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Stop bucking the tides...


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I'm getting sick of seeing speeds of 4.5 kts at 75% throttle because I'm not timing my departures properly. (Well, sometimes I get it right)

I have Eldridge's, but I'm new to it. There's a lot of flipping back and forth to different sections of the book. It's a new moon. If I time my departure wrong, I'm going to be slogging into some pretty foul current. I'll tell you what I've calculated and you tell me if I'm wrong:

  • According to Eldridge, on July 10th, at around 7am, "The Race, LIS" a Northwest FLOOD current is against me, trying to make Onset, MA. Max flood is 2h 45m after that, so I'll be grinding away into the current if I left at 7am.
  • The SE ebb starts at 12:48pm, max ebb is 2h 45m after that.
  • I could probably depart at noon and bump into the end of the fading flood for awhile, then take advantage of the switch.

One other frustrating note: Pages 98-103 show diagrams of the area that just barely includes Block Is. and the currents. For that short section, the currents are against me on the NW flood.

Pages 72-83 are for Buzzard's Bay, where I'm going. There is a small section of water between Block Island and say, Martha's Vineyard that isn't really covered. It seems like it would mark a transition point from Race currents to Buzzards Bay currents.

I don't want to take short advantage of Race currents and then find myself grinding into Buzzards Bay foul currents for a long time, if you understand what I'm saying.

@B.J. Porter @estarzinger and others, what's the trick to timing a fair current from Block to the CCC?

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18 minutes ago, Ajax said:

 

...what's the trick to timing a fair current from Block to the CCC?

Relax. What's the hurry? You've been waiting years for this. The longer it takes the better, right? Throttle back to 3 knots and enjoy. No crime in passing the same point in a channel several times in one leg. Many experienced cruisers have said it takes a week or two to get into a comfortable rhythm. True for me. Takes some effort to relax, unfortunately :-)

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23 minutes ago, Ajax said:

I didn't wait years to put extra hours and stress on my engine for no reason. 

Better stress on the engine than on the skipper :-) Anyway, engines last a long time. Can be difficult to time tides all along a route. Since a boat’s speed cannot be doubled, relax, slow down. Sail or putt-putt slowly. 
 

Somewhere way ^^^ up thread someone wrote that schedules are the worst…

 

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1 hour ago, Ajax said:

I'm getting sick of seeing speeds of 4.5 kts at 75% throttle because I'm not timing my departures properly. (Well, sometimes I get it right)

I have Eldridge's, but I'm new to it. There's a lot of flipping back and forth to different sections of the book. It's a new moon. If I time my departure wrong, I'm going to be slogging into some pretty foul current. I'll tell you what I've calculated and you tell me if I'm wrong:

  • According to Eldridge, on July 10th, at around 7am, "The Race, LIS" a Northwest FLOOD current is against me, trying to make Onset, MA. Max flood is 2h 45m after that, so I'll be grinding away into the current if I left at 7am.
  • The SE ebb starts at 12:48pm, max ebb is 2h 45m after that.
  • I could probably depart at noon and bump into the end of the fading flood for awhile, then take advantage of the switch.

One other frustrating note: Pages 98-103 show diagrams of the area that just barely includes Block Is. and the currents. For that short section, the currents are against me on the NW flood.

Pages 72-83 are for Buzzard's Bay, where I'm going. There is a small section of water between Block Island and say, Martha's Vineyard that isn't really covered. It seems like it would mark a transition point from Race currents to Buzzards Bay currents.

I don't want to take short advantage of Race currents and then find myself grinding into Buzzards Bay foul currents for a long time, if you understand what I'm saying.

@B.J. Porter @estarzinger and others, what's the trick to timing a fair current from Block to the CCC?

Look at the discussion on page 91 of the 2021 Eldridge, about holding a fair current between eastern LI and Nantucket. The most critical thing for you is timing your passage through the CC canal. Your boat cannot power against that current.

Thanks to larger tides the further north you go, strong currents will be a fact of life. You can’t always avoid foul current here.

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Get a good anchor and do it like they used to do it pre big engines times (use the tide to your advantage and wait patiently when it is against you)

I know little about your coast but IME, the best tactic is to leave 1 or 2 hours before the tide is favourable and go as far as possible before going backward during the next tide. 

when there are tide gates, aim to be there early, it is less stressful to be early rather than cutting it fine when the wind drops.

