UK-Cherub Forum
Cherub Chat => Tech Chat => Topic started by: daryl_wilkinson on July 19, 2010, 02:26:39 PM
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Any of the other woody owners using a Muscle box for a kicker purchase system? Experiences?
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I have a cantilever style arrangement on mine, as you can probably just about see in this photo. I don't have any more showing it though.
(http://sphotos.ak.fbcdn.net/hphotos-ak-snc3/hs383.snc3/23429_577398763318_222700417_4990609_5037328_n.jpg)
We used to fit muscle boxes on foredecks of Wayfarers in place of chocks. Not really sure you'd get enough travel in it for a kicker to make it worthwhile. What is wrong with the standard kicker arrangement? You don't need as much on the older boats, I just wang on the mainsheet when head to wind and basically take the slack out with the kicker on my system!
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Sorry I'm not putting a Muscle box on the 2619, it's what it has. Looks like from new. And yes there's not much travel in it. Hence I was asking what experiences people had had. To keep sailing time to max I was thinking of adding a light wind strop with a block and 'v' cleat purchase on the end of the wire cable that goes from boom to M box for a little extra throw.
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you can just see a wire to boom. That's about max out kicker.
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We had a drum and roller system on 2534 which worked quite well, although winding turns on or off the drum to get you into the correct range of movement was moderately hazardous to fingertips. I've put a dyneema cascade system onto 2631 which is alright, but again lacks a bit of range.
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we have a 16:1 dynema cascade. You have to get the lines the right lengths because this system is limited for travel.
another solution is replacing the lower two blocks of the cascade with a 4:1 purchase, you need a double block to make this work and a longer control line but the system gives lots more travel. I use this on the ent to good effect.
For small sails you could try a 12:1 purchase. You will need a single with becket at the boom to give a 3:1 there. After that it's two more singles each doubling the puchase to reach 12:1.
I have never used a muscle box but assumed they would have a lot of friction compared to a cascade system.
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For small sails you could try a 12:1 purchase. You will need a single with becket at the boom to give a 3:1 there. After that it's two more singles each doubling the puchase to reach 12:1.
I Used something like this on Flat Stanley with a 97 main and was fine. I used a 3x at the boom end which was sk75 spliced through those wire blocks with the hole in middle and then a standard 6x at the base. This worked well but was obviously 18x in total. I started using 24x but did not have enough travel.
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could anyone tell me what a muscle box is? i have never encountered one before?
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http://www.sailboats.co.uk/Catalogue~Rwo_Muscle_Box_Long_10~p_R4530~c4807.html
Muscle Box - n. Box that gives you extra muscle. ;D
I think they are traditionally used for mast rams and the like but have never used one myself.
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Yes there is a lot of friction in the muscle box and not much throw. I'm currently trying to work out some system that, 1: doesn't cost much / any money. 2: is as fast as possible to make. The two of these are not currently mutually compatable. It may mean junking the muscle box and making a cascade just to get an efficient system, quickly. Quickly may be the wrong word in this case though. As it is likely to mean quite a lot of reconfiguring, due to the way the kicker system is currently made. Something I want to avoid.
The muscle box is bolted to the front bulkhead at floor level, the control line runs from the bottom of the mbox down the centre line, along the floor to the back of the case. The kicker cable runs vertically from the top of the muscle box, through a bullseye in the case capping, up to a modified gooseneck fitting with a ring end that the cable runs through at deck level. This takes all the kicker loads, as the cable runs straight to the boom attachment. So this is currently only 6:1 could be 8:1 I haven't looked at the muscle box much. The box is a small one as well. I'm trying to work out something that means I don't have to completely pull this all apart and cost £100 bucks, which is easily done! Currently I haven't had that eureka moment yet!
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My current thinking is to keep the muscle box and use it as a fine control and attach another system to it with more travel. I haven't sussed this bit yet.
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The cheapest method would probably be to use a leaver, which could be made from some aluminium plate or carbon plate or an offcut of carbon tube. It would be easy to get 4:1 from that if you then run a 2:1 from a spare trapeze adjuster that gets you a working kicker.
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To keep sailing time to max I was thinking of adding a light wind strop with a block and 'v' cleat ...
Does the current system not work at all? Most of sail around with not enough kicker on most of the time so I'm sure you'll be fine.
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Kicker is less of an issue today. As the forestay bow fitting pulled out yesterday resulting in the mast going over the side. Luckily no damage to the mast or the crew who was on the wire. Sticking it back together and bolting it through today.
Thanks to Dave for making sure the day wasn't a right off and taking Luke out in his Fireball, which Luke enjoyed enormously, especially trap helming.
