Fractional-rigged sloop boat

[Jim Cate]

Originally Posted by psk125

We have a fractional rig without swept-back spreaders. Works for us, even with a 152% genoa.

I suspect that these 90+% fractional rigs are a combination of styling (emulates lots of modern race boats) and cost, for with the forestay that near the masthead, no runners are needed. It's sorta like a Solent jib without the outer jib/genoa.

Seems to work ok, but the advantage over a regular masthead rig isn't clear to me... hence the styling comment.

Jim

[SVHarmonie]

SO many people giving so much advice and so few ask how the OP is going to use his boat. It matters. A lot.

The idea that there is no place in the sailing world for a masthead rig is stupid. And the idea that a fractional rig is aLways a bad choice is equally wrong.

Pretty ignore much anybody who says “All sailboats should be X”. It matters not a wit what “X” is.

[Draughty]

Originally Posted by psk125

We have a fractional rig without swept-back spreaders. Works for us, even with a 152% genoa.

Boat in the pics has swept spreaders; J36's had swept spreaders standard????

Rgds

[Draughty]

Originally Posted by Jim Cate

I suspect that these 90+% fractional rigs are a combination of styling (emulates lots of modern race boats) and cost, for with the forestay that near the masthead, no runners are needed. It's sorta like a Solent jib without the outer jib/genoa.

Seems to work ok, but the advantage over a regular masthead rig isn't clear to me... hence the styling comment.

Jim

Hi Jim,
I think the main reason to go almost, but not right to the masthead is to leave a nice clear space to fit halyard hardware for furling soft-luff sails clear above the fore-stay.

I've noticed before that you're a fan of the solent stay; I would look seriously at setting one up if I was going ocean cruising.
The only negative I've heard (or read somewhere) is that the two stays divide the force from the backstay, so neither is fully tight as it could be.
Have you noticed any issue with this.

Rgds

[Jim Cate]

Originally Posted by Draughty

Hi Jim,
I think the main reason to go almost, but not right to the masthead is to leave a nice clear space to fit halyard hardware for furling soft-luff sails clear above the fore-stay.
******
That's an interesting thought that I hadn't considered... could well be true!

I've noticed before that you're a fan of the solent stay; I would look seriously at setting one up if I was going ocean cruising.
The only negative I've heard (or read somewhere) is that the two stays divide the force from the backstay, so neither is fully tight as it could be.
Have you noticed any issue with this.
***********
Our Solent rig is on a fractional mast, so the forestay tension is backed by the cap shrouds (swept back spreaders) and the runners. And despite this, yes, it is hard to get good tension on the forestays, and harder yet to get them even.
Really loading up the runners does pretty well, though, and a good sailmaker can at least partially compensate for sag when he designs the sail. I'm not sure that I would choose such a rig in a custom design these days, but we've done well with what we bought.

Rgds

Cheers,

Jim

[fxykty]

Originally Posted by Draughty

Hi Jim,

I think the main reason to go almost, but not right to the masthead is to leave a nice clear space to fit halyard hardware for furling soft-luff sails clear above the fore-stay.



I've noticed before that you're a fan of the solent stay; I would look seriously at setting one up if I was going ocean cruising.

The only negative I've heard (or read somewhere) is that the two stays divide the force from the backstay, so neither is fully tight as it could be.

Have you noticed any issue with this.



Rgds

Why would the two stays divide the force of you only run a sail on one stay at a time if they are not dual forestays (that is, side by side).

The structural forestay is the one that carries all the static load, equaling the opposing shroud (if they’re on swept back spreaders) and backstay tensions. The inner forestay will carry virtually no static load.

With a sail set on the forestay, the load remains there and the inner stay almost nothing, though it may see some more load if the mast pumps - generally not likely on a cruising rig. Any sag in the forestay is due to lower shroud/backstay tension, not because the inner stay is stealing some of that opposing tension.

