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jetmate 2 top speed?

B

BB460

New member
Hey all...new to the forums and new to jet boats. I just picked up a 78 jetmate 2 with a 440hp 460. I had a few carb probs when I first launched but got them sorted out. My question is what should the boat in stock form top out at? The original owner told me about 65 but I could only get 47 out of it. Also, the electric diverter wasn't working so the nozzle was pointing down. I am assuming this would hinder my top end speed also. I have been lurking on these forums for a bit and I have to say there is a wealth of knowledge and some really nice builds from you guys. All help is appreciated!

Ben
 
You will have to get the nozzle adjustment working to maximize forward velocity (smile). With the nozzle down, you're running the hull 'wet'. Get the nose up and as little of the hull in the water as possible (without exploring airspace located above the vessel). Q's: Max RPM, pump, any accoutrements like stuffer, droop snoot, wedges, rooster booster,etc.
 
It's bone stock. berkely pump with the electronic diverter, which I got to work last night but the guage doesn't work. guess I need to dig a little deeper.
 
I don't know what impeller. I just picked it up Saturday. I am assuming it is stock. I had a buddy with a jet boat look at it and he said the bowl (???) if that's the proper term has been changed from gear oil to grease since there is a grease zerk on it.
 
In stock pump form and if you are pushing 440hp you should see 70gps if all is operating properly. Just the smallest imperfections in the impellor can cost ya 5-10mph. My Jetmate is running 60gps and will only turn to about 4200rpm so far with maybe 375hp 402 Chevy. I have been yold by many jet gurus I should see 70 with my low hp setup. Not betting on it lol. Enjoy it and good luck with it. They are definately a fun little boat.
 
Several different impellers can reside in there. Might be an 'AA' or an 'A' impeller in there now. Max rpm at present will begin to tell a story. In point of fact, the type of impeller and max rpm will indicate what hp you are producing with your setup. Inversely, max speed and rpm can point you to the type of impeller that might be in there. Lot's of fun and We'll get you up to speed in no time. Having the nozzle adjustment will make the next water test much more rewarding.
 
Just as a point of reference, buddy of mine had a 19' Baja jet boat (mid 70's year wise) with a mild 454 and it would go in the mid 60s'.
 
Thanks for the replies guys... I am learning a lot about this jet boat thing and really liking it so far. I have had Malibu's and Super Air Nautiques and my last boat was a Witchcraft with a built 225 that would run mid 80's. I didn't expect this little boat to be that fast but was figuring mid 60's. I will get tach numbers and see which jet drive is present for starters. The boat is really cool and I just want it to run to it's potential.
 
Jet boats are really fun. I had a Southwind Tunnel and I put a 455 Pontiac in it. (Maybe 425-450 HP). It had a Berkeley pump with a Dominator bowl, ride plate, shoe, and a Place diverter. It made a lot of noise, sucked gas, and still got passed by I/O boats with BBC's and Bravos.
 
Old Navy said:
Jet boats are really fun. I had a Southwind Tunnel and I put a 455 Pontiac in it. (Maybe 425-450 HP). It had a Berkeley pump with a Dominator bowl, ride plate, shoe, and a Place diverter. It made a lot of noise, sucked gas, and still got passed by I/O boats with BBC's and Bravos.
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That is all so true, but my inner 12 year old still wants a jet boat so damn bad!!!!
 
Also, I know for a fact that those inboards weren't passing while that jet boat was pushing 50 mph in 16 inches of water. (Smile)
 
The section of river that runs through my town is jet boat only territory because it's full of locations that are less than 2 ft of water and very rocky.

I was always jealous of John Lamon when he would post of running his Eluder down his leg of the same river.

The benefit of my section of the river is we are only a few hours drive away from some amazing canoeing sections with all kinds of Rapids just perfect size for running a 1-2 day excursion in open canoes.

We always see a jet boat or two when we do those canoe trips and I've though about buying one for our river but I'm in no financial position to own two boats.

Hopefully you get the issues all sorted out and get that boat running in all the shallow water you can find
 
Old Navy said:
Yes, shallow water running is a plus.
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Sometimes...We were taking previously mentioned buddies Baja boat out for a test spin, and took it to a local creek instead of the river because it was closer. We were barreling down the creek, and hit a log. Boat jumped out of the water, flew up a sandbar and hit a tree, which we glanced off and almost made it back down into the creek. Both of us hopped out, and man did the expletives fly! All of a sudden we heard an old woman scream at us, "You boys down there hush up with all that cussing." We apologized to her, and then had a hearty laugh.

Luckily there was a fisherman in a jon boat nearby, he said, yeah, I though you boys might hit that log when I heard you comin'. Anyway, with a little help from him we managed to get our boat back in the water, only to discover the log had ripped the rudder and the steering nozzle off the drive, and couldn't steer at all! So jon boat guy gave us a ride back to his truck, and then drove me home so I could get my neighbor with a bigger jon boat to tow us back.

About halfway back to our boat, we discovered we had traveled over a section of creek no more than 6" deep and about 1/2 a mile long. We had to float over that section with no power just to get to our boat. On the way back, we discovered that when not on plane, the heavy Baja was hitting bottom, and we had to push the boat over the 1/2 mile of shallows. Man, that sucked.
 
Jimway said:
Creek (or was it crick?), speed, log, air, sandbar, and tree. Oh and damage too. Now who was gigging me about flipping mine...
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Definitely a creek around here. Hell, it's as big as what they would call a river in the mountains, while it is shallow in spots, it's also 13+ feet deep in others.
 
Well the river where I run is wide and about 60+ feet deep...the only thing I have to worry about it floaters which usually reside a foot under the water as they are floating towards the gulf and wakeboard boats with a surf wake. I really don't wanna hit one of those at 60+
 
Ahh Yes, the ubiquitous wakeboard vessel. This brings to mind another useful and humorous capability of the jet boat. One can put that excess hp to use in creating a great big rooster tail. If the rascally wakeboard vessel happens to be on the receiving end of the rooster tail, so to speak, so much the merrier. If the wakeboard vessels operator does not appreciate your brand of humor and attempts to tresspass upon you and makes chase, you can lead him into the shallower parts of the river (which you will have reconnoitered previously with malice aforethought) where that v-drive and rudder located under that expensive wakeboard vessel just may come to grief.
 
yeah, I used to be one of the afore mentioned wake boat drivers...(Super Air Nautique) I am all too familiar with sharing the river...some don't get it though and think they are the only ones who should be out there. :brickwall:
 
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