What is this at the masthead?

[Daydream believer]

Would I be in thinking that swept back spreaders reduced the need for jumpers in small boat. Seems to work ok for my 3/4 rigs.

I do not see how that can be. Jumpers resist backward loading.( & add some side support) Swept back spreaders apply backward loading (Plus of course some side support) Swept back give pre bend jumpers resist pre bend

 

[flaming]

I do not see how that can be. Jumpers resist backward loading.( & add some side support) Swept back spreaders apply backward loading (Plus of course some side support) Swept back give pre bend jumpers resist pre bend

Swept back spreaders and pre bend go together to make a rig that is inherently stiffer than a straight tube and in line spreaders.

Added to which, the job the jumpers are really doing is making the top section considerably stiffer than the rest of the mast, to enable the backstay to better resist the forestay loads without recourse to checkstays or running backstays.
In a swept back spreader rig the shrouds and pre bend together do the job of supporting the rig against the loads of the forestay.

 

[Kelpie]

the jumpers... enable the backstay to better resist the forestay loads without recourse to checkstays or running backstays.

So... I was right?

 

[Daydream believer]

In a swept back spreader rig the shrouds and pre bend together do the job of supporting the rig against the loads of the forestay.

Ignoring side support. The pre bend is caused because the swept back spreaders are failing to prevent the load from the backstay being fully transferred to the forestay. Now no one is suggesting that pre bend is not desireable. I have 60mm pre bend on my 11/12 mast & 150mm when I tension the backstay. I have swept back spreaders. If I had jumpers ( as I had in my last 2 boats) the bend at the top would be less (because being in front of the mast they restrict that bending momen. I still used to get some, but it tended to be lower down. I am not discussing where it should, or not be, but only that your theory about the swept back spreaders preventing for & aft bending ( beyond pre bend) is not entirely correct.
However, we are clearly not going to agree. You have an opinion & are entitled to it. I have mine- I will not change. No point in disputing further.

 

[steveeasy]

Thought they were quite common on fractional riggs. As has been said they stiffen the top of the mast, My understanding is that with jumpers fitted when the backstay is tensioned any bend that is created to the mast is lower down and in a forwards direction allowing the mainsail to be flattened.

Can you have a 3/4 fractional rigg without jumper stays fitted. ? id have thought not.

Steveeasy

 

[flaming]

Ignoring side support. The pre bend is caused because the swept back spreaders are failing to prevent the load from the backstay being fully transferred to the forestay. Now no one is suggesting that pre bend is not desireable. I have 60mm pre bend on my 11/12 mast & 150mm when I tension the backstay. I have swept back spreaders. If I had jumpers ( as I had in my last 2 boats) the bend at the top would be less (because being in front of the mast they restrict that bending momen. I still used to get some, but it tended to be lower down. I am not discussing where it should, or not be, but only that your theory about the swept back spreaders preventing for & aft bending ( beyond pre bend) is not entirely correct.
However, we are clearly not going to agree. You have an opinion & are entitled to it. I have mine- I will not change. No point in disputing further.

No that’s not what I’m saying at all.
Sorry if I’ve been unclear. Pre-bend is induced into the mast with shroud tension. Backstay can be (and on our rig often is) entirely slack. Putting backstay on bends the rig further. I’m not saying at all that prebend prevents further bending, more that it makes the mast section and shrouds, when considered as a system, stiff enough, and in the right plane, to counter the forestay load with the backstay entirely slack. The addition of backstay to that sort of rig upwind is entirely a tuning aid, not a necessity to keep it upright.
Jumpers, as I understand it, were a way to allow an inline mast to use backstay to counter the forestay load, without having to use runners to prevent the mast from folding when a load is applied where it is not directly opposed by another stay.

Another wonderful little detail that got designed into boats, and then designed out when a better solution was found!

 

[William_H]

If it's a Trident, it's a key part of the rig, allowing good backstay tension without bending the mast. Being a 3/4 rig that top section is otherwise unsupported, and tensioning the backstay induces a curve in the mast preventing the main from setting properly, ruining windward performance.. Join our Facebook page Trident 24 if you have more questions. If you do buy, it's worth joining Trident Owners Association too. They will almost certainly know some of the history of your boat.

