Challenge: How do you solve this?

[Pelagic]

Great question Wotname! (I loved the old pre-GPS days when you sailed out into the unknown.)

I remember 8 years ago going to a place called Osprey Reef somewhere out there, (great diving).

My initial thought process and actions while the adrenalin slows down would be like this:

1)…. Quick Check of sounder for any bottom reading

2……Drop pole and preventer to get out of handcuffs, drop headsail while same time

3…. Delegate look-outs to watch, listen for any reef activity in a place that would protect their night vision. (you may have worked back out towards the inside of the barrier reef. Also Check all around the horizon to see if any stars are being blocked out by hills?

4…..Scribe approx 3 hrs of your estimated best speed made good from your last known position to see the worst case scenario as far as reefs or hazards. If you had a taft rail log, check reading.

If satisfied that you are not in any immediate danger….. Take a deep breath and start to figure out what you do know about your present position and fine tune a DR from last known position.

Query newbie as to when the wind started to drop and how often she checked compass heading and what the compass course read as she tried to follow the wind.

Check around compass to see if she placed a radio or walkman beside it.

If sure you are not in any wind shadow from the shore, get a sense of wind direction from any puffs and then try to assess if the wind backed or veered while you were running ahead of it.

Try and assess you position from any depth sounder readings by comparing to chart

Depending on #4 of your worst case scenario and from what you know now after fine tuning a new DR decide whether to wait for daylight to confirm your theory or slowly track south from your “guestimated position” towards your destination by following a line of sounding that “should” take you away from any dangers.

If the soundings don’t jell with your assumption, stop and reassess.

[Wotname]

Originally Posted by Morgan Paul

I would start the engine and then grab a spot light.

Morgan P, on this particular night, this action would have got you into a rather big mess.
Pelagic is more on the right track, I will wait awhile to see if any more chime in before explaining what happened next.

[Pelagic]

Sounds like fishing net

[David M]

Originally Posted by Wotname

Hmm... I thought Lodesman was correct with "rhumb line", perhaps you are looking for the more formal "loxodrome".

Pelagic, I think David M made it quite clear that the course was true in his challenge so assumptions weren't needed in this instance but I take your point, courses are assumed to be true unless otherwise stated.

Wotname,
You got the second question correct. A loxodromic curve. Congrats!

[Morgan Paul]

You said it was calm and you could not see anything. So start the engine (I did not say to engage the prop). Grab the brightest light you have and look for possible trouble.

[Pelagic]

My only caveat to that idea MP is that when you come on deck and something is amiss, you want ALL your senses including hearing to be given a chance to guide you. Starting an engine right away would blunt your hearing and even smell.

Waiting for Wotname to guide us

[Wotname]

OK to make this manageable and not too boring, I will spilt the reply into two parts - "what happened, lessons learnt" and "analysis".

Skipper looked around and couldn't see anything except the boat slowly drifting around in a calm on a low oily swell. Raced forward, releasing the preventer, called for newbie crew to sheet home the main and hold the wheel dead center and keep it there. Started to drop the pole as mate sticks his head up wanting to know what the fuss is about. He looks around and without a word, starts to reef the main. Just as the pole was secured, we are hit with 25 kts. (on the nose of course). Newbie starts screaming a bit so we send her below. After main is reefed and and #2 jib is hoisted in place of the genny, we put boat on an off shore tack, find some safety harnesses, settle down and sail close hauled into 25 /30 kts for the rest of the night - 30 minutes on off-shore tack, 20 minutes on in-shore tack. Come morning and we tacked inshore until the coastline was picked and a fix was established. Wind backed (as expected) to the south east during the next day and we finally could lay our destination close hauled on a port tack.

I think the main actions were OK but we should have taken the time to find to don the harnessess before going forward (even though at that moment it was calm). I should have also called the mate up as soon as I saw every thing was dark. I didn't because I was not 100 % sure of my actions and didn't want to appear stupid if I was wrong. Bad mistake, already better to look a bit foolish and err on the side of caution.

Later analysis showed we spent the night tacking across the 100 fathom line so we had 25/30 kts southerly pushing against 2 kts northerly current causing the sea to come up faster than we expected. Not sure what else we could have done except to maybe tack off shore for a few hours before working our south again; however we would still have to cross the 100 fathom line later on an in-shore tack and the sea state would have increased by then.

So Pelagic was certainly closest with his #2 action. His #1 action would have been prudent given the data supplied. He wasn't to know there was no chance whatsoever that the boat could have been in soundings as 3 hours at best speed from last known fix in any direction was all deep water.

The rest of his actions became irrelevant once the southerly buster hit.

[Morgan Paul]

WOW! I don't think I have ever seen winds go from near 0 to 25 in a matter of seconds. I guess it was a good thing the girl woke you.

