Radi:H36

[Don Guillette]

I decide to answer your post as a new topic because it contains a lot of good sail trim topic stuff.

First of all, I love sailing in San Fran but have only done it once. I was there a few years back for the Catalina30 National Regatta. It was great sailing along the water front, under the Golden Gate Bridge and around Alcatraz.

As far as sail drive forces for mainsails and jibs – that is way over my head but I can tell you that sails are boat specific and designed for a particular boat to give it 100% efficiency. When you start mixing and matching sails, efficiency suffers..

There is nothing wrong with being a conservative sailor. I see a lot of sailors who sail their boats way over their head. The main problem is a “man (skipper) doesn’t know what he doesn’t know” and that is what gets them in trouble. They jeopardize themselves, their boat and the sailors around them not to mention the folks who have to go out and rescue them.

Rolling up the jib part way is OK provided the furling system is designed for that purpose. One of the first things you should do when you are in an excessive heeling situation is drop the traveler. In most cases that will bring the boat back on its feet. Once the boat is stabilized you can pull up the traveler toward the center line of the boat and “dial in” the amount of heel you are comfortable with.

When you reduce the sail area on the jib and main it is like replacing your 460 Ford with a 350. You can never keep up with a comparable boat that is sailing with full sails. I never have gotten the concept of sailing a masthead rig with jib only. I know a lot of people do it. On a masthead rig, your better off furling the jib and sailing with the main only. That is just my personal opinion.

 

[rardi : H36 ( Cherubini)]

Appreciate Your Specific Sail Trim Posting

Dear Don:

Noticed your post (thanks) this evening after returning from an afternoon attending to my boat's hunk of iron that functions as the secondary means of propulsion ... to the sails. The old Yanmar actually is working just fine, but time for some of the routine TLC stuff.

I placed an order today for the Sail Trim Chart through this site's chandlery. Look forward to its guidance since I haven't yet gone beyond the simplest understanding of the interactions between the traveler, cunningham, boom vang, halyard/outhaul tensions, and mainsheet to achieve the best result for each point of sail and with varying wind velocity. Although I do futz around with all the mainsheet controls.

Appreciate your affirmation about my penchant for conservatism when conditions warrant. Although even with reduced sail area its still quite an energetic ride on those days when the Angel Island wind gauge is reporting 30 kts with higher gusts. Doesn't feel that conservative. (I don't have a wind speed/direction system on my boat yet, so Angel Island wind info is my substitute.)

rardi

 

[Medman]

Main sail on masthead?

Hello,
could you please explain why is better to sail a mast head boat with only main sail instead of genoa?
Personally, I see that using only the main sail will increase angles and consequently helm. These will not occur if using only the genoa. And especially on mast head the genoa provides a large "drive".
Looking forward your answer. Always willing to learn more!!
Thanks

PS: Of course using only main sail instead of genoa will tack the boat much easier. But that's another thing.

 

[Don12480]

Point of clarification

Don, In your reply you wrote that a 350 could never keep up with the 450 or as I understood it a reefed boat will not keep up with the same boat under full sail. It has always been my understanding that when the winds pick up and the boat becomes overpowered that reefing can actually make it sail flatter and faster.
Any comments?
Thanks Don

 

[Don Guillette]

Jib Only

Medman: Boats with two sails are designed to sail with both of them. In simple terms, when sailing with the jib only the boat wants to fall off. When sailing with the main only the boat wants to head up. The only time I would sail with only one sail would be when I'm trying to keep the boat under control and depowered. On a masthead rig, the engine is the jib. In my case, if the conditions permitted me to sail with the jib, then I would have the main up.

I have no idea why people sail with the jib only. All I can assume is they think they are sailing in a depowered mode.

Any of you guys out there that sail with the jib only could you please describe the conditions and what you are trying to accomplish? Obviously, folks have good reasons for doing what they do.

 

[Don Guillette]

Clarification

Don (White Rock): Yup, a stock 460 Ford is faster than a 350. The more sail area you have the faster you go. Obviously, not the land/sea speed record.

A sail with draft depth (belly) is more powerful than a flat sail. Think of the flaps on a plane. They apply flaps when they are seeking power. Based on that I don't think a flat, reefed sail is as powerful as a fully deloyed sail.

Next time your out sailing give it a test. Sail as normal and record your speed. Then take a reef and flatten the sail and record that speed. Check both and see for yourself.