If the forestay sail is furled or removed and a staysail set on the inner stay, now the inner stay has some load and will need to take some of the opposing tension from the shrouds and the backstay. But there’s not a set amount of tension that must be shared - the forestay is still carrying the structural load and the inner forestay adds its force - the shrouds and backstay increase the tension they feel. This is Newton’s third law in action.

But unless your inner forestay is very close to the locations of your shrouds and/or backstay, or doesn’t have running backstays, then the inner forestay will have more sag with a set sail. Not because there’s not enough total opposing force available, but because the opposing force isn’t easily directed to supporting the inner forestay.

[Draughty]

Hi fxykty,
I only have high school physics so can't claim expertise; it's what I read and it seems logical to me.
I can't see that whether there is a sail set or not, or if the stays are side by side or otherwise is relevant.
Just to be sure that we are singing from the same hymn book, we're talking about a solent stay here, not a conventional inner fore-stay, which is attached to the mast much lower than a solent stay.
I saw recently on Selden's web-site that solent stays shouldn't be attached to the mast more than 6% of the distance from the forestay/mast attachment to the deck.

I'm sure there are engineers out there who can clarify this.

Rgds

[Rucksta]

Originally Posted by fxykty

Why would the two stays divide the force of you only run a sail on one stay at a time if they are not dual forestays (that is, side by side).

The structural forestay is the one that carries all the static load, equaling the opposing shroud (if they’re on swept back spreaders) and backstay tensions. The inner forestay will carry virtually no static load.

This might be true if the mast was an immovable column and the stays only had to hold the mast up.

The load sharing argument might also be true on this theoretical immovable column.

Mast is dynamic as are the loads.
The primary load to consider is compression.
The other mast and sail shaping loads are secondary or even tertiary in importance.

[Jim Cate]

Well, theorize all you want, but I've not had much success in balancing the tension on the stays, nor in getting as much tension as I'd like... and I've had other folks with similar sorts of rigs say the same thing.

But, as I said, we've managed to get pretty good windward performance despite a bit of sag... but I think it could be better. It could be simply that I'm unwilling to load up the caps as much as I should. A mortal coward, I am! (One dismasting is enough for a lifetime).



Jim

[slug]

As soon as you load the stay with a sail , the load difference between the forestay and the Solent stay is unbalanced
The stay with the sail sags to leeward , The naked stay will go slack

With a cutter rig you compensate with running back stays

The Solent rig geometry is a Compromise because stay tension can’t be changed with a running bsckstay

[DanCan]

Originally Posted by SVHarmonie

SO many people giving so much advice and so few ask how the OP is going to use his boat. It matters. A lot.

The idea that there is no place in the sailing world for a masthead rig is stupid. And the idea that a fractional rig is aLways a bad choice is equally wrong.

Pretty ignore much anybody who says “All sailboats should be X”. It matters not a wit what “X” is.

True! Coastal. Not even close to feel confident for off shore for now.

[fxykty]

Originally Posted by Draughty

Hi fxykty,

I only have high school physics so can't claim expertise; it's what I read and it seems logical to me.

I can't see that whether there is a sail set or not, or if the stays are side by side or otherwise is relevant.

Just to be sure that we are singing from the same hymn book, we're talking about a solent stay here, not a conventional inner fore-stay, which is attached to the mast much lower than a solent stay.

I saw recently on Selden's web-site that solent stays shouldn't be attached to the mast more than 6% of the distance from the forestay/mast attachment to the deck.



I'm sure there are engineers out there who can clarify this.



Rgds

Where I referenced an inner stay I meant a Solent stay that at the mast is within 0.3-0.5 m of the forestay location. That very short column away from the forestay (and presumably the upper shroud termination and perhaps even running backstays if fitted) is basically immovable and the Solent stay will be well supported. On a masthead boat the backstay will be attached there. This spot is called the hounds (on a fractionally rigged mast, not sure the name for a masthead rigged mast).

I don’t know about 6% exactly, but basically as long as the Solent stay is relatively close to the forestay then it gets the same support.

