Issuma

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Strong Currents and Snow

20 November 2011 | Southeast Alaska
Richard
Buoy 8 marks a shallow ledge in Sergius Narrows. The white patch on the buoy is snow and the strands wrapped around it are kelp.

The inside route to Sitka involves passing a very narrow section with fast tidal currents called Sergius Narrows. The chart says the currents reach 8 knots. The Coast Pilot notes:
At the strength of the current it is not safe for any vessel bound either way...The channel is so narrow and the current so variable in direction that if a vessel gets a sheer she may be carried onto the ledges or shore before she can be straightened out.

The channel has a sharp 90 degree turn immediately after the narrows with another rock which needs to be avoided. While there are buoys marking the channel thru Sergius Narrows, the buoys are not lit, and unfamiliar places with rocks and fast currents are best avoided at night.

After a gale died down, we left Tenakee Springs before dawn with a good tailwind, some freezing spray and a favorable current. I wanted to go thru Sergius Narrows during daylight, so we motored until well after dark, then threaded our way thru a narrow passage between rocks and an island to anchor half a mile away, with a light wind and clear skies. I was quite concerned about getting the timing right so we'd arrive at slack water, and hopefully without so much wind as to make steering difficult. I carefully planned out when we needed to raise anchor, get out of the bay we were in and get to the narrows for slack water.

Naturally, there was a snowstorm the following day! So, instead of going thru Sergius Narrows in the dark with light wind and clear skies, we entered with gusty winds and blowing snow (there was no point in waiting for another day, as the wind was forecast to increase to a gale late in the day).

We arrived early, in case slack water arrived earlier than predicted, and held position by steering up into the current and wind (the wind was funnelling down the channel). We had current predictions for Sergius Narrows and for points nearby, so by estimating the speed of the current at a nearby point, I could tell if slack water was going to arrive at the predicted time or not. I steered from outside, in the wind and snow, where the visibility was better.

Ten minutes before predicted slack water we headed for Sergius Narrows. At full throttle, we had no problems, and quickly passed thru and into wider, deeper, slower water.
Comments
Vessel Name: Issuma
Vessel Make/Model: Damien II, 15m/50' steel staysail schooner with lifting keel
Extra: Designed for Antarctica. Built in France by META in 1981. Draft 1.3m/4.5' with keel up, 3.2m/10.5' with keel down. More details at http://www.issuma.com/rhudson/issumaboat/IssumaDetails.htm
Home Page: http://www.issuma.com/rhudson/
Issuma's Photos - Main
Survey pictures taken of Shekin V
14 Photos
Created 29 April 2008