Just For Fun... Sail Trim Evaluation

[Rick D]

This is just for fun. I was looking over some photos of last year's Ensenada, Baja Mx race and I found this classic photo of my Attitude Adjustment 2 Hunter 40.5 and a Catalina 42.

We had great fun covering and generally molesting each other in same-rated boats for about 3.5 hours before we split off in opposite tacks. She was very well sailed and had good gear.

So, you have a good view of sail trim on these photos. Two different rigs for boats that rate the same PHRF. Trimmed very differently. So, what is your analysis of the two boat's trim? You'll have to blow it up to make a choice. BTW, this isn't just an exercise; I like doing better than the next guy and welcome your thoughts.

 

[RichH]

I'll bite ......

Sail # ...480 doesnt seem to have the main 'all the way up' as noted by the aft end of the boom drooping. If there was any weather helm (as noted by rudder angle), thats' the probable 'culprit'. (The arrow straight leech, says its probably on a roller furler and therefore cant adjust halyard tension on the fly, and it looks somewhat 'over-flattened'.)
The shadow along the luff of the jib shows probable 'perfect' fairlead angle --- max 'depth of shadow' near the 'centroid of area' on the jib.
....480 has a much higher aspect ratio rig and shorter LP jib, so it should outpoint the other boat even with the same PHRF. It 'may' have its backstay too tight, as I dont see any noticeable 'luff hollow' on the headstay wire using a straight edge along the pic ... if thats the case it would still point AND be 'faster' with a wee-bit 'more slack' forestay.

Sail #...743, again by the shadow on the jib luff, seems to have its fairlead car 'a tad' too far aft or may not be sheeted with enough tension on the winch. The luff shadow is showing the 'max' shadow 'waaay high' in the sail and well above the centroid of area.
If this sail wasnt cut with a 'full shoulder' (power high in the sail) then definitely the fairlead is too far back .... (and If I were ...480 and saw that 'high' shadow shape, Id get ....743 into a tacking duel because ...743 wouldnt be pointing as well, today). A barber hauler (in) might help in this case.

of course all this based from pics taken at a high angle above the boats.

Nice boats. Who 'won' the leg?

 

[Don Guillette]

Rick: How are you doing? Do you still have your place in Arrowhead, Ca?

It is hard to tell from a side view. Sail trim is best judged from a rear view looking forward. Both boats are nicely trimmed, with little heel, and both mainsails mirror their jibs. I would not want to be behind either boat and trying to overtake them. When I was behind boats, trying to catch them, I always checked their sail trim. If it was a mess I knew it would just be a matter of time. On the other hand, if their sail trim was pretty good I knew it would be a long day.

During sail trim seminars, I have a number of sailboat advertising pictures I've taken from sailing mags. I ask the participants to tell me what is wrong with the picture and how would they correct the situation. It is a fun exercise. Most times, while the jib looks photogenic, it way twisted off. Next time you're scanning a magazine check out what I'm saying.

 

[Rick D]

Rich, the reason I was asking is that I have had crew comment that I don't trim my main to windward as much as they do (standard mainsail, not RF) . In fact, in this photo, my boom on #480 is considerably to leeward of #243 boom which is more to the centerline. I also have more mainsail twist which is why the leech looks so straight from that angle I think. I did add purchase to the outhaul, going to 6 to 1 to make adjustments easier, and I may well have made to too tight when flattening it for windward work. It may be that my crew is used to sailing masthead rigs and I have had more fractional. However, their observation is correct about my mainsail trim, an I was wondering if anyone here wanted to weigh in.

#243 and I worked each other pretty good. I tried to get by on the leeward side, but he kept me covered well. I crossed his stern and got windward of him and managed to get a couple of boatlenghts ahead. #243 then crossed my stern and went more to windward on a shift; I fell off and I didn't see her again. We both finished mid-pack about 26 hours later and I corrected out 30 minutes ahead of him; not much for 125 miles. Anyhow, thanks for your comments.

 

[Rick D]

Hi, Don! Yes, we are still in the mountains and still in the same place. When it comes tax time tho, I'm a bit envious of where you live, California's tax load being what it is! BTW, I still refer people to your book. It's a lot clearer than so many other attempts at sail trim tutorials.

See my reply to Rich's post. It sure is easier to see sail trim from off the boat in a photo than right on it. The adjustable Garhauer jib cars have made a big difference especially since my slot has to be just-so. I did some buoy racing in Long Beach to see what I could do, and I have to tell you that local knowledge is a huge advantage. I have to enter a lot more.

