TOPIC:

Hi

Having just been to the Weymouth Regatta for the Southerns, we found we were getting killed downwind.



Having checked the rig, it appears not to be going all the way forward.



The lack of boat speed downwind on the Saturday was clearly noticable, on the Sunday, we just kept the tension on due to the weather.



We will work on the boat this weekend and see what if any difference it will make at the Nationals



regards

Paul

AL6956

This way up

That sounds like quite the string, keep us posted!

Just to add to things...



I have re-rigged my rake control today, so I now have a "single string" rake adjustment - the shrouds and the jib haliyard are connected so that all I need to do to change the rake is pull on one string.


This eases the both shrouds, tightens the jib and reduces rig tension all in one. The macro adjustments are then used to release the leeward shroud which in turn straightens the mast more and puts more fullness in the jib.

It works in the dinghy park, but I have yet to test it on the water.

'Mmm thats interesting. I'll go and have a look at mine.



And I suppose there is no reason why we couldn't put a small purchase to stop the mast lifting up out the keel fitting. Lasers now have to have a line attached so as they can't loose the rig in the event of inversion.

Dom

AL1717

Should have said my rig tension goes back on when it is lumpy.

I think Neville nearly put the mast through the bottom of the boat at Lyme last year when the mast foot jumped out.

The other reason for a little more rig tension in lumpy stuff is to stop the mast slopping about in the lighter winds.



I dont think my mast foot fitting would take a pin - it has a slot to locate it fore and aft, but I think there is a slight curve along the base so as long as the pin is in the middle I dont think it would prevent rake movement.




John JohnW2010-06-12 09:28:58

I can understand the need for the pin and recognise it could prevent an embarrasing and expensive incident. I am also wonder whether the pin would stop the mast from canting forwards? Can anyone comment?

Dom

AL1717

John - I think this is a great summary, and very succinct. I also like Steve's subsequent note which will save any disasters. Well done!

There may be a clue to the jib luff tensioning issue in Steve's note too, in the nature of the water we're sailing on. I think a slack jib luff downwind is probably good (fast) on flat water, but it needs progressively more as the playing surface gets more bouncy.

I would consider putting a pin through the mast foot with all this slack rig tension especially in waves.

Wow ~ what can I say. Thanks.

I have spent most of the afternoon sorting my rig and getting the rake and tension settings right, so your your comments are most helpful.

I also asked a similar question on the Y&Y dinghy development forum and there are also some similar comments which are also very useful.

www.yachtsandyachting.com/forum/forum_topics.asp?FID=8



And I think you are right, very few people know the answers and what we do know is that rake certainly helps up wind and the converse must be the case downwind.



With highfield levers off, there is very little suport for the rig and so I reckon tightening the forestay by leading it back to a jammer on the deck will be of benefit when sailing on a run.



I also noted that the Speed tuning guide made mention of sailing all the time with 240 lbs rig tension and with the rig tension droppping to 200lbs when detensioned. I expect this will keep the mast in place in the event of a capsize.



Thanks again John for applying yourself to this and what do you think of the idea of archiving questions and answers like these so they can be retrieved by searching under various suitable headings?



I just need to get out and practice now.



Dom AL1717

OK, I will have a crack at this...



We need to consider two things here, mast rake and rig tension. How these are used varies from class to class often as a result of class rules - for example the Firefly sails with very loose rigging so that the mast can flop forward downwind (they are not allowed to adjust rigging on the water), however Phantoms and US Albacores drop the rig backwards downwind as this allows the boom to go out further (neither are allowed adjustable shouds).



In the UK Albacores we can more or less adjust the rig how we like on the water within a few constraints.



Rake

In general more rake de-powers the boat - I have yet to hear a convincing reason why this is, but most people would agree that it is true.

When I asked Mike Mac his thoughts on this, he said that he believed no one really knew.


There are lots of explaintions banded about the bar but most of them dont add up when scrutinised (If you really know, please do share).

Rake also helps with pointing, again I am not sure why, but try raking your mast right forward upwind and see how the boat points.



Rig Tension

Rig tension will have an effect on the mast (and hence mainsail) shape and the jib luff (and hence the jib) shape.

More rig tension will tighten the jib luff which will in general flatten the jib.




