Sailing - A few more things

I will include these items in this email and put them into a larger file that went with the last email. That file will be a PDF file and will have a Version name as 1-1.

On Thursday Sept. 2, 2010 we had a start course as 270 degrees then just before the start the race committee changed it to 290 then at the start the wind continued to vear (turned to the right or clockwise) up to something like 320 or so. We had pretty much a single beat up to the mark with only a small hitch to windward on port. That wind shift told us there would be a Jibe-Set at the windward mark. If Foredeck crew can memorise this fact then they will know ahead of time why a Jib-Set is called. Someone wanted to know once how is it that some people know things in advance. Memorize this fact, if the wind vears a lot on the upwind leg (assuming the buoys to port flag is flying on the committee boat of course), then when we go around the two up wind marks the wind will be off to the left by a lot, by so much that the spinnaker pole will need to be on the port side of the boat. That means a jibe of the boat comes first before the spinnaker goes up, and the Genoa will be transferred over the spin pole to the starboard side of the boat first as well. That procedure is called a Jib-Set. See Jib-Set below.

On Thursday we had an offshore wind starting at 270 (due West). That means more wind shear because the land slows the wind more that is lower in altitude. It also slows the wind more as you get close to the shore. That means more of a difference between the top and bottom speeds of the wind on the mast. The wind was also vearing moving from 270 to 290 to about 320. That vearing wind means more wind shear because wind vears first up top and then down lower near the water. We also had a decreasing wind speed at one point and that also means more shear because the boat is going faster than the wind allows and so the component of induced wind was greater. Recall that there are three winds on a boat we need to consider. True wind, induced wind, and apparent wind. Vectors come into play and your high school math classes. See what happened now since you may have been sleeping during those math classes then you likely don't recall what a vector is. Wind is a vector that has both a unit quantity and a direction. Lets not get into that math here thought. Rest assure that Brent HAS gotten into the math at some point in his sailing career and does understand it.

To sum it all up on Thursday we had a higher level of wind shear meaning that on the starboard tack the true wind twist was a vearing twist as you go up the mast and the Apparent wind twist was also a vearing twist as you go up the mast and that meant the two summate and create a lot of sail twist. Both sails have to compensate for this twist. The port Genoa lead is brought back more so as to loosen the leach at the top of the sail and let the top fall off more at the top to match up to the wind angle. The sheet needs to be eased more and the boat cannot sail as close to the wind as it can on the port tack. The main sail must be matched to the Genoa. That means the traveller goes up a bit and the sheet goes out a bit. Now both sails are matched to the twist of the wind and the boat is fast, but sailing off a bit, not as close to the wind.

On port tack the true wind still vears, but the apparent wind now backs, comes more from the left as one goes up the mast. That means that there is less twist in both the sails. If anyone wants the math on this then just ask, but it will get into understanding wind vectors as one goes up the mast. The apparent wind backing and the true wind vearing almost cancel each other out. That means the starboard fairlead is moved forward a few inches to tighten the leach. The sheet can be pulled in more now too and that allows the boat to go up more closer to the wind, ie point better. The main sail now needs to have it's traveller placed down more than on the other side and also the sheet needs to be pulled in tighter to flatten it more. Nobody said this racing stuff was simple eh.

We are sailing up wind and a Jibe_Set is called. What does the foredeck crew do?

#1. Take off the starboard spin sheet from the outboard end of the spin pole Easy-Latch.

#2. Change the spinnaker pole from the starboard side of the forestay to the port side by dipping it under the forestay.

#6. Lower the pole-mast fitting so the Genoa can slide over the pole better during the jibe.

#1. Raise the pole on the mast to its proper height depending on the wind. The stronger the wind the higher the pole on the mast. This takes experience to learn. It is really important in heavy wind because in heavy wind there is so much force on the pole that it is very difficult to move the pole on the mast when the chute is up and drawing. Getting it up ahead of time is necessary in heavy wind.

#2. Raise the outboard end of the pole and ensure that it stays on the port side of the forestay as it goes up. Sometimes in heavy waves it can flop to the starboard side of the forestay and then the pit man cannot raise it. The pit man should always be looking at the outboard end of the pole as he starts to raise it to ensure that it is on the proper side of the forestay for that tack.

#3. Go to the bag and release the velcro ties and feed out the spinnaker. (Note: On some boats they do not want a person on the bow and so eliminate this job.) Just remember that a person on the bow hurts the boat even on a run. The spinnaker pushes the bow into the water and that is not good for fore and aft balance. A person on the bow aggravates this, so get off the bow quickly please.

Okay a quick note now. If the spinnaker flyer is on the high side and the wind lets up to the point that the high side becomes the low side then the spinnaker flyer and the other crew should move to the low side. On Force, that spin flyer on the port tack also has to trim the Genoa and so is expected to do two jobs at the same time, and on Thursday I also had to hand off the starboard spin sheet to Jim below meaning a third job. Well all of those jobs have to be done one at a time so things are a bit slower, but not that much as I am pretty fast. See the next section please.

If the spinnaker floats down very fast then it can cover the Genoa winch and fairlead. That means the person on the Starboard Genoa cannot see the sail, the winch, nor the fairlead. In my opinion the person should not be cranking in the Genoa sheet blind. I have seen the spinnaker caught in the fairlead in past races and called for a stop on sheeting. This is very hard on the spinnaker to get caught in the fairlead. If the Genoa trimmer cannot see then I suggest waiting a few seconds for the chute to be cleared. On top of all that the spinnaker port sheet was run instead of released and the port clew end of the spinnaker tangled in the Genoa sheet near the fairlead. I had to pull that in before fully sheeting the Genoa.

Next I would like to talk about the particular situation of rounding the downwind mark after the chute comes down. There are two ways various boats do this. One is to call for the Genoa sheet to be trimmer in hard and full right off the bat, before the boat fully rounds up, and then let the skipper settle into finding the grove. In my opinion that is slow because the sail is not driving when it is over sheeted, but sometimes it can be good if competition is right off the stern and the skipper wants to come up fast close to the wind or maybe even higher then optimal in order to force the competition to go down below us. Most times I would think the Genoa should be brought in full and driving and trimmed in as the boat goes up. That requires coordination between skipper and the trimmer. So the skipper should let the trimmer know what he is intending. A good thing for the port side trimmer to do is look behind the boat and see where the competition is and tell the skipper. Sometimes competition can be really sneaky when they are on your tail and try to go high. The skipper needs to know that ASAP.

I forgot to mention in the last email that the pit person need to watch the spin pole outboard end as it goes up to ensure it does not get trapped under the forestay.

A few more things to discuss