Designing class 5 yacht

Welcome to the forum Stephan.

Beautiful drawings Stephan.

Maybe you should review the steering head angle. As has been discussed here several times, the steering head axis needs to coincide with the contact point of the front wheel to result in neutral steering. This can vary from yacht to yacht though.

The general rule is that "lead" as you have results in directional instability making the yacht skittish and difficult to control, especially in running push off starts

"Trail" will produce directional stability and a yacht that will most likely sail by itself. Have your running shoes on if you want to catch it. Too much "trail" will make the steering very heavy.

A small amount of trail is usually a good thing and very useful in running push off starts.

Your English is excellent and please keep us posted with your progress.

The knowledge base on this forum is huge. Use it to your advantage.

Hi Stephen
Excelent work.
You have lots of questions and I think all of us will get you there.
I think you will find all that you need in building wheels on this link
www.seabreeze.com.au/forums/Land-Yacht-Sailing/Construction/These-look-wheely-goodis-there-a-problem/?page=1

I had problems with the original wheel design but since I started using 26" bike rims there has been no problems. We now use a flat sheet of ply/mdf as a mold as we now build wider rims so the dics can now be flat.This has made the whole process easier.

I now use polyester resin and make up s sheet of glass(Chopped strand) for the spokes. I use 8 spokes, Paul uses 5 (i think)

The mast post center on my yacht is now 1360mm from the center of the rear axles
(I think the mast was to far forward before and with some advice from french friends I moved it back which has been a great improvement)

Most of the OTT use some type of dampener on the front tube now to eliminate sail shake,you may want to look at that.

Ask plenty of question,I still have a huge amount to learn but enjoy playing around with design changes.

What did you use to draw up your plans, best I have seen.
Cheers
Vic

Hi Stephan. Lookig at your first side view drawing, the angle of the steering pivot is more like 60 degrees rather than 28.4. That is why a line down thru the steering arm doesn't touch the grond where the wheel sits. Neat drawings, I'd like to know how you draw them also..wok

the chassis/wheels/sails should all be pretty straight forward for you ,but the seat is a rather large challenge.
if you are going to jump into class 5sportiv I would take advantage of being in the right part of Europe ,and try to obtain a yacht that you can restore. this gives you the advantage of trying out different mast positions etc for where you will sail, allow you to trial your new wheels as you build them,and get an idea of the best seat design to suit you. The seat I built from a mold was rather constricting when I sailed on a french beach. so the whole seat needs to be chopped up and redesigned,to be something more along the lines of the more common designs around Europe

Lots of reactions, thank you for that. I will get through them chronological.

At first, the drawings I made with the CAD program Unigraphics NX 5. This actually is a very expensive program, but since I am a mechanical engineering student, I can use this program through the university.

Then, the steering head angle. I saw the (approximately) 30 degrees on yankeesailors design, I copied that. I think our other yachts also have lead instead of trail, but I will have to check that. As you advice me, I will change the design to let the steering head axis coincide with the contact point on the ground and (perhaps) add a little trail. I will have a look at a damper to add, but I think that it may be wise to first build it without, and to add it later if everything works.

For the rear wheels I didn't find this topic before that you posted, Vic. It looks very complete and I think indeed it will be very helpful. I will look for (cheap) 26", around 40 mm wide rims and use flat sides. And if you say that 20 mm bearings are good enough, I will use them. Aluminium for the hub and stainless steel bearings? I have access to a lathe (also through the university), so that will be very helpful I believe.
For the rear axles I will just try it, as you are doing yankeesailor. My dimensions are approximately the same as yours? And I will have a look at your drawing too, gibberjoe.
For the frame I will make the distance between the mast step and the rear axle more like 1360 mm and I will change to 10 mm nuts and bolts at the connections. However, the connection method between the two tubes with different dimensions remains a bit unclear for me.

Finally the seat. At the site of FISLY I can only find the maximum allowed dimensions. Maybe it is a good idea, as landyacht suggests, to mainly have a look at the French and Belgium designs I can find when I'm land sailing in de Panne, but I'm afraid it will take some time before I am there again.

My plan right now is to start with the wheels, then make the frame and keep the seat for the end. The sail I will just order. I think it will take a month before I actually have time to start building anything, but in the meantime I will search for material, adjust my design and post it. When I'm finally started building, I surely will make photos and post them here.

Thanks for your help up to now and I hope you can also help with the new questions in this post.

Ok, changed the design to M10 bolts and nuts at the connections and changed to the suggested dimensions. Wokelliot, you were right about the steering angle, it was more like 60 degrees, I made a mistake there. In the new drawing it is correct. I also added a global seat design.





The seat is mostly based on the seat of the F 1510



The rear end of the seat is now 870 mm behind the rear axle. Isn't this too much, so I will have the chance of tipping over to the rear? Or do you all have dimensions like this? And since the seat can only be mounted on the frame at the 600 mm approximately at the front, it must be self-supporting. That will take much fiberglass, isn't it? How many layers of fiberglass have you used for the seat?

For the wheel design I have found a 26" rim with 34 mm width and am planning to order the Schwalbe Kojak 2" tyres. Since it isn't that wide, I'm going to make one flat side plate and one curved.
By the way, Vic, I really like your high tec disc truing machine (www.seabreeze.com.au/forums/Land-Yacht-Sailing/Construction/I-will-NOT-build-another-landyachtI-will-not/?page=3). I think I'm going to build myself one too.



