//WL2K Slow Boat to Fiji – Day 2

Well we’re not getting there fast, that’s for sure.

And its still pretty cold. Getting warmer, but not so as you’d want to be running around in shorts just yet. Or even just one layer of clothes.

We’re still sailing downwind and putting up less than stellar performance numbers; the noon-to-noon distance for the last twenty four hours was a paltry 164 miles, and THAT wasn’t all “VMG” or ””Velocity Made Good” which is navigation-speak for “of the miles I travelled, how many of them actually got me closer to where I was going”.

This bit refers to vector math, which is handy if you want to figure out exactly how fast you aren’t sailing. If we were able to sail directly at Fiji while making eight knots then our “Velocity Made Good” for one hour would be eight nautical miles. We traveled eight miles through the water, and it got us eight miles closer to Fiji. Very straightforward. But if we are sailing a course that is 30 West of directly at Fiji then sailing eight miles does not actually move us eight miles closer to Fiji, it moves us some amount West and some amount towards Fiji. So you subtract the West vector from our total course vector and the remaining vector is our “Made Good” vector towards Tahiti.

In this example I made it easy, as it is a simple 30/60/90 right triangle with a hypotenuse of eight, the West vector is the short side and our VMG is the longer vector. Or in this case VMG = 1/2 * (8) * Square Root (3) = 6.93 miles. Simple, right? Every eight miles we sail at 30 degrees off our target moves us only 6.93 miles closer to our destination. (please feel to correct my math in the comments if I muffed this!)

Which means our measly 164 miles of sailing in the last twenty-four hours actually only accomplished about 142 miles of getting closer to Fiji if you assume we are about 30 degrees off the course we want to sail, which isn’t too far off really. By comparison, on our trip to the Marquesas we had several days when we made more than 200 miles, and averaged about 186 miles per day all pretty much in the direction we intended to go

So why is this so slow? We actually actually have reasonably strong winds, we’ve seen winds in the teens and twenties. Its because we are trying to head Dead Down Wind. If the wind were ninety degrees to the boat we’d be flying straight at Tahiti making 8-10 knots with three sails drawing, blasting over and through the waves.

Going Dead Down Wind (or DDW) though means the physics don’t quite work so well for you. The wind behind the boat makes the main sail blanket the forward sails; we can’t even fly the staysail in these conditions it will just flop and droop. Even the genoa doesn’t stay full well. With the boat boat much less “powered up” we are more at the mercy of the waves, which can roll the boat and backwind the sails which makes them flutter and flap rather that push the boat forward. So progress is a series of smooth accelerations and building speed.right until we roll off a wave the wrong way, backwind the sails and lose several knots of speed. Lather, rinse, repeat.

So we can be slow both physically AND mathematically!

There are ways to combat this, and if the DDW conditions persist tomorrow we may have to break out “the poles”. These are the dreaded spinnaker poles which are permanently mounted on the side of the boat. I say “dreaded” because they are very large, very heavy, and until recently demonstrated a strong proclivity to fall of their fittings on the mast when one tried to use them. Having a twenty foot long 100lb+ pole decide to drop on your head in a seaway is NOT a fun experience, in fact it could be fatal. So we’ve avoided using the poles over the years from a quite literal fear of death and/or maiming.

We thought we’d fixed the problem when we left in 2012, we spent a fair amount of money replacing the end fittings on the poles both on the poles themselves and the fitting on the mast where it looked worn. This really didn’t help, the the vibration caused by thousands of miles of sailing wore the fittings again. However, in New Zealand we took a more unorthodox tactic, and had the rigger drill through the detachable fittings and put a bolt through there. This should keep the poles form trying to kill us, but we are still quite understandably nervous.

The use of the poles involves setting the main on one side of the boat and running the head sail sheet through the jaws in the end of the pole on the other side of the boat. The pole is positioned to hold the sail out opposite the main in a “wing and wing” configuration, and should keep the head sail from constantly collapsing, rubbing, chafing and shaking the boat. The full sail should help the boat sail much more quickly, and more importantly closer to dead down wind which increases that all important VMG.

Of course Wing & Wing is not without risks, you sail closer to the wind and thesk of gybing is higher. I’ve sailed Wing & Wing many times, though I usually do it with hand steering in flatter conditions so the boats roll is less of a factor.

Given our pathological fear of our own spinnaker poles, this is not a technique we’ve used a lot with this boat. But if this DDW stuff persists we may be working out some new techniques.

Related Posts Plugin for WordPress, Blogger...
This entry was posted in Down Wind, Fiji, passages. Bookmark the permalink. Follow any comments here with the RSS feed for this post. Both comments and trackbacks are currently closed.

Comments are closed.