If the motor is turning about 2000 rpm by setting the idle fast, is the reverse cup not allowed to drop down over the nozzel? Is there some kind of safty build into the jet to not allow the cover to drop down over the jet at full speed? It would seem that there would be enough pressure to tear it off?
At some RPM it is going to be almost impossible to get the reverse gate down, there is a lot of water pressure at the outlet and your trying to force something into what it almost like a solid object. I think my shift handle would break before I was able to put it in reverse at full throttle. If I somehow managed that feat I think your right the bucket would come off.
Why would you ever throw it into reverse when you've got your foot in it? Mine has a hand throttle, so you move all the way to no throttle before going into reverse...
Has anybody ever used the reverse bucket for braking??
i have used the reverse bucket for braking, with not so good results after the fact... i have a 12JG pump and while playing around one hot afternoon, i figured out that if i take my foot off the gas going about 20 or so, put it in reverse and stab the throttle, i can put a huge wave over the bow.
it's great fun and you'll need a good bilge pump, but it's not a good idea for a couple reasons. first, as mentioned, you can blow off the reverse gate. second reason is that by doing all this, i actually compressed my jetovator cable. on a 12JG, the cable is in compression to put the jetovator to a down position. the reverse gate is creating a torque on the jetovator forcing it upwards, and it will buckle. other jet pumps put the jetovator cable in tension while in reverse.
here is a pic of a compressed 43 morse cable:
http://www.heli-chair.com/images_pub...e/PICT7109.JPG
right up until i discovered that cable problem the next day, i was having a great time putting it in reverse and getting on the gas. i know there is a safety argument to be made here (why was i doing this in the first place), but if you can't push the limits of your craft, what's the point? drive it like you live. i got away with this particular stunt about half a dozen times that day.
oh, one other consideration with usage of reverse is that in shallow water, you'll stir up the junk on the bottom of the lake and then suck it into your pump; something else to think about.
happy floating!
Yikes!! Thats supposed to be an advantage of jetdrives, using reverse as a brake, but I've never had the guts to do it on the move. A guy I know used to do it all the time, but he was crazy and I would never get into the same boat (or any anything else) with him in control...
I can get enough water over my bow easy enough as it is!!
Never done this in a fiberglass boat, or really any sort of performance boat, but have been on board many times in a big (23' North River Commander) aluminum sled and hit the brakes. Its got a hamilton 212 pump and hand throttle so you have to let off the gas as you go through "neutral", into reverse, and then back onto the gas. It stops in a couple of boat lengths and throws a huge wave over the bow. Definetely gives the bilge pumps a workout. It's not my North River but when my friend took the demo drive before he bought it, they showed him how to do this, so its not exactly "not recommended" by the manufacturer. I would say its probably harder on equipment than just cruising down the lake but its very effective if you need an emergency stop or an emergency cool off. Its best to let your passengers know before you do it because it stops fast. The dealer also used the same boat to push the tow vehicle up the launch ramp when the 4X4 suburban couldn't get traction. Of course he ran out of water pretty quickly but he got the truck moving enough to develop enough momentum to get it up the ramp. Not recommended if you don't have some experience with your truck driver as it could easily jacknife the trailer, but pretty cool none the less. Pretty rediculous boats if you ask me. Its truely the H1 Hummer of the boat world-Aluminum Squirt
Other than the cables being an issue, why would it be hard on the components? This is how jet airplanes stop, and there is no more load on the engine going reverse than forward, the water is just being redirected. Maybe I just don't understand???
the water coming out the jet will try to blow the reverse gate ("bucket") off. as for the cables, a solution is to have the jetovator (if installed) against the stop when doing this so that the pump can take the loads and not the jetovator cable. not sure what bending loads this puts on housings, tension loads on bolts/studs, etc...but i do know that CP performance wasn't too impressed with the concept when i quizzed them about it.
aside from the gate trying to cap off a LOT of pressure coming out the nozzle, the real problem is the torque due to the angle of the reverse gate, this angle creates a lot of bending loads on the nozzle assembly. in normal operation, the thrust is vectored out the nozzle and creates compressive loads on everything. this is just from a sort of casual perspective based on looking at the jet pump assembly, i haven't tested the actual loads imposed. generally speaking, compressive forces are okay, tensile loads are what cause things to fail. anytime you bend something, one half goes into tension and the other in compression.
my engine idles around 700-800, i find it far easier to shift forward/reverse with this lower speed. also having a foot throttle and a separate shifter makes maneuvering a bit easier. i don't see any problem with going 20-30mph, backing out of the throttle and putting the reverse gate down. it's just when you get on the gas in reverse that you begin pushing the limits.
i've got two 1100gph bilge pumps to take care of the water over the bow.
http://www.heli-chair.com/images_pub...r/PICT1006.JPG
If the motor is turning about 2000 rpm by setting the idle fast
Turn your idle speed down. There is no reason to have a motor idle that fast.
This is how jet airplanes stop
Not exactly - They have wheel brakes, and air brakes in addition to reverse thrust. Re-directing air is a lot easier on parts then re-directing water.
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