The quest for a 100mph gas boat

[Rep732]

So as you all know we start getting bored when we've finished our builds and we look for more stuff to build right?

My next build adventure is building and acquiring the things I'd need to build a gas powered 100mph boat.. question is can it be done.

 

[RcJunkie13]

Anything can be done as long as

 

[Rep732]

Tooth paste?

 

[RcJunkie13]

Yes I just noticed that
But are u doing this with the current boat or a new one?

 

[Rep732]

Gunna build a new one. Im happy with the fountain so it time to build a new one for pure speed and pushing the limit of gas

 

[misterleon]

Get yourself some of this

Serious question… does it actual need to “brap”

 

[Rep732]

No Bobby but if gas is going to hinder the speed goal i will go e word but really don't want to

 

[RcJunkie13]

Have you considered some boost bottles and an rb innovations supercharger? That should get you over 120 in ur current one

 

[Rep732]

I have my own brand of snake oil.. and its not necessarily the power of the engine for boats you need high rpm for spinning the prop faster

I am leaning on this hull tho

 

[RcJunkie13]

Ok probable stupid question but what if U put some sort of trans in there just to be able to make the prob go faster with a gear ratio? To get 100mph strictly off rpms seems very unnefective and hard

 

[Rep732]

You can get a lawn mower to do 100 mph the problem is the amount of gears it will take and the distance needed to reach 100mph... and yes I would need a gear box to amplify the output shaft speed of the engine so it would need to turn the prop 2 or more times per one revolution of the clutch bell

That hydro doesn't look too easy to cram stuff in there so it would either be gas and max it out on the engine rpm and mess with props or go electric to get a motor than can turn 40k+ rpm

 

[spents]

now bare with me cos i've never had much to do wi boats,
but is there such a thing in the boat world as an adjustable pitch prop ?
what i mean is a prop that ya can adjust on the fly ,

or a jet boat, i don't mean turbine,
i mean water intake under the boat and prop/impeller rin a directional unit on the boats arse ?

 

[Seandonato73]

Just a thought rep, better make sure that hull is rated for 100mph. One of the issues my old man had in full size was hull designed not to flip over at that speed.
Spents jet drives are fun. Bit not practical for speed runs imo. Having a variable trim would be more worthwhile then anything. Also have to remember its not just rpm that makes a boat fast, prop diameter and pitch makes all the difference. Keeping the boat light and having good weight distribution plays an equally important roll as well.

 

[PortCityRC]

Just a hull type example you need Rep.. they hit 100mph with these type of racing hydros with our 30.5s. It s been done. Have to dig for the vid later. Jet drives are great for basher boats and areas with shallow water, but are not good for any top speed. Thrasher Boats put out a 6s version jet propulsion but is no speed racer by any means. Anything rc is just not meant to survive a 100mph hit on water as that turns to asphalt at them speeds. I don't believe a catamaran or vhull you will ever hit them speeds without going electric unfortunately, then it becomes quite easy as guy are doing this on stock motors and escs on the proboat miss geico with just a prop swap and good lipos. Also the tfl Zonda which can be had in carbon fiber.

 

[Rep732]

Thanks port. Ive seen the rigger hulls and their not too great looking and I said I want to achieve 100mph out of a gas boat so that may be the only option...wonder if a hydro can do it as their almost similar to a rigger hull but obviously different... seen a video last nite of a guy running a rigger and he clocked 92mph id be ok with that but definitely want triple digits

 

[Micha-IN]

I know how hard it is to reach 100km/h... good luck!

 

[Polar_Bus]

Its not all about raw hp, now one has ti start paying extreme attention to hull design and efficiency. In theory it takes X amount of hp to move X amount of mass within a specified time. Drag racers have been using this formula for decades. The problem with theoritical numbers is the fact that enviromental resistence is the speed killer. In this case "water"(resistence) is the speed killer. Sounds like a really interesting venture.

 

[Rep732]

I think a rigger/hydro hull has the potential as those hulls have the least amount of contact with the water on plane

 

[Seandonato73]

My grandpa ran STV hulls. They were very fast and had darn near nothing in the water when on plane for some reason they were very stable at speeds over 100mph. I would think it would be easy to replicate in scale rc with hulls that are produced currently. No way in hell would I run that God awful looking thing port put up lol. Don't care how fast it can go. Be too ashamed to get it out of the truck.
Not grandpa's but you get the idea of the hull design.

 

[PortCityRC]

Neither would I just for the record. Just saying the rc speed riggers that are currently pulling triple digits with 2 stroke smallbores. Yes very ugly. And they do have that hull shape for sale somewhere, like you posted of your grandfathers boat I'll have to find it later.