If you run your rig loose, as Jim pointed out, you will have more sag. It doesn’t matter how many stays you have, they all will sag. Conversely, with a relatively tight rig (in general terms this means when sailing upwind fully powered up (about to reef), the leeward shroud(s) retain(s) some tension and is(are) not flapping around loose) the forestay and Solent stay will have less sag.

You will not be setting sails on both stays at the same time, so only one stay will be active and see the dynamic load. The forestay still maintains the structural loads if lazy and the Solent stay if lazy will see very little tension. When either stay is loaded with a sail, most of the dynamic forces will go to that stay. The point being that the amount of force is not limited, until you get to the break limits of your rig. There is no division of force, it’s additive.

The danger of moving the upper attachment of the inner forestay too far below the hounds is that it will no longer be well supported by the shrouds and/or backstay. If you set a sail you may pull the middle of the mast forward and risk breaking it. For this reason inner forestays/baby stays will usually be placed where the lower shrouds attach. If that’s not possible, running backstays will be fitted.

Note that many Solent stays (and inner stays other than baby) are removable. The Solent stay does not carry any structural loads. The exception is a cutter rig, but in that case the inner forestay is well supported as described above and shares the structural load. But again, the dynamic forces increase to account for the loading in both stays, there is no increased sag just because there are two stays rather than one.

[slug]

Originally Posted by fxykty

Where I referenced an inner stay I meant a Solent stay that at the mast is within 0.3-0.5 m of the forestay location. That very short column away from the forestay (and presumably the upper shroud termination and perhaps even running backstays if fitted) is basically immovable and the Solent stay will be well supported. On a masthead boat the backstay will be attached there. This spot is called the hounds (on a fractionally rigged mast, not sure the name for a masthead rigged mast).

I don’t know about 6% exactly, but basically as long as the Solent stay is relatively close to the forestay then it gets the same support.

If you run your rig loose, as Jim pointed out, you will have more sag. It doesn’t matter how many stays you have, they all will sag. Conversely, with a relatively tight rig (in general terms this means when sailing upwind fully powered up (about to reef), the leeward shroud(s) retain(s) some tension and is(are) not flapping around loose) the forestay and Solent stay will have less sag.

You will not be setting sails on both stays at the same time, so only one stay will be active and see the dynamic load. The forestay still maintains the structural loads if lazy and the Solent stay if lazy will see very little tension. When either stay is loaded with a sail, most of the dynamic forces will go to that stay. The point being that the amount of force is not limited, until you get to the break limits of your rig. There is no division of force, it’s additive.

The danger of moving the upper attachment of the inner forestay too far below the hounds is that it will no longer be well supported by the shrouds and/or backstay. If you set a sail you may pull the middle of the mast forward and risk breaking it. For this reason inner forestays/baby stays will usually be placed where the lower shrouds attach. If that’s not possible, running backstays will be fitted.

Note that many Solent stays (and inner stays other than baby) are removable. The Solent stay does not carry any structural loads. The exception is a cutter rig, but in that case the inner forestay is well supported as described above and shares the structural load. But again, the dynamic forces increase to account for the loading in both stays, there is no increased sag just because there are two stays rather than one.

Twin headsails , Solent plus Genoa , is a fast rig at 125 degree plus wind angles

Solent to windward on the pole , Genoa to leeward

[psk125]

Originally Posted by Draughty

Boat in the pics has swept spreaders; J36's had swept spreaders standard????

Rgds

We haven’t changed anything in the rig.
The spreaders are swept minimally, if at all. When I go up the mast they look to me like they stick pretty much straight out sideways:

https://sailboatdata.com/sailboat/j36

We do have jumper struts forward. The mast is pretty stiff; we use the runners when the spinnaker’s up in more than 25 knots of breeze.

[Draughty]

Hi all,
I can now see that solent stays have been covered well on this forum before, in particular back in 2011-12, a very expansive and quite technical post from RichH. Should be read!

Rgds