Knox-Johnston: " The sea makes us all cautious but youth makes us brave"

They are much faster, which is due to the fact they do not have a heavy, leaden keel slowing them down.

But that also means they are much more volatile.

A keel acts as a self-righting mechanism - it doesn't matter how far you push the boat, the keel will almost always bring her upright again.

But in a catamaran or a trimaran there comes a point when she will just flip over.

Race sailing is always about finding the balance between speed and safety.

But on multihulls the line is even finer.

One has to know the boat's limits so one can push her to the extreme - but remain just the right side.

Over the last 30 years, developments in technology and design have meant a phenomenal increase in average speeds.

Knox-Johnston now organises two prestigious round-the-world sailing races

Trimarans accelerate much quicker and I suppose inherently they are more dangerous, but just like a fast car, in the hands of the right skipper they are as safe as any other boat.

I would expect her to spend this season learning as much as possible from Gautier and then next season maybe enter the trimaran Grand Prix series as skipper of her own boat.

That means Ellen probably spending most of her time in France rather than here in Britain but sadly the lack of media coverage of sailing in this country makes that inevitable.

She is still young, but I have never been one to hold much store by that - during the war we had 25-year-olds captaining destroyers.

In fact, age can be a great advantage - the sea makes us all cautious but youth makes us brave and can be a tremendous advantage.

I expect Ellen to take to trimarans and have a lot of fun doing it. I don't expect the transition from sailing alone to being part of a crew to be a problem.

In the Vendee Globe, Ellen had to be an all-rounder; cook, navigator, technician, sail maker - and not least sail the boat well.

On board Foncia she will be one of the gang, where she will need different skills; good communication, teamwork and consideration for others.

But if you have faith in those around you, fitting in is not a problem.

One's mental strength is obviously far more important when you are on your own.

You obviously need to be fit and strong but you also need to have an inner determination because when things go wrong there is no-one to bail you out.

Sir Robin Knox-Johnston was talking to BBC Sport Online's Claire Stocks.