How far Offshore

[delevi]

How far off shore do tides play a role? I figure location probably plays a role. I'm asking because I'm trying to plan a Farallon Island trip. This would be a bit of a marathaon, since the entire round-trip must be done in a day, due to the islands being 30 miles off the San Francisco coast. There is no safe anchorate at the islands or in between. When you add 15 miles of going through the bay, we're talking 45 miles X 2=90 miles to cover in a day. I would like to do the whole thing completely under sail. Just trying to see how realistic this is i.e. if I leave just after high tide and return during high tide. The longest I have gone under sail in one day was around 75 nautical miles, but that was in the Greek Isles in a 32 foot keel boat. I would like to make the trip in September when typical conditions would be 10-20 kts wind with moderate swells. The Mac is fastest with such wind velocity and if I get a little help from the currents, the trip might be doable in 12-15 hours.

Appreciate your feedback as always,
Leon

[NiceAft]

I understand your theory Leon. Have the tide help suck you out, and then spit you back, but is 6-7.5 mph average realistic? What do keel boats in our size range do it in?

Ray

[delevi]

Absolutely realistic, provided sea state isn't too harsh. I have logged speeds in excess of 9 mph upwind in light chop on SF Bay (maintaining speeds in the 8s.) In big seas/chop, however, I have trouble getting the boat up to speed due to its light weight. One day, just a few miles outside the golden gate, I hit 11 mph+ on a close reach. She was in the high 9's to low 10s much of the time. I know the current was pushing me at a very nice clip. Winds were around 10 kts, full main & genoa, boat heeling 10-15 degrees.

Leon

[johnnyonspot]

I say go for it. Watch the time and if it looks like you are running short on the way out, then turn around and head back without making the islands. Still be a lot of fun either way IMHO. After all, you will be sailing.

[dennisneal]

I believe the tidal currents dissipate to almost zero just a few miles away from the Golden Gate.

I have no personal Knowledge, but I looked it up:

http://sfports.wr.usgs.gov/SFPORTS/vec_map/centbay.html

[pokerrick1]

I looked it up too - - but I didn't know what I was reading

Rick

[delevi]

4 kts currents. Looked up gulf of the Farallones, and it seems like there is a current system there as well due to the continental shelf, but patterns are not predictable like tides. Just looked at satelite imagery of the winds. Forecasts are typically NW which would theoretically enable a beat directly west, though based on satelite, it is a bit closer west than NW. This has also been my experience when sailing out of the gate. The closest I've been able to sail is about 250 degrees, vs. approx 260 needed. However, 250 may get me directly to South Farallon, then fire up the engine and head NW into the wind to hit the other 2 isles approx 5 miles apart. Should be fun either way. I guess I'll need my engine afterall.

L.

[bastonjock]

i would assume that there is something similar in the USA.I use an nautical almanac,one of the items of information in that alamanc is tidal streams and flows.I know for instance that the tide runs from east to south west at my home port from HW-2 to HW +4 then there is "slack" before it starts to run west to east,if i want to go anywhere with a purpose i need to consider the tidal flows as they can reach 3-4 knots close to where i sail,i also have a 7 meter tidal drop to contend with.

also is you are going across the current,that will push you one way then the other,sorry if you already know this stuff Leon,here i the UK you have to know it or you will get nowhere,i once had the experience of going backwards in my friends 35footer,the tide was runing harder than the boats engines could push it.

If i was going to head out to those islands,id calculate the optimum time using tidal set and drift,you can make up large tracks of ground if you do it right.

C130 and i sailed with the tide on our first trip,we were hitting 8-9 knots speed,if we were heading the other way,i would have expected us to be doing4-5 knots speed.

Im thinking of doing a 66nm trip this month,i will use the tide to my advantage by sailing for the first 8 hours,i would hope that with the right winds to cover 50nm in 8 hours

[hmb-barry]

Without throwing too much green water on the trip; the sail to the Farallones can be treacherous. One has to cross all the major shipping channels for the Golden Gate. If the weather turns on you - fog, high seas, etc.; one might join the recent boats and souls of Davy Jones's Farallones trips. Suggest you read the past year or two's worth of Latitude 38, particularly the Singlehanded and Doublehanded Farallones Races - good info in these. It might also be prudent for you to make a few trips to Drakes Bay and some to Half Moon Bay before the Farallones, if not previously sailed them? Drakes Bay is about the same distance as the Farallones and you can anchor overnight there. HMB is a bit closer than the Farallones and one can anchor in a protected harbor or rent a slip ($23.00/night). This would keep you out of the shipping channels while getting similar sea time and conditions. Have fun and good luck. Hoping to read a safe and fascinating report from you.
Barry in HMB