Some dimensions may still change, depending on what material I can lay my hands on.

Just because I'm curious, has anyone here ever made a segmented mast? That would make it a lot easier to take the yacht with me to the beach.

Hi Stephan.
I think the surface that you sail on has a lot to do with how far back you have the seat, I had to move mine right forward up to the mast post as the front was to light for the surface I sail on.
This link might help, it was a great help for me.
Cheers
Vic

www.seabreeze.com.au/forums/Land-Yacht-Sailing/Construction/How-to-find-the-balance-points-for-a-Landyacht/?page=1


Seat position on AUS230

I guess I was only referring to competition sailing, for fun use anything that will get you under sail.
Cheers
Vic

Cisco , having read what you have to say about mast design , I would be rather amazed if what your saying would last very long , I don't have a class 5 but having seen a few they develop a lot of power and seem to able to out last a lot of land yachts ( in Australia )in the amount of sail they can use , that doesn't come about by fluke , I would assume that comes about through the masts they use the sections have a lot more lap than you suggest you have always struck me as some one that has no knowledge is that true as you never achived anything with blokarts so what makes you such an expert ( or drip under pressure ) as you call your self
I have had a sail in one a few years ago one nite at gillies it was unbelievably quick
You should go away and sail with who ever as you can never claim your the fastest thing going around if you sail by your self we are all very fast in that circumstance

Well, the mast designs seems very interesting and I will keep them in mind. I assume that the last post of this thread is the photo of landyacht's design of an aluminium mast that you are referring to, Cisco: www.seabreeze.com.au/forums/Land-Yacht-Sailing/Construction/3-piece-mast-as-proven-by-Bill-Finch/ ?
Still, I think that that the aluminium mast of this design also doesn't fit into the FISLY class 5 rules, since it says

"The mast may be made from a maximum of four different diameter tubes, each tube must have a constant outer diameter and wall thickness over its full length. At each change of diameter, 3 CM are free to allow for chamfering or for protection of the mast pocket."

The chamfering in landyachts drawing is much more then the allowed 3 CM.
Not that I am into competition sailing, so actually it isn't that much a problem that my yacht won't completely match the FISLY rules. It is more that I thought that if I'm going to build a yacht, why not according to the FISLY rules, so it could be possible to go take it into competition. On the other hand, if I had a mast that isn't according to the rules, it takes no effort at all to order a new aluminium tube in one piece for a mast that does fit into the rules.

Still, I'm going to start with the wheels. I once saw a thread of the worlds championship 2012 at Cherrueix and landyacht complaining of his hookworm tires being too small for the conditions. Since I think the conditions in IJmuiden and de Panne, where I mostly go for sailing, are similar, I'm afraid I indeed will have to consider larger tires. After some research I found a dutch dealer for Surly tires and am thinking of the Surly Black Floyd Tire 26 x 3.8". Then the site of Surly says that they go best on 65 mm width rims, but where do I get those? I can weld 2 or 3 rims together, but then I will have to find more rims. But then I found this topic: www.seabreeze.com.au/forums/Land-Yacht-Sailing/Construction/lighterstronger26x75mmperhaps/#1115679. Landyacht, you end it by saying that the rims are very satisfactory. You're still using them and still glad with them? I'm really considering building my rims in the same way. The only problem I would have, the fact that I can only weld with Gas metal arc welding, is even solved with this method. On the other hand, if I make my rims around 75 mm width, I can surely make flat sides on it, which makes that production part easier.

Then the seating position. As I read in the topic you posted, Vic, I will need to be in my land yacht to determine what is the best seating position. I already need a seat then. Maybe I have to start with a simple, wooden seat, and then determine how far it has to be forward. When I find the right position, I can then build the final seat out of fiberglass.
Also in this topic it is stated that a soft and loose surface will need some more weight on the front wheel, so maybe for my yacht it isn't that smart making the length of the mast step to the rear axle as small as at your land yacht, Vic, since I will have to have myself positioned more forward to get this extra weight on the front wheel.
The aluminium tubes at the inside of the top edge of the seat for more stiffness do sound like an excellent idea.

Ok, if they use this dimension in Europe too, than it must also be possible for me to work it out with this length.

I was already having second thoughts about the damping, maybe I will add it immediately at the first build. I was thinking of adding it at the front end of the aluminium tube, near the front wheel, similar to the F1510 from the photo I posted earlier. When I find some time for it, I will elaborate my design and post it here too.

For the FISLY mast rules I think I misunderstood them. So according to you, Paul, your design fits the FISLY rules. That makes it even more interesting to consider building it.

The rims are definitely going to be 75 mm wide. Yesterday I started by making some spacer strips. And as I found an aluminium rod with 50 mm outside diameter, the bearings are going to be changed to 6004-2RS, so I can use the aluminium we had already laying around.

Hi Chook
It has the center pivot of a Huffy mountain bike (from the tip)which I cut of and attached to the back of the mast post(at the bottom) I put the guide in to eliminate sideways movement. There is no movement at all sideways. It works a treat.
Cheers
Vic