Jetboats blowing over

[Jungle Boy]

I've noticed in another thread that the subject of a jetboat blowing over was mentioned. I have very little to none experience with any boats other than the aluminum boats that we run, so correct me if I'm wrong. I have never heard of one of our type of boats blowing over and we air them out to the maximum and I know of a few that run 120 MPH. I have also believed that the main reason for this is that a jetboat can only lift so high before the pump sucks air and then it looses thrust and that causes the the boat to drop back down again. The prop boat blowovers on the other hand seem to get the full bottom of the boat in the air, but the difference is they still have the prop in the water pushing them. Am I missing something or do some jetboats (100 - 120 MPH type boats) have a risk of blowing over. I'm sure that there are plenty of drag race jets that will blow over just due to the big speed numbers they run.

[Bense468]

Most of the boats blowing over are lighter boats. 300-350lbs. Thats not to say that a heavier lake boat cannot lift with the perfect conditions and enough HP to get that lift. Once they lift they are gone, the pump sucking air does not bring them back down at those speeds. It all happens in a fraction of a second. Gotta watch your horizon

[HammerDown]

I'd have to be heading into one hell of a head wind to flip my 21 Daytona at 80 mph.:rolleyes:

[Cs19]

Most of the blow overs are the air enrampment hulls around 19' long,they start to lift due to the air under the hull or a sudden gust of wind that packed a little too much air,unfortunatly it does happen.Here is a daytona that went over.
http://www.***boat.com/image_center/data/520/20DSCF0032.jpg

[Jungle Boy]

Cool shot cs19. I bet that guy shit his pants. The length issue was one reason that Eagle stopped making the 19' tunnels. They were getting loose at high speeds and needed to have a more bow length to stay stable.

[blown428fe]

Jungle Boy , you guys deffinently air your boats,i checked out those eagle racing vidios. pretty sick.

[MAXIMUS]

From what I have been told, once the pump breaks its suction (from the boat lifting off the water) then there is nothing holding the boat in the water & away they go!:(

[Jet Hydro]

For those that think it cant happen at 80+ MPH think again... I know for a fact that it can if your in a boat that has air traps.
My boat is about 1500lbs. I was only going about 85 at the 1/8 mile when my boat took flight at Waco TX this year. If I wouldn't have lifted, it would have been real ugly. :yuk:
Never Say Never!

[bp]

Originally posted by Bense468
Most of the boats blowing over are lighter boats. 300-350lbs. Thats not to say that a heavier lake boat cannot lift with the perfect conditions and enough HP to get that lift. Once they lift they are gone, the pump sucking air does not bring them back down at those speeds. It all happens in a fraction of a second. Gotta watch your horizon
lift and attitude are two very different things. get enough attitude in hull, and it will blow over. blowovers are never "cool", as in most of those cases, the drivers are severely damaged as a result. if you must get tossed at 80 or above, much better to just get thrown out of a hooking boat.
if the hull is too -tight- (running with waves coming off the sides, down in the water), it nees more -lift- so that it get's -loose- (riding on top of the water, not down in the water).
attitude refers to the nose up attitude of the boat when compared to the water line. generally, 3-4 degrees of attitude is acceptable, depending on speed. but, if you get the nose all jacked up, like doin' a wheely at 80, you are putting an awful lot of air pressure on a big wall, and it can go over.

[Bense468]

Cool BP. Yeah I know what you are talking about. I just worded it wrong I guess. I was not getting that detailed. You did a good job of clearing that up.
I need to come meet you one of these times. I am always up at ming and have never stopped by. I have seen you run a 100 times and the boat looks good. I was just up there last weekend.

[Cs19]

Looks BP got a nice photo in ***boat,congrats Bob.. :)

[565edge]

Here a good shot of blue thunder.

[565edge]

here is another.

[565edge]

Here are some pieces of the prop duster.

[565edge]

Here is a good shot of how much of these boats are in the water at speed.I beleive this is the original r&d express before it crashed on this run,look at the scoop.

[Cs19]

that one of franks boat about 20 feet in the air is one of scariest pics i have ever seen edge.where did you find that?

[LVjetboy]

As the term may suggest, blow-over's a product of aerodynamic lifting forces on the hull. Nothing to do with pump loosing suction. Bp mentioned attitude...that's one thing. Aerodynamic lifting forces created by hull design are just as important...if not more. A 4 degree attitude safe in one hull may be dangerous in another.
JungleBoy, nose up and air-out with an Eagle has no history of blow-over? Not surprising. Try that in a CP gull-wing and have fun! Hull design makes a big difference in stability at high speeds and the danger of blow-over. Some hull designs compromise stability to squeeze that last 5 mph with less power.
Others like the Eagle don't. I'm guessing you already knew that.
jer

[Liberator TJ1984]

Hey MAX get another AVITAR !!!
Only room for One Liberator in here:rolleyes:--------------------------
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