Raking Rigs on older boats

31/10/2013 15:21:36
Edward
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?

31/10/2013 18:31:37
Miles 3646
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. 

Some on has probably already tried it,no doubt you will soon find out.

Alternative is the lever system, I'm testing one at the moment but not sure whether this would be suitable for an older boat if there is not a low tank at the front (where would the lever go?). I think general consensus is strings and pulleys are best but I like to experiment. Getting those purchases correct with pulleys is a challenge in itself.

http://www.littlejoesolutions.co.uk/merlin/raking%20rig%20onestring%20schematic.JPG
01/11/2013 08:12:59
Edward
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.

01/11/2013 09:30:59
Andrew M
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!

01/11/2013 09:43:55
Miles 3646
Edward,more photos at littlejoesolutions.co.uk/merlin

jib halyard adjustment is under the foredeck and stays clear of the spinny.

http://www.littlejoesolutions.co.uk/merlin/
01/11/2013 10:14:03
Edward
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.

06/11/2013 08:25:52
Chris M
How old is the boat?

A modern raking rig on a high tank boat won't achieve much unless the hull is stiffened with a space frame.

06/11/2013 08:33:07
Chris M
just seen you have a low tank.

just bear in mind you won't have throw of a deck stepped mast. I know of at least one hog stepped semi one string boat and it does rake backwards/forwards fine. The problems you'll run into are whether the woodwork lends itself to mounting some of the fittings.

If you're woodwork skills are up to it you may be better off deck stepping the boat and installing a conventional system working from scratch. This of course depends on what fittings you have lying around, it will rapidly become expensive if you have to buy them!

The positive is that you'll have a working system that is proven to work, and raking works much better with a deck stepped mast due to spreader geometry.

06/11/2013 12:44:22
ex Merlin
I find the mechanics of this interesting.
There are a couple of advantages to hog stepped:
1) no need to worry about the kicker in a 1 string system if it is all attached to the mast: mast, boom and kicker move together.

2) For a particular amount of rake e.g. 1' backwards, the boom end drops less leaving more room for the helm when tacking.

28/11/2013 16:22:20
Gareth Griffiths Notting Hill Rigging Co
Hi

Just thinking about systems for the boat I am about to refit this winter and I was wondering if anyone had tried using a halyard lock for the jib halyard and using a forestay tensioner/jib cunningham system at the tack end?

A halyard lock would reduce compression in the mast massively.

28/11/2013 18:17:57
Chris M
I've done a little looking into this, Scorpions do it and some 505s.

The conventional one string works very well, and I think a placcy would need some mods and beefing up to accommodate such a system which is enough reason for me to not bother currently. A wood hull is a different story and it could be made to work relatively easier, provided that the structure lends itself to installing the fittings in the right place.

However, you're new to the fleet why rock the boat before you've learned to sail it? Stick to standard kit as much as possible and copy known fast settings so you know what you have can be made to work.

28/11/2013 18:55:51
Andy Hay - Business as Usual
A halyard lock doesn't change the compression forces acting down the tube.

I've been contemplating running the forestay to a tackle under the foredeck, but the only solution I have thus far come up with is to have a stuff luff on the jib with the halyard returning back through the luff and connecting to the "one string" system that would be located under the deck.

Using the jib cunningham alone would mean that at full rake the jib foot would be somewhat above the deck which wouldn't be right. There are advantages to having to running the jib this way - reduced windage at the hounds, lower CoG, one less string in the mast - but as Chris says, the current systems / engineering are pretty well refined now, so probably not worth reinventing the wheel - I can't believe I just wrote that .... put it down to too much epoxy dust from the insides of BAU!

28/11/2013 22:34:21
Gareth Griffiths
Hi

Not using the Jib halyard definitely reduces compression. It is the system we use on all modern race boats, maxis, volvos TPs etc same rules apply to dinghies but on a smaller scale. The vertical direction of the halyard returning down the rig employs the compression rather than the diagonal loading of the forestay.

The reason I am looking at alternatives is that I am starting with a blank canvass and have the ability to be able to employ.

I have seen it used on International 14s, and as you mentioned 505s.

I have been studying various systems used in the fleet and there are a few refinements that can be made for sure. Reducing compression has to beneficial to the integrity of any mast?

Regarding the jib rising and falling at the tack height a circular halyard built into the jib luff and Cunningham would control the jib height.

28/11/2013 23:08:31
Miles 3646
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)

28/11/2013 23:13:24
Miles 3646
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?

28/11/2013 23:40:22
Gareth Griffiths
Hi miles

Good point re fairleads.

I have thought of a way to float the jib by floating the jib on the forestay using a Cunningham to maintain the tack height which should mean the fairleads wouldn't be effected.

Will give it a try before trying out a halyard lock to see if it works I guess..!

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