Introducing "Blue Flyer" and "Blue flyer II". Prior to sifting through the many posts on different mini front ends. I had a brain wave and thought a front mast pipe would be easier to make up than a spine mounted one. 76 Od pipe would give me some play when using the thick base aerial masts. Lots of grinding and filing to get it fairly square, weld it up and the front of the chassis is complete - steering and mast base. Three chain links were welded to the mast tube in lieu of a 3 way pulley block. An ex stop sign post is the spine and the back end is standard LLM.
A 20" bike wheel and fork were set up to the correct angle. The headstem of the forks was heavier steel than I expected and welded easily. An 8" boat trailer wheel was also made up for a front end.
Test day 1 arrived and instead of getting a run it was ratted for the 20" front wheel to replace a collapsed steering arm on another land yacht and it donated both back axles and wheels to two separate landyachts that had clashed axles. It came back home with an odd pair of bent back axles.
A two seater had been on the agenda for a while. One of the bent rear axles was able to be panel beaten straight and a 25mm tube was slid inside and welded in to beef it up. The other rear axle (in photo above) was too kinked so was cut off just below the bend and lengthened by about 400mm over original length. A length of 2mm wall 25mm RHS was ran full length inside the whole length.
Test day 2 was more successful. A gusty northerly blowing down the local airstrip meant lots of 30 metre reaches were needed to work your way upwind. With short and long rear axles, the short side would tend to lift in gusts and the longer side tended to drift suddenly on the gravel airstrip. Steep spoon drains with bushes that had to be crossed when reaching added to the excitement. A tad less than 30kph was the top speed reached, the short runs across wind didn't give much time to wind up. What became obvious was the massive low down grunt the uncut 7.1 m2 sail had when allowed to belly out, able to pull me up the bank of a spoon drain over 3/4 inch gravel. Always able to sail back to the car in the 1.5 hours spent there. The back end felt really loose when gusts hit, lots of opposite lock needed to keep a straight line. Despite the corrugations, bushes and spoon drains the extended rear axle remained straight.
The extended axle and tandem seat spine
The only modification needed to any LLM is a lug welded on the chassis to pick up the front tandem chassis. The rear fits any standard LLM 35mm axle centre.
Test day 3, 7.30 am 20kph breeze The 11 year old pilots loved it. (and so did the older pilots)
The sail is not trimmed very well in the photo above. When sheeted in it took a good shape. The back end always felt skittish when a gust hit, The steering was pretty responsive and pulled the rest back into line unless you over corrected, then it fishtailed. Heading upwind you could fish tail all the way up the driveway using the low speed grunt of the sail to keep you moving. The easterly last Saturday meant we could use the main driveway, the trees on the west side play havoc with a westerly wind. For the first time ever we have officially gone faster than the wind. As recorded at the Bourke airport nearby Average wind speed for the morning 22 to 28 kph. Peak gust wind speed for the day was 37 kph. Michael and young passenger got it up to 45 kilometres per hour, Myself and young passenger only managed 42 kph and when the two heavyweights Michael and I did a run we got it to 40.8 (165kg). Strong winds expected this Saturday so might have to find a smaller sail, a pity, this sail mast and boom work so well together. 
Thanks for the write up and photos. Excellent work and looks like everyone had fun!
Memories in the making! Great stuff My 2 minis have the mast well forward like yours the mast mount tubes are squashed oval so that the masts can be raked fwd or back with wedges You may find with smaller sails some extra rake back will give better balance
Expecting lots of wind this morning we went out with a tall wild winds storm sail on (the same height as the 7 metre sail but only 4 square metres). It handled a lot more smoothly and the top speed was pretty close to that with the larger sail without the twitchy back end. Then the wind dropped off and the rain set in. The damp black soil made our wheels a couple of inches bigger until you got enough speed to throw the mud off. The extra 400mm width on one side and the weight of the passenger makes a big difference to the stability. A bit like a keel boat compared to dinghy like single LLM. The next chassis will have a squashed tube mast base, that should suit the squashed tennis ball at the bottom keeping the base of the mast from crunching on the diagonal surface of the steering tube. It should go pretty close to fitting neatly on the oval surface of the front of the chassis where the steering tube mounts.
Hi Chook,
Please can I ask for advice. I am building a sailing shunting proa and want to use twin 4.8m windsurfer rigs, can you give me some advice about:
mast step angle [90degree], by the way - shunting proas don't tack as such!
