Re: Tidal Flow and Other Mysteries of the Sea

From: HandyM2@aol.com
Date: Sat Mar 18 2000 - 17:46:45 PST


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Hello Alan, I assume you have my original post so I will not reforward it
back to you.

<< HI Michael,
     I was just rereading your response(3/4/00) to my question concerning
 what are must haves on a P-19. You note that one should "never fight a
 serious tidal flow with your outboard". What do you consider a serious
 tidal flow?

A tide book and good charts will show you WHEN and Where and HOW FAST a tidal
flow is expected in your sailing area. Thus the required list includes a
good watch, charts and a LOCAL TIDE BOOK. Old time sailors would "SAIL WITH
THE TIDE." An outgoing Tide would allow them to use the tidal flow to move
there ships out to sea safely. Coming into harbor was reversed.

My Potter 19 Traveller has a GPS rated speed in a NO Current situation of
about 5 MPH with 1/2 throttle. NO I cannot do 10 MPH with full throttle..
Indeed I cannot break 7 MPH at any effort.

I PLAN on using my 1/2 Throttle speed/power to maneuver as to leave me with
OPTIONS if I need more.

Many Tidal Flows AT PEAK Exceed 5 MPH.. Some Exceed 12 MPH due to a
compression of water flow through a narrow passage.

Would you ride a Bicycle on a Super Highways On Ramp? Michael will not.
Thus my concern about a serious tidal flow.

With a good Watch, Tide Book and Charts (to preexamine the routes available)
you can know what tidal conditions to expect at what location.

>>I assume you are saying that the outboard is limited in what it can do. I
was just wondering what is that limitation.

I *Think* I pointed out the limits above. I could have a 8 HP O/B on
Travellers stern but would NOT be able to out power a 10 MPH Tidal Flow
heading me toward that BRIDGE EMBANKMENT for example. Your EFFECTIVE HULL
SPEED Vs that of the expected by local Tide Books flow is the issue.

>>When should I begin to worry? And what does one do if you find yourself in
such a situation of being overpowered by a tidal flow? Thanks for your help.

Well, Alan, it's a lot like Reefing, IF you are wondering if you should Reef
then it is almost too late to reef. Sailors cannot Bull there way through
like some Powerboaters do. We MUST think through the situation.

If perchance you forgot to check the time and you are fighting a powerful
tidal flow you must first determine what way you are Currently being pushed
by this flow. NOTE I said CURRENTLY. Tidal action can be affected by a LOT
of factors to include underwater factors that you cannot determine SO STAY
ALERT!

Next see what hazards you are being pushed into. Remember that you cannot win
this fight by pushing against the tidal flow. You can do some maneuvering by
acting at an angle Vs the flow. The need to determine your location and REAL
MOTION is critical IMHO. Thus I love my GPS. I might think I am getting
progress upstream but the GPS will tell me the real deal.

Sometimes you simply must Go With The Flow and use your available Outboard
Horsepower to maneuver your Potter away from hazards as they come up. Maybe
you can maneuver into an eddy backwater where the tidal flow is reduced by
the effects of a spit of land and WAIT until that tidal flow subsides.

Then continue on your way.

Others with more information and experiences are welcome to add to this
posting.

Michael
P19 Traveller
Columbia SC



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