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Seems to be a day for blowing up old rigs. It was blowing its nuts off up here today too. We pulled a shroud out of a spreader end on a wicked 2-sail reach (sheared the cap on the spreader). Combined with a ton of kicker led to some pretty extreme mast bend! At least the rig stayed upright and came back sort of straight. We're running a really crap ancient, floppy Needlespar. Anyone got an M7 lying about?
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2303 performed excellently yesterday as always. We also have a skinny noodle needlespar mast. We just have main shrouds on it but I'm thinking it really needs some lowers to keep things aligned. Seems to lose all power as soon as you get someone on the wire. Excellent fun though on a 2 sail reach when you have some breeze.
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The Needlespar on 2631 is ludicrously soft. I cranked on a good bit of cunno before launching today and the thing started looking like a bow and arrow (without the arrow). By the time the kicker went on the front of the mast was trying to set the back of the foredeck on fire by rubbing on it vigorously with every gust. I'm torn between trying to keep it more straight with the addition of lowers +/- D2's as Tim suggests, or just binning it and starting again with something else. Roland pointed out a while back that these old Needlespars make a good mandrel for a narrow diameter carbon stick, but that might not be quite in the spirit of the classic theme.
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On competitive boats back in those days the thin needlespars would have been stabilised by a spigot. This was a species of mast stump, rigidly fitted into the boat, and projecting up 6 inches or so, onto which the main mast telescoped with as little play as was compatible with being able to get the mast on and off. In the absence of one of those you badly need lowers, otherwise, as described, the mast will just bend up when the weight on the wire takes the load off the spreaders. This is also a sign of inadequate rig tension...
If decent rig tension is inadvisable - shroud ought to have, I reckon, at least 20% more tension than the weight of the crew and the more the better - then in theory you could fit check stays to the base of the spreaders, then the leeward one would tend to stop the mast bending up to windward when the load comes off the windward shroud with the crew on the wire. I've never tried this on a boat of that era though. A concern would be that it would be easy to put all the extra load you've not dared to put n the shroud onto the checkstays!
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Luckily we don't have to much of a problem with lack of power at the moment as the crews combined weight is only 105kg - 32kg of which is no the wire! We also look like we have a needle spar, which is actually quite deeply pitted from foot to gooseneck. Seriously considering trading up my insurance to fully comp just in case!
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Jim, I'm sure you're right about the spigot. The Needlespar on 2631 has had a new bottom section about 2 feet long grafted onto the bottom of the main tube at some stage. This extension piece seems to be made of something monumentally heavy, in that the centre of gravity of the whole spar is now only about 30% up from the foot! Although the hull of 2631 was built in 1986, the rig is probably a lot older. Apparently Rob Stephens (who had the boat built by Andy Paterson) had an old Forman 4 or something, and simply transferred most of the gear from his old boat onto the new hull. Certainly the 2 mainsails that came with it have 2549 on them, which I think would put it somewhere in the late 1970's. Daryl - had your lad done any trapezing on other boats before, or did you just get him going straight away on the Cherub?
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My girlfriend had done no sailing whatsoever before I got her out in the cherub. I personally think that the F4c is the ultimate training vessel... enough sail to generate power to trapeze in a reasonable wind, yet stable enough to not go swimming on a regular basis... and sailing off 1115py it is good fun to take a fight to normal run of the mill club sailing boats. Can beat the classic Finns when it is windy... and tussle with the squaddy toppers when its not!
Neil, I was chatting to Rob down at Poole about your boat (think it was a kit from Andy P). He had some excellent stories from the old days in the Cherubs.
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Daryl - had your lad done any trapezing on other boats before, or did you just get him going straight away on the Cherub?
Well he went out with me a ben in Loco when he was about 7. Not that there was any wind around. And apart from Minorca in May where he spent the afternoons trapezing with me in a 29er or xx that's it. Oh and about 3 times in the Banshee at B.S.C ( very shifty ), which highlighted that he needed something to learn on a bit more. I would have probabley gone for a 29er if money was no object. But it is, so we have a classic Cherub instead. In hind sight it may have been better to get the old boat first, whilst the banshee was being built, but i didn't really think that through at the time. Funnily enough he says he actually feels happier trap helming, than crewing. As he hasn't really ever crewed so it is all a bit alien to him. There is less for him to think about when you add the trapezeing element I suppose.
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Neil, I was chatting to Rob down at Poole about your boat (think it was a kit from Andy P). He had some excellent stories from the old days in the Cherubs.
Andy P sent me this photo a while back. He thinks he supplied the boat as a shell with crewdeck, and Rob did the main decking and finished it off.
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He also sent me this one, but wouldn't own up to who owned the car!