I agree with those above
You need to have the ski axles clamped to something solid that goes right across the tub in my opinion
Hi guys,
Thanks for the comments. The problem of how best to anchore the skis in has been on my mind for a while.
I had originaly thought about having the angle section out at the tub sides in a similer fashion to that described by US772. The reason I was thinking of attaching at a center web is one mostly born from ease.
The tub has 5 deg (aprox) of tumblehome so in order for the angle to meet the skis correctly i need to make up some 5deg blocks to take acount of it. attaching them at a center web ment i didnt have to faff around with making up these blocks.
Everyones comments ring true however so i will make the effort :-)
I think I'll keep the center web as its acting as additional support for the seat back.
Thanks again for the comments.
Hopefully some more progress will be made this weekend
Hi Guys,
Just some images of the stearing pivot point. Its a ball joint constrained between two ali plates. I described the stearing in a previous post (i could hear the singgering even here in the UK) Its got two chances :-)
What do people think of the rigging plan? i think its relatively conventional but please comment. The boom is ali 45 OD with a 1.6mm wall. As the main purchase is at the aft end of the boom I wasn't going to put a doublerin the middel as i have seen in some of the other designs with the sheet taken from the center of the boom.
All the best
Dave
Hi Dave. The setup is ok but there is an advantage to be had by carrying the middle pulley on the boom forward to the mast end of the boom to incorporate the luff downhaul as well. There are some good drawings in the forum topics showing how to do that. This enables downhaul and sail luff to be tightened automatically when you sheet in hard and relaxes the sail luff when running. The advantage also is that it gets the forward sheet pulley forward and away from your body and easier to haul in the sheet. The boom at 45x1.6 Ali as you have is fine....wok
I agree with Wok I think what he is referring to has been named a "Crockett down haul" in the forums. Works great
Size of the boom is OK but you might consider making a sleeve to go round the boom to fix your centre block to, it makes a good reinforcement and means you do not have to weaken it by drilling and fixing it also also allows you to fine tune the position of the blocks. I have just been playing around with the set up on my yacht and I have gone back to centre sheeting from a set up as you are proposing, the centre sheeting (with sufficient power) I find much more responsive as you are tightening and easing less mainsheet, this might be easier and safer if you are new to sailing. Still if you are lke the rest of us as soon as you get sailing you never finish a session without thinking what if I changed, so make sure you leave your options opening
Hi Guys,
Thanks for all the comments. I looked up the Crockett down haul and i can see its advantages. I'd like to incorporate it but I'll wait and see what space is like when i get the mast and sail up. I think the tub may get in the way of it working properly.
Ill add on a doubler to the boom as you suggest. Like you say, im sure half the fun of these things is tinkering with set up and the like. Always engjoyed that when i was dingy racing.
Progress from the weekend is below. Got both of the runners on the cart. Hopfully you can see what im going for on the stearing if it wasnt all that clear from before. Next step is to finalise the clamping of the skis. Then its on to the excitment of fitting the mast step and the decks!!
Hope everyone is keeping well
All the best
Dave
Hi Guys,
Cracked on with the brackest for holding the skies last night. So it now has 3 wheels! very exciting.
Next job is to sort out the stearing. Once thats done its the final leg of the construction.
All the best
Dave
Hi Guys,
Got a question about center of effert
I figured out the center of lateral resistance at the weekend my putting the bathroom scales under each wheel of the cart (while sitting in it) and noating down the reading. From this i calculated the longitudinal center of gravity of the cart and myself. As the tires are all the same (or the assumption is that the coefficient of friction is constent between all three) the lateral center of effert will act through this calcuated LCG.
I have plotted this on my drawing of the cart and as it stands i have about 100mm diffrence between the center of lateral risistance and center of effert of the rig.
If this were a dingy i would say that currently it had weather helm (so always wants to turn to windward) what are peoples thoughts on this? I can move the center of effert forward by reducing the rake angle of the rig. So is it better for the yacht to have a tendancy to go to windward or to leward? Dingys the prefrence is for windward as thats safer as a tendancy to turn to windward reduces the risk of a crash jibe.
All the best
Dave
I think in the end you will have to suck it an see as your calcs may not give what you expect when you sail. Being able to adjust the rake helps balance a rig to suit a particular sail size, wind and surface. You can cope if the back end is a bit twitchy but too much lift on the front end and you may loose steering.
Keep in mind that the CE (centre of effort) and CR (centre of resistance) are constantly changing, theoretical measurements are often way off compared to 'real life'.
CE will change depending on wind and sail angle and how much the sail is sheeted on, CR will change when you have force on the sail ie. when you lift a wheel CR is spread across 2 wheels rather than 3.
I agree.
Just get your bum in it and sail it.
That's the fantastic thing about mini's, there are no restrictive/expensive constraints. Just the 4 rules that you need to comply with.
I'm loving your design and workmanship. Cant wait to see how it sails.
Hi guys thanks for the responces :-)
I think im going to put a slot in the main deck so i can make the rake addjustable through a range of say 3 to 10 degrees that way i can fiddel around with it when ive had a go :-)
Ive been building this for nearly a year now so the itch to "just get in and sail" is now getting pretty insistant. Unfortunaly i dont get a huge amout of garage time but im almost there. another month or two of faffing around and it should be good to role :-)
All the best
Dave
Hi Guys,
Now that we have sun and light evenings (and the daughter is going to bed and to sleep 9 times out of 10) I have been getting out in the garage.
