I am putting a masthead kite on a 24foot Farr727 quarter tonner. Will add a masthead jumper stay / strut system. Attached below in black ink is the current mast and standing rigging. In red is shown the new jumper system - stays and spreaders. Stays masthead to chainplates via jumpers and main spreaders. New jumpers same sweep back as main spreaders. In blue is additional optional diamonds. Has anyone done this successfully - in which case used just the red items or both red and blue. The present standing rigging is 5mm forestay and caps, 4mm lowers and backstay. I was going to use 3mm wire for the new jumper and maybe diamond stays - does this seem ok? All advice much appreciated.
Thanks in advance. rgds
Hi
would have to ask why ?
You would have to have a limited wind range, also wind angle ,is your pole longer ,why not just put a set of diamonds on ,instead on going all the way to the deck
Have you put a sleeve in the mast above the jumpers ?
Do have twin back stays ?
As soon as you put your kite up the mast will want to go forward inverting it without a good twin back stay arrangement
Soon as you do any type of reaching the mast will want to go side ways ,also inverting, also healing you over more ,flogging the main.
the boat is setup as a 3/4 rig .also your shroud base is designed for 2 fittings, your diamond are only designed for one tang .
looks to me you want to set up a mast head rig on 3/4 rig, not sure your insurance would cover these modifications .
I am not rigger i would suggest you contact one or the Farr office
Your system will not work, as you have no side support on the top of the mast. When you pull your back stay on it will only loosen your jumpers leaving no support. A swept back spreader rig requires the fore stay to work and give rig tension. In you case you would require a masthead fore stay which is not possible . Your new jumpers should be swept forward and not swept back. This way when you pull the back stay on it will tension the jumpers. I had this system on my Young 11 and we never ripped the top of the mast off (we certainly gave it a good go). I would be consulting a good rigger prior to doing anything as all the angles are critical.
Thanks for responses, points taken. Yes the focus on having the jumpers the same sweep back as the main spreaders so that the masthead to deck 3mm stay can go through the main spreaders also has its problems. The Holland 11m one design has fwd jumpers as you say. Selden also mentions that this is the norm. The masthead to deck stay will be dispensed with and just the jumpers and their diamond stays used - configured so the jumpers go straight out laterally or slightly fwd. The jumper length needs to be so that the stay to mast angle is 11 degrees. This kite would not be used above 15-18knots, and only broad reaching and square running. Have other kites on the existing lower normal halyard for higher winds and closer reaching. I have a good rigger in mind to pass it across.
Select to expand quoterobwsyd said..
Thanks for responses, points taken. Yes the focus on having the jumpers the same sweep back as the main spreaders so that the masthead to deck 3mm stay can go through the main spreaders also has its problems. The Holland 11m one design has fwd jumpers as you say. Selden also mentions that this is the norm. The masthead to deck stay will be dispensed with and just the jumpers and their diamond stays used - configured so the jumpers go straight out laterally or slightly fwd. The jumper length needs to be so that the stay to mast angle is 11 degrees. This kite would not be used above 15-18knots, and only broad reaching and square running. Have other kites on the existing lower normal halyard for higher winds and closer reaching. I have a good rigger in mind to pass it across.
Sounds like you are on the right track now. I do remember the 11 deg from some where. I also think that the jumpers were also swept forward by 11deg. But can not be sure.
Hi robwsyd
Might just add my "2 bob's worth" to this as I have boat of similar size (tad larger) running triple spreaders and cathedral rig. We have both mast head and fractional kites on a fractional rig with prodder, all assy's.
My suggestions is that if you talk to the Kiwis you will find that someone has already done something similar and will happily give you the feedback pros and cons.
I have found them very happy to share thoughts and where and what they have done in the past. Can give you their forum address if you wish.
They are still sailing them there and have active website.
Enjoy
David
Hello Jode5, David - many thanks. Yes am aware of the kiwi site have previously communicated with them including buying sails. rgds Rob
Isn't the main point of a fractional rig the ability to introduce, and control, mast bend? Forward angled jumpers will screw around with that.
If you just add in-line jumpers, you will support the side loads, and the backstay will take the forward loads. However you will now add side bending loads to the mast at the jumper lower attachments.
Overall adding weight to the top of the mast is not good. I would be inclined to stay with the original design concept.
Select to expand quoteYara said..
