SailNet Community (http://www.sailnet.com/forums/)
-   -   Check my math (http://www.sailnet.com/forums/seamanship-navigation/65549-check-my-math.html)

 davidpm 06-12-2010 10:42 PM

Check my math

OK here is a typical Long Island Sound situation.

I want to go due west.
The wind is light coming directly from the west.
The current is strong also coming from the west.
I'm sailing some old shoe with blown out sails that on a good day can tack through 100 degrees.
I'm making a blistering 3 knots through the water.

With no current I could tack tack to my destination doing my 100 degree tacks about 50 degrees off the wind.

With the current I've got to steer about 40 degrees up wind which of course I can't do in this situation.

The end result is that the best I can do is north or south and I'll never go west unless the tide turns. Maybe 5 degrees and 185 degrees but not much more.

Is this what you get?

 sailingdog 06-12-2010 11:21 PM

That's when you start motoring... :D The real problem is if you have blown out sails, your ability to go to windward is going to really be limited.

Sailing in areas with strong currents really require you to use some forethought and planning in timing your passages. For instance, a boat that can only do 5 knots really will get hammered if there is a 3 knot current. If the current is against you, you end up going at 40% of your boat's real speed... but if you have the same current with you, you end up going 160% of your boat's real speed, and end up making the voyage in ONE-FOURTH the time... :D

 Yorksailor 06-13-2010 05:02 AM

That's why you need to learn tidal planning. Sometimes 'you just can't get to there from here!' Or at least until the tide turns!

 MARC2012 06-13-2010 06:44 AM

Been here done this.Anchor,have some beer & wait.marc

 Joesaila 06-13-2010 07:27 AM

What are you doing on my boat? :laugher The difference in current and tide is equal to the distance squared....twice.:confused:

 paulk 06-13-2010 08:27 AM

You need to sail over to the Connecticut shore where there's less current. By the time you get there, it will have changed to be in your favor. (Though there will be less of it.) It sounds like you need new sails - even "new to you" old sails might be an improvement.

 chucklesR 06-14-2010 07:28 AM

Crank the motor on at just above idle, that should give you 3 kts or so of push; which will also bring the apparent wind forward and let you point a little higher.

It's a win/win, faster and higher, and maybe 1/4 gallon per hour of fuel.

 Boasun 06-14-2010 11:27 AM

You are on an Ebb Current. Wait until it becomes a Flood current. Then the current will carry you westward and the light west wind will have an apparent faster speed and you can sail to the west easily.

 nk235 06-14-2010 11:50 AM

I agree with DS and the others. In some bodies of water timing the current is the only way to do it. Heading East or West in Long Island Sound is one of those times.

If you do time it right however it can really HELP you instead of being a pain in the arse. For instance every year my gf and I sail our old shoe Morgan 32' (very slow in light air) out to Block Island from Mt. Sinai harbor. We always leave so that we time the start of the Ebb as our departure time. First day we sail a short leg to Mattituck inlet which is only 4 hours (doing an average of 7 knots with current) and then a longer 8-10 hour day to Block the next day. Some years we litterally had to wake up at 3:30AM while it is pitch black outside to get underway for a 4:15 Ebb start. The benefit is that for a good 5 hours we are doing a bare minimum of 7 knots, while sometimes shooting as high as 11 knots over ground (while going through the Race). Gets us to Block in a total of around 12 hours (inlcuding the Mt. Sinai to Mattituck leg). If we were to do one long leg right from Mt. Sinai to Block without stopping it would probably take 18 hours PLUS! Thats because for half the trip we would be doing about 2-3 knots over ground!

So all in all it is a pain to have to deal with it but if used to your advantage it can really give you a speed boost you don't see in other bodies of water.

-Nick

 hellosailor 06-14-2010 06:29 PM

Heck, I've been motorsailing at over 6 knots through the water without being able to make fifty feet over the ground. that when it pays off learning how to eek every extra tenth of a knot out of your boat, so at least you're not going backwards.

All times are GMT -4. The time now is 02:05 AM.