building a raft to do 7.5miles on a river?

helpimcrap · 16 Dec 2011 at 17:57

been asked to do one for a race and it has to A) not sink and B) beat the others lol.

i'm gonna concentrate on A first.... lol

thinking dual hull ala catamaran style with 3 big plastic light weight barrels containing air or helium on each side. the gap in between would be a wooden frame - maybe metal to keep strength up and the weight down? (titanium anyone? lol)

in terms of propulsion - obvious ones are sail or an engine. Sails are out so it's a motor. I'm thinking something 2 stroke (scooter motor or petrol mower engine?) as they're low weight for the power. Doesn't have to be mega fast as it just needs to be enough to steer the boat which will be a big plastic rudder.

obviously his needs to be mega cheap!

Glaucus · 16 Dec 2011 at 17:59

Helium lol.
Is this a charity event?

3 barrels. Either side with wood will be fine.

If you want motor I would go with a moped engine and proper water propellant. Unless you can find any cheap proper outboards on eBay for nothing.

Skillmister · 16 Dec 2011 at 18:05

Helium.....

Maybe if they had filled the titanic with helium it wouldn't have sunk

Edrof · 16 Dec 2011 at 18:06

Ignore me!

EdGey · 16 Dec 2011 at 18:09

Oars!

Post pics of said raft when complete

Werewolf · 16 Dec 2011 at 18:21

EdGey said:
Oars!

Post pics of said raft when complete

Whatever propulsion is chosen, take oars for backup/assistance.
If nothing else they are
A: Good for pushing the raft away from obstacles
B: Good for splashing the other contestants.

Reaper 392 · 16 Dec 2011 at 18:27

you can thank me later

Hyburnate · 16 Dec 2011 at 18:30

Lawn mower moto?

RomanNose · 16 Dec 2011 at 18:31

Nuclear reactor and generator tbh, only way to win. It's probably what the Iranian who was caught with a radioactive isotope was trying to do.

Reaper 392 · 16 Dec 2011 at 18:33

time for a serious reply now.

im not sure of the budget for this, but you could see if there are any dirt cheap jetskis/boats with working engines down at your nearest scrapyard and use them

its what they always did on scrapheap challenge

Cosimo · 16 Dec 2011 at 18:39

Reaper 392 said:
you can thank me later

[/QUOTE]

You won't be getting thanks. :D

tres · 16 Dec 2011 at 19:04

From someone who has organised many a raft race before...

Use insulating foam - you can shave/sculpt it easily, light as hell, and you can make very fast shapes!

http://www.facebook.com/photo.php?v=408947028815

Trifid · 16 Dec 2011 at 19:17

I hope you have something better than some rope, a few planks of wood and empty barrels. When I built one it barely lasted the 100 or so metres we needed to go.

manic111 · 16 Dec 2011 at 19:31

At this time of year, I'd suggest putting a heater on it somewhere too

Edrof · 16 Dec 2011 at 19:55

Two cheap dinghies, one plank of wood to connect them, profit!

HardwareGeek · 16 Dec 2011 at 20:07

What are the rules?

But maybe...

2 kayaks with jets ski engines / impellers mounted in the back, lashed together with netting across waterworld style?

Volitous · 16 Dec 2011 at 20:42

Surplus aircraft drop-tanks are what the Cadets round our way completely dominate the race in every year. Proabably because there nice and streamlined.

Malevolence · 16 Dec 2011 at 20:48

My friends and I used to make rafts in our childhood and use them to sail down the Trent. Now you're talking a time before H&S because so intrusive, so we just used planks of wood, shedloads of polystyrene packaging and twine.

Weirdly though, they were actually pretty decent.

helpimcrap · 17 Dec 2011 at 15:23

tres said:
From someone who has organised many a raft race before...

Use insulating foam - you can shave/sculpt it easily, light as hell, and you can make very fast shapes!

http://www.facebook.com/photo.php?v=408947028815

Thanks - will certainly bear that in mind!

HardwareGeek said:
What are the rules?

But maybe...

2 kayaks with jets ski engines / impellers mounted in the back, lashed together with netting across waterworld style?

I had thought of the 2 kayak idea but wasn't sure - i'll research waterworld now! lol

Malevolence said:
My friends and I used to make rafts in our childhood and use them to sail down the Trent. Now you're talking a time before H&S because so intrusive, so we just used planks of wood, shedloads of polystyrene packaging and twine.

Weirdly though, they were actually pretty decent.

H&S? What's that....

helpimcrap · 17 Dec 2011 at 15:26

Reaper 392 said:
time for a serious reply now.

im not sure of the budget for this, but you could see if there are any dirt cheap jetskis/boats with working engines down at your nearest scrapyard and use them

its what they always did on scrapheap challenge

Will research that thanks

Hyburnate said:
Lawn mower moto?

If it's a 2 troke it will be condiered - 4 strokes ones are so big and heavy for the power given.

Werewolf said:
Whatever propulsion is chosen, take oars for backup/assistance.
If nothing else they are
A: Good for pushing the raft away from obstacles
B: Good for splashing the other contestants.

Noted - good points!