devilman

Well-known member
Not to be terribly simple, but its just gonna take driving your boat & learning it as you go. what to do & what not to do in different situations, etc... You are already picking up stuff & maybe not realize it, like how your boat acts when you move the diverter around. I have learned that all boats are different & even if you have 2 hulls of the same manufacture, they may not do the exact same thing even when similarly equipped. Just the nature of the beast.

The sharp turning thing under acceleration, I have done that a few times, never took any water in the boat but mine doesn't ride as low as some. It looks close though, enough to freak the wife out, lol... Its another one of those deals where you do something, the result is not favorable & you just know from then on "don't do that".

Far as the condition of the pump, only way you're gonna know for sure is to check the clearances on it. Just cuz it was supposed to have been "done" by someone, doesn't necessarily mean anything.

The diverter, I say manual just cuz there is less stuff to malfunction than on a hydraulic set-up. Lots of folks running them though & like them. Just a matter of personal preferance.

Put it this way, I've had mine for goin on 6 years now & I still feel life I'm learning stuff. So by all means, if you have questions, ask away!
 
B

Becket

New member
Devilman said:
Not to be terribly simple, but its just gonna take driving your boat & learning it as you go. what to do & what not to do in different situations, etc... You are already picking up stuff & maybe not realize it, like how your boat acts when you move the diverter around. I have learned that all boats are different & even if you have 2 hulls of the same manufacture, they may not do the exact same thing even when similarly equipped. Just the nature of the beast.

The sharp turning thing under acceleration, I have done that a few times, never took any water in the boat but mine doesn't ride as low as some. It looks close though, enough to freak the wife out, lol... Its another one of those deals where you do something, the result is not favorable & you just know from then on "don't do that".

Far as the condition of the pump, only way you're gonna know for sure is to check the clearances on it. Just cuz it was supposed to have been "done" by someone, doesn't necessarily mean anything.

The diverter, I say manual just cuz there is less stuff to malfunction than on a hydraulic set-up. Lots of folks running them though & like them. Just a matter of personal preferance.

Put it this way, I've had mine for goin on 6 years now & I still feel life I'm learning stuff. So by all means, if you have questions, ask away!
Click to expand...
X's 2  clap.gif
 
Drumzilla

Drumzilla

Active member
Dont listen to them Shimp.. I've owned 15 jet boats in the last 30 yrs so heres what to do.. pay attention because it's pretty tough...
.. diverter nozzle all the way up and the gas pedal all the way down !! lets rock and rolllllll ..... :smile17:
....lol.. before too many peeps start commenting-just to be clear I was Joking  !! or was I ??
I will say this after owning both types of diverters a manual diverter is much easier to know where your sweet spot is and you can go from no roost to full roost in a second and less to go wrong with one..
As far as everything else Kenny's right. Every boat is different so just taker your time and try stuff and see what works best for you and for your sled..
 
H

HellinnFrnt

New member
sharp turns under acceleration is a good way to get out of the boat ...  :shocked:
ALL jets seem to like a sharp jab to the pedal to get on plane;rolling into it just lets you see the clouds...
where ever the boat likes the diverter is the best place for it .....  :grin: (mine likes it at a foot high)
35 mph at 3000 rpm is just fine for lake/river cruising ...  :rolleyes:
diverter up and floor it is for boats that NEVER have an engine failure .....  :angry:

I start mine off like a motorcycle ... 1 down and 4 up and 8 seconds of Heaven .....  clap.gif
 
John

John

New member
thrust wether from a impeller or propeller acts the same, jets being a lot lighter getting on plane is not that much of an issue, however a prop boat to get on as quick is possible i trim (in your case diverter) all the way down wich in my boat puts the prop at a -10* line past horizontal this once on plane will make you plow water like.........well like a plow, so as soon at it breaks over i start trimming up, most jets i see getting after it the roost is like a foot or so off the water, probably one notch up over neutral, that way you have a little force on the back of the boat thus raising the nose and allowing the hull to dry up a little, to much though youll start to porpoise ans scrub speed.......in other words trial and error
 
R

Red Horse

New member
ALot of piloting (jet boat thing) a jet boat is seeing how it responds to certain driver input. In other words, seat time!!

Here are a few things that I know. Jets need thrust to turn. Not many still have the little rudder on the nozzle anymore. And besides, it didnt do much anyway. WHen I am coming off of plane, I always blip the throttle to maintain course. When turning, make sure your PRMs are up a little over idle. Try running in calm water about 40 MPH and then just letting go of the throttle and watching your wake and the way the boat goes. You will see your wake come together and how big it gets. If you slow down....slower you willl get a shorter wake and less water in the boat. By blipping the throttle you will maintain steerage and lessen the amount of water coming in the boat.

BILGE PUMP. Jets should have an automatic pump! Most of our boats have a low freeboard and water gets into them real easy. In addition most are older and do not have positive floatation. They will SINK. Bilge pump discharge should exit the boat on the same side as the driver so you can see it discharging.

Boats build up a bow wave that need to be crossed before you break free from the water. This waves builds up on the last 1/3 of your hull. Give or take depending on weight placement. To get the stern over that either take speed, or trim. You can get over this wave with just throttle alone and most do, but a little down nozzle will get you on plane faster when heavily loaded or pulling a skier. In our little boats, most of the time a neutral nozzle will be just fine. There is a fine line to trim when running and it depends on speed. More speed, more trim, less hull in water to a point. Once the bow starts going up and down you are trimmed up too much for the speed. Go down a notch and the boat will smooth out. Play with it and you will see where it performs best. A GPS will really help you find the good trim/throttle combination. You will be surprised that a trim adjustment will give or take 2-3 mph.

Down nozzle works best when backing. It helps push the thrust under the boat better and gives you better directional control.

Never run your boat in real shallow water. If you have too, keep the RPMS LOW, like under 1000. You will suck stuff off of the bottom. You will not like pumping rocks or sticks.

Boats turn from the rear. The fulcrum of the turn actually changes as the speed changes. When you are slowing and turning hard the fulcrum moves foward and the stern comes around hard creating the tall wake. The boat almost stops and then you have a tall wave that crashes over the stern loading you up with water. If you are trying to avoid something in the water such as a beer can, you want to actually turn to it keeping the back of the boat and pump from it.

To practice slow boat handling, find a no wake bouy and motor around it slowly trying to get your bow right up to it with out touching it. Try this will several other points on your boat. You will find that your boat actually turns one way better than the other and backs up better one certain way. Jets are not affected much by the turning impellar, but prop boats are. Still, the engine rotation does affect your handling.

Soon you will be trailering your boat in a 30 mph crosswind with no problem.

I love this stuff!! SOme people smoke crack, I have to be around fiberglass!!!

More on the water if we get to meet someday.
 
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