lets talk pop-off and jet-a-way

**brgrcru** · 07-23-2012, 04:44 PM

Thank God, Mike is ok. Is there a speed that neither will help getting a boat to sit straight while the engine fails? But since it was brought up in the other thread. I didn't want to take up pages with my ? I know on shut down the pop off works great to settle the boat, but would of a jet-a-way also helped? or does it just not matter at a certain speed? has anyone else lately had catastrophic engine failure at 100mph+40 and both worked like clock work? Just asking.

**Infomaniac** · 07-23-2012, 04:48 PM

It depends on the application sir.

The N2 jets that are running low 7's have very aggressive underwater hardware and aggressive wing angles. Engines are way forward etc. All of which would push the nose in during sudden unexpected deceleration.

It is not typical behavior with a jet=a-way and pop off as their setup and performance is not typical.

Bottom line. Boats with extreme performance really can't be used to gauge typical behavior.

**Dominator** · 07-23-2012, 05:08 PM

Im glad someone brought this up cause since hearing the news and Mike obviously having the top notch equipment available you would think how can this happen and why? I am a little nervous even though I run NO WHERE NEAR as fast as he does but why spend the money on all this shut down equipment if its not gonna insure our ass?

**Red Rocket** · 07-23-2012, 06:15 PM

The pop off valve did exactly what it was designed to do and he has a jetaway also. There were other factors causing the crash and hardware was not one of them. I'm not gonna say what they are I believe the issue was posted somewhere else. Anybody running more than 90mph imo should be running a pop off. Nothing else will suffice. I was running a bgj at elsinore with much more aggressive hardware than Mike runs and lost a fuel pump drive belt at the finish line on a 6.95 143 mph pass and the valve did exactly what it is supposed to do and no jetaway and the boat went straight with no issue.

**TNYoungblood** · 07-23-2012, 06:21 PM

Good topic, keep em comin

**bigdog** · 07-23-2012, 06:28 PM

Im no expert but if you had an engine failure where the engine locked up instantly and you were turning 7200 rpm. All the momentum of the rotating parts suddenly coming to an abrupt stop would be transfered to the block then to the boat. With a lite boat that would have a huge effect on things. You could have all the safety gear in the world and it may not help.

Nobody would want to test the reaction of a race boat with an engine failure but it happens from time to time. Im sure every situation is a little bit different.

Glad Mike is okay it could have been much worse.

**BUSBY** · 07-23-2012, 07:17 PM

both are needed IMO

Pop off: designed as a pressure relief with an overcharge in the suction piece

Jetaway: allows the impeller to freewheel (so to say) in case of engine failure & locking up.

If you are choosing one or the other ... I'd have to go with Pop off. But if you can afford it, get both. Cheap insurance in the big picture.

**Bodean's Hammer** · 07-23-2012, 07:22 PM

Please correct me if I'm wrong, but the pro class guys sometimes use their chute to save the boat when its getting out of shape. I completely understand the safety aspect, and I know alot of the pro NHRA guys bitch about it, but would having an auto deploying chute (upon catasrophic failure) helped straighten this hull out? I havent seen a video or anything, just a slow guy thinking out loud.

**brgrcru** · 07-23-2012, 07:40 PM

I am runnin a jet a way on my 19' cp but was also thinking of a pop off this winter. I am probably in the 100 to 105 range. I know all boats act differently. F bomb and other real fast jets are pushing it to the limit and probably could even go faster. They are just awesome to watch go down the drag strip. But my ass puckers just a little when I see them make those 140+blasts. I guess that's why we love going fast, even in my boat.

**speedealer** · 07-23-2012, 08:08 PM

Originally Posted by Red Rocket

The pop off valve did exactly what it was designed to do and he has a jetaway also. There were other factors causing the crash and hardware was not one of them. I'm not gonna say what they are I believe the issue was posted somewhere else. Anybody running more than 90mph imo should be running a pop off. Nothing else will suffice. I was running a bgj at elsinore with much more aggressive hardware than Mike runs and lost a fuel pump drive belt at the finish line on a 6.95 143 mph pass and the valve did exactly what it is supposed to do and no jetaway and the boat went straight with no issue.

hey rocket i don,t doubt your boat set down straight but loosing a fuel pump isn't the same as a engine locking up. i know guys that have shut the ing. off wfo and no problems and the same boat tossing the out when the the engine locked up. also had a 100+ daytona turn left just from an agrresive shut down. i think its really just a matter of luck. remember its when not if your going to fall out. just my 2cts

**FARMER JOHN** · 07-23-2012, 08:42 PM

Originally Posted by Bodean's Hammer

Please correct me if I'm wrong, but the pro class guys sometimes use their chute to save the boat when its getting out of shape. I completely understand the safety aspect, and I know alot of the pro NHRA guys bitch about it, but would having an auto deploying chute (upon catasrophic failure) helped straighten this hull out? I havent seen a video or anything, just a slow guy thinking out loud.

I don't see a auto chute working, first of all it happens so fast your out of the boat instantly, and if your out of the boat slowing down with your own chute, the last thing you want is that boat straightend out behind or in front of you, just my opinion
I am a firm advocate of both a popoff and a jet-away, i even run both on my ski boat which is overkill for a ski boat but you can't put a price tag on yours or others safety

**MURPHY'S LAW** · 07-23-2012, 08:52 PM

Originally Posted by FARMER JOHN

I don't see a auto chute working, first of all it happens so fast your out of the boat instantly, and if your out of the boat slowing down with your own chute, the last thing you want is that boat straightend out behind or in front of you, just my opinion
I am a firm advocate of both a popoff and a jet-away, i even run both on my ski boat which is overkill for a ski boat but you can't put a price tag on yours or others safety

ya farmer Im sure your ski boat goes over 100MPH

**Infomaniac** · 07-23-2012, 08:54 PM

As opposed as I am to running as hard as these guys are. I am still taking up for them. Unforseen things do happen.

They do a great job of getting down the track. But you can't tell me they are not running on the edge. Everything has to function perfectly or it's a big problem.

My point is, you can't use these boats as the typical example of pop off and jet-a-way performance. Those devices are wonderful for the majority of hot or race boats. Some boats are at a performance level where other factors or failures render them uneffective.

For Example: Run a wing at or near the most aggressive angle and you better make a full run and a normal deceleration.

My opinion UNBIASED. I don't race with these guys and they are not my customers.

**NO REGRET$** · 07-23-2012, 08:57 PM

Originally Posted by FARMER JOHN

I don't see a auto chute working, first of all it happens so fast your out of the boat instantly, and if your out of the boat slowing down with your own chute, the last thing you want is that boat straightend out behind or in front of you, just my opinion
I am a firm advocate of both a popoff and a jet-away, i even run both on my ski boat which is overkill for a ski boat but you can't put a price tag on yours or others safety

BOTH !!!

is the way to go,,,,,,,,,, never skimp on safety !!!

and i guess you would when your little skee boat runs 120 + ..lol

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lets talk pop-off and jet-a-way

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