Just to show everyone what ive been up to this week, the canting keel trainer concept is moving on to the next stage…
The hull is nothing like how the final boat will end up, its to wide and too heavy (0.35kg, should be able to halve that), it just happened to be kicking around. The mast is the shaft along the bottom, it has a curved carbon ‘gaff’ for the squaretop una rig it will carry, also the bottom section is removeable so a small sail cam be used w/ot having the expense of 2 masts. The long flat thing is the keel strut and the three other bits make up the keel bearings, all of which are carbon (the final bearings will have brass inserts, I’m just more interested on getting the boat on the water at the moment). With a bit of luck It will be on the water by the end of next week…[:)]
Way to go , Matt! I’ve got to find a way to post pictures-I’ve got some stuff to put up as well. Making progress…I missed it somewhere; what brand winch are you using?
The winch is a Hitech HS-725BB. The strut is 400mm long with a 100mm lever inside. The bulb will be somewhere between 500 and 600 grammes. This is gonna be some light boat, even with the heavy hull!
The rig is going to be a bit clever, it will cant backwards and to windward as it’s sheeted out (this is very simple in the way it is done, as the pics will show when its finished). This will move the center of effort of the rig closer to the centerline of the boat downwind, so less rudder has to be used to counter the turning effect of the rig. Also the rig canting aft should help keep the bow up, particually with the narrow hull that intend to use for the final boat…
I’ve been experimenting with a rig similartothe microMOTH with he mast stepped in the boom and the upper "bent back tip pivotble.
But I’ve been looking at a design for the boom that wil allow the pivot point of the boom to be changed for light and heavy air: in light air the pivot when the sail is on te centerline will be parallel with the mast-more or less.
In heavy air the pivot will move forward and angle back so that as the sheet is eased the top of the rig angles back and moves to weater. The problem is that it looks to me like two separate pivot mounts will be required because of the big difference in pivot position.
I don’t think the angled pivot will work too well in light air because the mast will be raked so far aft downwind-but I’m still looking at it.
A boat called the “Mickey Finn” made in the UK years ago used a mast whose lower section under the boom was angled forward at the bottom. The whole mast rotated and as it did so the rig angled aft and to weather.
I think you’ve got a good idea especially if you’ve solved the lite air problem…
Another thing I’m thinking about is like a vang that rakes the mast forward instead of pushing the boom down, has the same effect if you think about it. I’m trying to suss out a way of being able to adjust it on the water without adding too much weight and cost. I think it will add alot to the boat if the rig could be adjusted in that way, as in my experence with fullsize squaretops/fathead rigs you have so much control over the top of the rig just using the kicker. It should mean It will be possible to hold onto the big sail in stronger winds. Lots of things to play with…
Hi Doug/Matthew,
I have been playing around with Una rigs on my footy class yachts.
My pivot is vertical and the mast raking aft.
The top of the mast and the extended line of the pivot meet at the top of the mast. This allows the mast to be raking back when sailing upwind and verical when sailing downwind.
It is a very similar to what Doug has on his MicroMoth.
I am using a pocket luff and square top sail.
Despite the rigs I have made only having about 2/3rds the area of my conventional sloop rigs they seem to be very fast indeed.
I have no problems with my vertical pivot in lite airs.
I will post some pics when I can.
Brett
update,drawing attachment added.
I think I basically like(on a rig like the microMOTH) the idea of the pivot point being vertical in light air; slightly raked aft upwind in heavy air and raked way aft downwind in heavy air.Since the action of the raked pivot also moves the rig to weather so much the better. I just haven’t figured out how to accomplish this w/o servos and without two pivot positions.
Brett, I hope you’d consider doing a CK Trainr proto…
Just a thought, these boats are going to be so light and trim dependant in really light winds all you might have to do is move the batteries forward, You’ll want to do that anyway to reduce wetted area and it will also bring the rig more upright downwind. Works for fullsize skiffs anyway…
Brett; On the footies I built I put an una rig ontop of a servo modded to travel 360 degrees, worked real well, you could even sail backwards! No good for anythig bigger unless you want to mash servos… Got to get my footies back on the water sometime, they’re fun little boats to sail!
Got quite a bit further with it today, stuck the keel strut on! Looks insane! Bulb’s almost done and I layed up the U section boom too. Just need to make the foils (centerboard and rudder-balsa most likely), the deck (flat sheet of carbon) plus a few riggy bits, radio fit out and sail, and we shall see just how fast this thing will go! Can’t wait to put it on a broard reach and watch it fly…
Pretty much there, just need to rig up the radio gear and put some rags on it, taken longer than I’d hoped but, provided i find enough time and nothing silly goes wrong it will be on the water next weekend! Your comments please…
Got it on the water yesterday, wind about a force 3 and all over the place! First impression was how twitchy it is, you have to be super quick on the keel control in the lulls particualy to keep moving fast. On a reach its alot of fun, I can’t be sure that it was planing but it was doing aload more than its hullspeed, almost a walking pace at times. Upwind it tracks nicely but any big header will have it heeling to windward, you just have to be quick bearing away to stop it stalling. Tacking’s not much good at the moment, I think it needs a bigger rudder. I also tried canting the keel to leward on a reach just to see what happened, it went to about 80 degrees and sat there, occasionally dipping the hatch. I didnt get any pics as I was on my own and letting go of the controls is asking for trouble (and I was having too much fun [;)]).
Matt,
As I stated earlier " You are the Man".
How very clever!, I really like it.
No B.S. just the photos, no claims etc, fantastic, done your self proud.
Awaiting YOUR comments on sailing, Fun and what next.
JOHN.
Matt congrats again! I’ve got some questions: on your “squaretop/gaff rig” can the upper (peak) outhaul be adjusted?
What t/c ratio are you using on the strut and daggerboard?
Have you sailed it enough to note any balance changes upwind from no cant to max cant?
What percentage of the main is ahead of the rig pivot?
You’re doing great!