Design of novel ski rope management...

What it does

Design of novel ski rope management systemPHY435 – Theme 2- Product invention

Dan Friend, Department of Physics and AstronomyUniversity of Sheffie ld

The ski rope management system is a tension controlled winch that is to be fitted towards the rear of a boat and providethe connection between the boat and the rope. Its purpose is to decrease the number of rope inflicted injuries sustained

by water-skiers and also make the sport easier to learn.

Safety

• Water skiing is growing sport with approximately 17million people taking part each year in the USA.

• In 2003 the US Coastguard reported that water skiingwas responsible for 700 serious accidents and 19deaths.

• Many of these accidents were caused by water skiersbeing dragged under water as they became entangled inthe trailing ski rope whilst being retrieved by the boat.

Why is this product needed? Aided learning• Water skiing is a difficult sport for beginners. Being able

to simply get out of the water generally takes several hoursof practice.

• Once out of the water staying up isn’t easy. The key tosuccess is balancing the force from the boat with thefriction between the water and the skis, in order to maintainconstant speed.

• If at any point the skier goes faster than the boat (eg whenthe boat accelerates in to the trough of a wave), the ropegoes slack, leaving the skier with nothing to pull againstresulting in them falling off backwards.

How it Works

• The ski rope management system is controlled by a tension switch that triggers a winch to wind in the rope.

• If the water skier falls off, the decreased tension will cause the rope to be safely retracted back to the boat.

• Once the rope is aboard the boat it is unable to injure the skier or other people.

• When the rope goes slack it is quickly recoiled until the the tension in the rope reaches a level suitable for water-skiing.

• This gives novice skiers a greater success rate.

CoverPlastic cover fits over the mechanicalsystem to protect components andalso keep people away from movingparts.

WinchGeared winch to rapidly recoil rope whenturned on and slowly release rope whenturned off.

Selling points and market• This product is unique………….No competition!

• Reduces risk of accident.

• Increases rate of learning.

• East to fit to the boat.

• Large market – Tens of millions of waterskiers 100,000 + boats

Cost• Approximate cost - £500.

• Typical water skiing prices-

Ski Boat £20,000 +Water ski - £500Ski rope - £75Life jacket - £100

Limitations andfuture development

• Components may become damaged/worn.

• Only designed for boats with a ski pole.

• Make universal system in future.

• Add extra features such as skier position detector.

Tension controlled switchAs the rope goes slack the spring expandstriggering a micro switch that controls thewinch.

Micro switch

Connection to winch mountings

Spring

Attachment bracketBracket is compressed around the ski pole.

Bolt

Stainless steel bracket

Fixed steel casing

Welded mountings

Eclectic motor

Spool

Wheels and runnersAllows winch to move as tension inrope changes.

Fixed casing

Sliding casing Wheel300mm

350mm

200mm