March WNS

TonyJones

Well-Known Member
Joined
9 Mar 2005
Messages
270
Visit site
WNS README FIRST.
The purpose of What Now Skip is to give forum members the opportunity of learning from each other's experiences and opinions. To that end, awkward boating scenarios are presented for forum members to discuss. WNS is not a test with replies measured against predetermined ‘correct’ answer. In fact, in most cases, their usually more than just one solution to the posed scenario. Selected posts will appear in the next issue of the magazine along with the author’s preferred solution.
However, please read the scenario carefully as some of the information given may imply certain possibilities or restrictions on possible courses of action – without spelling them out specifically.
The author always tries to describe the situation as fully as possible but ambiguities sometimes arise. If you are unclear as to any particular aspect or require clarification of an issue – just ask.

During a final late season cruise along the coast in your 38ft flybridge cruiser with your partner and teenage son the weather turns a bit unpleasant. There’s now a F3/F4 on the nose against a 2kt flooding tide, it’s started to rain and the visibility is poor. You elect to divert to a nearby fishing harbour with an easy entrance and good protection from the elements. The approach is crosswind with a sharp chop on top of a longer swell, making the boat roll uncomfortably. You try coming off the plane but that only makes things worse and will prolong the misery, so you decide to close the harbour entrance on the plane at 20kt. There are no legal or seamanship reasons not to do so and you know things will be reasonably calm once inside the outer harbour breakwater.
Your rather ancient chartplotter broke down a couple of months ago and you are planning to replace it with a new one over the winter. So navigation has been by visual pilotage with the knowledge that you can always switch on your hand-held GPS should you need an exact fix for some reason.
About half a mile out, your son leaves the flybridge to prepare the fenders which are stowed in the lazarette. After about five minutes there is no sign of the fenders so you send you partner to investigate. She finds the lazarette hatch up, the transom gate swinging on its hinges and no sign of your son. He has obviously gone overboard. He is wearing warm clothing, a modest foul weather jacket and a manual gas inflation lifejacket. But he does not have a hand-held VHF, personal EPIRB or miniflares.
Obviously you need to backtrack in an attempt to find him. What other actions should you take? And what would your search pattern be? In fact, What Now Skip?
 
Immediately call it in as a Mayday, take a 3 point fix using your compass and turn the boat around quickly through 180 degrees and start heading slowly back. whilst checking your bearing so that you know you are on the right course? work out roughly how long ago you saw your son,so you know roughly how far to travel back, and then slowly proceed along the course.
Make sure your wife is ready to throw him a lifebelt/rope etc
make sure you allow for the fact that wind/tide will be making him drift so adjust heading accordingly.
 
Firstly immediate mayday over vhf.

But the rest of the scenario doesn't make sense. Boat travelling at 20kts, half mile out from harbour son sent to deploy fenders, 5 minutes later notice he's missing. At 20kts you would now have travelled over 1.5 miles and therefore either have missed the harbour completely or be in the harbour tieing up the boat!

Leaving that aside and assuming you were only 0.5 mile out of the harbour then your search area is pretty small so make immediate turn on reciprocal course at displacement speed. 2kts of tide in 5 minutes will have moved casualty about 300 metres from where he fell in, so this needs to be taken into account. Not sure from your description if tide was with or against you, but if with you as I assume, it's also possible son has now been swept past harbour entrance so search must start there. I'd use a gentle zig zag, both skipper and crew on flybridge keeping good look out going back over the previous half mile, or maybe more if the contradictarory info requires it.

Not that much difference to most of our trips with divers in the water, although 2kts of tide would be unusual. And of course they would have surface marker buoys but even they can be difficult to spot if looking into the sun.
 
Teenage son goes off the back of the boat? Well, I guess it's one of those things. Trying to hold back the tears with the thought that men going into the North Sea in WWI lasted on average one minute you head for home, have his room fumigated and advertise for a lodger.
 
a serious situation. As well as all of the above I would also press red on the dsc radio and fire off a flare. Help could be very near. You are just outside a harbour and a shore observer could just have seen where your son went in.

afterwards kick yourself for sending somebody out with fenders in the first place. you should have waited until you were inside the harbour.
 