I have sorted the stearing out, its all a bit tight under there but i have foot stearing :-). I have a boom sorted out now (ali and from a moth)
All the main pannels are on apart from the foredeck to glue and a hatch in the aft deck to allow access to the ski clamps.
But next stop is prepping for painting. Then its almost ready to test and brake :-)
Dave
Westward, I suspect this steering system is going to be diabolical in practical use.
You have a steering bar, how is it going to work from there? Going back to your mast rake on my yacht 10deg is the starting point,a bit more upright in light winds, dropping it back in high winds. I still worry that you are putting so much effort into a design that will be difficult to chop and change if it does not sail, try it as soon as can.
The big question mark for me is the steering I suggest you concentrate on that get your bum in it and get someone to push you around the yard to prove that all is well with the design of the steering as it is unconventional
Remember that there will be big side loads to cope with also
I understand you want to plough your own furrow That is one of the attractions of building these things.
looking at your steering pics i think the yacht wont even turn in your yard . you are going to need alot more turning circle than that
Unfortunately I can't generate graphics, which would make an explanation so much easier But here goes anyway - the major problem is the location of the pivot. Being so far offset from the centre plane of the wheel the steering will be constantly loaded, trying to rotate about the pivot. Assuming the axle is pivoted from the port side, the set up will be perpetually wanting to turn right. Depending on the loads on the front wheel, which will vary constantly in use, combined with the lever effect of the offset, simply travelling straight will require constant variable effort to stop the it from turning right. all steering input would be,from the right foot only, regardless of turning right or left.
this could be overcome by utilising a hub centre steering set up, if you were willing to undertake the engineering involved.
Hi Guys,
Thanks again for all of your comments.
Before i took it apart to make a start on the paint and varnish i pushed it around the drive and it seemed to turn within about 3 times its length. I wasnt sure weather that was good or bad at the time. I have taken the consept for the stearing from the Vector plans I am working from. At the time of shoving it around I must admit to thinking that as it was close to the original it was probably ok.
I have got a "get out of jaile" that i can use to increase the amout of stearing angle if when i try it out the turning is truly "diabolical". if i pack the ash supports away from the tub ill increase the gap and give the wheel more room to trun before skuffing the runners.
I have made a quick sketch of the stearing arrangment. the tub and ash runners are slotted to allow the axil and stearing bar to slide back and forward.
Im really trying to push on with the build now as its been a long time in the makeing. its amazing how little you can acheave in an hour!!
Almost at the stage of painting the tub so it shouldnt be to long before i can test it. I want to get a coat of paint on the wood before hitting the beach to give it some protection from the elements. i dont have a space localy to try it out in "the dry"
One lesson i have lernt from all this is to never use plywood from the builders merchance to do anything like this. its the worst grade of material i think i could have bought!
Thanks again for takeing the time to read and comments.
All the best
Dave
Rubbish Tp1............ 
He has more that enough steering if it will complete a circle in 3 times it's own length.
You only need more turning ability when parking. You don't ever build a yacht to park.
I reckon mine would really struggle to turn that sharp Westward. I'll check it for you tomorrow.
You were quick to change your 2 to 1 ratio "Tp1".
Did a lap with "Poultry in motion" my latest 5.6 mini and it has a turning circle with an outside diameter of 9.45 meters.
So that equates to a 5.5 times its length ratio.
Hope that helps.
I am wondering like team wally about the offset pivot on the steering Wont that have a bias to the right all the time?
Great for one foot steering I suppose 
Select to expand quoteHiko said..
I am wondering like team wally about the offset pivot on the steering Wont that have a bias to the right all the time?
Great for one foot steering I suppose
Yeh I'm keen to find that out as well.
Turning right will have a smaller turning circle than turning left and may change CofE also
I am not wondering at all, I have a fairly good idea of what is going to happen. The easiest way I can try to explain it is by suggesting you imagine your conventional steering set up but with the centre line of the tyre offset from the centre line of the steering head by 6-8 inches with a set of offset forks to accommodate it.
Then imagine your conventional steering with zero steering head rake and subsequently zero trail or castor, neither positive or negative.
Then combine the characteristics of the two.
This is essentially what this set up entails.
It will steer at low speed but will be diabolical at anything much above a fast jog.
It will be doubly diabolical when on two wheels.
Hi Guys,
Im pleased the stearing has sparked some debate. Its intresting to see the divergance in what people think the acceptable turning radius should be.
I can see that the right hand side will always have pressure on and it will always want to turn right.
TeamWally it would be great if you could point me in the direction of some lituriture on "trail, castor ect. i have no knowlage of that stuff or how it effects the handling. It is what it is at the minuite, if it turns out to be naff when i test it it will have to be all change :-)
I'm almost ready to start painting now, ive just got to finish the filling and fairing.
I've cut a hole in the aft deck so i can have access to the skis and support brakets and the mast now fits :-)
I hope that every one is well.
All the best
Dave
