TheTwister
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I recently started sailing with a guy who likes to trim the boom above the centerline of the boat going upwind. I am curious as to why this is fast and in what conditions, it seems counterintuitive to me.
Main Trim Question
- Thread starter TheTwister
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full circle
Super Anarchist
knobblyoldjimbo
Super Anarchist
Yes, it drives me mad too, however if you look carefully at the roach of the sail (the back part) it should have enough twist in it such that the lower part of the sail exhausts directly backwards and I understand the top part is falling off a little.
If the roach is hooked up to windward then there is a good likelyhood of the sail stalling and therefore slowing the boat.
I think you can check this by putting telltales (ribbons) on the roach and seeing if they all are flowing nicely. If not then the trim need to be changed.
It does depend on the conditions too - lighter conditions might require more twist, therefor you bring the boom above the centreline and loosen off the vang, heavier conditions require the opposite, the pressure will be trying to blow the top of the sail off so you require more vang, lower traveller and tighter mainsheet.
This is my understanding.
If the roach is hooked up to windward then there is a good likelyhood of the sail stalling and therefore slowing the boat.
I think you can check this by putting telltales (ribbons) on the roach and seeing if they all are flowing nicely. If not then the trim need to be changed.
It does depend on the conditions too - lighter conditions might require more twist, therefor you bring the boom above the centreline and loosen off the vang, heavier conditions require the opposite, the pressure will be trying to blow the top of the sail off so you require more vang, lower traveller and tighter mainsheet.
This is my understanding.
NoStrings
Super Anarchist
This is also not true for every boat.
PBO
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TT, this one of those excellent questions that I doubt you'll get a one line answer your looking for...as FC asked, what are the particulars...the more info you offer the better the advice will be
I'm sure KOJ (and countless others) would agree, if you look at "poorly trimmed" sails...the main is so often the worst offender...anyone got a theory on why that is?
Mark K
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How far?
It's not uncommon.
When sailing with an open leech, and/or twist, sometimes
getting the boom a bit above C/L brings more of the sail
in trim.
Short answer is don't worry about the boom being a bit above C/L,
if it's fast........
The right idea here, every boat is different but in the lighter stuff (8 or so) you want to see those telltales 80-90% of the time with them stalling ever so slightly.......very fast imho
djparker23
New member
I'm sure KOJ (and countless others) would agree, if you look at "poorly trimmed" sails...the main is so often the worst offender...anyone got a theory on why that is?
Overtrimmed sails "look good"... "if I am gonna be DFL at least my sails look good"...
IMO.. the reason the main is frequently poorly trimmed is
A) It is a very complex piece of geometry
B) AS the Maintrim you ARE sitting too close to the owner and tactician and They are always very free with the "advice"
C) The info loop between driver and maintrim is critical and if the maintrimmer is constantly trying to chase an overactive helmsman, They over trim.
D) different drivers have different trim needs. EVERY driver's groove is different.
E) Drivers think they are driving the boat... maintrimmers are... the dude with the stick is the brake!
My $.02
feet facing in, trav between the legs.
Overtrimmed sails "look good"... "if I am gonna be DFL at least my sails look good"...
IMO.. the reason the main is frequently poorly trimmed is
A) It is a very complex piece of geometry
B) AS the Maintrim you ARE sitting too close to the owner and tactician and They are always very free with the "advice"
C) The info loop between driver and maintrim is critical and if the maintrimmer is constantly trying to chase an overactive helmsman, They over trim.
D) different drivers have different trim needs. EVERY driver's groove is different.
E) Drivers think they are driving the boat... maintrimmers are... the dude with the stick is the brake!
My $.02
feet facing in, trav between the legs.
When my helm says., 'it feels very neutral', I know we're going quick, fortunatly he's good enough to deal with it!
I tend to agree (sorry boss) - when the owner wants 'more feel" in light airs, I have to trim in/trav up a bit so we effectively handbrake a little. Probably less of a penalty though than the owner steering all over the place trying to find the groove as happens on a lot of boats.
Fortunately I have my owner pretty well trained at the moment - he holds a steady helm and takes constructive criticism quite well (most of the time)
Kevlar Edge
Super Anarchist
:blink: holy crap is it amateur night at the apollo, disregard all the OPINIONS here and get a good book on sail trim
trying to get the answer here will oinly confuse you.
trying to get the answer here will oinly confuse you.
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Franklins Tower
Super Anarchist
Wow. How do you people get around the race course? WHAT KIND OF BOAT IS IT?
Trimmed for Speed..
Member
Having the boom above CL is very common, but it really depends on the type of boat we're talking about. Without that information, we're throwing blind suggestions.
That being said - I typically see the boom above CL on the Etchells in almost all conditions except heavy to medium-heavy (depending on heal/helm feel). On other offshore boats: it really depends on the boat, sail shape, sea state, and wind pressure etc. In light to moderate conditions, especially with a fair amount of leach twist - a boom above the CL is very common going up wind. What you should be looking at is the tell-tails, boat-spead, angle of heal/helm feel, height, competition, etc. - not the end of the boom placement... if the boom is above CL, and you've got speed and point on everyone - keep it going.
That being said - I typically see the boom above CL on the Etchells in almost all conditions except heavy to medium-heavy (depending on heal/helm feel). On other offshore boats: it really depends on the boat, sail shape, sea state, and wind pressure etc. In light to moderate conditions, especially with a fair amount of leach twist - a boom above the CL is very common going up wind. What you should be looking at is the tell-tails, boat-spead, angle of heal/helm feel, height, competition, etc. - not the end of the boom placement... if the boom is above CL, and you've got speed and point on everyone - keep it going.
