Athena 38: Sailing with Genny only

[FSmith]

I believe fp does not recommend sailing with only the Genoa, no mainsail, on my Athena. What is the problem if you have a tight topping lift and a tight mainsheet. Wouldn't this support the mast?

[MikeFergie]

Lagoon seems to say the same.

The most ironical of all is in my Leopard manual it’s says in extreme conditions have the full mainsail down and ONLY sail with a bit of Genoa.

It might be due to rigging types. I recently sailed a FP orana 44 which had huge turn buckles on only full length stays but 2 spreaders and 2 diamonds set ups holding the mast. I also recently sailed a Lagoon S2 400 which had the same massive turnbuckles on the full stays and the same 2 spreader mast arrangement.
My leopard has single spreader and full stays and half stays and the turnbuckles are less than half the size of the lagoon or FP.

So I’m assuming that a 2 spreader arrangement without the half stay makes the difference ?

[redneckrob]

Originally Posted by FSmith

I believe fp does not recommend sailing with only the Genoa, no mainsail, on my Athena. What is the problem if you have a tight topping lift and a tight mainsheet. Wouldn't this support the mast?

I was told that about the Mahe 36 as well, but it's not in any manual that I can find. I agree with you, the backstay and sheet hold the mast back. And heck, the mast has more forward and side loading with the main and jib up than just the jib. What are we missing from a statics and strengths perspective?

[a64pilot]

Could it be that the boats are primarily main driven and perform poorly with just the jib?

[redneckrob]

Originally Posted by a64pilot

Could it be that the boats are primarily main driven and perform poorly with just the jib?

The story I've been told is that you'll break the mast off by just flying the jib, but as you can probably tell I find the story suspect. I actually feel like the jib is probably 30-40% of the power close hauled or on a reach on my Mahe. It can be a couple knots difference in speed between a well trimmed jib and a poorly trimmed one.

[a64pilot]

If the jib can break it, I suppose a Spinnaker is absolutely out of the question or a Code Zero?

Now I’m certainly not any kind of naval architect or anything, but I’m having trouble understanding how a main and a jib in all situations would be less load than just the jib?

[jmh2002]

I believe that this situation is not so much about the total load, but about the design of the rig and how the load is applied.

These rigs often don't have a conventional centreline backstay like your Island Packet and instead assume that that the mainsail and mainsheet loads help to provide a pull in this direction to counter the headsail load.

A similar situation exists with some boats with staysails where running backstays are required to counter the staysail load midway up the mast.

Using your example of a Spinnaker or a code Zero, well on some racing boats yes, it is absolutely vital to have the running backstays on (top mast running backstays in some cases) otherwise yes the rig will absolutely come down. So a crew error can result in catastrophe.

Most cruising boats are not that extreme of course.

[redneckrob]

Originally Posted by jmh2002

I believe that this situation is not so much about the total load, but about the design of the rig and how the load is applied.

These rigs often don't have a conventional centreline backstay like your Island Packet and instead assume that that the mainsail and mainsheet loads help to provide a pull in this direction to counter the headsail load.

A similar situation exists with some boats with staysails where running backstays are required to counter the staysail load midway up the mast.

Using your example of a Spinnaker or a code Zero, well on some racing boats yes, it is absolutely vital to have the running backstays on (top mast running backstays in some cases) otherwise yes the rig will absolutely come down. So a crew error can result in catastrophe.

Most cruising boats are not that extreme of course.

The point is that the load at any point on the mast is never less with the main and jib up than with the jib alone. The assertion is that you're only unsafe if you don't have the main up, and that's the part that I just don't get the physics of. For backstory, the two boats we're talking about have a topping lift from the top of the mast to the end of the boom and the sheet from the bottom of the boom to the traveler.

[jmh2002]

My reply was more for a64pilot and I think you may have taken it slightly out of context.

The point that I was trying to make is that these types of rigs are designed and supported in a different way to a conventional monohull rig, and he was questioning the overall load, which is not the issue.

