reef design

What is the stardard, if there is one, for the size of a reef? Or, put another way, is there a rule of thumb that each reef will be, say, 15% of the luff?

 

How many reef lines are you having? It would depend if you have one, two or three.

 

I posed the question in the abstract, rather than about a particular boat. Phil Bolger uses a gaff schooner rig with main/fore/jib areas in a 3/2/1 ratio. One of the advantages that he cites is that a double-reefed main and single-reefed fore (no jib) makes a good heavy weather rig. I was wondering if something similar could be worked out for a leg o'mutton schooner rig, for a smaller, simpler boat, when I realized I didn't know, in general, how designers decided how deep to make the reefs.

 

I think the deepes reef is about 40% and the other one or two are split evenly.

 

I had a 35' sloop with two reefs in the mainsail.... and it worked so well in the dock. But halfway between Bonaire and RD, in a 60k breeze, on a wet coachroof and shackled to the mast I could neither reach nor catch the reeflines.
Now I have a 35' sloop with reefs spaced so I can grab the next one when the last one is tied off (and some old, empty grommets).

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Thanks for your observations. I take the answer to be that one should figure out what suits his own situation and not worry about what anyone else has done. Of course, the designer has limited control over what the sailmaker does.

 

I would figure it out thinking about forces: for example, you sail comfortably with 12 knots of wind, and the boat heels at 15°... you want to sail at that angle also with 22 knots, so the moments have to be the same; you can solve the problem thinking that forces are proportional to the square speed of wind, and also that the center of effort lowers when you reef.
I know this sounds a bit tricky

 

Assuming that you understand trigonometry and 'moments and stuff', then I would agree with what the previous guy said - it's easy enough to find the formulas for the physics of wind pressures on flat plates.

So, just decide at what windspeed and heel angle you want to reef at and size them accordingly assuming the sails are flat plates and compensating for heel. That's assuming the boat already exists and you can measure heel angle and windspeed unreefed with the wind abeam. If not it gets a bit theoretical and there are too many variables to be accurate.

 

So we have now officially begged the question, i.e. pursued the issue until we got back to the starting point. We could rephrase the original question to be "At what wind strength do we put in each reef?" It does get more complicated with split rigs, etc.

As to the complexities of the real world, comparisons with known boats should fill in most of the gaps in the math models.

 

If you spill your beer, while your butt gets wet, because green water is well over the cabin, as you lie in the hammock strung between the sticks, then you must untie the line around your toes (coming form the tiller of course) and each reef should be an easy reach from the mast as it would be time to tuck one in . . .

 

..I guess there's not a common answer.. a good skipper should understand when it's time to put in a reef, I think he should forecast the situation and do it before things get too much tough. It's more difficult to understand the real situation if the boat is running before wind, and then it depends also if we're racing or cruising..

 

You shouldn't need to have to reach the reefing line cringle. Lead 1 reef line all the time when cruising, and put the second reef line in for passage making. Lead a loop of light v/b. cord between the 2nd and 3rd reef points. Put a small loop on the big loop.

If you are on the i2nd reef and it looks like getting worse, take the first reef line out, put it through the small loop, take another turn of the cord around it. Then use the cord to pull the reef line upthrough the 3rd reefing eyelet abd back down to the boom. Easier than it sounds.

Alternatively, reefing lines these days can be quite light so they aren't a hassdle to leave lead when cruising.

 

And here's another factor (since this is an abstract discusion)... if you intend to race a boat you will need to refer to the safety authority that it races under. If it's going in an offshore race you will probably find that there is a minimum depth of reefing required.

 

Reef

Depends on how large a percentage of your sail area your main is, how stiff your boat is, and whether you have a lot of sail area, moderate sail area, or small sail area (for your displacement and length).

 

This is one of those how long is a piece of string questions. It depends heavily on the boat design, its sail inventory and its proposed uses. Boats that are easily driven, have efficient foils and single sparred rigs, and which gain a lot of thier stability from ballasting carried deeply below the boat can get by with fewer and smaller reefs. Burdensome vessels with inefficient rigs (like leg of mutton schooner rigs) will need more sets of reef points in order to obtain enough drive for the conditions. Sails that are made of a sail cloth that is is light enough to perform in winds under 8 to 10 knots are rarely heavy enough to be used in winds over 30 or so knots no matter how deeply reefed the sail is. Boats that are intended for offshore use may have fewer reef points but depend on storm trysails. Where as lake sailors that might have more reef points or deeper reef points since they will only have to deal with heavy air for short periods of time.

Jeff