Symmetric or Asymmetric Spinnaker for Simplicity?

[Alistair242]

Using the guy “bridle” through a block on each bow and a shute in a sock should be relatively simple to set up. Let us know what you decide.

[Chotu]

Originally Posted by Alistair242

Using the guy “bridle” through a block on each bow and a shute in a sock should be relatively simple to set up. Let us know what you decide.

That’s what I’m going with.

Sock, symmetrical, flown from the bow cleats.

Just not sure how to size it. I’ve been a little stuck on that but felt kind of ridiculous asking about that part too. So many questions.


I have the height to my shrouds (fractional rig).

I have my measurement from the mast step to the cleats it would fly off of.

I have the distance between the bow cleats.

But I’m not sure which size used spinnaker to get.

Also I need a sock.

The whole thing seems anemic compared to the big asymmetrical I had on my last cat. Seems kind of small.

I don’t understand how to compensate for the “belly” of the sail.

If my distance from the tangs to the cleat is 57ft, how does that translate into a very round sail? What length on the sail to compensate for the belly?

Same with the distance between cleats. I don’t understand how that translates into the actual sail measurements since the sail is round.

[Alistair242]

Your luff should be around the same as your mast height. You can probably start there. This site gives some good advice.

https://www.rollytaskersailsaustrali...ical-spinnaker

[Franziska]

Originally Posted by Chotu

That’s what I’m going with.



Sock, symmetrical, flown from the bow cleats.



Just not sure how to size it. I’ve been a little stuck on that but felt kind of ridiculous asking about that part too. So many questions.





I have the height to my shrouds (fractional rig).



I have my measurement from the mast step to the cleats it would fly off of.



I have the distance between the bow cleats.



But I’m not sure which size used spinnaker to get.



Also I need a sock.



The whole thing seems anemic compared to the big asymmetrical I had on my last cat. Seems kind of small.



I don’t understand how to compensate for the “belly” of the sail.



If my distance from the tangs to the cleat is 57ft, how does that translate into a very round sail? What length on the sail to compensate for the belly?



Same with the distance between cleats. I don’t understand how that translates into the actual sail measurements since the sail is round.

Chotu, see on Richard Woods site:

https://www.sailingcatamarans.com/in...nder-spinnaker

He writes there:
"... A conventional spinnaker will have the leeches approximately the same length as the forestay, with a foot approximately 80% of LOA, giving an area of approximately 63% x LOA x forestay length. An asymmetric spinnaker will be about 10% larger. That's just a guide, obviously you need to discuss it with your designer/builder and sail maker. I'd recommend a tri radial cut as it makes a much better reaching sail. At the very least get one with a radial head... ".

Richard is a very experienced cruising multihull designer and gets that sort of stuff right.

Good luck with picking the right spi, I just bought ours and settled for a symmetrical one for downwind sailing.

Remember the old saying:

" Ladies don't go to windward either, just the same as gentlemen don't. [emoji4]"

[Chotu]

Thanks for the input! I will check out his site.

I am a huge fan of Richard Woods. He helped me out when I was building the boat. Many times. He is a wealth of knowledge and information.

He also knows how to design very simple very fast Catamarans. He designs a great boat.

I am pretty sure people can take anything he says as accurate.

I don’t have a sail maker. I’m buying a used spinnaker. That’s why I’m trying to figure the sizes out. Because I’m on my own. I already have the main and the blade jib. they came with my rig.

[rslifkin]

Being that you're buying used, I'd buy something that seems to be probably in the ballpark, erring on the too-small side. If you decide it's not enough sail for what you want, you can always re-sell it and find a bigger one (or have big and small spinnakers for various wind strengths).

That, and see if your rigger has any thoughts on spinnaker size and wind strength before you might have to worry about anything rig-related (and whether there would be a benefit to going a little shorter and flying it from closer to the forestay vs the masthead).

[Chotu]

Originally Posted by rslifkin

Being that you're buying used, I'd buy something that seems to be probably in the ballpark, erring on the too-small side. If you decide it's not enough sail for what you want, you can always re-sell it and find a bigger one (or have big and small spinnakers for various wind strengths).

That, and see if your rigger has any thoughts on spinnaker size and wind strength before you might have to worry about anything rig-related (and whether there would be a benefit to going a little shorter and flying it from closer to the forestay vs the masthead).

I’ve definitely already made that decision. I’m running from the Tang area. I believe I have a sheave up there anyway that’s extra for a spinnaker.

There are a pair of them just above the forestay.

That way I don’t have to worry about inducing a bunch of bend on the top of the mast. I don’t have to worry about having extra running back stays from up there and all of that. That’s a big hassle. So to keep it simple I will just run it from the Tang area and if it’s too small, like you said, I can always upgrade. That’s a good idea.


They’re also not that expensive in general used.

[malbert73]

Call Bacon sails in Annapolis as they may have sizing advice and sell used spinnakers

[thomm225]

Originally Posted by malbert73

Call Bacon sails in Annapolis as they may have sizing advice and sell used spinnakers

Yeah and a lot of their used sails need work.