Finally when the tide is against you, you want to hug the coast as much as you dare, obviously calling tacks with just one metre of water under your keel is bad for the skipper nerves so don't abuse this!

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4 minutes ago, accnick said:

Look at the discussion on page 91 of the 2021 Eldridge, about holding a fair current between eastern LI and Nantucket. The most critical thing for you is timing your passage through the CC canal. Your boat cannot power against that current.

Thanks to larger tides the further north you go, strong currents will be a fact of life. You can’t always avoid foul current here.

The other thing to remember is that you are not doing your engine any favors by babying it. Check your fluids daily, and run the engine hard. You won’t push your boat beyond nominal hull speed with a small Diesel engine, however. That takes more serious grunt.

My 19,000 pound 34 footer can make about 19 knots using all 420 hp produced by the 7.2 liter diesel at 2800 rpm. But it makes displacement hull speed of 9 kt using only about 125 of those horses at 1750-1800 rpm

it’s pretty easy to figure out the difference in fuel consumption on that one.

But I run the engine up near WOT for at least 15 minutes on every operating day if conditions allow.

diesels like to work.

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21 minutes ago, accnick said:

Look at the discussion on page 91 of the 2021 Eldridge, about holding a fair current between eastern LI and Nantucket. The most critical thing for you is timing your passage through the CC canal. Your boat cannot power against that current.

Thanks to larger tides the further north you go, strong currents will be a fact of life. You can’t always avoid foul current here.

Ok, I've read that section and I think I've figured it out. There is a crazy convergence zone NE of Block where you play "hand off" with the two currents. 

I'll leave around 11am to catch the current up Buzzards. I'll probably be bucking a weak Race current for a few hours to do that. 

Looks like a 9-11 hour day with a very light headwind that I may be able to use with the engine. 

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I can't add much except be wary at the end of Buzzards bay where the canal comes in. That can be the worst stretch of water on the whole coast. Remember to look up the old channel for an alternative. It's easy and has helped us out a few times. It's all downhill from there. :) 

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39 minutes ago, penumbra said:

Sounds like you might use a different tool. Have a look at tidemaps.com

 

 

Using your tool, that's what looks like will happen except that I'll actually have a fair current out of Block. I'll transit the convergence zone (for which no data is really shown on tidemaps)  It's 40 miles to Cuttyhunk where I pick up the Buzzard's current. At 6 knots it'll take 6.66 hours to Cutty where I'll ride the current most of the way.

I actually arrive a little late to Cuttyhunk but it would still work. Of course, I'm not thrilled about arriving at 11pm.

If I back it up to 6am, it looks like I'll leave Block at the end of fair current out of there. If I hustle and get over to that transition zone I can avoid most foul current. If I arrive at Cuttyhunk at 1 or 2 pm, I'll pick up the beginnings of the fair current up Buzzard's Bay. 

If I get ground down to a 5kt average, it's 13 hours so arrive at 7pm. If I go faster, it'll be maybe 5pm so either is good. I know I'll be working against some current in places, I'd just like to keep it reasonable.

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3 hours ago, accnick said:

The other thing to remember is that you are not doing your engine any favors by babying it. Check your fluids daily, and run the engine hard. You won’t push your boat beyond nominal hull speed with a small Diesel engine, however. That takes more serious grunt.

My 19,000 pound 34 footer can make about 19 knots using all 420 hp produced by the 7.2 liter diesel at 2800 rpm. But it makes displacement hull speed of 9 kt using only about 125 of those horses at 1750-1800 rpm

it’s pretty easy to figure out the difference in fuel consumption on that one.

But I run the engine up near WOT for at least 15 minutes on every operating day if conditions allow.

diesels like to work.

I'm curious here. Is it normal to have a 420 hp diesel in a 34 foot sailboat?

 

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8 hours ago, Ajax said:

Using your tool, that's what looks like will happen except that I'll actually have a fair current out of Block. I'll transit the convergence zone (for which no data is really shown on tidemaps)  It's 40 miles to Cuttyhunk where I pick up the Buzzard's current. At 6 knots it'll take 6.66 hours to Cutty where I'll ride the current most of the way.

