Would I be killed in a blaze of glory/gory?

[clarksonisawilly]

If I were to buy a small rowing boat type affair, and fit a small car engine and matched prop?

Of course it's not that simple, but you know what I mean

Naturally for lake/river use only and after a LOT of boating tuition?

Kind of a credit-crunch hill-billy hotrod boat I guess

[Munter]

1 * Canoe
1 * Pivot arrangement
1 * long propshaft & Prop
1 * Chevvy V8

They do it in the Amazon and such places. What could possibly go wrong.

[Sam_68]

Probably not, but you might be disappointed.

Unless the hull is designed to plane, you reach a point where no matter how much power you throw at it, the hull just absorbs it by making bigger waves.

On hydroplanes and planing hulls, the point at which this exponential rise in water drag is overcome as the boat rises onto the plane is known as 'getting over the hump', because once it gets onto the plane the amount of power need to drive it forward suddenly drops off and it picks up speed quite rapidly.

To give you some idea, Donald Campbell's 'Bluebird K7' had difficulties getting over the hump, despite a 5,000lb thrust Bristol Orpheus jet engine, and there was a guy called Tony Fahey in who built a Jet engined speed record boat called 'British Pursuit' in the early '80's that completely failed to get up to planing speed despite a Viper turbojet.

At the other extreme, one of my proudest inventions was a Heath Robinson device that used the guts out of a Soda Stream fizzy drinks maker to blow compressed CO2 into the prop of my mate's Imp engined hydroplane, to allow the engine to spin up to the revs necessary to get it over the hump (being that a full race Imp doesn't produce enough torque to pull the skin of a rice pudding below about 6,000 revs).

Then you need to google 'propellor cavitation'.

[Simpo Two]

Munter said:

1 * Chevvy V8
They do it in the Amazon and such places.

And we get it up the arse for the carbon emissions

Sam_68 said:

At the other extreme, one of my proudest inventions was a Heath Robinson device that used the guts out of a Soda Stream fizzy drinks maker to blow compressed CO2 into...

I thought you were going to inject it under the hull step to reduce the surface tension or summat and help the boat lift... sort of like aeroplane flaps but the other way up.


Surely the best solution is a hydrofoil? (or ekranoplanz, but that's really a plane that can't climb)

[Munter]

Simpo Two said:

Surely the best solution is a hydrofoil? (or ekranoplanz, but that's really a plane that can't climb)

This bad boy has to be the way forward.

http://www.youtube.com/watch?v=86HrvaUNCJg

[Sam_68]

Simpo Two said:

Surely the best solution is a hydrofoil?

Sadly not. The speed record for hydrofoils is a lot lower than you might expect (just over 100mph, IIRC).

Cavitation, again. The low pressure on the upper surface of the foil forms a bubble and the lift breaks down. You can use supercavitating foil designs, but they kind of defeat the object - if you're not gaining any lift from the upper face of the foil, it and the struts that attach it to the main hull are just dead drag; you might as well just use a conventional skimming hydroplane.

There was a jet engined hydrofoil built for the Water Speed Record in the 1950's called 'White Hawk', designed by the same guy who later designe Bluebird K7, but it failed to go faster than 70mph.

Hydroplanes are now reasonably well tried and tested up to about 200mph (300+ if you've got a spare jet engine and like Russian roulette), but you're certainly not gong to go anywhere fast by just bolting a V8 into a rowing boat

[maser_spyder]

So I couldn't interest you in a;



?

[maser_spyder]

Paddy_N_Murphy said:

No Maser, Way too much bulk.

Think more "RS" like

But.... Surely that's a tea tray, with some fins. And an engine.

[Tango13]

I remember reading somewhere that Claude Dornier had great difficulty getting one of his flying boats to fly until he redesigned it with a step in the rear of the hull.