Length of mast step and
reinforcement of the windsurfer mast?
tx Clive in the UK
G'day Clive, You have your Chooks mixed up, Chook2 is the fellow on this forum who has put in many hours to get the best out of windsurfer rigs on landyachts. Finding older posts on this forum can be a bit tricky, you need to go through the Gallery to search for them or type in land yacht mast reinforcement in google and see what comes up. You are not using huge sails so a normal mast with a length of reinforcement cut from a broken mast or a length of timber shaped and slid up inside the base should go close. A twin sailed shunting proa needs a different approach to a landyacht. Do you Trim the sails for steering balance on the proa by adjusting the drive of each sail? There were images of a proa with two Laser sails on the net, a similar sail size to what you're thinking. Running four sets of main sheets to give you the 180 degrees of adjustment needed will keep you busy when shunting. Do you intend to have your mast step projecting above the hull as a pipe or built into the hull like on a Laser?
all the best Colin
If you want to trawl through old posts,in the search engine just put seabreze construction page 2 and it brings up all the old pages same with general page 2 etc
Hi Colin,
5 star answer , tx,
The main sheet issue is still to be addressed but I don't think is insurmountable; after all its a bit like spinnaker rigs with 2 ropes on each clew.
what I think is more important:
Is a 90 degree mast steps say 60cms high (or longer thane cut down later) with
the 2nd hand masts reinforced with timber for at least 2 meters with a double glass tape reinforcement (50% overlap) for the bottom 2 meters of the mast and
some form of reefing system ( not sure about this yet.
Luckily, by younger brother was a member of the UK Olympic Tornado sail team and worked for Performance Sailcraft UK ( Laser) until he retired a couple of years ago!
Cheerho
Clive
00447771855197
Hi Colin,
5 star answer , tx,
The main sheet issue is still to be addressed but I don't think is insurmountable; after all its a bit like spinnaker rigs with 2 ropes on each clew.
what I think is more important:
Is a 90 degree mast steps say 60cms high (or longer thane cut down later) with
the 2nd hand masts reinforced with timber for at least 2 meters with a double glass tape reinforcement (50% overlap) for the bottom 2 meters of the mast and
some form of reefing system ( not sure about this yet.
Luckily, by younger brother was a member of the UK Olympic Tornado sail team and worked for Performance Sailcraft UK ( Laser) until he retired a couple of years ago!
Cheerho
Clive
00447771855197
To get the best out of your windsurfer sails they need to be hauled down tight to get them to their optimum shape. depending on the sails cut the mast may need to curve a long way. Normally a sail will be matched to a mast with the correct flex. By reinforcing the mast to nearly half of its length the mast will stiffen at the base a fair bit so getting the correct shape might be fun or not possible. What will be greater than anything we normally encounter on land yachts / windsurfers is the stresses on the base when a gust hits.
A windsurfer is relatively light and unstable so a gust will accelerate it and / or heel it over and spill air readily. Mast is supported at base and effectively guyed at boom height by the rider who is also the mainsheet. Reinforcement is not necessary.
A land yacht is more stable ,the weight is held much lower and there is no sideways support of the mast at the original wishbone height. Spilling the wind by tipping in response to a gust puts more force on the base and takes longer, the mainsheet does take some of the force but its attachment point is effectively much lower on the mast and drive is split between the sheet and the mast base. With only the base supported some reinforcement becomes necessary especially at the point where the hull mast base ends and the mast becomes free to flex. This is a rotating wear point too. The boom arrangement on landyachts also brings a stress point down lower. 600mm to 1000mmm seems to be the popular length of mast base reinforcement allowing the rest of the mast to flex back and give the sail a good shape as well as flex sideways when a gust hits.
Your Proa will be heavier again and I imagine more stable so the forces through the mast base will be greater for a longer period of time as it tries to heel. I'm guessing you want to retain the wishbone boom arrangement on each of your sails which will simplify things.
By reinforcing the mast even higher with timber inside you are taking away more of the flex and the ability of the mast to offload when a gust hits, this will put more stress on the base. Sufficient reinforcement to strengthen the base and stiffen the mast up to a short distance above the wishbone / boom attachment might be all you need. Once above the mast base spigot the reinforcement should not be rigid and still allow flex. A length of old mast fitted internally that is a tight fit where it goes into the base but sloppy further up will suit the purpose.
90 degrees mast bases will be fine, you have two sails so the balancing will be done between them rather than by tilting each sail.
Laser sail shapes are different and suited to the stiffer aluminium mast. Traditional landyacht sails followed a similar pattern being suited to stiffer masts and the original Lake Leffroy Mini plans included details to build a stiffer mast and recut windsurfer sails to suit the stiff masts. This was the norm for several decades until CHOOK2 and a number of others worked hard on how to get modern windsurfer sails to rig up as originally designed AND fit land yachts with great results.
I am only just working out myself how much better a flexible mast / matched sail goes compared to the old stiff mast and ill fitting sail combination that we were happy to use when we first started. One of our best masts now is 400mm shorter than when we first started with it after snapping twice at the base. Then we Reinforced it internally for about 1200mm with a length of light duty mast so it effectively has a base with walls twice as thick that tapers off quickly to give a stiff bottom section that still flexes easily. It hasn't missed a beat since then and is only an old pink one piece fibreglass mast.