 

[Don]

Over Powered

Don, Your the expert so I certainly don't mean to challenge you, however maybe we have a misunderstanding.
I have your book and recall the airplane wing theory. When a plane is taking off it wants the lift and power and thus the flaps arte down to create max power. When it wants speed they are flattened so the air can move faster around the wing - same as a sail.
My boats a little different (H35.5) - when the wind picks up 15 -25 the boat gets overpowered - I get excessive heel - which leads to excessive weather helm - excessive rudder angles and the boat speed suffers.
I go through all the steps flattening the sails - developing twist to spill air yet it does not improve. Sails are fairly old and baggy.
I am under the impression that when all other options have been tried, put a reef in and the boat will sail flatter, less weather helm and actually go faster. I don't reef a lot but the odd time I tried it the theory seemed to hold true, certainly no loss of speed.
Regards Don

 

[Bilbo]

a correction

"Think of the flaps on a plane. They apply flaps when they are seeking power. "

They apply flaps to increase the wings lift at lower speeds. The important usage is 1) to decrease the minimum stall speed of the aircraft by increasing the lift.
and 2) To add more drag thus helping the aircraft to reduce speed or to maintain a speed on descent. So, aircraft flaps are generally used at times where the aircraft is landing or taking off in order to decrease the air speed without losing lift and as an added benefit, decrease the necessary runway length requirements.

This is mentioned without going into the multitude of different types of flaps or air brakes that various aircraft use.

To conclude with my foot ever deeper in my mouth,
"A sail with draft depth (belly) is more powerful than a flat sail."
So, for a sailboat to have more draft, it is like changing the airfoil of a wing. This would be the difference between having a relatively slow speed high lift wing (such as a Ford Trimotor) see:
http://www.airliners.net/photo/Eastern-Air-Transport/Ford-4-AT-E-Trimotor/1270725/M/

and (with less draft depth) a faster, less lift wing such as that of a Learjet http://www.bombardier.com/
I'd think that increasing the draft depth will generally cause the sailboat to accelerate faster when the wind increases or (As in the instance of regaining speed after a tack.) but this deeper draft will not provide the top end speed of a flatter-draft sail.

 

[Don Guillette]

Correction

Don/Bilbo: I just a common seaman and not an expert and additionally I don't really understand the scientific part of sail trim but I do know what works and what doesn't. I hate using plane wing examples because pilots always catch me with things.

Next time your out sailing and the wind will cooperate, which it rarely does, you should try this experiment. First let me explain how it works. In light winds, you want the sail as flat as possable. because the wind does not have enough power to get around the sail. As the wind pipes up you gradually induce draft depth depth (belly) until the wind speed gets up around 13 or 14 knots and then you gradually flatten out the sail.

Next time your on the water do the opposite. Belly out the sail in light wind, gradually flatten it and then belly it out at 15 knots and above and see what happens. Actually, if you can get a day where the wind is say 13 knots just play with the outhaul - take the belly in and out and see what happens. If your happy with the results just put it in your bag of tricks.

 

[Don Guillette]

Overpowered (Don White Rock)

Alan, Stu, Joe fron San Diego and some of you Hunter owners. Help me out here!!

I don't know why he is going faster with a reefed sail. Maybe he is putting some shape in a baggy sail and making it look like it was when it was new.

Usually, I'm not at a loss for words or thoughts (a number of times I'm wrong) but I just don't know on this one and it can't be unique to a Hunter.

 

[Bilbo]

Don

I understand you point....I believe.
I am far from an expert on aircraft but I think that from some knowledge of the airfoil and how wind passes, I can transfer some to the sailboat.
I think that I need to understand that the wind then pulls the (Bermuda rig sloop) lee side of the sail rather than pushes on it like a square rigged ship -unless we are heading more downwind of course.

I also think that as the wind pipes up with a lot of draft, you get to a point where the wind won't want to go around behind so much as push on the front of the sail's draft causing the shape at that location to sort of deflate. So, this may be why you'd want to begin to have less draft in a stronger breeze? To keep the sail working?

Also, isn't inducing some twist better for higher winds because it's using less of the top section of the sail?
My problem with the C22 here is that by letting out the short ~24" traveler to lee side isn't going to always cut it in a strong gust. I end up having to release the main sheet some and sometimes the jib to keep it on her feet. (I do know enough to adjust the jib cars back... if needed.)

Please understand that my comments are more geared towards my learning by the interaction with an expert such as yourself. I'm curious to understand.

 

[Stu Jackson]

Gotta completely disagree with you, Don

"I never have gotten the concept of sailing a masthead rig with jib only. I know a lot of people do it. On a masthead rig, your better off furling the jib and sailing with the main only. That is just my personal opinion."

This my opinion, too, but sailing San Francisco Bay (not San Fran...geez) during the summer for the past 25 years on masthead sloops (C22, C25 and C34) the jib only is the best method for comfort and ability to retain some semblance of upwind ability. We often traverse The Slot, either way on jib alone, and cruise all over for relaxing days that way. Jib only upriver to the delta, you bet. Saves a lotta gybing at Carquinez Straight to Benecia.

Sailing main ONLY is MUCH slower with NO ability to go upwind.

OK, that's MY opinion, BUT for those of you who are reading this, I recommend, yet again: GO TRY IT OUT and see what works for you. Main only is slower, so if you lie that go for it. Jib only is also easier, and ya don't even have to take the mainsail cover off.

 

[FrankR3878]

On a C36 MKI with Main only -

I have great difficulty keeping a straingt course when using just the main - the boat seems to wander all over the place. I have messed with the travller and vang without much inprovement in this condition. With the jib in use I can ballance the boat to where it will practically steer itself. Doesn't the Momement of Effort move much further back behingd the mast with main only causing more torquing, causing more wandering - needing more corrective steering?

