New Kicker for Koko

[Steve_scott]

Hi all,

I'm toying with replacing the lever bar kicker on Koko with a more up to date (crew shin friendly) cascade pully system.  Can anybody out there advise me what ratio I should be aiming for?  I can hit 8:1 with ease and 16:1 with adding another cascade but I'm worried at 16:1 I'll just end up having to pull an awful lot of rope in to make headway.... and perhaps bottom out the cascade before anything much happens?

Without measuring it, I think the current balance bar is about a 3:1 lever and there's a cascade pully so it should be 6:1.  I guess 8:1 should be fine? 

Any input/photos of your systems would be useful including input regarding combined cascade and multiblock systems...  I'd just rather get it right first time out!
     

[Tim Noyce]

Hi Steve,

I have recently re-rigged my '97 rules' Bistro and have ended up with a 16:1. This is probably the least I would want as the kicker is the most important sail control and largely under utilised with roachy mainsails. It took a bit of adjusting the cascade splices to get it so you can get the mainsail onto the boom and gooseneck but think that I just about have enough travel in it and it is nice and easy to pull on.

I have attached a couple of images which I hope you may find of some use, but the system is largely made up from parts I found in the toolbox rather than being specifically designed! Red circles are single blocks, Green circle is a double block, Grey lines are spliced 4mm Dyneema, Orange line is control line and blue squares are cleats on each side.

[Clive Everest]

That looks like 32:1 to me, and it appears to be bending your boom.

[Tim Noyce]

That looks like 32:1 to me, and it appears to be bending your boom.

I thought it was easy to pull on... I must have wrongly assumed that I had just got stronger!

[PaulClements]

24?

[Steve_scott]

Thanks Tim - if I'm working it out right, your lower three singles could as easily be a triple at the foot of the mast?  I think this would make it a 32:1 with the other cascades in series?

I know that roach of Koko is wide open unless the kicker is jammed on tight so I guess I'll have a play to get a 16:1 system working, perhaps with a multiblock lower down like your system.  Hopefully she'll point a bit better then!

I'm also looking out for a carbon windsurf mast to use as a boom so perhaps the kicker can wait until I know when I'm going to attach it. 

[Tim Noyce]

Yep, you could probably replace the 3 singles for a triple. I didn't because A) I am a cheap skate, and B) I decided that having the singles would help to reduce friction when directing the tail out to the wing as they could move independently. I am thinking that there is probably only just enough space for the arrangement I have, and I am yet to sail in enough breeze where it has needed testing properly. I have scope for some more adjustment in the primary and secondary splices, and can also remove the thimbles as that will give a fair bit more travel.

It might also be worth checking your bridle length before you start splicing your kicker. Until you are overpowered you should be able to control the leech of the mainsail with mainsheet tension if you pull it hard enough so maybe use that as a starting point for travel.

[JimC]

On my one off singlehander, where I needed something extreme in purchase, I used a triple block with cleat at the bottom as a coarse adjustment (had the cleat on the end of the cascade. Let it right off and it was easy to get the clew on, pull it right in to a stop point and it had the right adjustment range for sailing, other than light airs when I had to let the coarse off a bit and do without calibration.

FWIW personally I used to reckon 24 was good on a 97 rules rig, certainly not less than 16. We shouldn't forget though that the position of the anchors has a big effect on the effective purchase.

[phil_kirk]

Usually with 16:1 cascades of single blocks you need to be accurate to get the right amount of travel. I preffer to replace the bottom 2 singles in a cascade for a 4:1 purchase similar to that at the bottom of your diagram.  I haven't used a higher purchase than 16:1 though.

In your diagram I would stick with singles for leading the control line to the side decks.  unless the control lines are going down the centreline of the boat beofre being led outboard, using a tripple will lead to wear and high friction.

[Steve_scott]

Currently I have a double at the foot of the mast and a single pulling down on the lever bar, which in itself is about a 2.5:1 purchase.  If I'm right, which I might not be, I have about a 5:1 effect and a lump of metal plate that seems to take a chunk out of every crew I take out in it!  So, to get the ball rolling and mostly to tidy it all up, I've gone for a triple at the foot of the mast, recycled the double to the base of the cascade and I'll throw in two single cascades to start with without changing the mounting point on the boom. 

In theory, this should result in a 24:1 system so hopefully I can then move the mounting point forward to give the crew more space and tidy up the pointy end of the boat.

I've also ordered an ISO kite sock from Rooster as the dimensions appear to be perfect for my annoying kite with a single downhaul point... finding a way to mount that to the deck is going to be fun!