Skip to main content

024 - MagVar

We were traveling down one of the straighter sections of canal when a faster sailboat roared by us at 7kts versus our 6kts.  Even under power it’s hard to lose to another sailboat.  But he wasn’t keeping a tight helm and I could imagine the pilot yacking away and periodically looking up and making course adjustments, so I felt better about losing out.  When he did a strong S-curve up ahead underneath a bridge, I assumed he swerved to avoid a log or something in the water.  Ha, no such thing, now I think he was using his auto pilot and it was simply searching for the magnetic heading.  Because as we traveled under the same bridge our autopilot did the same thing to our boat!  The iron in the bridge added about 20deg variance to the heading and then swung back minus 20 as it oscillated back to the original heading.  This became entertainment for me measuring the MagVar as we transited different bridges.  The old railroad bridges had the most magvar, the new road bridges the least.  Likely the result of modern highway using steel versus iron.  Checkout the video below on a different bridge.


Comments

Post a Comment

Popular posts from this blog

034 - USS Niagara

What a beautiful working replica of this historic ship.  It is used today as a training ship and offers 10day expeditions for youth to learn the ways of sailing a Brigg.  It is about as exact as you can expect.  I loved their use manila rope, linseed oil, and other items that gives it the smell of an old ship – I don’t know what it is but it’s very familiar.  Below decks were tight, it only had a 5ft ceiling in the galley area – how anyone could operate in that space long term was beyond me but the professional crew does. Galley stove and 5ft ceiling - how do they do it? Watching it sail was like stepping back it time.  It passed us on the breakwater silently, tall, and majestic.  It was easy to imagine the awe seeing this come into an isolated harbor like Presque Island 200 years ago.  Something so big and complicated carrying so many men and cannon would change the balance of power with its arrival.  It would intimidate the st...
Post a Comment
Read more

033 - Presque Island Is A Beautiful Oddity

Most the shore of Lake Erie is a long straight beach.  But jutting out is a very large peninsula that loops back on itself creating a bay.  They say it’s formed by glaciers but this isn’t obvious to the casual observer.  For starters, I don’t see how a glacier can flow if it doesn’t have a mountain to slide down and there is nothing to the North I’d call a mountain worthy of the lake depth gouge.  Call me a geo skeptic, but some of the stories they tell sound more like conjecture than science. Behind the beach is a steep hill that drops to a valley and then a significant mountain behind it so it generally looks like it was formed by a really big dozier.  So why this odd shaped bay jutting out into the lake?  And the bay it creates is very deep and the channel small, what glacier movement did this?  No matter how it was formed, the place is important to American history and is very beautiful and home to a great hot dog stand, “Sara’s.” Lake E...
Post a Comment
Read more

048 - Big Water

The Great Lakes are mislabeled, they are really inland seas.  They are so big that one end can have very different weather than the other end or even the middle.  Waves however don’t really care where they come from and can travel hundreds of miles, reflecting off hard coastlines.  Shallow waters amplify the waves by making for a shorter period; this can create little waves that brings the boat to a complete stop as it goes up and down pounding against a wall of water.  Similarly, one end of the lake may be experiencing 20+kts of wind and the other end could be in a dead calm with waves that originated from the other end.  Makes it tough to know what the conditions are for your journey, so when its good take advantage of it, it will likely change.
Post a Comment
Read more