I almost bought a used jib from them but it stated on the ad the repairs that needed to be made. The cost of the sail and the repairs were about the same as new.

So I bought a new sail from Sail Warehouse for about the same price.

For a 50' boat though, most any sail will have a ridiculously high price.

Then if it's a spinnaker on a 50' boat you better have a system of getting it down easy or else if you are single handing in a breeze say 18-20 knots and the wind increases you could have a problem

My small spinnakers on my single handed beach cat I raced were easy to douse if needed, but I still pitchpoled from time to time.

The halyard was a continuous line to raise and lower. It worked quite well. I had a spinlock on the forward beam that held the halyard during raising. It was easy to release also.

It was vintage 2000-2001

Photo with black spinnaker is after I had just finished a race and turned down after crossing the line which is why the hulls are both in the water.

The wind that day was between 18-22 knots and almost caused race postponements but we were able to get all 5 races in.

It was a 4 day event.

I only had the spinnaker jam in the sock one time but was able to sail with it like that for one leg. See upwind photo

We were hitting speeds in the mid 20's on the downwind leg that day with boats very close. I believe I only pitchpoled one time....

Downwind mark roundings were interesting for us singlehanders also

[Chotu]

Thomm. That’s really interesting actually about the continuous line halyard for the spinnaker.

I wonder why more people don’t do that. That makes a lot of sense as an emergency back up if you have some kind of jam. Like if you can’t get it back in the sock for some reason. I kind of like the idea overall.

[thomm225]

Originally Posted by Chotu

Thomm. That’s really interesting actually about the continuous line halyard for the spinnaker.

I wonder why more people don’t do that. That makes a lot of sense as an emergency back up if you have some kind of jam. Like if you can’t get it back in the sock for some reason. I kind of like the idea overall.

Maybe it has something to do with the size of the spinnaker.

I don't know how well it would work with a huge spinnaker on a big boat.

There may be other good systems available today though.

We have quite a few days here though where the wind will increase way past forecast and before you know it it's at 25-31 knots so being able to get sails under control easily is very important especially as a singlehander

Photo shows similar setup on newer two handed boat. Tack is attached to front of spinnker sock boom.

Trailer photo similar to mine and all others for one beach cat w/beach wheels.

The halyard passes through the sail where the white spots are. See black spinnaker

Then sheets on the clew.

The boat was a PITA to setup and take down though before and after every event with all those lines etc. Then you still had to get it on the trailer

Spinnaker Sniffer halyard setup starts on page 16 below.

https://www.nacrasailing.com/wp-cont...20-manuals.pdf

[Chotu]

Ohhh. That’s not what I was picturing when you described it

Now I see what you are talking about.

I was thinking of the simple halyard on a larger boat that you use to raise the sock up.

It would be kind of cool if that was a continuous loop. That way you could lower the attachment point of the spinnaker sock down to deck level to collapse the spinnaker in an emergency.

Just a side thought based on what you were saying. But I think I know what I’m looking for now. Definitely have to get that ordered so it’s ready in time.

[fxykty]

Originally Posted by Franziska

Chotu, see on Richard Woods site:

https://www.sailingcatamarans.com/in...nder-spinnaker

He writes there:
"... A conventional spinnaker will have the leeches approximately the same length as the forestay, with a foot approximately 80% of LOA, giving an area of approximately 63% x LOA x forestay length. An asymmetric spinnaker will be about 10% larger. That's just a guide, obviously you need to discuss it with your designer/builder and sail maker. I'd recommend a tri radial cut as it makes a much better reaching sail. At the very least get one with a radial head... ".

Richard is a very experienced cruising multihull designer and gets that sort of stuff right.

Good luck with picking the right spi, I just bought ours and settled for a symmetrical one for downwind sailing.

Remember the old saying:

" Ladies don't go to windward either, just the same as gentlemen don't. [emoji4]"

One more thing to add for sizing, which I’m sure sailmakers know: the spinnaker luffs need to be shorter by the amount taken by the sock when it is fully hoisted above the head. On our cat the hoisted sock takes up about 1m of vertical space at and above the head.

[Chotu]

Originally Posted by fxykty

One more thing to add for sizing, which I’m sure sailmakers know: the spinnaker luffs need to be shorter by the amount taken by the sock when it is fully hoisted above the head. On our cat the hoisted sock takes up about 1m of vertical space at and above the head.

Yes. Definitely. Thank you for mentioning it. Good to get every detail right.

[Franziska]

Originally Posted by fxykty

One more thing to add for sizing, which I’m sure sailmakers know: the spinnaker luffs need to be shorter by the amount taken by the sock when it is fully hoisted above the head. On our cat the hoisted sock takes up about 1m of vertical space at and above the head.

Interesting, could you explain more why that would be an issue?

In case of a symmetric spi, the foot is flying lose when the sail is hoisted.
The sail "bulges" upwards, so the luffs are not straightened/fully stretched (unless oversheeted), hence I can not see a big issue with that length being taken up by the sock at the top.
When the luffs are sized at an equal length as the forestay as Richard writes the clews will always fly higher than the lowest point of the forestay.

Appreciate your comment. Or are you referring to an assymetric in a sock, which is a different story?