Dual genoa discussion

[rwoodnz]

Hi

I am fascinated by the concept and benefits of having two genoa sails of same size on a dual track system and opening them butterfly, furling together as appropriate. See this video:

https://youtu.be/G8LmSX-vEys

I also saw a video where the second sail was of spinnaker material.

In both these instances they are only raising the second sail for downwind and in this video it is clearly stated that he wouldn't leave them like that upwind for long, although not explained why.

My questions are in a cruising context:
How about have two exactly identical sails (in the video they are different cuts) and leave them up alongside each other for upwind as well?

Would they sufficiently share the load upwind such that they could be half the cloth weight each?

Would there be a chaffing problem between them.

Any thoughts or limitations seen with this idea?

A further question is whether a spinnaker pole of typical size is needed in this situation. Would a lesser diameter pole or poles do the job?

[BugzyCan]

This looks amazing doesn't it, so simple and effective, and without a boom you don't need to care about Jibes or all the other details that go along with downwind sailing.

If it worked upwind as well then you save a lot of space on the boat with no boom or mainsail needed at all.

Looks kind of like the difference between a car with manual transmission VS one with automatic.

Only downside I see is that you lose a lot of visibility ahead, actually in the example video, the captain can't see anything lol, but perhaps that could be avoided with a different sail cut or add a camera out front.

[Jim Cate]

If it worked upwind as well then you save a lot of space on the boat with no boom or mainsail needed at all.

That's a very big IF!!! Similar schemes have been on offer for many years... their scarcity in t he active sailing world is perhaps a comment on the reality of the concept.

Jim

[sailormed]

Dual genoas were the self steering system used by the single hander Hans Maurenbrecher, a retired air force officer who sailed from the Netherlands in 1964 for a circumnavigation. His boat was the Takebora, a 9 meter polyester boat.

He arrived in New Zealand in 1966 and then continued over the Coral sea to the Indian ocean. Regretfully he never made it around the north cape of Australia. The wreck of Takebora has been found but Hans Maurenbrecher was lost at sea.

There were no autopilots in those years and he succesfully used his twin genoa setup for keeping course.

[rwoodnz]

Yep. Odd mainsail-less rigs (suggested in earlier reply) are not really the question I am posing.

What I'm suggesting is have two identical lighter genoas side by side on a dual track furling system and a usual mainsail.

Then instead of taking the second genoa down and up for different wind angles, just keep them both up together for upwind, butterfly them for downwind.

The issue of visibility was a good one to be raised, although already exists for those that use a dual system downwind so perhaps such folks could comment on that.

[mikedefieslife]

Isn't it a pretty common set-up for those crossing the Atlantic? Every sailor I've met in the Canaries has talked about twin headsails. You'll see loads of boats around the marinas in the Canaries with two whisker/spinnaker poles.

I do have a second headsail that I was going to run free flying since I don't have a second groove in my foil, but I've found that in typical 17-25knts true from the beam, I can go plenty fast enough with just the genoa and tiny stay sail poled out.

[Jim Cate]

In my previous post I did not mean that running two headsails downwind is a bad idea... I've done a lot of miles thus rigged. But rolling two sails up on the same furler is IMO a bad i dea.

The major problems will arise w hen attempting to sail upwind. First, the load sharing between the two sails is not going to be uniform and the sail shape of the pair will doubtless suffer. Consider that all the sheet loads will be on the leeward sail. It will stretch, whilst the windward one will not, and try to imagine what this will do to the shape. And if one needs to reduce sail area upwind, reefing will be even worse than with a single sail, and we all know that this isn't a good result upwind. The combined bulk of two sails partly rolled up will create a good deal of turbulence at t he luiff and spoil laminar flow across the sail.

Back in the seventies there was a Dutch sail,maker who promoted a pair of genoas sewn to a single luff tape... somewhat a better aspect for furling than two separate luffs, and it soon disappeared from the market place... just didn't work out in the real world.

There are several conventional means of flying two headsails downwind. I do hope that you will consider one of these as a b better option.

Jim

[wingssail]

Originally Posted by rwoodnz

Hi

I am fascinated by the concept and benefits of having two genoa sails of same size on a dual track system and opening them butterfly, furling together as appropriate. See this video:

https://youtu.be/G8LmSX-vEys

I also saw a video where the second sail was of spinnaker material.

In both these instances they are only raising the second sail for downwind and in this video it is clearly stated that he wouldn't leave them like that upwind for long, although not explained why.

My questions are in a cruising context:
How about have two exactly identical sails (in the video they are different cuts) and leave them up alongside each other for upwind as well?

Would they sufficiently share the load upwind such that they could be half the cloth weight each?

Would there be a chaffing problem between them.

Any thoughts or limitations seen with this idea?

A further question is whether a spinnaker pole of typical size is needed in this situation. Would a lesser diameter pole or poles do the job?

I'm not sure that the 2nd, full sized, genoa will be that advantageous. I watched the video, saw quite a lot of set-up required, and to what gain? I didn't see it.

Generally a genoa and a main will be good power for most boats.

Reaching, with both sails to leeward works well.

Sailing deep downwind you can carry the genoa to windward with a spinnaker pole or a whisker pole to hold it out (you'd need this on the windward side with dual genoas anyhow).

Where you need a bit more power, if you are so inclined, I'd recommend an asymmetrical spinnaker (obviously a big one). You set this sail when you really want the power. Otherwise you just keep the sail set-up dead simple and standard.

[a64pilot]

You know putting two Genoa’s on one furler was my initial plan, but then I got a code zero, and in my opinion that works better than dual Genoa’s.
You hit on one reason, Genoa’s are often heavier cloth, which is fine if there is strong wind, but it seems that downwind sailing is both sort of slow and hot, and of course boat speed is subtracted from wind speed, so I think a large lightweight sail is a nice thing to have, cause you think you have a strong sailing wind until you head downwind.

Of course that’s a Spinnaker, but I went around talking to cruisers that had them and asked if they used it, almost always the answer was we did once and would if we had to go downwind for a very long ways, but it’s so much trouble we just don’t use it.
So while I’m certain that a Spinnaker is better downwind Sail than a Code zero, it’s harder to use, and isn’t usable for much else, and we use the Code zero more often than I would have thought.

[rwoodnz]

Thanks for the very helpful answers.

These points I'd question and why:

Weight and bulk furled- the proposal I am making would weigh the same as one genoa, two thin genoas furled may not be much bulker than usual.

More setup - compared to a cruising spinnaker seems less as no bag or additional furler, unless one went for two poles. Assume it needs additional halyard as per video.

Different sheet loads upwind means different stretch - very good point but perhaps could be overcome with innovation in how sheets are connected, to apply load to less stretched.

There are existing solutions and it's been tried before - appreciated and for many that's end-of-story. For some of us we like to consider different ideas and revisit even if we find out they are old ones ...