You might be right on a Trident however one fleet of racing boats here known a s Bakewell 7 have a very bendy mast no jumper struts. The back stay main sheet and vang all come out in a box on the cockpit floor for the main sheet man to operate. In a gust the idea which is quite plain to see is that when yopu haul bn the back stay you get a lot of mast bend especially at top. This takes camber out of the main sail but also noticably allows the top iof the main sail to fall away so reducing heeling force. So in this case (design) bending the mast (where jumper struts would resit bend) actually aids main sail shape. (for a gust on the wind) Yes a fairly bendy mast. Seems to survive ok but not to give confidence in a cruising boat. ol'will

 

[oldharry]

You might be right on a Trident however one fleet of racing boats here known a s Bakewell 7 have a very bendy mast no jumper struts. The back stay main sheet and vang all come out in a box on the cockpit floor for the main sheet man to operate. In a gust the idea which is quite plain to see is that when yopu haul bn the back stay you get a lot of mast bend especially at top. This takes camber out of the main sail but also noticably allows the top iof the main sail to fall away so reducing heeling force. So in this case (design) bending the mast (where jumper struts would resit bend) actually aids main sail shape. (for a gust on the wind) Yes a fairly bendy mast. Seems to survive ok but not to give confidence in a cruising boat. ol'will

Yes, well aware that many 3/4 rig boats have bendy unsupported masts, but the Trident rig is engineered to carry the tension between the forestay and the backstay so as to keep the mast straight. The Owners Association (which I currently run) has detailed instructions from designer Alan Hill for setting them up correctly so as to ensure a straight luff and forestay.

 

[steveeasy]

Unless I’m wrong how could you have a 3/4 fractional rig without jumper stays. Whilst the forestry is not meant to be too tight on a fractional rigg, without jumpers the mast at the point of forestry would be Under excess force.

With little knowledge but having had a 3/4 rigg with jumpers I’m not totally convinced it’s black and white what pros and cons they offer.
Structural rigidity to the upper section of the mast. I believe transferring bend lower down to flatten main sail. But equally to depower the main sailing down wind. To be effective sails need to well set I suspect.
Then I’ve never understood how a masthead can be bent either

Steveeasy

 

[William_H]

Unless I’m wrong how could you have a 3/4 fractional rig without jumper stays. Whilst the forestry is not meant to be too tight on a fractional rigg, without jumpers the mast at the point of forestry would be Under excess force.

With little knowledge but having had a 3/4 rigg with jumpers I’m not totally convinced it’s black and white what pros and cons they offer.
Structural rigidity to the upper section of the mast. I believe transferring bend lower down to flatten main sail. But equally to depower the main sailing down wind. To be effective sails need to well set I suspect.
Then I’ve never understood how a masthead can be bent either

Steveeasy

A whole lot of design factors come in to decide on need for jumper struts on a 3/4 rig. Needed even less on a lesser fractional rig. (ie 7/8) Much depends on stiffness of the tapered mast section at the top. I wouyld suggest Steveeasy keeps his jumper struts. Perhaps ok without but then maybe not.
Mine is perhaps somewhere between 3/4 and 7/8 and seems to have stiffness of the tapered top adequate for a bit of mast bend in strong winds but not too much while adding tension to the forestay. A lighter top section might bend too much before adequate forestay tension is achieved without jumper struts. So I would say jumper struts not so common around here on fractional rigs. But then nor are running backstays and in my opinion jumper struts are a better option than runners.
Re mend of mast head rig mast. It hard to achieve much bend. Many around here have the adjustable back stay and adjustable inner forestay to get bend but I think it more wishful thinking than much bend. Hopefully done to remove camber from mainsail. ol'will

 

[oldharry]

Pro Dave, did you hear back from the Owner, or has the boat been sold?

 

[ProDave]

That boat has been sold. so we are still looking for a mid 20ft cruiser. Considering a L23, and there is another Trident 24 for sale at the same place, but it needs work. Looking at the pictures of it, there was something odd about the finish to the walls in the main cabin. Zooming on on the photos suggests it has been wallpapered. That's a first for me on a boat!!!!

The L23 while probably a lesser boat, the example we are enquiring about has had just about everything possible done to it so looks a better poposition.

 

[Concerto]

Thought they were quite common on fractional riggs. As has been said they stiffen the top of the mast, My understanding is that with jumpers fitted when the backstay is tensioned any bend that is created to the mast is lower down and in a forwards direction allowing the mainsail to be flattened.

Can you have a 3/4 fractional rigg without jumper stays fitted. ? id have thought not.

