Yamax2?

the WaTeRhAwK

the WaTeRhAwK

fryin' up a/m electrics..
Location
okc
Vumad said:
Hydrodynamics plays an important part in motor performance. The light weight of a standup can reduce speed. Unlike a prop-driven boat, a stand up requires the hull to remain in the water so the pump can continue to intake fluid. At high rates of speed, aerodynamics and bounce play an important role in keeping a pump hooked up. Despite the power of any engine, a machine can only travel at the rate it's cumulative componets can deliver. This argument does not prove a standup is incapable of obtaining record speeds, simply that fitting a large motor alone does not mean a stand up will obtain those recorded speeds.
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understood, but they're making them do well into the 60's with 951's. compared to the power and ultra motor makes, 20mph isn't much to add to the top.
 
Vumad

Vumad

Super Hero, with a cape!
Location
St. Pete, FL
the WaTeRhAwK said:
understood, but they're making them do well into the 60's with 951's. compared to the power and ultra motor makes, 20mph isn't much to add to the top.
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There's a lot more technology in cars, so it's a good place to look for examples of performance dynamics.

Cars with standard ICE motors take arround 500-600 HP to reach 200 MPH. The next 60-80 MPH takes an additional 500-600 HP.

HP has diminishing returns at increasing rates of speed. That extra 20mph above 60 isn't very easy.
 
SuperJETT

SuperJETT

So long and thanks for all the fish
Location
none
A stock 550 with 40hp went around 40mph, modded 951's with 150+ are going ~25mph faster. 110hp to get an extra 25mph.
 
Crab

Crab

thanks darin...noswad!
Location
Seattle
They use to say something like "for every 10 mph over 50 you need to almost double the horsepower, jet pumps are way too inefficient"
 
SuperJETT

SuperJETT

So long and thanks for all the fish
Location
none
the WaTeRhAwK said:
so, you think a 200+hp motor is going to crack 80+?
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No, I don't.

The performance sitdown guys have all kinds of tweaks to the hull/rideplate/etc that they can do to get the hull further out of the water. Standups don't have v-hulls like they do so those kinds of tweaks don't work.

Plus, my point is it takes like a 100hp gain to go from 40 to 65, and the hp increase needed per hp going up dramatically the faster you go. A 50 hp increase just isn't going to gain you much on a standup because your wetted hull area doesn't change much once you get on plane.
 
the WaTeRhAwK

the WaTeRhAwK

fryin' up a/m electrics..
Location
okc
SuperJETT said:
No, I don't.

The performance sitdown guys have all kinds of tweaks to the hull/rideplate/etc that they can do to get the hull further out of the water. Standups don't have v-hulls like they do so those kinds of tweaks don't work.

Plus, my point is it takes like a 100hp gain to go from 40 to 65, and the hp increase needed per hp going up dramatically the faster you go. A 50 hp increase just isn't going to gain you much on a standup because your wetted hull area doesn't change much once you get on plane.
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what about the weight differential between couches and standups? you don't think the 300+ lbs. minus the extra weight would have an effect on necessary hp. needed to make a couch fly, put into a standup?
 
betrezra

betrezra

Eat, Drink, Breath x2's
Fast Stand-up

I want to go that fast on a stand-up :)

If you ever get a chance to ride a properly built 951-SXR give it a try!!!!

I got to ride M Mcqueen's SXR-Doo and it rocks the house and runs an honest mid-upper 60's and get's there VERY FAST. And it's not all top end..... it has killer tq/hit all over the place. all with near-stock compression, and reasonable rpm :)

I WILL have an x2 with 951 power....... tweeker is working on something now........ :lightning:

-----
super-ram-jet.... I'll be watching your x2 build....... it is what I dream about weekly....... once you've had a taste of a 951 powered sport ski...... an old style kawi twin just won't do :)
 
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the WaTeRhAwK

the WaTeRhAwK

fryin' up a/m electrics..
Location
okc
I think if you set up an sxi pro with ultra 150 engine, and set it up for all top end, 85mph is not out of the question. especially for a boat that small with that much top end power.
 
superramjet

superramjet

Location
Hutchinson, Kansas
the WaTeRhAwK said:
I think if you set up an sxi pro with ultra 150 engine, and set it up for all top end, 85mph is not out of the question. especially for a boat that small with that much top end power.
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85 mph is out of the question, if you put a sitdown motor in a stand up, the standup will be slower than the sitdown. Ultra 150 motor is 150hp, it takes around 200hp to get near 70mph in a standup, if i had to guess id say it'd take over 350hp to get to 85 in a standup

how many motors you know with 350hp fit in a standup?
 
Vumad

Vumad

Super Hero, with a cape!
Location
St. Pete, FL
the WaTeRhAwK said:
I think if you set up an sxi pro with ultra 150 engine, and set it up for all top end, 85mph is not out of the question. especially for a boat that small with that much top end power.
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You could put 1200 HP in a Honda CRX. The 1200 HP caddy is going to go faster.

I say we take a sitdown, hack the seat, add the pole... presto! 13' long, 900 lbs, 85 MPH, standup!

I'm not saying it can't be done... Just that it would take a LOT of HP and a BIG engine. SXR would be a better platform. I'd be interested to see something bigger than a 215 going in that hull.
 
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