[Wotname]

1. Don't take any information from a newbie as gospel. Take the information and give it a broad interpretation. In this instance "There is nothing wrong but the boat won't sail properly" is an oxymoron as the boat had been sailing properly so something must be "wrong". She really meant something like " something has changed but I don't know what". Coming up on deck showed the boat was OK in so much as it was doing what a boat should do in a calm. An experienced crew might have said "The wind has dropped and there is a heavy cloud cover".

2. When I saw everthing was dark, it was really dark, not just the horizon but the stars were "gone". The only rational explanation for ALL the stars not being visible was a heavy cloud cover.

3. The speed of the cloud cover was reasonably fast. 3 hours max, probably much quicker. The northerly that had been establish for a couple of days had died at the same time so something was up. And whatever that was, a prevented main and a poled out genny was asking for trouble. The boat had to be put back to more safe configuration before anything else was done as that was the most immediate danger. Interestingly, the mate came to exactly the same conclusion as soon as he came on deck.

4. I reckon that as a generalization, there was a more acute situation awareness in the pre GPS days. The whole process of taking bearings whenever possible, drawing lines on charts, confirming log and sounder data, anticipating next fix, analysing safe distances from dangers depending on quality and frequency of fixes, calculating set and drift and leeway, scanning for headlands, bays, islands, marks etc all contributed to general awareness of general situation of the boats postion that could be called upon in a instant without reference to a chart or GPS.

I am not suggesting that the pre GPS days were better, they weren't, but we have lost some things that we might not always be aware of.

In this instance, such situation awareness allowed me to know there could NOT be any navigational dangers regardless of what happened in the previous three hours. I didn't have to think about it or consult anything, I just knew it to be true.

5. Deal with the most immediate danger first, then assess the rest.

As previously explained, we made a few slip-ups and learnt something from the event.

[Wotname]

Originally Posted by Lodesman

N pole; rhumb line

Originally Posted by Wotname

Hmm... I thought Lodesman was correct with "rhumb line", perhaps you are looking for the more formal "loxodrome".
.....

Originally Posted by David M

Wotname,
You got the second question correct. A loxodromic curve. Congrats!

OK David M, I think I have worked it out.

All loxodromic curves are rhumb lines but not all rhumb lines are loxodromic curves. Please enlighten me if I am incorrect in my thinking here.

[Wotname]

Originally Posted by Morgan Paul

You said it was calm and you could not see anything. So start the engine (I did not say to engage the prop). Grab the brightest light you have and look for possible trouble.

Morgan P, I did jump to the conclusion that the prop was engaged - sorry.

I am not saying starting the engine in itself was a bad idea although Pelagic makes valid points against starting it. It is just there is no real benefit to have the engine running while there were immediate dangers like the potential change in the weather. The real give away was the lack of visible stars when the sky had been perfecly clear only hours before coupled with the complete calm after a couple of days of a gentle constant wind.

On this particular night, the time taken to start the engine would have caught us with our pants down. Another time it might not have mattered. The lesson being "deal with the most pressing danger first".

[CharlieCobra]

Originally Posted by Morgan Paul

WOW! I don't think I have ever seen winds go from near 0 to 25 in a matter of seconds. I guess it was a good thing the girl woke you.

I've seen it go from S 15 to 0 to W 50 in less than two minutes as a Cold Front hit. Caught us with the chute up it did. Nice to see the boat stay dry with both sticks in the water. We learned a lesson or two that day.

[Pelagic]

Originally Posted by Wotname

2. When I saw everthing was dark, it was really dark, not just the horizon but the stars were "gone". The only rational explanation for ALL the stars not being visible was a heavy cloud cover.

That was the key bit of information you didn’t share with us Wotname which is why I focussed on the navigational dangers.

I’ve experienced those southerly changes and the speed of change is impressive

If I may say your biggest mistake was putting a newbie on watch at night in a handcuffed boat. Luckily for you she didn’t decide to just wait it out to see if the wind picked up….I shiver at the thought!

Good Lesson!

[Wotname]

Originally Posted by Wotname

... He has a quick look around and can't see anything except the boat slowly drifting around in a calm on an low oilyswell.

Originally Posted by Pelagic

That was the key bit of information you didn’t share with us Wotname which is why I focussed on the navigational dangers.
......If I may say your biggest mistake was putting a newbie on watch at night in a handcuffed boat. Luckily for you she didn’t decide to just wait it out to see if the wind picked up….I shiver at the thought!

Good Lesson!

Pelagic, if I may say, you didn't read the question fully and yes, you are correct, I should not have put the newbie solo at night with the boat "handcuffed". Still learning something from that incident after 25 years - thanks.

[David M]

Originally Posted by Wotname

OK David M, I think I have worked it out.

All loxodromic curves are rhumb lines but not all rhumb lines are loxodromic curves. Please enlighten me if I am incorrect in my thinking here.

That is correct. I was looking for loxodromic curve or loxodrome for the answer but rhumb line is also a technically correct answer.

From Wikipedia:
"In navigation, a rhumb line (or loxodrome) is a line crossing all meridians at the same angle, i.e. a path of constant bearing.

Rhumb line - Wikipedia


Next question anyone?