ill informed boat knowledge

QC

Supreme Mariner
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Mar 22, 2005
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Re: ill informed boat knowledge

Remember, I boat at Havasu ;)
 

emilsr

Senior Chief Petty Officer
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Dec 16, 2010
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Re: ill informed boat knowledge

Remember, I boat at Havasu ;)

Yea, I know....so you should know this already since there's a handful of hot rod boats there. ;)
 

QC

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Re: ill informed boat knowledge

Just a few.
 

TilliamWe

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Re: ill informed boat knowledge

Depends on the boat weight and speed. I never said all boats will go faster with dual prop drives in case that is what you are thinking I said.

I am just saying drag boats use 2 blade props because only half the prop is in the water at any one time.

Volvo claims Duo-Prop drives are faster than single prop drives...

I just wanted to make sure you weren't saying that first part. I understand the dragboat prop thing, but if you remember, Mercruiser had the surface piercing Blackhawk drive and it had 6 blade! yikes.

I think Volvo's statement can be made the way they made it, more because of what QC says. Their single prop drives aren't the fastest to begin with. :)

I hear what you all are saying about RPMs and such, and I will say that both boats hit the exact same WOT rpm with each drive. So as I am saying, it was as constant of a test you can get. I will "dare say" that with either drive, the boats were propped "perfectly". (I know that's not possible, but you know what I mean) If we had changed the B1 prop to make it as fast as the B3 out of the hole, it would have been much slower on the top end. If we had propped the B3 to run faster on the bottom end, ti would have lost it's holeshot advantage. The "amazing" thing in the test was that the boats switched characteristic, exactly.
So it's not ill informed knowledge that a dual prop drive is slower on the top end, it happened. (Yes, it happened just once)
 

bruceb58

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Re: ill informed boat knowledge

So it's not ill informed knowledge that a dual prop drive is slower on the top end, it happened. (Yes, it happened just once)
If you read what I said in post #22 I said TRUE and FALSE. It depends on the boat. The OP is stating that a dual prop boat is always slower. Your test of one boat doesn't prove or disprove that either.

In any case, most people aren't making a choice between dual props and single props because of top speed. That little bit of performance difference(more or less) just falls out of the mix if one is deciding if the dual prop is worth getting because of all the other extra advantages.
 

smokeonthewater

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Re: ill informed boat knowledge

S-10 pickups are faster than mustangs... I know this to be true because back in the day I had one with a built 350 and I smoked lots of 5.0 mustangs..........
Same flawed logic
 

QC

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Mar 22, 2005
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Re: ill informed boat knowledge

How about this:

For high speed applications most manufacturers recommend a single prop, trimmable drive system.

There. Next!
 

bruceb58

Supreme Mariner
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Re: ill informed boat knowledge

How about this:

For high speed applications most manufacturers recommend a single prop, trimmable drive system.

There. Next!
I like that.

The OP who started this thread also started the 20 year loan thread. He is good at starting controversial topics.
 

QC

Supreme Mariner
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Mar 22, 2005
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Re: ill informed boat knowledge

Like how I slipped in a subtle slapdown of the inboard crowd? :eek: :behindsofa:

He is good at starting controversial topics.
Yeah, we noticed . . . ;)
 

bruceb58

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Re: ill informed boat knowledge

Yamaha used to have a duo prop outboard. Stopped selling it because of poor sales. Probably don't need it on a lighter boat.

2003_2_1502-6trpox66vmax.jpg


Because of how Yamaha designed this engine to be able to sit higher on the transom, it was faster than the single prop version.
http://books.google.com/books?id=Q2...6AEwAg#v=onepage&q=150 Vmax dual prop&f=false
 

QC

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Re: ill informed boat knowledge

Because of how Yamaha designed this engine to be able to sit higher on the transom, it was faster than the single prop version.
I am sure that is most of it. If that design was truly faster for equal horsepower you can bet your bottom dollar all bass rigs would run it today. These guys will kill for 1 MPH.
 

tpenfield

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Staff member
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Re: ill informed boat knowledge

Here ya go . . . .

IMG_1145ac.jpg


too much spare time on a Saturday morning . . . :lol:
 

smokeonthewater

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Re: ill informed boat knowledge

Sooo I just found something cool and I am now gonna HIJACK the SHIZZNIT out of this otherwise highly focused thread.

