Raking Rigs on older boats
Before I try and reinvent the wheel I would be interested to know if alternatives to mutli-purchase block systems have been tried for rake adjustment. I understand the issues about raking hog stepped masts and spreader angles but some linked adjustment might be useful with the hassle of deck stepping. I presently have linked muscle boxes on the shrouds and one the jib halyard. To make a rig rake it seems to me that firstly you have to sort out the ratio of jib halyard movement to shroud movement. Lets say for sake of argument that if you let off the jib halyard by 3cms you have to take up the shrouds by 2.5cms. Devising a multi-purchase block system to do this is complex and expensive. Winding the wire or the relevant control line on to a winch spindle is easy. If you have a stepped spindle say with a 25cms diameter and a 30cms diameter and the lines are wound in opposite directions one will come in and the other go out in the right proportion as the spindle rotates, The ratios will remain constant as long as the line doesn't overlap itself so a larger drum is preferable. This could then be operated with an old style kicking strap winch type wheel on the end led to a simple thwart mounted control system. Has anything like this been tried - friction might be an issue if I keep the muscle boxes but if they are replaced with high load ball bearing blocks, then I think it would work. Anybody got any thoughts?
I think drums were used in the Flying Dutchman and Cherub at one time there used to be some pics of rig systems on the web, just google the class name under images.
Miles - thanks for this - I have to low bow tank and the epoxy glued hull. So a tank mounted lever is a possibility I have considered. This is a cost issue more than anything - lots of ball bearing blocks = high cost where as engineering a stepped winch or lever system is a relatively cheap solution. As I have a hog stepped mast I don't need to link the kicker in as it is contained within the rig.
I used to have a winch for the kicker - was probably standard fitting for Bob Hoare's boats in the 1960's. It did work but it chewed up the wire quite quickly. The engineering associated with a stepped drum is probably pretty significant & you will need decent bearings to minimise friction. A lever is probably a neater solution & these have been invented a few times. Then the issue is the space to fit it and particularly making sure it doesn't mince the spinny. Have fun & post some pictures if you make it work!
Edward,more photos at littlejoesolutions.co.uk/merlin
Andrew - yes those old winches did mash the wire - I had in mind to keep the wire out of the system and to try to link just the ends of the purchase systems on to a drum - this way the loads are much lighter. The difficult bit is to stop the line wrapping over itself as this will change the ratio and jam the system up. Stainless bearings are about £8 each - the winch drum could be carbon or alloy tube. The biggest difficulty I see is the rope drum on the end of the winch drum to get an 6 or 8 to 1 purchase or you are stuck with small spindle sizes like the old winches and they wont take up enough rope to work properly.Levers of course are much more compact and lighter.
How old is the boat?
just seen you have a low tank.
I find the mechanics of this interesting.
Gareth Griffiths Notting Hill Rigging Co
I've done a little looking into this, Scorpions do it and some 505s.
Andy Hay - Business as Usual
A halyard lock doesn't change the compression forces acting down the tube.
Andy, have tried the stuff luff, with halyard coming back to controls under the foredeck- it does work but there is just too much sag in the jib luff. the halyard coming back on itself has half the tension, even side by side it is not enough. So I ended up with system as shown in my previous link (you don't need to use a lever as I have done)
Gareth,have also tried the fixed jib halyard and tackle at the tack. This also works, only snag is that the tack has to move up and down which alters the sheeting angles the 'wrong way' when you rake the mast. I suppose you could connect the jib fairleads to the system; so that they move with the mast?