Our daily fix
06 March 2012 | 230nm to go to the Galapagos
After fully overcast skies yesterday (Monday 05MAR) and the night before, things cleared up this morning and we continued our slow sail at a slow jog's pace under blue skies with a few tradewind clouds (even though there aren't much tradewinds around). Beautifully relaxed sailing on a close reach from midnight last night until about 2200 tonight. Now motorsailing under a nearly full moon and starry skies. Nana went up the mast to take some pictures earlier today and Nicky had his turn up the stick as well (properly harnessed and belayed of course). Kiddy pool bath time again before dinner (this is a clean ship ;-).
We're also running a little experiment on this passage: While we use the GPS for our "real" navigation, we're keeping a separate log and position plot that relies purely on dead reckoning ("DR", i.e. combining estimated speed through the water and compass course steered with assumed current effect to extrapolate our position over time) and the occasional sextant fix. We're curious if - theoretically - we would be able to make landfall in the Galapagos without the help of GPS. We use data from the Pilot Charts (long run historical averages from other ships' observations) to estimate currents and eyeball speed through the water by looking at Namani's wake (turns out that the gurgeling sound of water flowing along the hull which can be heard in the quarter berth is also very good speed indicator). Of course the experiment is not entirely on "real terms" as all navigational decisions are still based on our accurate GPS position, which may cause us to adjust the course steered at a point where the DR data would have had us going straight. Nevertheless, it's very interesting and insightful to see how and why DR and GPS tracks diverge. We were getting a little "concerned" early today when the difference between our GPS and DR positions widened to 55nm (enough to potentially make us miss the Galapagos in our theoretical scenario). We hadn't been able to take any sextant sight for about 48 hours because of overcast skies and a hazy horizon at dusk, and the current in these waters is signicant and changeable (we've also been underestimating our speed thgrough the water). Luckily, the sky cleared later this morning and we got a good running fix between a noon sight and an afternoon shot of the sun which got us with 10nm of our GPS position again. We also were able to take moon, star and planet sights at dusk tonight (we haven't reduced them to a fix yet - we'll see tomorrow if they're any good). In any case - we may make landfall after all in our little theoretical scenario as well - stay tuned... ;-)