Hi folks,

New to the forum. Studying at uni in Scotland, and part of our course this year is designing and building a land yacht from scratch in teams of 5. Loving it so far. We have constructed a CAD model, which can calculate the centre of gravity, however, one of the lecturers has posed us with the question, "ok, you have the centre of gravity; why is the centre of gravity there better than in any other position?" We were stumped for an answer.

Is there an ideal place for the centre of gravity on a land yacht? If so, why is that? Ours is between our seat and our mast, closer to the seat.

I've tried searching around the forum a bit, and have also been googling "ideal centre of gravity for a land yacht" and similar terms for around an hour with no joy. Sorry if it's been brought up before.

Any help much appreciated.

Cheers,

Tom

Ruddy Nebbs got his reply in while I was bashing away at the keyboard!

think of oversteer and understeer in a motor vehicle- similar principle with weight distribution and your power source affecting handling.

An educated guess (allbeit a very poorly educated one) from me is you would - in theory - be best with the centre of gravity lining up with the centre of effort line point of the loaded landyacht.

the design of a perfect landyacht is a juggling act with length, width, seat and mast location only part of the whole equasion.
Mast angle, sail shape and size, passenger size, shape and weight being variables, are all doing their bit to complicate matters.

if C.O.G is too far back- front wheel is too light and you will have trouble with front wheel drifting all over the place.
if C.O.G is too far foreward, steering will be harder to operate.

There are a few fellas on this forum who are way more knowledgable on this subject than me, and they will show up sooner or later, but until then check out the sticky topics at the top of the construction page, one is about balance points of landyachts.
search for sail design, centre of effort etc and there is lots more info to confuse you even more (just like it still does to me)

stephen

Turning upwind is a common problem Ron especially if you are not sheeted in hard
The front wheel gets very light in those circumstances
Moving your body forward/sitting up and sheeting in hard can help
A sail flapping through the tack just lifts the front wheel and makes steering very tough
I have been for a few swims like that All good clean fun

Hiko said...

Turning upwind is a common problem Ron especially if you are not sheeted in hard
The front wheel gets very light in those circumstances
Moving your body forward/sitting up and sheeting in hard can help
A sail flapping through the tack just lifts the front wheel and makes steering very tough
I have been for a few swims like that All good clean fun

Speak fer yer bleedin self HIKO, I melt in salt water Luckily it wasn't too cold.
I am glad it didn't happen to me in spring or I would have snap frozen.
Your description of ehat happens is about what happened to me... So the Moral to the Story is be sure of your Sailing Venue before going Flat Out but then how was I to know that a great gust would happen at an inopportune moment
Ron

Hello again guys,

I'd just like to thank you all for taking the time in your responses. Seems like you guys know what you are all talking about!

Was very interesting to hear about the advantages and trade offs of various COG/COE positions. It is much appreciated.

I will create a build thread once it finally gets underway - if our team's design is one of the selection chosen!

Can't wait.

Take it easy