Subject: a bridle shower for Mo Metcalf? Midwinters racing leads to bridle and vang talk
Hi, Morris:
I'll do my best to answer (in green) below.
Uncle Al (W3854)
----- Original Message -----
From: Morris Metcalf
Sent: Friday, February 18, 2005 1:11 PM
Subject: ... Bridle


... I am now using a fixed bridle and like the thinking that goes with the adjustable bridle described in the Wayfarer Institute bridle  section. Not so much that it is adjustable but rather the bridle won't center the boom.
I really would advise sticking with the (fixed) bridle. Mike Mac won the 1992 Worlds with one. Remeber, the bridle does not force you to centre the boom upwind, it just makes it easier to do so! With a decent amount of vang tension applied, you just ease the main as required to keep the boat fairly flat - see pic of my 90-pound son, Dave, and me below in the 2002 Around-the-Island Race in Toronto where (to our very pleasant surprise!) we caught and passed two good heavy-air teams that had much more hiking weight

Note how far out the boom is and how good vang tension keeps the boom from rising. I have never forgotten this setting (and picture) since we went amazingly well with it. Usually I let the boat heel too much - as most people do!
Since I have a lot of experience with travelers, the bridle is new to me. 
The traveller is really only useful if you want to ease your sheeting point off to leeward. This kills pointing and is only useful in survival conditions plus waves of serious height - five feet or more - when pointing becomes a secondary consideration to keeping the boat moving forward.
I like the non-adjusting bridle as it allows one to concentrate on other things and I find that appealing. 
I will be getting more vang tension with a revamped vang which will increase the offset as the boom lowers as described in the WI.  I realize the centered boom is not always desirable and feel there is a happy medium allowable with the bridle. What do you suggest as the starting point for bridle length using a dimension from  the rear deck to the centerline of the block in the bridle.
I have never made an exact measurement since this will vary from boat to boat, depending on rake and mainsail cut and size and type of boom and bridle block (we use Harken 082 bullet blocks: one at the boom end and one on the bride - see but most people (needlessly) use bulkier blocks, and mainsheets that are needlessly fat. The starting point I have suggested is that the block on the bridle should be able to come no higher than half-way to the boom when the main is hoisted and there is no down pull on the mainsheet. In essence, I want the bridle to be low enough that I can "oversheet" the main (i.e. make the upper leech ticker stall) in medium air conditions up to the wind strength when my crew and I can sit to windward but not on the deck yet. With that set-up, we can now sheet block-to-block as soon as we both start having to sit up on the deck, knowing that we have lots of main leech tension (which equals lots of pointing ability) but not too much - see photo from Midwinters below. 

The key is not to have the bridle too long, i.e. if in doubt, shorten it. We sail mostly in relatively light airs and a bridle that is too long will kill your pointing because it either keeps you from using all the leech tension your mainsail can tolerate in the medium breezes mentioned above (and pointing ability is directly proportional to main leech tension!!!), or you will have to vang to get the desired leech tension. But that will (a) depower your main needlessly, and (b) keep you from centering the boom (also a key pointing ingredient!). In the really light stuff, I have found that the short bridle doesn't seem to cost me anything even though my boom ends up off centre (off the corner off the transom in the real drifters) - see pic from Worlds below.

I think this is because when it gets really light, sheeting the boom off centre a bit, lets the sail produce a greater % of forward force, something the centreboard appreciates since it does not function at peak efficiency in the really slow going.
I'm having trouble finding a really good pic of bidle length but have added a few shots below that should help you get the picture:

Marc and I going out for the practice race at the Worlds - bridle block no more than halfway up towards boom end.


The 3rd-place boat from this past Worlds - note bridle ends further inboard which does not matter since the key is how high off the deck you get the bridle block.

The fast Irish guys at the Worlds (10th?). This shows the boom-end arrangement nicely. Their bridle block is higher than I would want it - and we outpointed them in the light-to-medium stuff.

This shows our bridle block height pretty well. We are just completing a tack and I have begun to sheet in, hence the boom has started to move closer to the bridle block. On this tack, we proceeded to pinch off the Brits who placed 2-3 in the Worlds even though we were all getting a persistent lift and they were inside us (to windward) and should have killed us. Again, if in doubt make the bridle too short to start with - leave some loose rope hanging in case you want to try it longer. My own view is that the bridle block does not want to be much more than 12" off the back deck? I guess one could measure my distance here by printing this pic, measuring the height off the deck and comparing it to the 15' 10" hull length?
Before I jump to a conclusion and return to the traveler system I would like to try a more correct bridle and vang combination. I realize there is a lot more going on with the vang traveler combination than I can describe here. I guess I am looking for a better starting point to work from with regards to bridle length than what I have now.
Gosh I hope this makes sense.
It does - and I hope the answer helps you. I think I may post this in the Weekly Whiffle for Monday.
Morris Metcalf

----- Original Message -----
Sent: Sunday, February 20, 2005 2:42 PM
Subject: bridle revisited

Hi, Morris:
Thought of you and your bridle as I was doing captions for the second page of race 2 of the Midwinters just now. Look at the pic below which illustrates perfectly the problem of a bridle that is too long!! I will add parts of my intended caption below the pic.

Meanwhile, Jim and Mike have rounded onto their beat but will not point with the best as long as their main leech falls off to leeward like this. Since they are sheeted in almost block to block, Jim should shorten his bridle to give himself the ability to put more downpull on his leech without having to resort to the vang.
Best regards,
Uncle Al (W3854)

Hi, Morris:
Thanks for the reference to the Mike Mac article which I will work into not only the bridle appendix that will result from this exchange of ideas with you, but also as another source of tuning basics that I will add as a link (somewhere!) in the WIT.