The issue is how the load is applied and in what direction(s).

Many rigs have such limitations in varying ways. I mentioned a couple, and another example is conventional monohull rig but with inline spreaders. This may also require extra support when using different sail configurations.

I don't disagree with you that the topping lift and mainsheet 'solution' may be viable however I would then also caution to ensure that the fittings involved are up to the task.

IE: the average topping lift often has a tiny shackle attached which may not cope being cranked on by the mainsheet tackle and winch.

And I would reiterate, this situation is not about the total load, it is about an uneven and possibly unsupported (or poorly supported load) being applied in a manner for which the rig may not have been designed.

It's not complicated to understand the physics of this.

[a64pilot]

Originally Posted by jmh2002

It's not complicated to understand the physics of this.

It’s difficult to believe that anyone would knowingly produce a production boat that the rig can’t stand the stresses of a partial sail plan.
Then especially if it’s true to not have a big statement in red in the manual.
So if one of these boats jams or tears a main, their only choice is to motor home?

I can’t imagine the lawsuit of yes your honor we knew that if they flew the jib by itself the rig would come down, possibly endangering lives, but we decided it might hurt sales if we put that in the manual?

To me, it just doesn’t pass the sniff test

[Cheechako]

On any boat, mono's too, there is no main pressure on the mast to help keep it straight if you only fly the headsail. Flying headsail alone works good sometimes but be aware... if you look up the mast it can be pretty scary looking if the wind pipes up much. Top of the mast bent way forward! Normally the main pulls the mast toward the aft a bit.

[jmh2002]

Originally Posted by a64pilot

It’s difficult to believe that anyone would knowingly produce a production boat that the rig can’t stand the stresses of a partial sail plan.

Yeah I don't think it's quite that serious in this case and of course there will still be quite a safety margin but the possibility could be there, especially offshore in a seaway with the mast pumping, so that's why it gets mentioned.

Also this type of situation has come about because these are not really proper offshore boats. And customers want simple rigs, and certainly no running backstays, etc.

In my opinion proper offshore boats should have inner forestays, and I think they should have running backstays too, for extra rig security.

But modern customers don't want all that complication, so a simpler rig starts to have some limitations.

[thinwater]

Originally Posted by FSmith

I believe fp does not recommend sailing with only the Genoa, no mainsail, on my Athena. What is the problem if you have a tight topping lift and a tight mainsheet. Wouldn't this support the mast?

It is probably because it is not a masthead rig and they would like the reefed main to support the mid-mast. The jumpers and diamond wires should do the job, but masts have been pulled out of column on non-masthead cats by sailing genoa-only; I've seen the broken parts.

Additionally, without runners, you will NOT be able to maintain good forestay tension without undue compression loads on the mast. The angles are wrong. Cat-rigged boats depend on mainsheet tension to tension the forestay going to windward. This is also one of the reasons many cats don't use masthead genoas (it's really hard to keep the forestay tight).

This is the nature of non-mast head, non-backstay rigs. Simple physics. The compromise for being able to use a lot of roach. Performance cat sailors, including beach cat racers, know this. Read a book on racing beach cats.

[jmh2002]

Yes that's right.

And of course runners are the answer to a lot of these issues, even if you don't need them for every day normal sailing.

Plus running backstays don't have to be as scary as when they developed their bad reputation - all wire, with heavy flying blocks, etc.

Now they can be made light, friendly, and easily led forward out of the way when not required.

But even that might be too much for the average joe customer.

[jmh2002]

PS: a64pilot, you might be quite concerned to see just how much the rig moves on many racing boats, especially the top portion of a fractional rig.

And these days most racing fractional rigs also fly masthead spinnakers and code type sails.

So sometimes you have running backstays going to the middle of the mast, the fractional (headstay) position, and to the masthead too.

And no permanent backstay at all because the mainsail roach is too big and wouldn't clear a fixed backstay.



Just for fun, here are the running backstays on the Super Maxi Comanche: