Pressure Sensor

[HOSS]

Jet pressure topic got me thinking. I would like to install a pump pressure sensor in my pump. Anyone done this and where should it be located. Would like to see "first hand " what my improvements actually do. Should there be 2 sensors. One at intake and one before steering knucle. Where can I drill and tap safely? What sensor and gauge. I really see this being beneficial for signs of pump wear and impeller fatigue/failures.
I would think a sensor could not be placed at the top of intake because of many variances like air (main one)but can see one on the bowl. Would you recommend having a JG so as to place it in the snoot?

[Hotcrusader76]

HOSS,
I am working on a "Patented" Emergency water-cutoff system for Jetboaters, which also serves the purpose of regulating the water pressure coming off the jet automatically with a 12VDC power source (your battery) and regulating proper system pressures. These pressures often depend on engine RPM and pump type/work performed.
There are many manufactures out there that sell gauges and or sensors with many types of signal returns; 1-5VDC, 2-20ohms, 5-40mA, etc.
Check the Grainger catalog for such a device. They have been an awesome source for components of that nature and offer a great deal of help on proper selection of parts.
As far as your other question with regards to location, you might want to contact Froggy and or Greg @ G&S Marine. They have always offered a wealth of reliable information on these types of questions.
~Ty

[Blown 472]

How would your system work?? are you talking about shuting off the inlet water??

[Hotcrusader76]

Without getting into too much detail. :D
If your boat suffered a water line rupture anywhere within your raw water system my system will activate an electrically operated valve that will be signaled to close off the Jet's water outlet from a strategically mounted sensor(s) and in-turn signal the helm with a visual and audible alarm that your system has been triggered.
You then have 8-10 seconds to safely navigate your craft to safety (away from a jetty or levee at 70mph) before the E-Valve system shuts down the engine, which will prevent your motor from overheating and burning your Chrome off the headers.(due to the fact your water system has been shut-off).
It will be offered in stainless steel and powdercoat finishes of choice and utilizes a small electronic box (The black box), which contains all the necessary circuits to arm and disarm the system.
Along with this “E-Valve system” as I call it, there will be a regulator mounted inline to manually regulate the amount of water your motor will see to prevent head gasket bursting or exhaust valve water reversion. It too will have a gauge and sensor mounted so that adjustments can be accurately made.
It will be prototyped this season on three different boats all utilizing different pump types; Berkley, Dominator (sort of different), and Panther. Be on the lookout! wink
[ February 05, 2003, 01:14 PM: Message edited by: Hotcrusader76 ]

[Blown 472]

Interesting, what about the motor, any way to back the rpm down?

[Hotcrusader76]

My design had to be capable of supporting all ignition types and by getting into RPM limiting with RC Circuits and where to get the signal, it's easier to attack one area of the motor to shut her off.
Otherwise Yes! An easier design would be to limit the amount of spark and bring the RPM down gradually. But not everyone uses high end electronic ignitions which would help in the design.
All in all my system will weigh less than 7-8lbs and will be very competitive in price.
[ February 05, 2003, 01:19 PM: Message edited by: Hotcrusader76 ]

[Blown 472]

Sounds cool, good luck to you. wink

[Froggystyle]

I have my intake pressure gauge port at the second "E" in Berkeley. Drill right through the center of it, and tap it with a 1/4" pipe tap.
I then run a pressure gauge with a 10' hose into the passenger compartment. This is used to diagnose intake loading issues. I don't know where to tap for the pressure side. That part was not a concern to me.
Squirts up!

[HOSS]

Anyone got pics? Froggy, just curious, why only on intake? Was this done to see if you are properly loading? What impeller and what psi at what rpm? Also, did you notice changes with loaders or impellers. What about diverters, droops, nozzle sizes?
[ February 05, 2003, 07:01 PM: Message edited by: HOSS ]

[flat broke]

Hoss,
The main reason most folks only measure the intake side is because they are looking to see the effects of their running gear setup on the amount of water being fed to the impeller. To measure your increase in thrust, all you need is a tach, GPS, and known baselines. If you increase your thrust (pressure side) you will see icreased performance at a given RPM.
Chris

[Froggystyle]

HOSS:
Anyone got pics? Froggy, just curious, why only on intake? Was this done to see if you are properly loading? What impeller and what psi at what rpm? Also, did you notice changes with loaders or impellers. What about diverters, droops, nozzle sizes? I was having loading issues. I was cavitating out of the hole, and with my setup the way it was, I needed to know what was going on.
I will get a digi in a couple hours here hopefully and take some snaps for you.
I didn't ever do anything that caused a difference in intake pressure. Nothing. Full speed, it would run 12-13 lbs.
I have not done it yet with the new inducer and impeller. I am interested to see if it changed it at all.

[HOSS]

Please post the pics, thanks. Have you thought of placing a sensor on the thrust side? Is the 12-13 lbs. average? I have a JC bowl C impeller. I have to re-seal the intake. I`m thinking of setting pump back but that is another thread already discussed. Also, I really don`t feel that my hull is worth the effort. Really want a pickle fork so will probably end up selling mine. Undecided. I like my hull cause its got room. Plus I really don`t feel like going through the expense again of resto. But anyway, please post the pics.
I`m thinking of taking out the speedo and putting a psi gauge for this. Is there a dual psi gauge out there?

[Froggystyle]

Probably only aviation if there is one (gauge).
I think you are supposed to run around 20-30 lbs at full throttle. I have never done anything to get over 20. No shoe deep enough, no loader aggressive enough.
It works fine, but I think there is room for improvement in the loading area still. The inducer was a very effective bandaid however, and cured most of my ails.

[Jungle Boy]

Here's where I have my water pressure guage plumbed in. It works good. I run with about 24 - 28 PSI.
http://free.***boat.net/ubb/Avatars/Reader_Rides/Jet_Boats/F1130006.JPG

[Blown 472]

What size it that nozzle?? also why no trim?

[HOSS]

Good idea. Right thru cleanout cap. If you don`t mind me asking jungle boy, why do you run a psi gauge? Just curious. Is it more of a safety feature, wear purposes, or see what changes affect what.

[Jungle Boy]

Gents, I don't have the exact measurement of the nozzle in my head any more, but I think it is around 2.75 in. We don't run any trim because they get knocked off on rocks and can lock up with twigs and debris. Once the wedge is set for the best performace, there is no real need to change it. We don't care about the rooster tail height wink , just the best overall handing and speed. I run a gauge because it will tell me if I have rocks or shit in the grate. Also, I got tired of holding the gauge when testing different grates and impellers, so I just hard mounted it in the boat. Do I sense some gathering interest in this type of boating :D You guys would love it. :cool:
[ February 07, 2003, 12:40 PM: Message edited by: Jungle Boy ]