DEFINITION OF ACCELERATION:



One top fuel dragster 500 cubic inch (approx 8.3 litres) engine makes more horsepower than the first 4 rows of stock cars at the Daytona 500.

It takes just 15/100ths of a second for all 8,000+ horsepower of an NHRA Top Fuel dragster engine to reach the rear wheels.

Under full throttle, a dragster engine consumes 1-1/2 gallons of nitro methane per second; a fully loaded 747 consumes jet fuel at the same rate with 25% less energy being produced.

A stock Dodge Hemi V8 engine cannot produce enough power to drive the dragster's supercharger.

With 3,000 CFM of air being rammed in by the supercharger on overdrive, the fuel mixture is compressed into a near-solid form before ignition.

Cylinders run on the verge of hydraulic lock at full throttle.

At the stoichiometric (stoichiometry: methodology and technology by which quantities of reactants and products in chemical reactions are determined) 1.7:1 air/fuel mixture of nitro methane, the flame front temperature measures 7,050 deg F.

Nitro methane burns yellow... The spectacular white flame seen above the stacks at night is raw burning hydrogen, dissociated from atmospheric water vapor by the searing exhaust gases.

Dual magnetos supply 44 amps to each spark plug. This is the output of an arc welder in each cylinder.

Spark plug electrodes are totally consumed during a pass. After halfway, the engine is dieseling from compression, plus the glow of exhaust valves at 1,400 deg F. The engine can only be shut down by cutting the fuel flow.

If spark momentarily fails early in the run, unburned nitro builds up in the affected cylinders and then explodes with sufficient force to blow cylinder heads off the block in pieces or split the block in half.

In order to exceed 300 mph in 4.5 seconds, dragsters must accelerate an average of over 4G's. In order to reach 200 mph (well before half-track), the launch acceleration approaches 8G's.

Dragsters reach over 300 miles per hour before you have completed reading this sentence.

Top fuel engines turn approximately 540 revolutions from light to light ! Including the burnout, the engine must only survive 900 revolutions under load.

The redline is actually quite high at 9,500 rpm.

Assuming all the equipment is paid off, the crew worked for free, and for once NOTHING BLOWS UP, each run costs an estimate $1:000:00 per second.

The current top fuel dragster elapsed time record is 4.428 seconds for the quarter mile (11/12/06, Tony Schumacher, at Pomona , CA ). The top speed record is 336.15 mph as measured over the last 66' of the run (05/25/05 Tony Schumacher, at Hebron , OH ).

Putting all of this into perspective:

You are driving the average $140,000 Lingenfelter 'twin-turbo' powered Corvette Z06.. Over a mile up the road, a top fuel dragster is staged and ready to launch down a quarter mile strip as you pass. You have the advantage of a flying start. You run the 'Vette hard up through the gears and blast across the starting line and pass the dragster at an honest 200 mph. The 'tree' goes green for both of you at that moment.

The dragster launches and starts after you. You keep your foot down hard, but you hear an incredibly brutal whine that sears your eardrums and within 3 seconds, the dragster catches and passes you. He beats you to the finish line, a quarter mile away from where you just passed him.

Think about it, from a standing start, the dragster had spotted you 200 mph and not only caught, but nearly blasted you off the road when he passed you within a mere 1,320 foot long race course.

....... and that my friend, is ACCELERATION!!


Morale of the story......


wait for it.......


Cars engines are more powerful than boat engines!!!!!!!!!!!
 

tpenfield

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Staff member
Joined
Jul 18, 2011
Messages
18,758
Re: ill informed boat knowledge

Sooo I just found something cool and I am now gonna HIJACK the SHIZZNIT out of this otherwise highly focused thread.

DEFINITION OF ACCELERATION:



One top fuel dragster 500 cubic inch (approx 8.3 litres) engine makes more horsepower than the first 4 rows of stock cars at the Daytona 500.

It takes just 15/100ths of a second for all 8,000+ horsepower of an NHRA Top Fuel dragster engine to reach the rear wheels.



....... and that my friend, is ACCELERATION!!


Morale of the story......


wait for it.......


Cars engines are more powerful than boat engines!!!!!!!!!!!

Did you know that an automotive airbag deployment is about the same time as it takes for the dragsters wheels to get 8,000 horsepower ???

Do dragsters have airbags :noidea:

Are all car engines more powerful than boat engines ???
 
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