# Boom above midline?



## ctlow (Apr 10, 2011)

Hello, Sailnet Racing Community,

Since a thread called "Twist" here last year, which moved into wider areas of racing sail trim, I learned a lot in a short time and my racing trim improved. In particular, on my boat, I get a much more balanced helm when up to weather by bringing the traveller way up high and easing the main, which results in a flatter sail but with more twist. But I do remind the crew, when doing this, to keep the boom below midline.

(I also often get to the crew to just ease the foresail sheet one inch from as close as it will winch in. It doesn't seem to hurt the tacking-angle, and gives better speed and balance, and less mainsail backwinding.)

I am quite sure that I recall that Steve Colgate in his book _Performance Sailing and Racing_ says never to take the boom above midline.

An old salt at the club the other day disagreed with this, and for higher pointing and faster tacks, points the boom's aft end up towards the windward quarter. And he's a good, experienced sailboat racer, but is the only Soling in what we call our "large-keel" class (based on PHRF, not size), and has some trouble placing well on corrected time, but the variables in there are formidable.

Now, I have a 33 foot masthead rig ( US Yachts 33, huge foresail, takes a while to tack it) and he has a Soling, just under 27 feet, with a fractional rig and a self-tacking jib. I don't think that those are important distinctions for this question, are they?

Is there an always-correct answer to this? Can it ever work well to trim the boom above midline?

Thank you.

Charles


----------



## SHNOOL (Jun 7, 2007)

Its not about the boom, its about the leech. If you press the leech above centerline, you are essentially stalling the main. Many times I know my boom to be above centerline, but the leech is below.

Your opening question puzzles me though, you were talking about bringing the traveler up and easing the mainsheet... That might be true, for light air to add twist, or to spill off air but that isn't really flat.

As long as I am not overpowered, and my only goal is fastest speed upwind, my traveler comes up above centerline (slightly in heavier air, or a lot in lighter), and I adjust mainsheet and vang until I get the proper power I need for a given wind (you have to play with these settings to figure out what those are, then write them down or memorize them).

But your boats point is also about matching sail shape.... if your genoa cars are back to far, or not far enough inboard, you can play with the main all you want, and not get very good point. I just went through this sailing with a friend... his S2 7.9 wouldn't point well, and he had 2 major problems... 1 was his genoa cars were back too far, preventing ability to flatten the top half of the genoa and keep it in at top as much as bottom... the other problem was his cleats for his traveler weren't holding position... so the car would fall at or below centerline. I proved to him that if he would get the traveler up/locked and eased mainsheet a bit to keep the leech below centerline, along with bring his genoa cars back, his boat would point nearly as well as the other S2s in our club.

If you have enough wind, you can get away with traveler at centerline, mainsheet on hard, outhaul on hard, and you'll have a flat pointing main, but my experience is that is a pretty rare day.

He had additional handicaps of using a furler, and older blown out main, but just the same it made a significant difference in the sailing performance of his boat.

Am hoping some of the more experienced racers weigh in, as I've seen at lot of opinions on these settings, and these are the settings that seem to work best for me. I'm used to dropping the traveler in gusts... and if the winds are really up, I'm easing the sheet instead (making sure the vang is adjusted properly).


----------



## Stumble (Feb 2, 2012)

It really depends on the boat. Normally holding the boom just above centerline can be good since the vast majority of the sail is carried below centerline. But if you need to do it all the time it may indicate a mainsail that has lost shape and can't really be flattened properly.


----------



## pdqaltair (Nov 14, 2008)

We should also clarify that depending on the wind (light), sea condition (chop), and distance from boom to traveler (high boom) it is quite common to have the traveler well above the centerline. That does not mean the boom is above the centerline.

As others have said, it is about twist, though the answers are boat and condition specific. One thing that can help is ribbons on the trailing edge; they should never suck around to the backside of the sail. If they do, adjust until they just don't.


----------



## SVAuspicious (Oct 31, 2006)

Stumble said:


> It really depends on the boat. Normally holding the boom just above centerline can be good since the vast majority of the sail is carried below centerline. But if you need to do it all the time it may indicate a mainsail that has lost shape and can't really be flattened properly.


Agreed. It may also indicate that you aren't using your vang effectively.


----------



## ctlow (Apr 10, 2011)

Thanks, Schnool and Stumble.

So among other things I should experiment (of course) with the boom in varying conditions. The winds here are always shifting and gusting, to some degree, which makes conclusions harder to draw.

Here's a quote from Steve Colgate's book, _Performance Sailing and Racing_:



> ... we can say that mainsheet tension makes any cross section of the sail fuller, whereas an eased mainsheet, and the corresponding twist in the sail as the boom rises, makes the cross section of the sail flatter.


I wrote to him suggesting that the concept could stand a deeper analysis and further amplification in a (hypothetical) second edition, and an associate answered confirming their belief in the concept. I wonder if it has to do with the concept that tightening the sail fabric in one direction (leech in this case) loosens it in the other (chord) so allowing greater depth. I find this completely counter-intuitive, but they (at the Colgate school) are convinced.

It sure seems to work - we move the traveller well to windward and ease the sheet, keep the vang off, and the weather helm eases, backwinding disappears, heel reduces - but do we go faster?

The only reference I can find in the book at this moment to keeping the boom below the centreline is for light airs - other than that, I don't think it's explicitly discussed, although I might have inferred something that wasn't directly stated.

Thanks again.

Charles


----------



## chip (Oct 23, 2008)

I race on a Capri 25, and the only time we have the boom above the centerline is if we get stuck at a windward mark. Sometimes we're cutting it really close as it is, then we'll get a windshift or a drop in windspeed just before the mark and we can't point high enough to make it, or it's right on the edge. If we're nearly there, it's often faster for us to bring the boom above center with the traveler and just keep going rather than tack twice.

I don't think that's a fast way to sail in general, and I'm not sure that we're getting any useful power off the main at all in that circumstance...we might just be keeping it from luffing and coasting past the mark on a pinched genoa, but we're usually just doublehanding and tacking a 155 twice right at the mark (if there's even room) is definitely slow for us.

I'm also curious to hear what others have to say though.


----------



## SHNOOL (Jun 7, 2007)

chip your description is of "pinching" and really has less to do with point. Pinching, or shooting a mark is a whole different ball game... No question over-sheeting the main, will allow you to point more (pinch), slowing you down, with a corresponding over-sheet of the genoa... What you describe really is just getting the mainsail out of the way of the flow from the genoa. We did this JUST today actually. it's slow and bad form, you are much better served to make your mark on a fast close reach. I get why you'd do it (and why we did)... the wind shifts within 100 feet of the mark were 90-100 degrees (in a shadow of a point) in our case... Knowing the shifts were there, it was actually better to PLAN to shoot to mark.

By the way, a better way to shoot the mark, is to foot like heck, get speed, and coast up, and sheet/oversheet, when you hit top speed, JUST before the mark (also something we did today on our 2nd lap - and we were fouled twice by another sailor - another story... It totally messes with the others in the race (when you shoot the mark), especially when you correspondingly call for mark room, just don't LUFF your sails when you do it, or you blow your right to mark room, that then just makes you an A$$ (we were close today fitting that description), and you must then dipp, then double-tack.


----------

