Fisherman's Reef

Stu Jackson · Jun 23, 2011

Depending on how deep your draft is (sails, not keel)...

A "fisherman's reef" by definition, is a deliberate action to avoid reefing by dropping the main and getting, for starters, that bubble. For sailing speed, however, it does work.

Joe · Jun 23, 2011

Easing the cunningham to move draft position back a bit will help reduce backwinding. On a big masthead rig, though, you are going to get some when the wind pipes up... remember though that most of the main's power is coming from the sail's rear half...so some backwinding will be tolerable. If it gets out of hand, time to reef.

Joe · Jun 24, 2011

Sam Salter said:
How will reefing help?

It will get rid of the bubble. Isn't that your goal?

Not sure I agree that most of the power comes from the rear of the main. And if it was, wouldn't that power be drag?

Sam, you're the one with the problem with the bubble, I'm just offering you something new to ponder.

Remember, you must think of the sailplan as one entity... the genoa and the main working together. Why do you think the most important telltales are at the genoa luff and the main leech? It's like one wing with the front sail overlapping the back one. Ideally the air flows continously on the leeward side of both sails in one continous stream.

Here's an excerpt from one of my favorite books "Getting Started in Sailboat Racing" by Adam Cort:

....... Don't worry it the main is backwinded by the jib or begins bellying near the luff. As long as it isn't actually flogging, the air is still attached across the sailplan - all the sails that are flying on a boat's rig - and you aren't losing as much aerodynamic efficiency as you might think. In fact, that bubble in the main is a great way to allow more wind through the slot (see photo next page).

Finally, this video "The Shape of Speed" from North Sails deals with masthead IORC type sailboats. It's on VHS ,cheap, from Amazon; DVD from many sources; and I noticed a free download from http://thepiratebay.org/torrent/4700954/The_Shape_of_Speed http://www.thepiratebay.org if you like the "torrents" thing.

Ted · Jun 24, 2011

The bubble in the main is still a fast shape unless it's happening in low wind speed conditions. Don't make yourself crazy trying to get rid of it but if you must, try moving your genoa leads outboard to open up the slot between the main and genoa. That will definitely help remove the bubble but your pointing ability will suffer slightly. There are a few reasons that may cause a bubble in the main. If your traveller is too far to leeward, if your main is twisted too much, if your sails are blown out, if the draft position of your genoa is too far aft, if your genoa leech line is too tight, or if your genoa is trimmed in to tight. Doesn't the C&C 26 have a babystay? You can also try bending the mast to flatten the main by tensioning the babystay.

Stu Jackson · Jun 24, 2011

Sam, an aha moment for me: by "dropping the main" I should have written "by dropping the traveler" - hope that helps, know you were talking about the main.
Question is still valid: is your mainsail really flat?

Joe · Jun 24, 2011

Sam Salter said:
Joe - thanks for the quote and the link. When you said time to reef, I was thinking main, but you were talking genoa. As I get older my brain fills up quicker!
Stu - Yes the main is flat, but maybe I'm not flattening it enough.
Ted - There is no baby-stay and I'm not sure the mast would bend anyway.
As an aside, with a masthead rig and such a stout mast, is there any mileage in mounting an adjustable backstay.
Joe - I know you are right about thinking of the sailplan as one entity and I understand Arvil Gentry's stuff. But moving it from theory to practice is sometimes difficult. And I can deffinately get genoa luff and main leach tell-tales flying.

A backstay adjuster on your masthead rigged 26 footer would give you a lot more options for trimming the HEADSAIL. On your rig the bacstay adjuster is used to control tension on the headstay, which gives you a lot of draft control over the genoa. There are a number of adjuster types.... but on your size boat a simple block and tackle setup will be sufficient. Google "backstay adjusters" for some examples.

I'll tell you this, Sam, it's a lot more satisfying project than worrying about the bubble... It'll definitely help your racing.

Here's a link you may find interesting:

http://sailmagazine.com/boatworks/upgrades/adjustable_backstays/

RichH · Jun 24, 2011

A 'happy bubble' is usually of NO consequence. Backwinding is nothing more than the 'circulation flows' around BOTH sails canceling each other out in 'the slot'. However if the amount of 'backwinding' is significant then sail SHAPE changes can affect correction - and you need a complete set of tell tales to do this.

1. DECREASE mainsail luff tension to get a flatter luff shape .... but only up to the point of gaining 'weather helm'
1a. LESS mainsail halyard/cunningham tension
1b. Increase mast prebend ..... forward bow in a single spreader rig should be 3/4" forward mast bow. For multiple spreader rigs should be 1/2" per each spreader set. Proper bow will help 'flatten' the main.
Note ... Initial 'set' on a main should be (when beating) should be (95% of the time) that the second batten down from the top should have the 'aft portion' or portion that is supporting the leech ........ should be PARALLEL to the boats centerline, and then ALL tell tales flying correctly /' 'straight back' and with the traveller on the CENTERLINE.
If the mainsail is not shaped/set/trimmed to perfection then you will never have good airflow over the genoa!!!!!!!!

