Another boat motor...

[Beavis]

How "efficient" are props at that kind of hp?

[MartyHusseinXF]

Fap!

[CoreyM]

Fuck. It looked tough in the Edo pics, but the hi-rez shots made my pants tight.

[edo]

leg retails at around $50k

[edo]

How "efficient" are props at that kind of hp?

Props that they charge $10k plus for are pretty efficient.

Oh, thats cheap, off shore props are $50k & ones for racing yachts (ie fucking sail boats) are regularly over $150k...they are kinda trick the way the fold up & they do have to be hugely efficient so a teeny engine can be used.

Anyway, there is a lot more to props than meets the eye.

[edo]

so how fast is that thing meant to go with 2khp

Hoping for an average speed of 150mph, top whack somewhere near 170mph

[JabberWocky]

The big yachts now are using snake drives. I know Shockwave used one and suspect Wild Oats, Leopard all do as well as they are Nigel Gee designed and built here in Mona Vale at McConaghy's.

Props can be efficient where ever you want them to be as they are more often then not made to suit, not bought off of the shelf.

[edo]

Ok so WTF is a snake drive?

[MickyD]

I used to work at that Bearing Wholesalers place in the background.

/useless comment.

[JabberWocky]

An impeller, just like a water jet but blows the water back out into the water. I don't know the technical name, have always just called them a snake drive. That way they don't have an exposed prop and can shut a hatch over both ends to leave the hull line smooth.
Can't exactly remember the rules but pretty sure they need to be able to drive their boats under power at 10knts, so these things work well enough for the job.

[edo]

Cool, thats good enough for my brain to picture it

[JabberWocky]

Yeah I figured . Trying to find a pic.

Sort of like the water jet below, however imagine the end of the jet, aft of 30, looking more like the shape of the entrance at 17. Flows up and then back down. I thought it would have simply moved the water through the tunnel and given fuck all propulsion. I even had money on it not working when they tried it and they beat their own expectations.



edit: Indeed it was out_in_front

Someone on here works on the big boats and should know what I'm talking about.

[out_in_front]

Holy Fucking Huge pictures batman

Another suprising Fact - Wild Oats (not sure if it's 10,11 or 12 or all of them) propeller is driven by the hydraulic system. apparently good for about 15knts too considering its bloody tiny.

[The Pupat]

Holy Fucking Huge pictures batman

Another suprising Fact - Wild Oats (not sure if it's 10,11 or 12 or all of them) propeller is driven by the hydraulic system. apparently good for about 15knts too considering its bloody tiny.

Hence it costs 150k

[2rismo]

GTSboy - a perfect shape for airflow is not always a perfect shape for power, intakes that make power often seem to be at odds with what would work best from a pure flow point of view.
Things like port entry angle, swirl & biasing flow towards one side of the port can make an intake look awkward despite the fact that it makes more power than an 'ideal' intake.

I've seen plenty of intakes and exhausts that 'shouldn't' work but do. The distribution through the runner might be uneven and biased towards the outer of the bend but if that puts the gas at a better angle into the chamber for the application then it will clearly make more power than a runner with 'ideal' distribution across the cross-section of the tube. No-one cares how well or how even the gasses are distributed - just that the thing makes power.