I actually arrive a little late to Cuttyhunk but it would still work. Of course, I'm not thrilled about arriving at 11pm.

If I back it up to 6am, it looks like I'll leave Block at the end of fair current out of there. If I hustle and get over to that transition zone I can avoid most foul current. If I arrive at Cuttyhunk at 1 or 2 pm, I'll pick up the beginnings of the fair current up Buzzard's Bay. 

If I get ground down to a 5kt average, it's 13 hours so arrive at 7pm. If I go faster, it'll be maybe 5pm so either is good. I know I'll be working against some current in places, I'd just like to keep it reasonable.

The current going across RI sound was never nearly as much of a factor as it was near the CCC or at the entrance to Narr. Bay off Newport. But Buzzards Bay and the CCC do have some current.

If you chunk it up to arrive at Cutty, then stay there until you can leave the next day and ride good current up to Onset. Then you pop out of Onset the next day on the slack just as the tide runs north, and jump in the CCC. You can wait longer if you want more speed through the canal, depends on your time of day.

If you are trying to hit the canal at the right time from further away, it's a much tougher target than popping out of Onset at the right time.

The worst current effects in that area are on Vineyard Sound and the passes through the Elizabeth islands, and you won't be going through there.

Planning at 7 knots on a whole log of trips from Brenton Reef to Cutty I never really worried about the current very often, it's there but its not egregious until Vineyard Sound or until you start getting up further into Buzzards.

This is from recollection now, I've not sailed in this area for close to a decade, and Buzzards wasn't really my stomping ground, though I did go through the canal a number of times.

-----

Eldridge's takes a little getting used to. I'd always start by picking the page for where I wanted to be optimally, then writing on it the time from the tables I'd want to be there on the day in question. Then I'd page backwards, taking an hour off and writing the time in pencil until I hit the last measured time point. All those pages are like "X hours before/after the high tide at Y" so I'd make sure I had the hour intervals marked on each page for this trip, so the times were on each chart page in Eldridge's for that day.

From there, you could sort of extrapolate roughly what you should expect as you cross the stretch of water. You could rough out where you'd expect to be at each time on your plotted course, and check it against your notes on the pages to see how badly you screwed yourself on current.

Sometimes you'd find weird things, like if I try to be at West Chop at time X I'll catch the slack, but I'll get crap tides all the way up the sound. So if you wait Y hours, you'll get good current and a ripping ride around the Chops. As long as the wind isn't your face making standing waves, or course. It's good to check a couple of scenarios.

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Might want to give Navionics a look. They have good tide height and stream indicators and you can scroll forward and backwards in time to see what it will be doing when you plan on passing through.

I usually try to time things for a favorable tide on departure. Arrival and mid trip tides theres not much you can do other than maintain your planned avg speed, anchor and wait, or carry on to the next place.  Sometimes you just have to deal with going slow.

The biggest safety thing for me is sometimes needing to make a tidal window where a fast current will be opposing the wind and making for really sketch conditions.  If thats the case its sometimes worth working backwards. Again I like building a route in Navionics to get an estimated ETA at each waypoint.

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3 minutes ago, B.J. Porter said:

Eldridge's takes a little getting used to. I'd always start by picking the page for where I wanted to be optimally, then writing on it the time from the tables I'd want to be there on the day in question. Then I'd page backwards, taking an hour off and writing the time in pencil until I hit the last measured time point. All those pages are like "X hours before/after the high tide at Y" so I'd make sure I had the hour intervals marked on each page for this trip, so the times were on each chart page in Eldridge's for that day.

 

This was unclear...

  1. Pick the day you are coming through, and the chart that is relevant from Eldridges.
  2. Write the time of day on each chart that's correct for that day, e.g. at "Two hours after high tide at X" put in that time. Do every page in the tidal range
  3. Now you have a picture of that days currents you can look at.
  4. Figure out where you want to be when, and back fill your departure time from there
  5. Compare your estimated positions from your plot to the page from that time

This should give you a sense if your departure is good, or if you're booting yourself in the nuts.

The trick is to get a picture of what the tides are doing throughout the day, and with your expected boatspeed, put yourself in the right place not to get douched too hard by the current.

