Melbourne (FL) to Keys April 4th to 11th 2009

[NautiHippie]

Originally Posted by Chuck Baier

Key Biscayne to Rodriguez Key is about 50 miles at 5 knots = 10 hours and from Miami add the additional miles, so maybe 12 hours. we do it all the time. Of course if you go faster it takes less time.

That makes sense I usually visit friends that are moored at Watson Island and back to Key Largo but motor sail and get about 7.5 knots.....makes it a bit faster

[Tropic Cat]

Originally Posted by amytom

Hmmm several options. I think I'll put it all on paper showing current and VMG then let the admiral decide. ?

Crossing the Gulf Stream current with your PDQ

How the Gulf Stream affects boat speed & course heading to the Little Bahama Bank from Ft. Pierce, FL

5 Knots Boat speed
3.5 Knots current speed
55 current angle relative to boat in degrees

4.14 knots is the velocity made good on your course
34.99 degrees current will affect course heading to destination

I did this too fast this morning, and there was a slight mistake in the last calculation. You'll be pointing the boat at 125 degrees true. This would put the Gulf Stream current 55 degrees off the starboard bow of the boat. The current will affect your course by 35 degrees. 125-35= a true course of 90 degrees true. You'll fight the current for 11 hours, at which time you'll be 5-7 miles north of the edge of the Little Bahama Bank. You can enter the bank there or skirt it.. Either way, you're in the Bahamas mon... with your draft, you can go where ever you please.

Actually, I created an Excel spread sheet to do these calculations. I lifted the formulas from an aircraft piloting / navigating course. These calculations are for discussion only.

[amytom]

Can you post your spreadsheet? I'd like to see it.

[amytom]

BTW why are we estimateing 5 knots SOW? This is a PDQ :-) Actually from the history on weather underground it looks like a N wind is the norm for this time frame. That would kill a trip to the west end but would help with the keys. With a 15 to 20 knt wind on a run I should get about 8 knot SOW.
I know the GS gets pretty rough with a N wind but what about the coast line? Are we talking 4-5 swells or 8-10 short period?

[Tropic Cat]

Crossing the Gulf Stream current with your PDQ
How the Gulf Stream affects boat speed & course heading to the Little Bahama Bank from Port Canaveral, FL



5 Knots boat speed
3.5 Knots current speed
38current angle relative to boat in degrees

3.11 velocity made good on your course
25.53 degrees current affect course heading to destination


It's 98 miles to approximately the same point above the Little Bahama Bank from Port Canaveral. The Gulf Stream is 24 miles off shore, so you'd be in the current for 74 NM. At 3 knots VMG you'd be fighting the current for more than 24 hours before you arrive in the lee of the Little Bahama Bank. Not advisable.

I think you'd agree that Ft. Pierce is the furthest north this route is advisable with a sail boat. Having said that, I wonder why no one has chimed in with some experience on this route.

These calculations are for discussion only.

[Vasco]

If you stay in close the waves are very different than in the stream when it blows from the north. I got caught once coming home in 20 knots from the north and we headed west until we got out of the stream, a bit slower but much more comfortable. If you're headed south it'll be fine.

The wind usually clocks before a front comes through. When we head across we wait until a front is coming and the wind goes to the SE and, depending on the velocity, head out then as it clocks to the S and W and usually we're well onto the Great Bahama Bank when all hell breaks loose and the front comes through.

Just a word of caution, it's been my experience that the conditions are seldom as forecast. Usually worse.

[Tropic Cat]

Originally Posted by amytom

Can you post your spreadsheet? I'd like to see it.

I don't know how to post it

[AnchorageGuy]

Originally Posted by Vasco

If you stay in close the waves are very different than in the stream when it blows from the north. I got caught once coming home in 20 knots from the north and we headed west until we got out of the stream, a bit slower but much more comfortable. If you're headed south it'll be fine.

The wind usually clocks before a front comes through. When we head across we wait until a front is coming and the wind goes to the SE and, depending on the velocity, head out then as it clocks to the S and W and usually we're well onto the Great Bahama Bank when all hell breaks loose and the front comes through.

Just a word of caution, it's been my experience that the conditions are seldom as forecast. Usually worse.

We know folks that like to cross just ahead of the fronts to get the SW winds. we would cautions those less experienced to consider that being in the wrong place at the wrong time on the banks during a strong frontal passage can be a very, very uncomfortable experience.

[NautiHippie]

Originally Posted by Chuck Baier

on the banks during a strong frontal passage can be a very, very uncomfortable experience.

Kinda like being in a washing machine from what I can remember

[pete33458]

Originally Posted by NautiHippie

Where do you leave Miami that it takes you 12-14 hours to sail to Key Largo?

GovernmentcCut. 59 miles (as the crow flies) to Port Largo. Generally to windward. You can do the math.

[AnchorageGuy]

Crossing the stream is not an exact science. The distance off the coast, the width of the stream and and the velocity of the current all will affect your angle of attack. You will need to get the latest information prior to departure, start with a generalized course line and adjust course as you cross using your GPS or plotter. The current will be stronger in the center than along the outer walls so constant attention will be needed.

[NautiHippie]

Originally Posted by pete33458

GovernmentcCut. 59 miles (as the crow flies) to Port Largo. Generally to windward. You can do the math.

So sheets only and no motoring..... that makes sense, on that trip the wind usually doesn't help me a lot in the 15 mile stretch between the lighthouse and I would say Boca Chita. Of course that's just my opinion