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47" mono build from scratch

6K views 25 replies 5 participants last post by  matt_971 
#1 ·
#10 ·
this is going to be very interesting. Can I ask what you do for a job. Seems like you have done this sort of thing before.


Look forward to more
 
#11 ·
Can I ask what you do for a job. Seems like you have done this sort of thing before.
I have done this type of thing before Matt - I have 2 trades under my belt - a Shipwright ( traditional boat builder) and a Boilermaker/welder. I gave up boat building 14 years ago and Boilermaking 4 years ago, now I'm in the housing side of things.
 
#13 ·
ahh ok well that would certainly help out lol.

Well I am looking forward to following this.

Cheers
 
#15 · (Edited)
Well , last weekend didn't work out too well but I did a little more during the week ..

Setting out for the hatch

Wood Automotive tire Bumper Automotive exterior Automotive design




Watercraft Boat Boats and boating--Equipment and supplies Naval architecture Wood



I spent some time brushing up on aerodynamics and made a few minor changes to increase " loading" on the hull at speed. If my calculations are correct we should have 9kg of downforce on the bow and 21kg at the transom at 80kmh to help the hull " stick" to the water at speed.
If anyone is knowledgeable on aerodynamics I'm also adding Vortex generators to the rear to help reduce drag

another view

Watercraft Wood Boat Composite material Natural material


and one more

Hood Tire Automotive tire Automotive lighting Wood


I did get a chance to mark out the next hull in front of the TV the other night...

This one will have a lot of aerodynamic design going into the build - looking into loading the front 1/3rd of the hull with 35kg of downforce at 100kmh .

35 kg at 100 clicks too much :crazy:

Wood Rectangle Art Font Tints and shades
 
#16 ·
care to explain some very BREIF understanding about the aero dynamics calc u done. How do you work out the load at each point?

is coming along very nicely
 
#17 ·
I'll try and explain.....

Any shaped object moving at any speed through air creates drag and drag is the opposing force of an object moving at speed.
Drag is variable - meaning the negative (suction) air force generated is an unstable, swirling force - called vortices .

Most of us would have experienced this when you tailgate a truck on the freeway in your car. You enter the unstable air zone (vortices) behind the truck and it throws your car around a little and you put your foot down to get through it . As you get closer to the rear of the truck the air 'smooths' out and you back off to allow the truck's drag to pull you along. - from this example you know how unstable and how much force drag can have just by tailgating a truck in your car.

The use of vortex generators 'smooths' out vortices reducing drag

Reducing /streamlining this negative force is What I'm trying to do.

Calculations - what's needed;

1.finding the drag coefficient - which is a dimensionless number (quantity) that is used to quantify drag
2. Finding the Reynolds number - is a number that gives a measure to ratio of a moving solid through air
3. Air Density
4 Lift Coefficient - expressed as a number relating to the lift generated by an aerodynamic body
5. Velocity - speed
6. Surface area
7. Angle of attack - in reference to boats - a horizontal line from bow to stern parallel to the keel

Once all of these are know then they can be applied BUT;
as the Angle of attack will always be variable in boats (waves, wake, water condition)I used a baseline angle of 5 degrees
Lift Coefficient was reversed as we want downforce and not lift in this case ( Lift Coefficient was not reversed when applied to the Hydro hull design)

downforce can also be calculated on its own if you just want to know the load of something simple like a spoiler or a wing

Then allow 5-6 hours of calculations and there you have it .....

it's not rocket science Head Smile Eye Jaw Microphone
 
#18 ·
thought there would be a far bit in it lol.

Is interesting though. Keeps the brain working lol.

So when you make these will it only be 1. Could you possibly make 2 lol.
 
#19 ·
Keeps the brain working
Brain overload !!

The first one out of the mold will be the trial version and if all goes well they will be available (See my signature below)

The planned line up will be - 47" Stepped mono, 47" hydro, 47" NAMBA & AMPBA legal mono, 47" cat followed by a 32" jet boat and then we'll see from there

All will be carbon/kevlar lay up and should max out at around 1.5 to 1.8 kg
 
#24 ·
they r indeed look great. I am willing to do some "testing" for you if ya like lol.

With motor combo I got I am hoping to push the low 90kmh mark. Should test the aero's of it hehe.

I love the look of the ski boat. Looks like a full scale model. Well done on that one.
 
#25 ·
Mate , if it doesn't do 100 plus I'll be P***ed ;)

Seriously , I'm aiming for 100 + with a good strong engine but trial runs will be a stocker with a hot pipe to set a bench mark . I'm aiming for around 60 - 70 with a stock engine.
We'll see how close we can get ....

The Ski boat on the other hand should come out around 600 grams bare and I'm expecting to see it around the 120 kmh mark ...

If it doesn't take flight

( note to self - add 3rd channel for parachute deployment )
 
#26 ·
its quite hard to actually push over that without some serious motor.

I running the RCMK s254 and it SHOULD be good for low to mid 90's in the cat hull.

A QD motor will do it. Benckie had my hull running a QD motor at about 80% throttle and hit 99kmh lol.

But there is about a 600 - 700 dollar difference in motor there. lol

Anyways looking forward to see them get wet
 
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