Steveeasy

My ¾ rigged Fulmar has no jumpers as the speaders are swept aft. The cap shroud tension is set to 20% of the breaking strain of the wire and the lowers at 15%. This supports the loading of the forestay and/or spinnaker. By comparison the backstay is quite slack as more tension only increases the set 8 to 9 inches of pre-bend in the mast. The pre-bend is controlled by the lower shrounds. Many modern fractional rigs have even more aft swept spreaders and have no backstay at all.

An old style ¾ rig with spreaders at right angle to the centre line of the boat require jumpers. Many of the boats designed in the 1950's and 60's with fractional rigs are like this. Your old Helix had jumpers that were specially designed by CR Holman as the original owner prefered a ¾ rig to the original masthead sail plan of the Twister.

 

[William_H]

My ¾ rigged Fulmar has no jumpers as the speaders are swept aft. The cap shroud tension is set to 20% of the breaking strain of the wire and the lowers at 15%. This supports the loading of the forestay and/or spinnaker. By comparison the backstay is quite slack as more tension only increases the set 8 to 9 inches of pre-bend in the mast. The pre-bend is controlled by the lower shrounds. Many modern fractional rigs have even more aft swept spreaders and have no backstay at all.

An old style ¾ rig with spreaders at right angle to the centre line of the boat require jumpers. Many of the boats designed in the 1950's and 60's with fractional rigs are like this. Your old Helix had jumpers that were specially designed by CR Holman as the original owner prefered a ¾ rig to the original masthead sail plan of the Twister.

Concerto seems to imply that it is a case of either swept back spreaders or jumper struts. I would disagree and say jumper struts are to support the top part of the mast while swept spreaders are really to support the middle of the mast. I say it is either jumper struts or a more robust upper section of mast. ol'will

 

[steveeasy]

My ¾ rigged Fulmar has no jumpers as the speaders are swept aft. The cap shroud tension is set to 20% of the breaking strain of the wire and the lowers at 15%. This supports the loading of the forestay and/or spinnaker. By comparison the backstay is quite slack as more tension only increases the set 8 to 9 inches of pre-bend in the mast. The pre-bend is controlled by the lower shrounds. Many modern fractional rigs have even more aft swept spreaders and have no backstay at all.

An old style ¾ rig with spreaders at right angle to the centre line of the boat require jumpers. Many of the boats designed in the 1950's and 60's with fractional rigs are like this. Your old Helix had jumpers that were specially designed by CR Holman as the original owner prefered a ¾ rig to the original masthead sail plan of the Twister.

Hi.
Thanks for the info. Your quite right the spreaders on helix we’re at right angles. Ok now thinking about spreaders being swept back I can understand how it works. Crucial the correct rig tensions then.
Interesting stuff.
Steveeasy

 

[Kelpie]

That boat has been sold. so we are still looking for a mid 20ft cruiser. Considering a L23, and there is another Trident 24 for sale at the same place, but it needs work. Looking at the pictures of it, there was something odd about the finish to the walls in the main cabin. Zooming on on the photos suggests it has been wallpapered. That's a first for me on a boat!!!!

The L23 while probably a lesser boat, the example we are enquiring about has had just about everything possible done to it so looks a better poposition.

I think L23 have a saildrive? Nothing inherently wrong with that of course but unusual for that size/age/style of boat. Worth checking when the membrane was last changed.
They do seem to have a huge amount of space inside, for such a small boat. Good luck!

 

[ProDave]

I think L23 have a saildrive? Nothing inherently wrong with that of course but unusual for that size/age/style of boat. Worth checking when the membrane was last changed.
They do seem to have a huge amount of space inside, for such a small boat. Good luck!

The L23 was available with inboard or outboard. The one we are considering has a 6HP OB with remote tank and charging. One of the attractions of this particular boat is it has been well maintained e.g. standing rigging replaced 2 years ago, and lots of other documented upgrades.

 

[oldharry]

That boat has been sold. so we are still looking for a mid 20ft cruiser. Considering a L23, and there is another Trident 24 for sale at the same place, but it needs work. Looking at the pictures of it, there was something odd about the finish to the walls in the main cabin. Zooming on on the photos suggests it has been wallpapered. That's a first for me on a boat!!!!

The L23 while probably a lesser boat, the example we are enquiring about has had just about everything possible done to it so looks a better poposition.

Wallpapered cabin reminds of an elderly catamaran I once viewed (but didnt buy!). I was assured it was waterproof, as it was bathgroom grade vinyl! More optomism than durability!

L23 was a nice comfortable boat, but without the sailing perfmance of the Trident.