Sail trim quiz question
- Thread starter Jackdaw
- Start date
OK, bridle systems like that are designed to as much as possible replicate the traveler's ability to bring the boom to centerline. They cannot quite get to centerline, because while the block at the top the the bridle will be on the c/l, the pressure of the breeze will always make the purchase between the bridle and the boom fall off somewhat.
But this distance is much less then if the mainsheet was attached to the deck. So performance is better.
Because it cannot be lowered, a vang is needed to vang sheet in breeze.
In any case, in a boat like the Melges 20 the driver is also trimming main, and only having the mainsheet (just like a laser) makes perfect sense.
But this distance is much less then if the mainsheet was attached to the deck. So performance is better.
Because it cannot be lowered, a vang is needed to vang sheet in breeze.
In any case, in a boat like the Melges 20 the driver is also trimming main, and only having the mainsheet (just like a laser) makes perfect sense.
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Not exactly
The bridle makes a triangle. The higher the triangle the longer the hypotenuse. The difference between the hypotnuse and half width is the amount one can cheat the boom across to windward.
Maybe im an idiot and have that backwards. One thing is for sure, if i had that set up, i would arrange it so the each side of the yellow line could be shortened.
Eventually, well have materials strong enough to replace the sheets like that with accuators that pivot boom up and down and another that pivots the boom port and starboard. Itll have a bluetooth contrller so everyone, even the skipper can be railmeat.
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Actually, it would be the case for all bridle arrangements but, I am changing my song here. As the boom is hauled to center, the block rises with the steepening angle. This causes it to move CLOSER to center, as jackdaw said. The lateral force would always force it off center to some degree. But, as the sheet is shortened, the triangle of the bridle becomes more equilateral.
I have been thinking about how my mariner sheet is setup and I will set it up initially the way it was previously, just to get it on the water but, this looks like a great system to change over to. I don't really care for the mid-boom sheeting.
Thank you, jwing, for this idea and discussion.
I can see that with a couple of cam cleats on either end of the bridle, I could even vang the boom with it.
- Will (Dragonfly)
I see it and agree.
To shorten the bridle on one side or the other, I said cam cleats but, I think people also call them snatch blocks?
- Will (Dragonfly)
True dat. Assuming that the apex of the bridle is centered, then the height of the apex determines how close the boom can get to the centerplane. If the height of the bridle block is the same as the height of the boom block, then the boom's offset from the centerplane is just the dimensions of the blocks. That is, there will be no length of mainsheet between the blocks. If the vang is set to pull the boom down to the apex of the bridle, then easing the mainsheet affects exactly like easing a traveler.
There are reasons to compromise of course. For more info, read the bridle height article I linked to in #114.
In my particular boat, most of the time, the driver is also trimming the main and the jib and fetching beer.
Man i was hoping this was going to be it solution to upwind sheeting. Looks like no matter what centerline is best that can happen. All roads lead to a traveler or a dual mainsheet, or compromise. I did see some examples of a rope traveler, but they look like a hassel versus a fixed track.I didn't make any photographs, but I plan to next spring. I will post them to usmariner.org
This diagram is a good illustration of what I did, except instead of two #2148 blocks at the end of the boom, I used one block with a becket:
For a discussion on how long the bridle should be, see http://www.wayfarer-international.o...iggingTips/UncleAl/Bridle/bridle_length2.html
While it will never be a functional as a real traveler, a bridle is a good solution for small boats, in particular ones that are sailed 'dinghy style', with the driver sailing with tiller in one hand and mainsheeet in the other. Its popular on small high performance OD boats, where everyone is limited in the same way.
My guess is that its better than the Catalina 22 traveler, which is too short (vs the vertical run of the mainsheet) to get the boom to centerline.
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My take on bridle is same as Will, a design necessity to allow the tiller and mainsheet to occupy the same space.
That's a nice knock-on effect; allowing the mainsheeting to be centered straight over where the tiller wants to be!
If you want, we can work some trig into this discussion.... ;^)
1) I'm sailing upwind at 44 degrees true, making 5.2 knots
2) I'm sailing upwind at 47 degrees true, making 5.4 knots
Which is faster to windward??
1) cos(44)5.2 = 3.74knots VMG
2) cos(47)5.4 = 3.68knots VMG
mariachee has a much better answer though: esp who is in the way. lol
Sail racing questions always assume the absence of other boats and wind/tide being equal. Else you could not even pose questions. But even so:
As long as you are going to windward and inside the laylines, it does not matter where the mark is.
We are talking about a 3 degree heading change. Not likely someone's going to be in or out of your way based on that!
yes, correct Jackdaw. AND I find Meriachee's answer entertaining, which I assume the smiley indicated as humor.
What is also interesting is a small heading change of 3degrees to gain boat speed really doesn't offer advantage, rather a disadvantage. I have not paid enough attention to VMG, rather trying to point as high as possible without pinching. It might be fun to play out some more scenarios when sailing.
What is also interesting is a small heading change of 3degrees to gain boat speed really doesn't offer advantage, rather a disadvantage. I have not paid enough attention to VMG, rather trying to point as high as possible without pinching. It might be fun to play out some more scenarios when sailing.
perahps I am looking at it wrong? BobbyFunn, wind direction is x-axis, so angle off wind is between x-axis and speed vector. Thus the windward (x) component is ADJ/HYP = cosine
???? yes/no ????
OH, and I was on starboard tack, so opposite of your sketch....
???? yes/no ????
OH, and I was on starboard tack, so opposite of your sketch....
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Awesome, thanks. For the sketch i have, i should have subtracted each angle from 90 degrees since i have the angles upside down