Isn't the main point of a fractional rig the ability to introduce, and control, mast bend? Forward angled jumpers will screw around with that.
If you just add in-line jumpers, you will support the side loads, and the backstay will take the forward loads. However you will now add side bending loads to the mast at the jumper lower attachments.
Overall adding weight to the top of the mast is not good. I would be inclined to stay with the original design concept.
Yara, I have raced with fractional rigged boats with big mast head kites for many years. Forward swept spreader actually help control your mast bend depending on the tension you have on the jumper wires. The back stay will still give you mast bent down lower where it is required to flatten the sail. Jumpers will stop the top of your main sail falling away Which is a plus. it is obvious from you comments you know very little about yacht rigging. I believe that you should not comment on forum items unless you know what you are talking about as it can be very misleading to the person chasing the information. The original concept is floored big time.
I think that robwsyd has way too much time on his hands !
The rest of his yacht must be 100% and sailed to 150% of its current capabilities ? And it's still not fast enough down wind ?
I can't see the value in the proposed modification
Select to expand quoteJode5 said..Yara said..
Isn't the main point of a fractional rig the ability to introduce, and control, mast bend? Forward angled jumpers will screw around with that.
If you just add in-line jumpers, you will support the side loads, and the backstay will take the forward loads. However you will now add side bending loads to the mast at the jumper lower attachments.
Overall adding weight to the top of the mast is not good. I would be inclined to stay with the original design concept.
Yara, I have raced with fractional rigged boats with big mast head kites for many years. Forward swept spreader actually help control your mast bend depending on the tension you have on the jumper wires. The back stay will still give you mast bent down lower where it is required to flatten the sail. Jumpers will stop the top of your main sail falling away Which is a plus. it is obvious from you comments you know very little about yacht rigging. I believe that you should not comment on forum items unless you know what you are talking about as it can be very misleading to the person chasing the information. The original concept is floored big time.
Jode,
My comments relate to basic engineering design, given that the OP post was, indeed, flawed.
No doubt the big boats you sailed on with jumpers were designed as such from the start. That is a very different situation to messing around with an existing design. The mast and stays form a combined system, and the modulus of the mast section and relevant tensions of the stays all interplay. Engineers know that if you stiffen one part of a complex structure, you can throw unexpected loads and deflections onto another part. So the advice is if you are going to do a mod like that, you are taking a risk, unless you have the skills and the data to do a proper analysis.
Select to expand quoteYara said..Jode5 said..Yara said..
Isn't the main point of a fractional rig the ability to introduce, and control, mast bend? Forward angled jumpers will screw around with that.
If you just add in-line jumpers, you will support the side loads, and the backstay will take the forward loads. However you will now add side bending loads to the mast at the jumper lower attachments.
Overall adding weight to the top of the mast is not good. I would be inclined to stay with the original design concept.
Yara, I have raced with fractional rigged boats with big mast head kites for many years. Forward swept spreader actually help control your mast bend depending on the tension you have on the jumper wires. The back stay will still give you mast bent down lower where it is required to flatten the sail. Jumpers will stop the top of your main sail falling away Which is a plus. it is obvious from you comments you know very little about yacht rigging. I believe that you should not comment on forum items unless you know what you are talking about as it can be very misleading to the person chasing the information. The original concept is floored big time.
Jode,
My comments relate to basic engineering design, given that the OP post was, indeed, flawed.
No doubt the big boats you sailed on with jumpers were designed as such from the start. That is a very different situation to messing around with an existing design. The mast and stays form a combined system, and the modulus of the mast section and relevant tensions of the stays all interplay. Engineers know that if you stiffen one part of a complex structure, you can throw unexpected loads and deflections onto another part. So the advice is if you are going to do a mod like that, you are taking a risk, unless you have the skills and the data to do a proper analysis.
Yara,
The boats I have owned with jumpers are a Sonata 8, Adams 10 and a Young 11 none of which are what I call large boats or were designed with jumpers. Many of this era boats were later fitted with jumpers soas the control the top of the mast as well as run masthead spinnakers. As I said in my original post "talk to a good rigger" A good rigger will have fitted many boats with jumpers, just go for a walk down the marina and see how many boats have jumpers of some sort, and whats more most will be small boats. Most modern boats have gone away from 3/4 rigs ang gone to 7/8 rigs which eliminates the need for jumpers. The below photos are of 2 boats moored just down from me in Machay marina.
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