With all due respect, I must beg to differ with Mike Mac on this one, and I am copying Mike to get his views - if he has the time - I'll also forward to Mike, the last email where we began the bridle talk. More in green below. Best regards,
Uncle Al (W3854)
PS: I am rearranging your letter somewhat by moving the Mike Mac quote nearer the beginning to make your thinking easier to follow when I post it in the Weekly Whiffle and the WIT. Hope you don't mind.
----- Original Message -----
Sent: Sunday, February 20, 2005 4:27 PM
Subject: bridle revisited


Mike McNamera wrote the following article in July 2001.  It took me awhile to relocate this part of it:

"The trend in recent years has been to bring the boom right in to the centerline. It is impossible to do this without overloading the leech with the conventional track and so a variety of strop systems have been developed. The most simple is a straightforward triangle of rope with a block for the 2:1 purchase at its apex. The height of this block above the transom is critical. The ideal height can be found by dropping the block over the transom and then fastening the bridle ends on each quarter so that the bearing surface of the block is level with the bottom of the keel."

This is how I set Murphy's Law  up. Having sailed with it this way, I can actually see what is really happening in your reference picture as well as pictures of my own boat. Taking it one step farther, I think I have an idea why this may not work for me.

One: Mike is wrong, which is unlikely. Wrong is perhaps too strong a word, but I think Mike fails to take into account the variations in mast bend and mainsail size not to mention block size, that, in my opinion, make it unwise to try to give people an "ideal height" or an exact one for all occasions. Mike's suggested "ideal height" may be a good starting point, but in the end, there is - certainly among North American Wayfarers - far more diversity in how far from deck level the boom hangs (with the main raised but not wind-filled or sheeted down at all) than can be properly catered to by one magic number. I stand by my recommendation that you need to make sure that the bridle on your boat is short enough that you can oversheet the main in the medium wind ranges where both crew members are sitting to windward but not yet on the deck, say. Not that you (usually) want to oversheet in those conditions, but you want to have the ability to do so for two reasons:

1. judicious oversheeting upwind (such that the upper leech ticker disappears for considerable stretches of time behind the leech) can really help your pointing once your speed is really good and the waves are not too bad. Of course when you do this, you have to be really sensitive to any drop in boat speed - when in doubt, let it out!

2. you want to have the ability to sheet in a bit further for that small but fairly frequent window where you and the crew are both on the deck, likely hiking out, but still able to hold the boat down without resorting to the vang to flatten the main.

On our boat, we can virtually always afford to sheet block to block as soon as we are both sitting on the windward deck to keep the boat flat, by which time it appears to become virtually impossible to make the leech tickers indicate a stall. My guideline would be: in these conditions, the main should take a serious effort (which translates into more leech tension which leads to better pointing!) to get sheeted block to block.  If it happens too easily, try shortening the bridle some more until you do have to make a real effort to get block to block! This is definitely not a case of "When in doubt, let it out!" From what I have seen of the English boats, they tend to have longer bridles, but I think we can point better over a greater variety of medium air conditions that most of them.

The other is I have a Mark III which has a very large deck hull overhang. This is I would guess about an inch or so on the transom. By letting the bridle hang over this edge to the po sition he indicates would add a couple of inches to the length of the bridle in its normal sailing position. This overhang is absent on I believe all the older models. In my mind this confirms the bridle length is too long and gives me an indicator as to how much to shorten it before the next trial. Sounds like a reasonable explanation, but what I think you should do is go out in medium winds with easily adjustable knots in your bridle and and adjust to my rough guidelines above. Start out with your bridle with say, 3-4" less clearance than it has now, try sheeting in block to block as you sail closehauled. If it's still too easy to reach the block-to-block position, shorten it some more. Repeat until you have to do serious pulling on the mainsheet to reach block-to-block status.

This a great explanation. It probably can be applied to all the European and US boats with maybe an exceptions being the Mark III and possibly the worlds.  The overhang would make a difference. A bridle a couple of inches shorter I would believe would be about right in my case. It would appear Murphy's Law has been applied again.

Sorry to beat a dead horse with this, but I find this to be very interesting. Thanks for your time and comments. I'm enjoying having to explain and justify our approach, too.

It has been very much appreciated and I think between this and a vang fix ( retaining lever and going to triple block rather than single) I can see a much brighter future. Now I just need to get Andrew out in the boat for some spinnaker practice. And don't forget to fiddle with your bridle! Andrew sounds keen and looks like he would be a good crew to have when it starts to get breezy and the sailing gets tough.

Thanks again.

Mo (W10245) for the record

----- Original Message -----
Sent: Monday, February 21, 2005 12:45 AM
Subject: bridle

Hi, Mike:
Background for the other email - in case you can find the time and the inclination. Hope all is well with you. Best regards,
Uncle Al (W3854)
PS: We used the old red chute you gave me in 1992 for this year's Midwinters and it performed very nicely.

... and a response from Mike McNamara, busy as he is:
----- Original Message -----
Sent: Monday, February 21, 2005 2:59 AM
Subject: bridle revisited

Thanks Al. I have no problem with changing "ideal" to "a good starting position". In fact it would be good idea to do so, because I do shorten it so that the block is level with my bottom rudder fitting on the transom in a breeze.

As you know I am constantly wary that I don`t oversheet the leech and if there is a plus to having a fixed bridle position, it is that, as the kicker (vang) is loaded to keep the whole luff length of the main backing at the same time, the aft boom end will go the boom drops down.

Best wishes,