[beerjet]

At what speed do you thing the "Jet-a-way" or a "Pop-off valve" is needed ?
Not so much with the drag guys cuz there rules and boundries have already been set ,
but lets bring this into the roundy round arena .
With Harold Bruce setting the bar up at the Kilos , I can only see it getting pushed .
What similarities and diffrences do you guys see between the drag guys and circle guys necessitating a safety device? And which one .

-beerjet-

[propless]

 Good question Omar.  I thing you guys are really close to needing these things.  I'm not to sure about the  "Pop-off valve" though.  From what I understand about them they read intake pressure and release through the hand hole clean out if it gets to high, that might be a problem with a circle boat (pressure spikes from rough water).  If you set it up to handle the constant pressure spikes it might not open if there is a problem.  But I might be way off on that I'm still learning. 

[beerjet]

I've seen one with a cable going to it .
I'm gonna assume it's hand or foot operated . 

-beerjet-

[propless]

From what I've read.

Even the air actuated ones can be opened manualy.

Provided you can react fast enough to save the boat.

But I think the hard part would be to find a good location for the release (easy to reach but not somewhere you would accidentally hit it).

                       

-propless-

[jet boat performance]

Guys, good questions ! In a perfect world IMO all jet boats fast or slow could have a resetable Pop off/Blow off  and/or jetaway , much in the same fashion (for safteys sake)  as a Hyundia just the same as a Mercedes ' both have air bags . The problem is clearly expense not to mention that boats with cleanouts inside cant effectivley have Pop-offs and engine movement is neccesary for Jet away installation . Pop offs as you may know require machining to "square up" the cleanout flange area and its respective bore (requires suction removal) . We now sell the Mersch and Mills valves and all the control mechanisms we also sell the Jetaways We're working a deal on a "river racer" type installation on the pop offs as well . BTW the manually deals like the Wilder probably have merit but most situations that will require or "take advantage" of a saftey device like that are "split second and dont leave time for a decision to push a pedal or pull a lever .Not sure how any of this could/would apply to a circle boat btw. We have an Older wilder valve at the shop now and have been studying it , it does look kind of cool for the purpous of "braking" and mayby "peddeling' the boat before the lights etc . re "speed" at which its neccesary , 80mph seems to be the speed most agree at which you can start to get in trouble , remember most of these boats were built,tested and designed to run 60ish I've  seen boats wreck at 70 .Wear you vest (get a good one) and invest in a kill switch Tom
heres a link on pop off on our new JBP site (not launched yet) and below is a "manual pop off"    http://www.jetboatperformance.biz/pages/jet_boat_pop_off_valve.html

 

[Brad @ SCJB]

im gunna blabble about this for a minute....maybe i will make sense.

i honestly dont see a reason to run a pop-off or jetaway in compjet.

lets look back to why exactly one is needed....

its to relieve pressure in a boat during shutdown so the bowl pressure doesnt build too high and smash the bow down violently causing the boat to hook/bow steer.

with how rough the water gets in compjet...the bow of the boat is constantly going through the measures of something like a hard shutdown as you hammer down the straight fighting the cross chop of your previous laps. if your boat is known to hook in a high speed shutdown (ie gullwing type boats), then i think your boat is WAY too unsafe for compjet. the water conditions are night and day between circle racing and drag racing.

for a high speed kilo run, i can see it benefiting in a sticky situation, but for going in circles, its pretty useless.

i dono. thats my take on the issue.

[beerjet]

The pop-off is pretty straight forward in terms of it application ,
the Jet-a-way on the other hand is self contained and multi faseted (sp?)

Now dont think for a second that I'm pushing to require a $1200 piece of hardware . I would rather spend the money on ballistic shorts .

Where is the bang for the buck in a safety devise .

-beerjet-

[GlassCutter]

Always looking for the "bang" ain't ya ? 

[wizard612]

Circle racing you should be able to set the boat up so a quick shut down will help set the boat for the turn.  Letting the pressure release will let the boat coast nicely right past the turn.  I always wanted my boat to take a real hard set then get back on the gas and be full bore at the apex.  Ski Jet we ran in the 80's but Comp Jet ran 90's+ and they would set the boats VERY hard with nozzles, plates anything to set the boat and popin' the transom out of the water was never a problem.  I think it might be that the drag boats are that much faster (+120)and much lighter where they need to be able to coast if something goes wrong.