 

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5 minutes ago, hoektron said:

Might want to give Navionics a look. They have good tide height and stream indicators and you can scroll forward and backwards in time to see what it will be doing when you plan on passing through.

I usually try to time things for a favorable tide on departure. Arrival and mid trip tides theres not much you can do other than maintain your planned avg speed, anchor and wait, or carry on to the next place.  Sometimes you just have to deal with going slow.

The biggest safety thing for me is sometimes needing to make a tidal window where a fast current will be opposing the wind and making for really sketch conditions.  If thats the case its sometimes worth working backwards. Again I like building a route in Navionics to get an estimated ETA at each waypoint.

This is a lot easier with Maxsea, too. It has current info that's pretty good, and you can look at the expected currents at each leg in the course, and adjust your start time to minimize the bad. There are ways to optimize your route with weather and current information...they aren't perfect but they can get you a good starting point.

 

416293359_Screenshot2021-07-10170300.jpg.c04cf175ed6ccafc55574f034b83ba32.jpg

 

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Just as a note - does not really help Ajax all that much, but I used to race in this area and with local knowledge you can almost always find a counter current or at least nil current if you know exactly where to go (like real close to shore or over shallow banks or to the other side).  So, my basic plan going north was to hit the tail end of the outgoing tide in the canal and then just mitigate anything contrary on the way to the canal by looking for the local currents.

Coming back south - it is a bit different - the timing is all about not coming out of the canal with the current against a SWly because then you get big standing waves as you come out and you are into a beat.  I usually tried to come out at night (or early morning) before the SWly builds up on the first of the favorable current.

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Having raced and cruised in BB for years, the last thing you want headed S is a fair tide through the CCC, followed by a beat out of BB against a strong SW’ly, which is what you get on most summer afternoons.

You can get the snot beat out of you in a small boat in a wind over tide situation exiting both the canal and BB. 

There are inshore countercurrents, particularly along the mainland side, but unless you are racing and know the area well, there are hazards—shoals and isolated rocks—that may pose unacceptable risks.

BB is a narrowing funnel for both wind and tide at the canal end.

for most cruisers, you just want to get it done if your goal is to get through the CCC.

Read the section in Eldridge on transiting the CCC carefully. I have seen 6’ standing waves in a few places during otherwise benign passages, much like you get off Roosevelt Island in the East River in NYC.

With patience, planning, and timing, it should be a non-event.

Eldridge may be old school and a bit obtuse, but the advice is sound.

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8 hours ago, estarzinger said:

the timing is all about not coming out of the canal with the current against a SWly because then you get big standing waves as you come out and you are into a beat.

Doing this has been the only time our dinghy has ever touched the water while in the davits.

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On 7/9/2021 at 4:29 PM, Ajax said:

Using your tool, that's what looks like will happen except that I'll actually have a fair current out of Block. I'll transit the convergence zone (for which no data is really shown on tidemaps)  It's 40 miles to Cuttyhunk where I pick up the Buzzard's current. At 6 knots it'll take 6.66 hours to Cutty where I'll ride the current most of the way.

I actually arrive a little late to Cuttyhunk but it would still work. Of course, I'm not thrilled about arriving at 11pm.

If I back it up to 6am, it looks like I'll leave Block at the end of fair current out of there. If I hustle and get over to that transition zone I can avoid most foul current. If I arrive at Cuttyhunk at 1 or 2 pm, I'll pick up the beginnings of the fair current up Buzzard's Bay. 

If I get ground down to a 5kt average, it's 13 hours so arrive at 7pm. If I go faster, it'll be maybe 5pm so either is good. I know I'll be working against some current in places, I'd just like to keep it reasonable.

This should pretty much match what you find if you were to look at the Eldridge tables and graphics. As far as I can tell, all of the other manufacturers (Navionics, etc) are using the same data source - NOAA, which has limited forecast locations and published max ebb/flood and slack times with flow. Heavy rain, storms, etc can throw the numbers off dramatically.

But, what you're suggesting is common - time and tide waits for no man, as they say. Sometimes you have to suck it up if you want performance.

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While exiting the SW end with a big fair current into a fresh Souwester is unfriendly, it pales in comparison to the East end on day 3 of a 3 day Noreaster with a big current behind you.  I used to tell the unfortunate crew " This is like the African coast, only in 1/3 scale".

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