2. INCREASED jib/genoa luff (halyard tension) ... will 'open' the leech of the Genoa/Jib (moves it away from the mainsail). Caution - increased halyard tension may cause the furler to jam

3. insufficient BACKSTAY tension .... allowing the FORESTAY to sag off to leeward which causes the jib to go 'draft aft and with a hooked-up leech shape' - the leech tell tales will not be flying 'straight back'. Caution - Do not exceed 30% backstay tension for long periods of time. Start with 15% backstay tension and watch the genoa's leech tell tales to be 'straight back'. see: http://i1086.photobucket.com/albums/j449/svAquila/MatchingLuffHollow.gif

4. Over-tensioned jib sheet .... dont overtension the jib sheet with a big winch --- causes excess forestay sag. Results in the same bad shape as in #3 above. If jib 'needs' extreme sheet tension then increase backstay tension (not to exceed 30% tension).
4a. Correct jib sheet tension will allow the genoa/jib leech to 'open' to increase the 'slot distance'. If your genoa tracks are inboard from the rail, use a barber-hauler and pull the clew outboard towards the rail.

5. If all the above doesnt correct the situation then consider to have more 'leech hollow' cut into the genoa/jib .... the leech section is TOO BIG and needs to be 'cut away'.

You need a FULL set to tell tales (luff/midcord/leeches) to do this 'assay'.
hope this helps.

LuzSD · Jun 24, 2011

Thanks to you all for such an informative, interesting and (fairly

) easy to follow conversation. I have been working the main for a while now and the more I concentrate on this one position the more I learn and enjoy it. (although my neck is killing me!) I really have gotten somegood information here in these conversations, so thanks very much.

RichH · Jun 24, 2011

Luz - I just noticed that you are sailing a Cat30. How 'old' is the mainsail??? and if its a mainsail made of woven dacron, then:

Go to: http://forums.sbo.sailboatowners.com/showthread.php?t=120970 and check how 'shrunken' the bolt rope is on your mainsail. Procedures for checking the 'as raised' dimensions are given in that 'article'. A shrunken boltrope will cause the 'fullness' in the mainsail that will cause such 'sensitivity' to being easily 'backwinded'. If thats the case, 'easing' of the boltrope will most certainly 'flatten' the mainsail. I also notice that you sail in SD which is somewhat notorious for 'light' winds and an additional 'easing', more than what is needed for sailing in 10-15, might be appropriate. The more the boltrope is 'eased' the flatter the sail becomes.

Applying MORE halyard tension to a sail with an already shrunken boltrope will cause the draft to 'go forward' ... and if the sail is currently 'full drafted' because of an 'aged condition' / shrunken boltrope , increased halyard tension will result in 'closing the slot' thus 'backwinding'.

FWIW - on any new mainsail made from woven dacron, strongly suggest that you have the sailmaker ADD additional length of boltrope and bind it with sail twine to the top of the headboard. When the boltrope eventually 'shrinks' the added length can be easily 'slipped' into the sail luff sleeve to correct the boltrope length ... a 1/2 hour job with a needle palm and sail twine, also an easy DIY procedure.

Warren Milberg · Jun 24, 2011

FWIW, getting back to the title of this thread, when I was seriously racing Snipes and other one designs, a "fisherman's reef" was the process of easing the main in a puff to keep the boat sailing as fast and flat as possible. We all kept the mainsheet in our hands, rather than cleated, when sailing or racing in a blow in order to let the main out quickly when needed, and then be able to bring it back in and trimmed when the gust passed.

LuzSD · Jun 24, 2011

Warren Milberg said:
FWIW, getting back to the title of this thread, when I was seriously racing Snipes and other one designs, a "fisherman's reef" was the process of easing the main in a puff to keep the boat sailing as fast and flat as possible. We all kept the mainsheet in our hands, rather than cleated, when sailing or racing in a blow in order to let the main out quickly when needed, and then be able to bring it back in and trimmed when the gust passed.

Warren, other than the obvious lack of shape change, can't one do almost the same working the traveler by keeping a hand on it constantly? (gosh please don't sound stupid she says to herself before hitting submit

)

Stu Jackson · Jun 24, 2011

Yes, that's right. Warren and I agree on the "definition" of a true fisherman's reef. Either the mainsheet or the traveler will move the boom out so the main backwinds.

Ted · Jun 25, 2011

Sam Salter said:
Ted - There is no baby-stay and I'm not sure the mast would bend anyway.
As an aside, with a masthead rig and such a stout mast, is there any mileage in mounting an adjustable backstay.

Sam, I don't remember if the C&C 26 has single or double lowers. If it's got double lowers you can put additional tension on the forward lowers to induce mast bend to flatten the main. If you have single lowers, an adjustable backstay alone might be able to induce some bend. The addition of a babystay will insure that it will. Adding the adjustable backstay will certainly help headsail trim as Rich has described so well.

LuzSD · Jun 25, 2011

Thanks Rich for such great detail...... will take a while to digest it all but I will work at it! Some makes immediate sense to me, others I need to consult a sailing dictionary as I read. Eventually I get it though.

Much appreciated!