Positioning jib tracks

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pandos

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I want to ad a blade (no3) flown on a silent stay.

My jib tracks are positioned well outboard and in any case I think do not extend sufficiently forward for a good sheeting angle on a small sail.

I have two short tracks with cars that are perfect for the job, but I find it hard to workout where to put them,

I'd rather not do trial and error as this will need holes in the cabin roof...

When the sail is altered to fit I'll be able to have a look and see but I wonder is there an actual formula/ geometric exercise that can be used?
 
pandos said:
but I wonder is there an actual formula/ geometric exercise that can be used?
Click to expand...
I seem to remember that a starting point could be a straight line starting at 50 percent of the the luff length and passing through the clew (where this line meets the deck).
 
BabaYaga said:
I seem to remember that a starting point could be a straight line starting at 50 percent of the the luff length and passing through the clew (where this line meets the deck).
Click to expand...
That makes sense., many thanks...

Once I work that out, probably not too much choice about how far off the centre line I can fit them given that I will need to avoid stays, cabin top features and still achieve fair access to winches..
 
I think the more modern approach is to se up barber haulers so that sheeting angle is adjustable. So set up a attachment for a block on deck forward of existing track and inboard. A ring or block is on the sheet which can be pulled down by a line through the block on deck back to cockpit cleat. Set up so that the smaller sail can be sheeted both downward and also inboard. You need to decide if sheeting is going to be inside shrouds or outside. Inside might be better for smaller sail to get sheeting closer to centre line. This is all about getting the smaller jib (or jib with rolls in furler) to be sheeted best for beating in to the wind.
For reaching the jib sheet is eased so you want sheeting forward to pull clew down but out board to keep all of the jib driving.
I saw a 100ft ocean racer at Hobart where fore and aft sheeting for the jib is handled by a barber hauler ring pulling sheet down. However the barber hauler was on a track from inboard to outboard to give variation to sheeting angle. So no fore and aft tracks.
I suggest OP not fit tracks but try barber hauler (I hope I have the correct name) for jib sheeting angle adjustment. ol'will
 
William_H said:
I think the more modern approach is to se up barber haulers so that sheeting angle is adjustable. So set up a attachment for a block on deck forward of existing track and inboard. A ring or block is on the sheet which can be pulled down by a line through the block on deck back to cockpit cleat. Set up so that the smaller sail can be sheeted both downward and also inboard. You need to decide if sheeting is going to be inside shrouds or outside. Inside might be better for smaller sail to get sheeting closer to centre line. This is all about getting the smaller jib (or jib with rolls in furler) to be sheeted best for beating in to the wind.
For reaching the jib sheet is eased so you want sheeting forward to pull clew down but out board to keep all of the jib driving.
I saw a 100ft ocean racer at Hobart where fore and aft sheeting for the jib is handled by a barber hauler ring pulling sheet down. However the barber hauler was on a track from inboard to outboard to give variation to sheeting angle. So no fore and aft tracks.
I suggest OP not fit tracks but try barber hauler (I hope I have the correct name) for jib sheeting angle adjustment. ol'will
Click to expand...
I have seen that system, the sailing French man did a Utube on it.

But the downside is the amount of lines crisscrossing the deck makes things a bit complicated for walking about...

I'll certainly have a look at perhaps using an existing u bolt on deck and an LFR on a strop, it would be a very easy solution...

Food for thought...

Thanks
 
Why are you specifically using a silent stay. Our stays might talk to each other - but I have no issues with their conversations. :)

The advantage of using the Barber haul and a strong point (assuming you have a strong point) is that you can define exactly how you want to sheet the sail - without any major modifications - you just need to strong point and a strop with an LFR on the end. Accepting your comment about the dangers of the cat's cradle on the foredeck you can then decide where the tracks should be located. Your problem with the tracks will be - holes in the deck and reinforcing - which may discourage you from a major modification as the cat's cradle being the lesser of 2 evils.

We added tracks on our cabin roof - but the builder had anticipated the need and added 10mm of marine ply and 5mm aluminium strip plus mouldings in the roof for both tracks and sheet winches and I simply drilled and tapped into the aluminium strip. I only used one winch and added a turning block for the other winch point. Interestingly - we still use Barber hauls.

The advantage of using a single winch is you half your investment but you also can tack without the need to. move from one winch to the other (which is a long way on a cat). You simply drop one sheet , locate the other on the winch without moving your feet. However you do need to be able to run the sheet on the turning block freely - easy across a cabin roof.

Jonathan
 
Four suggestions for calculating the jib sheeting angle.
1, follow this link for as much detail as you will ever want Jib Sheeting Angle – Bethwaite360
2, rough calculation is intersect the luff somewhere between 50% (as BabaYaga says) and point which accords to the ratio between height and width. A tall thin jib will need a higher angle than a short fat one.
3, if the clew reinforcement is of spread fingers variety then the longest one will probably be the right line to follow
4, hoist jib and experiment
 
If it helps, on my 31 foot sloop I have two sets of Genoa car tracks and a solent stay. The SS car tracks start 60mm forward of mast and approx 400mm each side of mast, and are approx 500mm long. I have a 90% blade jib and it works well with the ss car tracks as described.
 
I would think that on a calm day you could fiddle with the position of the new tracks just by holding them down to get a rough idea
 
pandos said:
I have seen that system, the sailing French man did a Utube on it.

But the downside is the amount of lines crisscrossing the deck makes things a bit complicated for walking about...

I'll certainly have a look at perhaps using an existing u bolt on deck and an LFR on a strop, it would be a very easy solution...

Food for thought...

Thanks
Click to expand...

You don't have to install it that way. But it is an excellent way to find the right location. Go sailing in light to moderate winds with temporary lines led to existing hard points (toe rail, mast base, any strong fitting). Put a carabiner or pulley on the sheet and winch the lines untill you get the shape you like. Put a straight edge on the sheet and it will hit the deck where you want the track. You only need to do one side!

I have done this when making a similar change, and it worked great. It also took a lot of stress out of mounting the track, knowing it was right.

When installing a track on a cored deck, I got a strip of 1 1/2" x 1/4" aluminum and made a LONG backing plate. In my case, there were also access problems, so I tapped the plate for the bolts, but you could use nuts.
 
thinwater said:
You don't have to install it that way. But it is an excellent way to find the right location. Go sailing in light to moderate winds with temporary lines led to existing hard points (toe rail, mast base, any strong fitting). Put a carabiner or pulley on the sheet and winch the lines untill you get the shape you like. Put a straight edge on the sheet and it will hit the deck where you want the track. You only need to do one side!

I have done this when making a similar change, and it worked great. It also took a lot of stress out of mounting the track, knowing it was right.

When installing a track on a cored deck, I got a strip of 1 1/2" x 1/4" aluminum and made a LONG backing plate. In my case, there were also access problems, so I tapped the plate for the bolts, but you could use nuts.
Click to expand...
Yep sounds sensible, access is no bother and as my mainsheet turns on a u bolt backed only by penny washers I don't predict an issue with strength of the deck/top.

Just need to chop my sail to the desired size and away I go...
 
When you fit friction rings with barber haulers etc to the cabin top to accept the sheet you need to consider the final lead into the winch. If you cannot get it low enough you may get a sudden problem with an overriding turn at an inopportune moment
 
Daydream believer said:
When you fit friction rings with barber haulers etc to the cabin top to accept the sheet you need to consider the final lead into the winch. If you cannot get it low enough you may get a sudden problem with an overriding turn at an inopportune moment
Click to expand...
Agreed sheet should approach winch from level with bottom of winch. usually sheet coming via an existing sheet block (on a track?) ol'will
 
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