Bad luck about the no trip Lachlan... when I saw you might be coming, I thought "All right!" but them's the breaks. For sure, let me know when it's back on and I'll bring the camera etc. out.
Ron
Thanks Ron. I promise to give you a little more warning next time. Sorry for getting your hopes up, i'll make sure everythings in order next time.
Select to expand quoteSandflyer said...
Howdy blokes,
Have in mind to counstruct a land yacht. Just some starting advise.
If the rear wheels are angled, what generally are the degrees?
As a rough giude. for fun vertical, for better grip in a good wind 4 degrees, for extreme racing gripand linear stability, up to 10 degrees.
How important is the position of the mast step?
Absolutely critical to get it in the right place in relation to the sail shape and the body weight of the pilot.
Gday Landyacht: is there a rule of thumb to use when determining mast step position?
I roughly positioned it so the sails centre of effort was just in front of the yachts center of lateral resistance. I have no idea what mast rake does to performance, I based it on aesthetics from pictures Ive seen 
. The angle seems relatively variable. I also tend to design with the pilots CofG placed above the yachts CofG as well to reduce change with different pilot weights.
Just wondering whether im on the right track with these rules? I know they are far more complex issues than Ive described here.
Howdy Lachie,
I understand mast step placement is important. Dimensions I was given in a post regarding a particular class LY seem to suggest a tolerance in placement of more than 500 mm along the spine, which on a craft of 2500mm in length is huge, 20% of its total length. The CoE (sail), CLR and CoG of craft and pilot are important to create best performance. I wonder if the tolerance for the class LY is to allow for individualisation of the craft to suit pilot height and body mass distribution. If you placed the mast on a water yacht at that variance with relation to length it would sail like a pig or not at all, and either have almost uncontrollable lee or weather helm.
I, like you have kicked around the net and elsewhere to get guidance on ratios and dimensions, there seems to be a rough rule of base to track ratio, within parimeters. Amongst my former Brazilian rainforest, I came across design drawings I had forgotten I had. They are of an ECHO V, new generation class V landyacht, designed by M Hampton C1986/87. I know these are old hat now, but have some interesting ideas. These little craft must have been OK, they were piloted by our blokes, to 10 and 11 in the European titles in '86, the drawings I have claim to be an upgrade/improved version.
Mast rake on a water yacht will, generally speaking, determine upwind and downwind performance, yes, hull, sail and rig design also have a hand in these things. Generally speaking a mast raked aft will allow the yacht to sail higher upwind, point higher into the wind. but downwind will not allow fastest sailing, downwind the mast needs to be more vertical or on some classes even a little forward. Some yachts have adjustable rigging, cams, over centre latches etc., which permit this on the run. One of the classes I sail, a couple of the vessels in the fleet have this rig option.
I appreciate your thoughts and insight towards design and construction. My LY project is 30+ years in the making, I purchased steel frame material when I was a teenager, it sat in the yard and rusted away to nothing. Like many of us, other things get in the way. It is now I have a bee in my bonnet and am in a position and keen to do something about a LY.
In the mid seventies we as Scouts built some very rustice LY, which we sailed as a regatta between the two Gawler troops on Port Gawler beach. These craft were mostly/all square rigged with canvas tarps, ground sheets etc., no go upwind. The craft I was involved with was paced by a motor vehicle north to south on the beach, and on many runs was paced at more than 40 mph, (60+ kmh). I or father have slide photos of these craft and that day, I will try and dig them out and then post, so all can have a laugh.
Keep up the good work, study and construction. What is your honours study project?
Thanks for the info Sandflyer. I guess mast position is a lot more forgiving on a landyacht due to the increased lateral friction obtained using wheels, not to say performance isn't reduced by an incorrect positioning though. Ive read somewhere that placing the CoE too far back greatly reduces sail power and too far forward reduces the amount of force needed to lift a wheel. Not sure how reputable the source was though.
I completed an applied science degree majoring in biotechnology and environmental science. The honours project is biotech, Im trying to identify a filamentous bacteria thats causing problems at the local waste water treatment facility. Exciting stuff!! 
EDIT: And photos, of any theme, are good as gold.
Hello everyone. back again, finally! Well was up to no good Easter weekend during some great conditions 
Had both the yachts out but spent most of the time in the larger one as my miniyacht was a little touchy. I had to point as high as possible to stop from being blown over ever second gust. After a few runs to the fence and then pushing it back i gave up and will wait for lighter conditions.
It seems it will carry out its purpose and that is to provide entertainment when the conditions are too light for the larger yachts. Im really looking forward to taking it out again ASAP.
I am going to have to visit you sometime Lachlan. I just love those wide open spaces you have there. You don't even have to leave home to have a sail. How good is that!!!
Well the locations are fairly close, within half hour so long as agricultural activities dont get in the way. We had a ripper paddock years ago, about 1km square without a tree in it, last year it was turned over 
Always on the search for smooth paddocks when travelling. The paddock you see in the pictures here was a bit rough, sailing around was rather shakey as there were still furrow lines.
EDIT: By the way, cow pads make for fun while sailing. sailing dodgem car style if you catch my drift Didn't hit any wet ones thankfully although i don't think I fully gained the experience by missing them.