 

[RichH]

OK the leeward traveller position would show a drooping boom from the camera angle.

If you are running a GPS VMG course that would be the easiest means to 'tweak' the mainsail trim; tweaking/trimming to get the highest speedo and VMG for the actual wind/waves. Also, Ive found over time that if you keep written records for your pursuit of optimum trim, rather than depending on memory, will go a long way in the process of optimization.
You can also better develop your optimum trim by partnering with a 'training horse boat' - yourself and another equally rated boat who develop a training program to work out the details during 'trial runs' where one 'tweaks' and the other stays static in trim.

 

[OldCat]

OK the leeward traveller position would show a drooping boom from the camera angle.

If you are running a GPS VMG course that would be the easiest means to 'tweak' the mainsail trim; tweaking/trimming to get the highest speedo and VMG for the actual wind/waves. Also, Ive found over time that if you keep written records for your pursuit of optimum trim, rather than depending on memory, will go a long way in the process of optimization.
You can also better develop your optimum trim by partnering with a 'training horse boat' - yourself and another equally rated boat who develop a training program to work out the details during 'trial runs' where one 'tweaks' and the other stays static in trim.

It truly astonishes me that you can LOOK at a distant picture of a sail and see so much. I figure that I am doing well when I get all the telltales flying (much easier thanks to Don's book). It also surprises me how many larger & faster boats we pass on the lake - apparently because they have no telltales (or most have ripped off the mainsail leech) & no idea of how to read them - how many sailors don't have even my basic understanding of all of this. The good racers, especially those with high-tech gennys, and even those without, are another matter...

I should get a gps and try that - I am still just looking for changes big enough to see on the bidata - and that does not get me VMG.

Cheers Rich, it is always interesting to read your stuff.

OC

 

[timvg]

My thoughts:

We trim our 40.5 about the same. With a large main, we feel that we go faster (less weather helm) when the main is let out as far as possible without luffing. With a larger jib, the masthead rigged boat is going to have more backwind on the main, thus needing to bring the main in tighter.

 

[RichH]

It truly astonishes me that you can LOOK at a distant picture of a sail and see so much.

Just a lot of 'technique' I picked up by rubbing elbows with many from the 'AC crowd'. Top shelf racers ALWAYS evaluate the competitors sail shape and set, looking for 'weakness' in the trim/shape so that they can exploit the others weakness by tactics. Example: If I see a drooping boom end or a loose forestay, I'll try to get them into a tacking duel; if not I'll do 'something else'. If I see bad fairlead position (via luff shadow), I'll include that malformed shape in my 'tactics', etc. 'nutherword' reading and *attacking* their shape/trim 'weaknesses' to MY advantage. Of course making/lofting my own sails and a 'hefty fluid dynamics' background helps too ;-)

 

[RichH]

My thoughts:

We trim our 40.5 about the same. With a large main, we feel that we go faster (less weather helm) when the main is let out as far as possible without luffing. With a larger jib, the masthead rigged boat is going to have more backwind on the main, thus needing to bring the main in tighter.

Most boats with conventional design mainsails seem to perform best (beating) with the aft end of second from the top batten (somewhat) parallel with the boats centerline, most computer plotting programs seem to use this as their 'target' (regardless of the 'days' needs for 'twist'). ..... Then to adjust for 'helm' increase or decrease halyard/cunningham tension ... and then make a few trials on the jib barber hauler (or athwartships jib lead traveller, if you have one) to get the distance of the 'slot opening' correct for the days wind speed.
For me with either a masthead boat or a fractional boat Im usually close to the best VMG for beating in 'moderate/flat' conditions by the above.

Such a shape will allow 'turbo sailing' in relatively 'flat water' which promotes significant gains towards windward (and not losing any speed in doing so).... another term is 'scalloping' upwind where one is always in a gentle "S" turn, and 'always 'testing' the 'steering tell tales', slowly breaking into a slight or beginnings of a 'luff' but being carried by the boats momentum and then immediately but gently & slightly 'dropping' down to a power setting (both sides streaming back) on the luff/steering tell tales ... and always alternating between power-pinching and full speed on the 'steering tales'. The great Buddy Melges was/is the absolute 'master' of the 'scallop' or 'turbo sailing'.