 

[jimq26]

My findings exactly Stu - Jib only and not main only.

Over many years of successful sailboat racing, we have sometimes had weather that overpowered our single reefed mainsail. We would change the jib down from a #2 to a #3, and drop the main completely. We could point, maintain good speed, and won many a race doing just that.
This year we added jib furling, and again find that we can point and maintain good speed even when it is reefed in a bit after dropping the mainsail.

 

[Scott]

Don, I'm going along ...

with Stu and Jim . The problem with main sail only with a mast head rig is that the boat moves like a slug, even when the wind is very strong and the boat should be moving. Let's say the wind is blowing like stink and you are only going to use one sail for whatever reason. I find that even with a 110 jib, the boat will get up to hull speed and sail comfortably, while at the same time, if you just had the main up, the boat would be comfortable, but moving so slowly that you die of tedium!

I suppose you might be able to make the case that if you were trying to stay very close to the wind, the mainsail would be the better choice. I find that I can still make headway with the jib alone and sail faster, which is more fun. I think that if my fairleads were on an inboard track, I could do even better upwind on jib alone (going back to my earlier thread).

 

[Don Guillette]

Disagree With Don

No problem, lots of people do.

Over the many years I've been conducting this forum I always preface everything I write with the notation "this is what I do" and most importantly to TEST what you want to do and if it works for you then use it.

Sailing with jib alone does not work for me. If I have the jib out then the mainsail is up. That is just the way I sail my boat. I use both sails to balance the boat. That is what they are designed to do.

I was thinking about this thread this morning during a conversation I was having with a fellow RV'er, who has a motor home similiar to mine. He was asking me about the technique I use to go down steep hills such as 6% to 8% grades. I told him I use the same gear going up as I use going down. Normally I down shift out of overdrive and use the engine to brake my descent. He said he prefers to stay in overdrive and use his brakes. My comment was more power to you and everyone hears a different drummer. Same with sail trim. I suggest folks use what turns them on. The only think I hope for is they understand the WHY of what they are doing. If you have no idea of the WHY you will have problems.

 

[Don Guillette]

Boat Moves Like A Slug

Scott;I know it does and that is exactly what I'm looking for when I'm sailing with the main only. When I'm in that configuration I'm about ready to reef and once I reef all I care about is getting this sucker back to the dock in one piece. As I mentioned in another message, if the conditions warrant the jib out, then my main is up. That is just the way I sail my boat. Additionally, I've got a half way decent idea a what to do with my sails in various wind conditions and points of sail.

 

[Dennis W.]

Hunter Owner Responds

In different situations I use each of the tactics dsecribed. On a recent vacation to the Channel Islands I was called upon to reduce speed to 2 knots by "Plead Control" (supervises the pacific missle range). After trying several configurations I settled on a furled main and a 110 rolled half way in to maintain my speed. Double reefed main and no jib was 3.5 kts. Same trip going from Little Scorpion at Santa Cruz is. to Channel Islands Hbr. 25kts and gusting, 6-7 ft seas, all on the quarter. The 110 well trimmed gave us 7-9.5 kts with a balance helm and <10* of heel. Our usual daysail is West from Angels Gate to Pt. Vicente and then after lunch a double reefed main and poled jib in the building wind back to Angels Gate. When we make the turn we have 20-25 kts on the nose back to the marina. Depending on actual wind speed (25-30) we will roll the jib and continue in under double reefed main alone. Part of the choice is it's easier to roll the jib than to furl the main while dodging tankers, freighters and tugs. All of the above has been learned by trial and error and may not work for you or for your boat. But my '99 H310 and the Admiral both like it.

 

[Alan]

Don

You've got to wonder 'why' your friend preferred to stay in overdrive and use his brakes instead. The only thing I can come up with is he simply has no clue what he's doing. He probably goes through a lot of brake pads. ;D

 

[Don Guillette]

No Clue

Alan: A friend of mine who was trying to get his sailing club in Marina Del Ray, Ca to let me conduct a sail trim seminar plus an "on the water" presentation stated it best - "a man does not know what he doesn't know". My RV friend here in Tucson is a lot like many sailors I deal with now and have delt with in the past and that is why I included it in that post.

My middle name is WHY. I wish I had a buck ($$$) for every time I've asked a sailor WHY he made a particular sail trim adjustment. Most beginners to intermediates don't have the answer and I understand that and that is how the learning process starts with some folks. They say they don't know and we go from there. It is the ones that proceed to BS me that really get me. They end up getting all tied up in their underware and we go nowhere - just like my RV friend using his brakes to go down hill. As I've said many times, if a mate knows why he is doing something and not guessing at it he can do just about anything.

Incidently, I never was able to break into that sailing club. They felt that there was not a lot for them to learn from me. Maybe they were right. I had sailed with my friend on a couple of their day cruises and I don't know about their sail trim. It looked pretty crappy to me but what do I know.