Working on the install of a I-20 self tacker to a TheMightyHobie18 curved beam. The tacker has 6 welded feet. I will need to take 3/4" off the 2 center and about 3/8" off the next 2 and the outer should sit right on top just above the tramp slot. I'm concerned about the sheeting angle. Can't find good pics to compare. Due to the rise of my crossbar the unit sits a little higher than it would on a flat beam. It seems that my sheet angle will be more straight back than down ie pulling the foot more than the leech. I'm not great with sail shape, how will this effect the trim off the jib? Should I mount the unit below the crossbar where it would typically sit on a flat crossbar and pulling more on the leech? Or is the angle of the unit to the jib clew irrelevant? Any and all advice welcome except the old " why don't you just buy an F18".

The angle will be important. Did you get a Tiger jib for the project? If yes then you will have a little play as it has 5 clew plate holes that you can attach to. I would try to get as even a pull on both the leech and the foot when I was pulling on the middle of the 5 holes. That way you can adjust up or down while looking at the leech of the sail. If you have a good feeling in your hand you can push the leech and the clew alternately, while sheeted, to see if they have the same pressure. You need to make sure that this is consistant throughout the travel of the jib.

I think that it was recommended that you mount a flat plate on the curved crossbar if you are going to mount the Tiger style traveller. If you do not then the traveller will not be able to swivel and you will be very limited on where you put the sheet on the clew.

Later,
Dan

Thanks Dan. After speaking w/Trey it appears I need to raise the jib a little further on the forestay to get the right angle. I have 12" of adjustment available there. Will have to secure the jib to the chainplate and forestay with line since the cleat will not reach the chainplate with the sail higher.
Dan, I had allready considered the movement of the unit. Mine is off a I-20 so its a little different attachment style. With the legs cut down and machined it will be able to pivot up and down in relation to the crossbar.
The sheet angle was my main concern and I think Trey is right about raising the jib, I believe the tiger runs longer bridles than the 18 which would force the sail to ride higher on a tiger than on my 18. That might be all there is to it.
BTW I do have a tiger jib!

how are you cutting down the legs of the self tacker to fit your beam and still going to get it to pivot? If the pins don't form a straight line through all of them, they are off axis and will not allow the tacker to pivot.

My thinking was that the feet are basically a T and mount horizontal, left to right, on the crossbar. The upright of the T has a hole in it, it fits into a slot in the bottom of the leg and pin runs thru. By cutting the legs and machining new slots and pin holes, then bending the feet straight up into the new slots I think they will pivot. It would mount across the bar right above the tramp track. The slots are wider than the upright and theres some play in the pins. Maybe I'm dead wrong thinking this will work? I haven't cut anything yet! It seems feasible looking at it, the crossbar isn't all that curved thru this much area, maybe 1" rise, but haven't measured. What do you think, will it work?

I helped someone fit a tiger jib to a TheMightyHobie18 and we had to lift it a couple on inches up the forestay to get the correct sheeting angle - so I'd guess you will have to do the same.

Chris.

Ok, drank a few beers and got the courage to cut the tacker legs. It looks good to me. Hopefully I can attach a few pictures for feedback. If you see anything wrong please speak up. Stiil need to cut grooves in the legs I shortened and redrill them for the feet and pins.

lets try again

another

last one

got anything bigger? If it pivots up and down then it worked!

It does pivot!! I was afraid I had miss judged and it wouldn't. Trying to decide if I should worry about mounting the middle feet. The Tiger system doesn't have feet in the center and the rivets would interfear with the tramp slot and possibly damage the tramp. The other four feet are beyond the slot. Do I need the center attachment points?

I cannot see how it pivots around the front beam. May not matter if you got it all just right.

It depends on the radius your jib swings through - but probably not. As long as the traveler car is not putting stress on the center of the self tacker when sheeted, you should be fine. The only time the traveler is ever there is when it is swinging to the other side and the loads should be very small at that point. Do you have a bigger picture?

Jake,
look at the third and fourth pics, they are bigger. This unit only pivots a few degrees from the factory. The legs are square on the bottom and hit the foot at a point, will not flip completely up or down.I think this is normal?

IIRC, my self tacker has a 90 degree field of travel.

That sounds about right, Tad. If it could flop against the beam it would be 180 degrees.

You mean this? Yeah, I'm familiar with it. It actually should rotate through 90 degrees or better. There were some issues with some of them. My story with installing the same self tacker (on a straight beam) starts HERE

Thanks for the pics Jake. Mine is very similar. Got it riveted on today. Raised the sail a little and I think the angle for sheeting is correct. May have the sail a little high.

Heres one more pic