Tiny hydroplane plans, First build

[mat_biker]

Hi all,

I have been looking around your site and you boys know your onions! so any help from people with knowledge would be cool, as I have never done a full size boat.

I have a 600cc 1992 Honda CBR engine

Power: 98 PS @ 12,000rpm 50 PS @ 9,500rpm 27 PS @ 9,000rpm
100 hp (74.6 kW)@12000 rpm
Torque 63.7 Nm (47 ft·lbf)@10500 rpm

Thinking of using it in a small single seater hydroplane, with a surface drive prop.

Does anyone know of more modern plans or are we still using plans from Science and Mechanics and Boat Builder Handbooks from 1970+?

If we are does anyone have info or experince with the "Air Marine Special" by Joe Michelini, especially any advise on runing hydroplanes with surface drive.

link to plans - http://www.svensons.com/boat/?p=Hydr...rMarineSpecial


Thanks Matt,

[marshmat]

Heya Matt, welcome aboard

Yes, there are more "modern" plans available, that should be somewhat better than what you might photocopy from old magazines. It depends on what, exactly, you're looking for. And a small hydroplane is a nice, not too complicated, but sufficiently challenging and satisfying first build; quite a few people start with something similar.

Your 600 sportbike engine is one hell of a high-strung screamer. It is about the same size as the 36-40 ci outboards used on Class-D stock outboard boats, some of which run 70+ mph.

Terms like "Practical" and "A logical choice" have little meaning among such boats. The selection of a size, class and style is an entirely emotional decision; class rules and engineering judgement take care of the details of how to make it work. Do you want a monohull? A tunnel hull? A 3-point hydro? You could do any of the above, and with suitable plans, they'd all be awfully fast. Or do you want to sacrifice a few miles per hour to go from 13-14' or so, as most Stock Outboard racers are, to something a little larger that will let you carry a friend or two and some gear? I can think of a few ply/glass runabouts of 15' or so that would go scary-fast with a motor like that and would still be able to take a few friends along.

[mat_biker]

thanks for your quick reply,

The engine although same size as class-d stock they normaly use Mercury 44xs with 55hp the one I have is 600cc and about 100hp

I dont realy know if I want a monohull, tunnel hull or 3-point hydro.
It just I can only find this design that can handle the power and is small enough to easly carry.
What I require is a TINY boat because me and a friend will have to lift it over wall and carry to the launch point, probbaly with removable drive gear.

It although small and light needs to handle 100Hp, easly much more but dont think it will ever need any more?
It will be in coastal water, if 2 people could fit that would be a plus but think it will increase size and weight?

What would you recomend and why?

thanks for ya help,

[fnirt]

Don't know if this is what you're looking for, but these guys are making tiny hydroplane racers..

http://www.muskokaseaflea.ca/

[Yellowjacket]

First of all, appreciate that with 100 hp any boat that two people can lift over a wall is going to be a very serious fast boat. The flying mile record for D stock runabouts is over 80 mph. You have 30 to 40% more power than they have and they weigh over 500 pounds including driver. Bare hulls weigh around 130 to 140 pounds. Do that math, you could see speeds in the 90's or more if the design is optimized for speed. That's a runabout, a hydro will be even faster.

That said there are some 2 place small boats by Glenn L that might be more what you are looking for, and some of them are inboard designs. The Dynojet weighs 125 pounds (hull alone) but might be seriously overpowered with 100 hp. You could get a jet pump from a jetski and couple it to your motor. Here is a link to the GlennL customer photos.. http://www.glen-l.com/picboards/picarchv.html

The TNT is an outboard but has been built as an inboard and a jet. Look in the photos of built boats on the site and maybe something there will strike your fancy. The Bullett weighs 140 pounds and is a bit bigger and might be safer from that standpoint. You need to think about weight distribution if you convert an outboard.

Clarkcraft has a sport runabout "Freckle 11" that might work, but they don't recommend that much power for it. They also have a 13' sport runabout that looks pretty robust and holds two.. Their 48 cu in three point hydroplane will do over 90 mph, and you have more power than they have..

I'd probably consider an outboard for the simple reason that you can carry it separate from the boat and that is going to make it a lot easier to lift over the proverbial wall, as compared to the hassle of pulling out an inboard motor to get the boat light enough to carry around.

Finally, you should also think about derating your engine some if you want it to live very long. If you wind it up to 9,000 rpm and hold it there (like you can in a boat) you will wear it out pretty quickly. Motorcycle and car engines simply aren't designed to be held at high power for more than a few minutes at a time. OTOH, you are going to be going so darn fast that maybe you will run out of room and have to back off before you can damage the motor. Tough decision.... Looks like fun.

[mat_biker]

Thanks yellowjacket,

I like the look of the clarkcraft's 3 point hydroplanes, but seems to be of the same age as the free design that I have. Has hydroplane design changed at all? I will be using more modern materials but with such will come a weight saving do u think this will cause problems?

I wont run the engine at full power as I think the result might hurt, possable 100 mph flips!

What sort of speed should a prop to spin?

[Jimboat]

Clark designs are very good for parts definition and construction techniques; design concepts are many years old, and should be updated to present-day high performance designs, and ensure safe operation.

[WestVanHan]

...this all reminds me of a guy about a mile down the beach who built something like this.

I looked at the boat with it's motorbike engine,decided it was a death trap.

