Lazyjacks - Have I got it right or wrong?

Norman_E

Norman_E

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My old lazyjacks needed replacement, partly because they were old, but mainly because there was not enough tension on the lines towards the clew of the sail, which often simply fell out of the bag. My sailbag has no battens in it and has 6 lazyjack attachment points. The old lazyjacks were low down at the clew end of the boom, and the sail could just fall over them. I installed my new arrangement after retuning to the marina from a cruise, so have not yet tested it, but I have put all the blocks as high as possible and have ensured that the two lines at the clew end have double the tension of the other four. All the blocks are now high up, and it is unlikely that the sail battens will catch them on hoist because the lazyjacks are pulled well apart at the top. Does this look OK to you?

http://i35.photobucket.com/albums/d164/Sauniere59/Lazyjacks.jpg
 
Looks fine.
However, I don't understand how you can get extra tension on the clew end. With the arrangement you have surely the tensions will all be the same?
 
The mast blocks are half way between the lower and upper spreaders, so a fair way up, and the lines are held apart because they pass through steel rings attached by cords to the cap shrouds, thus pulling the lazyjacks about a metre apart. Tension is a function of how the blocks divide it up. Essentially if you put a 200lb pull on the mast rope the highest block divides that in two so that each leg of the upper green rope in my diagram would have 100lb tension and the short blue rope would again divide that by two, further division would give a 25lb pull on all four of the green sail bag attachments, but the outer two coloured blue would have 50lb each. (4x25)+(2x50)=200, balancing the downward pull on the mast rope.
 
I think you have got it right in practical terms but your reasoning is a bit odd. The issue is not so much the amount of tension in the lines - one doesn't tension lazyjacks as such, merely take up the slack - but the weight of sail they have to contain. On that basis having the most divisions nearest the mast is completely sound as that's where the main weight of sail is when you drop it.
 
oldbilbo said:
I reckon you don't need 6 attachment points. 4 will be sufficient, with two central pairs of lines 'doubled-up' on attachments.
Click to expand...

I am stuck with 6 attachment points as the sail bag has them, and no battens to keep it in shape. I have found with the old lazyjacks, where the blocks were fairly low down, that they did need a bit of tension on them (counteracted by the sail bag being pulled to the boom end, and by attachment to the topping lift) otherwise the leach of the falling sail effectively collapsed the end of the bag and dropped off the boom. I hope the new arrangement solves that problem but will have to wait until I go out to sail again in September. I am however encouraged by the comments so far.
 
The mast blocks are half way between the lower and upper spreaders, so a fair way up,
Click to expand...

I was told to fix the blocks at approx two thirds up the mast and found by experiment that worked for me too. I too did all the simple maths but found in reality that the lengths were never exactly the same and I had to take a little bit of tension up on the end line which I do with the cleats I mentioned .
 
I had to look at some photos of the boat to see that the mast attachment points are in fact just below the upper spreaders, so close to 2/3 mast height.
 
Battens are key...without them you are fighting a loosing battle. All that unnescesary complexity and windage aloft! You could get some GRP battens from a sailmaker and just bolt them in place if needed, and lose half of the lazy jacks.

Every time you adjust your vang/traveller when sailing, or topping lift when stowing, you are going to encounter similar issues IMHO.
 
Iain C said:
Battens are key...without them you are fighting a loosing battle. All that unnescesary complexity and windage aloft! You could get some GRP battens from a sailmaker and just bolt them in place if needed, and lose half of the lazy jacks.

Every time you adjust your vang/traveller when sailing, or topping lift when stowing, you are going to encounter similar issues IMHO.
Click to expand...
+1
battens can be quite cheap, see
http://www.ecfibreglasssupplies.co.uk/c-533-fibreglass-carbon-fibre-rods-tubes.aspx
 
Norman_E,

You do have the arrangement wrong.

Wth your arangement the 2 outer lines carry twice the load of the inner 4 but hold far less sail.

I suggest you swap the out 2 with the inner 2 lines.

If you do this then this will even up the loads. So when you haul up the lazyjacks the greatest pull will be where most of the sail is, ie nearest the mast.
 
theoldsalt said:
Norman_E,

You do have the arrangement wrong.

Wth your arangement the 2 outer lines carry twice the load of the inner 4 but hold far less sail.

I suggest you swap the out 2 with the inner 2 lines.

If you do this then this will even up the loads. So when you haul up the lazyjacks the greatest pull will be where most of the sail is, ie nearest the mast.
Click to expand...

The problem is that the outer 2 lines are at about 45 degrees to the vertical so they will have less of an 'upward' pull than the ones closer to the mast.
Other than that I would agree with other's suggestions and have fewer lines/attachments but add some (circular rod, not flat) battens.
 
PetiteFleur said:
As mentioned earlier, fix a long batten to the upper edges of the sail bag - it will make your life much easier.
Click to expand...

If I was starting again I would do that, but the bag was designed and made by friends, and is generally very successful as it is a good fit over the sail. The top edge is not straight like battened bags, but curved slightly to provide a good fit over the sail and accomodate the fact that I have roller cars instead of sail slides, making the "stack" at the mast higher than it would otherwise be. I will try the present arrangement when I sail in September, before considering any further changes. Theoldsalt may be right, but the sail has never tried to fall out of the bag close to the mast when dropped, it is only the last few feet near to the leach that ever did that with the old arrangement.
 
but the sail has never tried to fall out of the bag close to the mast when dropped, it is only the last few feet near to the leach that ever did that with the old arrangement.
Click to expand...

Its for that very reason that I installed the in line cleats I mentioned earlier
 
Not sure my lazyjacks are remotely relevant to this thread, but since the boat's a dinghy, they couldn't be bought, and had to be fitted with sheer guesswork as a guide...

...with that in mind, I didn't rely on existing attachments on the boom for the lazyjacks, but ran a length of 4mm line along both sides, and tied bowlines at each point where I thought the feet of the lazyjacks belonged...

...meanwhile I attached two tiny Seasure blocks to my unused upper-diamond shroud attachments (no idea what they're called) and ran the lines back to the mast foot. Instead of six more mini-blocks in the lazyjacks, I used 3mm thimbles. All very cheap & cheerful.

I just plumped for ten-foot lengths of line, forming four-foot-high lower and upper triangles. I arranged the line at the mast-foot with bowlines at various points - so, one setting sees the boom steeply raised to avoid the bonce when rowing, another sets it horizontal, and another slackens the lazyjacks for sailing - I stupidly forgot that, yesterday, and sailed for an hour with the leeward lazyjacks constantly pressing the curve out of the sail. Not good...but not hard to put right.

But my point is that using a rope with knots as the boom attachment points, means I could very easily adjust them if they're not doing the job. Judge for yourself...

View attachment 33603

...today we hauled up the genoa, leaving the main on the boom till we'd launched...but then, we never bothered hoisting the main at all! Two and a half lazy uptide miles in fifty minutes under genoa alone with the boat handling beautifully, considering we were sitting on the floor, SWMBO dozing after her liquid lunch...

...then the same effortless distance back, more quickly. It wasn't very windy, but several times it would have been relatively fraught under all sail, although I'd never have made the trip without the option to raise the main at any time...but I doubt we'd have wanted to be in the boat, if the cockpit had been cluttered by boom and sail.

So...lazyjacks (or Dinghyjacks?)...wonderful things. :)
 
Dan,

a good friend who largely taught me to sail had a saying ' the best sailor is the laziest ' ie have everything prepared and working efficiently.

Glad you liked the Ospreys' handling, thought you would ! :)
 
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