Most (my) Albs have their spreaders raked backwards from the neutral so an increase in rig tension will tend to pre-bend the mast and thus de-power the sail. This may be less so for the more bendy masts, but those of you who have been out buying new Selden Alto masts will probably agree.



Putting it together

Upwind we want to point and have just as much power as we can handle. So in general we use more rake and rig tension for a flat entry on the jib and main, with more rake to de-power if needed.



Downwind we generally need as much power as we can get (unless it is really scary conditions). So we rake the rig forward proportionately more the further off the wind we are (less rake = more power)

Easing the shrouds will also release rig tension and allow the mast to straighen (fuller sails = more power). At some point the now full mainsail will touch the shrouds as it is eased. Easing off the leeward shroud allows the main to keep its shape as it is let out. However this further slackens the rig tension and can remove support for the mast if overdone which allows it to bend or even invert and snap.





I see two schools of thought with regard to adjustment of the jib haliyard. Jerry above pulls his jib tension on, this will help support the mast, but it will flatten and therefore depower the jib. I believe Mike Mac is also of this school. However, Barney leave the jib luff slack for a fuller jib.

(see pic on this thread www.albacore.org.uk/Discuss/forum/forum_posts.asp?TID=1520 ) Orlando was also of this school of thought.





It may depend on mast stiffness or jib aspect, but I am not sure.

Merlins and Scorpions with their "single string" rake adjustment keep the rig tension on the jib, but then they are flying kites downwind so power from the jib is less important.

Dom

I think the reluctance to post on this topic reflects the fact that none of us really know why these effects make boats go quicker on different points of sailing! Michael McNamara is the man to talk to on these points (see his reply on page 3 below of this forum to a question about jib aspect ratios)

Incidentally, the Star class are very like Albs & they let their masts rake forward to an alarming angle on a broad reach or run - they do have running backstays though!

Thank you Eric, that is a good link and makes good reading. I do think that we should have some information about tuning and set up which can be easily accessed for newcomers and others who want to search for such information.

Dom

AL1717 dom3152010-06-11 13:44:06

We've just moved from N12's to Albacore's. Both boats have similar rig adjustments, so here is the link to their rig adjustment guide, which explains what and why your trying to achieve by adjusting the rig. www.national12.org/hints/coaching/coaching_rig_adjustment.shtml



Eric

ALB 8065

That's interesting and thanks for the information.



I was a bit surprised that it has taken a few days for someone to respond to my questions on this topic. I began to think I had committed a sin and that I had asked a question in which people thought the answer was so obvious that nobody need to respond. So it was good to read your comments and honesty in your answer.



I'd still be interested to hear others' comments. I see that the later Albacores are fitted with course and fine adjustment controls for the rig as oppose to the levers that my old Albacore has. So there must be some sound thinking as to the benefits of an adjustable rig and why and when t to adjust it.




I am curious to understand more about the theory and practice of letting go rig tension when sailing down wind in dinghies? In addition to the Albacores, Merlins and Scorpions do it. But what do they do and when do they do it?


I know that rake is good when going up wind (look at the Contender class) and so letting the rig go forward when going down wind will enable the boom to go out further and move the centre of effort forwards as well. However the forestay will go loose changing the shape of the jib etc.


What happens on reaches and why and how much do these and other classes with adjustable rigs let there rigs go?

I am sure there is a wealth of knowledge out there and it would be a shame if we got some good answers that they then just become lost in the 'Posts' over time. Could we not have a special section for Hints and tuning tips accessible to all? I am sure that many potetial Albacore sailors would find that something like this would ecourtage them to join the class rather than be frightened off by the complexity and what might apper like the secrecy behind rig adjustment.



Perhaps this should be a new thread!

Dom

AL 1717

dom3152010-06-10 12:36:27

If only I knew the definitive answer to these questions I'd be a rich - no a very fast man! I let off about 1"-1.5" of shroud on rounding the windward mark onto a reach - dont forget to let off the kicker a lot and take up the slack (only) on the jib halyard.

I also have shroud levers which I let off on a broad reach or run - again just taking up the slack on the jib halyard.

Although this fiddling about is worth it on long open-water courses, it is far more important not to miss the next puff and get planing - especially on restricted courses with short reaching legs