1 Stop boat
2 Fire up h/h GPS
3 Conduct quick thorough search [make sure he's not in the bog]
4 Quick squint over the stern/side in case he is caught up nearby
5 Leg it back up to flybridge [with binos]
6 Hit waypoint on GPS
7 Turn boat in its length and proceed at displacement speed to get a stable platform
8 Take a proper squint in the general direction with binos
9 Now you know he is in the water and not in the immediate vicinity get your partner to call a Mayday

Quick mental calc tells you that in 5 mins with 2 knots of tide he could have been swept a maximum of 340 yards and that you would have travelled at least 3,400 yards in that time. Therefore if you allow another 5 mins to get back as far out as when you last saw him plus a couple of mins to turn around he could be at most 800 yards off track [if he fell in straight away]

10 plot an appropriate return course [you do remember what bearing you came in on don't you?]
11 Proceed at a safe planing speed [20 knots again?] keeping a good look out
12 Pick him up

Have a right go at him for not holding on [meanwhile regretting your decision to buy a blimmin silly flybridge boat that you cant see all you crew on, from the helm!]
 
Yes, if you (not you personally) are stupid enough to make your kids rig fenders when you're planing at 20 knots into an F4 in a wind against tide situation you really don't deserve to be allowed still to look after them.

For goodness sake, what do you need to be fendered against when you're outside the harbour?

It's about like asking them to nip across eight lanes of the M25 and pick up a piece of litter you've spotted on the far side.

I'm sorry but I think this is the stupidest WNS ever, for this reason, and deserves to be treated with contempt.
 
Agree with you ljs. Why would anybody be so stupid as to start getting fenders out 1/2mile out from harbour when the boat is doing 20kts in a lumpy sea and why would the skipper allow this to happen? And as you say, if it's taken 5 mins for the skipper to notice, he's already tied up in the harbour and putting the kettle on if he's entered the harbour at 20kts. Badly thought out scenario
Anyway what's to think about? After a Mayday, you have to go back out to look for the kid. He's your son after all. Assuming it takes 5 mins to get back out to roughly where he fell in ie 1/2 mile out, he's been in the water for upto 10mins which means he's drifted 1/3 nm down tide
What's the alternative? Put your feet up, turn the TV on and assume the lifeboat is going to pick him up?
 
By late season lets assume you mean end of the summer, which is good news 'cos at least the water is at its warmest, so provided he was able to inflate his jacket, then time is on your side. So the most imminent danger is that he took a bang to the head and wasn't able to manually inflate his jacket.

Given that it was several minutes ago he may have fallen in, you need to backtrack your course, so add or subtract 180 degs to the compass route you were on and set off back on that course. MOB is always a mayday, so call that in whilst partner gets a fix of where you are with the handheld GPS to give them. With help on the way you can now continue your own search. Judge the best speed by conditions, to give you the best chance of spotting him, and be sure to allow for 2 knt tide and how far he will have drifted.

The real answer of course is that you let your teenage son put the fenders out at planing speed, with the boat rolling all over the place, so you are not fit to look after yourself or anyone else, and you will probably run him over and slice him up with the props, so i'd leave it to someone else to save him.
 
You are half a mile out, right? At 20 knots and 5 minutes, you are now approximately a mile inland.
Put out the boarding ladder, climb down and walk back along the enormous trench your props have dug, and you should find him covered in mud somewhere.
 
Brendan banned me for a week but I have to brake silence for this one Tony, please change the reason for the MOB before you go to press.

Fenders wait until slow displacement speeds in calm waters, if that means pottering in the marina or even after being tied in a lock then so be it.

Movements from our flybridge are terminated with either FRS radio communication or sounding of the horn.
Same when we go back upstairs.

The in between bit has someone on the flybridge looking astern at all times until horn or FRS confirmation or in sight on the bow.

reply
make note of current position.(x)
180 turn
follow the wake/froth for 100 m that sets the course to follow, as the wind was on the nose this will give the perfect tide adjusted track.

vhf coastguard with position x and current track.

Position should also be given as 1/2 mile south of plonkers breakwater so everyone around knows to lookout and not just a few who bother to get a chart out.
 
[ QUOTE ]
Put out the boarding ladder, climb down and walk back along the enormous trench your props have dug, and you should find him covered in mud somewhere.

[/ QUOTE ]

/forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif
 
Agree the other comments about the bolloxness of the maths. And the skipper was stupid in allowing/asking for 20knot fender deployment. I 'd never ask for or allow fender deployment at 20kts in a calm sea, let alone a run-for-cover type sea like this one. It is utterly stupid; the side decks of a 38er aren't safe enough. Still, anyone who opens the tansom door in that weather is equally stupid becuase the aft cockpit is pretty safe but the side decks and swim platform aren't. So maybe Darwin is right.

Anyway, mayday, note course, fire up GPS and waypoint the current posn, turn around to retrace your track allowing for son's downtide drift at 1/10th your speed, so you should follow a recirocal course adjusted in a downtide direction by the angle whose cosine is 0.1, which is only a few degrees (The question doesn't actually give the tidal stream direction; I've assumed as others have that it's running along the coast but we need more info on this, And of course the boat can't be doing 20kts, or the time can't be 5 mins, or the track can't be 1/2nm). Also allow for the fact the boat is blown downwind but the casualty isn't. Anyway, work out all that when you have the correct info.