Two weeks later he wiped out at speeds estimated to be in excess of 100 mph.

Witnesses stated he hit the minor wake of another boat and flipped,the boat torn to pieces with him sustaining quadripalegia and severe brain damage.

Wife and 2 kids,insurance problems ensued and lost everything.
They went to live with her sister.

Last I heard (~1996) he was in a care home,dressed up in diapers and hooked up to machines for feeding.
In a state where he was somewhat aware of his situation but lacked intelligence to communicate.

Best wishes with your project.

[Jimboat]

WestVanHan - what an awful story about your friend down the beach. So sorry to hear of such a bad accident and tough consequences. I hope things get better for him and the family.

Your example is a good one to illustrate that performance boat building can get one into trouble if the design/setup is not made to accomodate the desired operating conditions. Scaling an existing design for more length or more weight or more power is not a trivial dimensional change, and must be done as a hull re-design to ensure dynamic stability throughout the new expected operating range to be safe and predictable. Your example is one of many that i've heard of, resulting from "dimensional" scaling of older designs to "more power", without properly redesigning the hull to accomodate the new conditions.

[marshmat]

There is a good reason why, for many years, PWC manufacturers had a sort of "gentlemen's agreement" that they would not sell any stock PWCs that could exceed about 60 mph.

60 is damned fast by most standards, and- as anyone who travels on highways knows- even a small vehicle at this speed can do serious damage. Increase to 90 mph and you have double the kinetic energy, with the space and time available to react to a problem cut by a third.

High speeds- and for the kind of boat we're talking about here, I'd say anything over 40-50 mph is high speed- require extreme care in all phases of design, construction and operation. Offshore powerboat racing drivers often wear parachute-equipped lifejackets, for example- hitting the water at 90 mph can be instantly fatal, so you need something to slow you down in the one second between "Get thrown out of crashing boat" and "Hit water".

[WestVanHan]

Fortuneately he wasn't a friend of mine.

May sound a horrid thing to say,but everyone-especially him-would have been better off if he'd been killed.

Something like that happens to me,my brother and a couple friends have my instructions to sneak in and pull the plugs or something.

Being a veg in a hospital, F$%k that.


And now these PWCs have 250-260 hp in them.

[Jimbo1490]

Originally Posted by marshmat

There is a good reason why, for many years, PWC manufacturers had a sort of "gentlemen's agreement" that they would not sell any stock PWCs that could exceed about 60 mph.

60 is damned fast by most standards, and- as anyone who travels on highways knows- even a small vehicle at this speed can do serious damage. Increase to 90 mph and you have double the kinetic energy, with the space and time available to react to a problem cut by a third.

As with the similar 'agreement' that once existed between all the Japanese motorcycle makers, BRP has shattered the 'safety pact' with their Sea-Doo RXP-X. For a company that is soooooo liability conscious (my bus partner was their chief counsel for many years, so I know a thing or 2 about BRP) it always amazes me (and him) that this product was ever built. I guess they figure in the end it's better to sell and risk being sued than to never sell. I disagree.

The Suzuki Huyabusa (GSXR1300-R) was the deal breaker with the bikes, BTW.

Jimbo

[messabout]

Pray tell, why are so many of us compelled to exceed the bounds of reason? I am/was as culpable as anyone. In my younger days I was an active APBA hydro racer and also a mid level motorcycle racer. As geezerism advanced I have sometimes wondered at the reasons for my previous irrational behavior. Testosterone overload maybe? The hydro guys had an expression that applied to ultrazealous drivers: " no brains and two sets of guts". The bike guys had a similar expression in: "a head full of guts". The need for speed is a near universal trait of virile males and a few females too. What's up with that? Any psyche majors out there with an opinion?

[Yellowjacket]

Originally Posted by messabout

Pray tell, why are so many of us compelled to exceed the bounds of reason? I am/was as culpable as anyone. In my younger days I was an active APBA hydro racer and also a mid level motorcycle racer. As geezerism advanced I have sometimes wondered at the reasons for my previous irrational behavior. Testosterone overload maybe? The hydro guys had an expression that applied to ultrazealous drivers: " no brains and two sets of guts". The bike guys had a similar expression in: "a head full of guts". The need for speed is a near universal trait of virile males and a few females too. What's up with that? Any psyche majors out there with an opinion?

So what's your point????

Of course the need for speed is universal. It has been going on since the wheel was invented and some Cro-Magnon man realized he could use it to haul butt down a hill. Horses have been raced for as long as they have been domesticated. The second ship ever built was probably designed to be faster than the first one….

Surely as a racer you understand the pleasure of driving a vehicle (be it wheeled or on the water) to the limits of its capability. Yes we get older and slow down some, and surely now we do a lot fewer dumb things than we did when we were young and stupid.

But pushing speed to the limits of control is a challenge that you either love or you don’t, but if you don’t, I feel sorry for you because haven’t probably ever really lived…

I think I need to get busy on the hull bottom design for that "D" runabout, but in the meantime I think I'll slap on the race tires and take the Z06 out for a track day, all this talking about enjoying speed has me in need of a fix…

[Jimboat]

The "need for speed" drives a thrill that most of us love. It's worth it to most of us, to achieve the "most" out of our performance powerboat.

Key is...hull needs to be designed to go the speed expected. Not hard to do...just needs to be done.