I'd also fire a few flares to summon local help and to alert son (as he can prob see the boat) that he is being searched for, which should make him feel a bit better. And prepare lots of long ropes, becuase I'm sure you'll need them for something
 
Yep, I think you could maybe lay the ropes on the water to form the triangle to calculate the tidal drift cos the lad will have gone overboard with the log tables in his hand, silly little git.
 
Some good answers most of which I agree with, but who would bother with fenders in those conditions until inside the shelter of harbour breakwater! It's an implausible reason for the mob, but the problem of an unnoticed or delayed MOB observation is a good one to tease out anyway. Do the people who dream up these WNS actually boat?
 
Firstly, what on earth are you doing sending someone to put fenders out at 20 knts in a choppy sea, totally irresponsible and shows a complete lack of seamanship.

Secondly, by your own admission you are now buried into the inner harbour wall smashed to a zillon bits, time, speed, distance etc.

Assuming you correct the mistake above first course of action is immediate mayday, giving your current position (you can switch on your GPS after as that could take a few mins to fire up) and the maximum length of time the person could have been in the water and the course your have been steering. Second, before charging off on a recipricol course check all around the boat to make sure he is not caught up under the platform or hanging off the side (he may have been sensible and attached a lifeline to the boat). Next set off two flares at 30 sec intervals, the second in case people shoreside are not quiet sure if the saw a flare or not, many a time people catch a brief glimpse and are not 100% sure, the second confirms what they saw. Being only 0.5 mile from the harbour (which does not concur with the WNS above but hey ho lets assume) someone may have seen him go over, indeed may have a fix on him if they have been watching with bins etc.

Next turn onto a recipricol course and at no more than 10 knts trace your course back again, do not under any circumstances fly off at 20 knts +, he may have only just fallen over, a head bobbing in the water in choppy conditions is very hard to see, at 20 knts you could fly past him or worse run him over. At seven mins at ten knots you will be back to where the maximum distance away he could be. Don't make the mistake of carrying on for more than a minute or so past this point, it will be difficult in adenaline fueled mode to bring yourself back to a datum of last known position. If you haven't found him by now then next step is to do a parrallel line forward search pattern in the direction of the tidal drift ( I am assuming this to be in the direction of the land based on it being a flood tide but of course this has many variables but same principle juts adjust which ever direction the tide is running). Based on the figures in WNS above you have travelled nearly 2 miles in 5 mins. Each leg is going to be 500 metres max at 300 metre spacings, you can roughly assume that your seven minute recipricol course has taken you roughly to the possible orginal datum less the approx 1/2 m he has travelled to you (at maximim range from first discovery).The person has been potentially in the water for fifteen / twenty minutes at 2 knt drift so could be .75 miles away from the position after falling in. In short he could be only 1.25 miles from the harbour enterance so that should be your maximum range.

It will take you some time to cover the search pattern back to the harbour but by then hopefully the relevant SAR will be on scene. It would also be advisable to raise the marina / habour and task as many vessels in the area to come and assist, the coasties will have already probably done this but no harm making sure they have. The chances of recovery of the person overboard improve dramatically the more resources are on scene. Having said that after 30 minutes the chances of a succesful outcome diminish exponentially every ten minutes, within an hour it will be looking very grim indeed and your lack of seamanship and judgement by sending your son out on deck at 20 knts in choppy conditions may have just cost him his life.
 
Nautical, I know that you of all people know about sea rescue and I was very interested in your comments. One question: as a professional, would you really want lots of boats churning around and potentially chopping up the victim or rather leave a clear field for the SAR team?

As a separate point, in the scenario originally set, following the recovery of the body from the water (should that be the outcome) I think the skipper could well expect to be charged with manslaughter.
 
On a personal level I would wish for as many eyes on scene as possible, the more the better, there is a small chance someone could run over him but very unlikely provided those assisting are keeping their speed to a minimum and have good look outs.

the above would be my course of action but others may handle the situation differently and indeed unless you are actually present it is very hard to judge exact course of action. There are many variables, wind, drift, sea conditions, fitness of crew, competence of crew and whether skipper has gone into panic mode or not. I am sure there are others that would detail down to smallest % of drift, wind, tide, search pattern etc but that all takes time. What you want here is speed of response which is the critical factor, sitting there punching numbers is a waste of time, if you are out a few degrees , few hundred yards don't worry about it, get moving and get covering as much area as possible as quickly as possible.

Been a while since I have been active and certainly wouldn't consider myself a professional, a part timer with a bit of training making a stab at it :-)
 
Top