Out at night - how do you defend against pot/net/buoys/ropes?

[Paul-F]

A load of interesting approaches here I don't normally go out at night but I have had the last hour or so in darkness heading home and I intend to do some more boat fishing where best arrival time at a particular sandbank/wreck may dictate an early start on the weekends I have available for such things, especially in winter. I don't mind being out at night really as far as navigation locally goes. On longer journeys the thought of getting the prop fouled or hitting something lurking where I can't see bothers me most ... shopping list so far is radar, IR camera, rope cutter, spotter, auxilliary, new twin engined boat .... Or I could just limit my time on the water with limited light availability!

 

[Groot T]

Forgive me if this constitutes towards thread-drift, I have been asked to respond by a member of this here parish.

Who am I? I own and run a small company and I've been providing the Maritime industry with FLIR Thermal Imaging cameras for the past seven years, in that time I've become the biggest distributor (by volume) in the UK. I supply Leisure, light and heavy commercial and small-scale MOD (Police / Marines, etc). I have seen success by filtering marketing and theoretical bull and providing accurate user information mixed with plenty of hands-on use. I've also seen the FLIR/Raymarine course changes with regards to their route-to-market and provided strong product feedback for the respective markets.

- First things first. Any Ti (Thermal Imager) is only as effective as the personal or software which is viewing it.
- Ti's work by picking up Infra-Red radiation, in this situation is the objects radiated heat (Hence Thermal Imager).
- The image the produce is by defining when a temperature difference is seen, so they are showing relative temperature difference. But even if you have two objects at the same temperature, they can show up on the Ti due to something called Emissivity.
- Tis require (almost) zero ambient light. And are easily confused with image intensifier technology, such as Night Vision.
- "How far can it see" is an entertinaing question. Any Ti can see the sun, which is very far away. But it's also massive. So...
- There are NATO standards for ranges, these are Detection (1 pixel x 3 pixels), Recognition and Identification. Aka DRI. For each of these, it is a number of pixels wide and high on the screen.
- DRI figures also have minimum temperature differentials for a target to be defined. Uncooled (i.e. any camera below £150k) will be 5C temp difference
- Brochure ranges are always theoretical and assume ideal conditions. This is where sensitivity comes into play.
- Humidity / moisture dents the range a lot as water absorbs Infra-Red (i.e. what a Ti sees). So Tis don't work through water or below the water line. And the thicker the fog, the greater the loss. Even in high-humidity environments they camera will struggle (see sensitivity)
- Sensitivity is the minimum temperature difference needed for the IR detector (thermal eye) to see the change in temperature. The lower the better. Anything over 50mK should be approach with caution as the Ti will suffer greater range loss when conditions deteriorate.
- Be careful looking at Man-sized targets on the DRI figures. Remember your MOB isn't Jesus, only the head and shoulders + lifejacket (if they've been responsible) will be above the water-line.
- Ti is very low resolution, featuring 320x240 and 640x480 pixels. Spread these across a 24 Degree Horizontal and 19 degree vertical, and it's not long before each pixel is covering a large area. But this is where the DRI figures come from.
- The faster you go, the less time you've got to react. Keep in mind the eyes have to watch the screen, and in moving seas they may only get a quick flash of the info. So if you do choose one, be mindful of the user.
- Gysotabilisation helps a lot when it comes to user fatigue and often avoids nausea kicking in.
- Ti cameras work in broad daylight, so help in daylight MOB situations and don't suffer image flaring. So you can look into the setting sun on the water and still see everything that's going on in that image without interruption.
- DO A CLAP TEST! (No, not the Doctor kind). Quite literally, position the camera to look at you and so you can see the screen, and then clap your hands. Look for the delay. I've seen some systems give up-to 2 / 3 seconds before. This may not be of concern, but it's an indicator as to the quality of the internals.

So, with all that said and done...

M-100/200 are a good answer to the leisure industry. FLIRs market research in 2012 told them if they launched a camera in the $4k USD bracket, they'd sell a lot more. Shocker! So that's what they've done. Not had any hands on experience with the units, but they look OK on paper, but FLIR are not publishing the sensitivity which concerns me. Furthermore, I have no experience of the unit or motors / drive train or MTBF on the new Thermal Core (Ti eye) of the unit.
**EDIT** - These cameras are IP Only, H.264 (not ONVIF, iirc). So if you have a system which can't receive the IP video, then a IP to analogue video converter is needed. A stand alone use is around £750-1k, or a PC card is £150. Go figure).

With FLIR, you can spend more and get Gyro and built in Daylight colour camera, etc. IIRC these start at £7k-ish + VAT, range and price climb rapidly.

And finally, from personal experience. Never ever buy a handheld Ti for Maritime use. Just get an immensely powerful torch save yourself the 2k+.

 

[paul salliss]

I just go slow and keep my hand on the throttle to go into neutral if I see one to late to miss it.
And if you take steps to maximise your night vision it is surprising how well you do see.
Having said that the only night trips we do regularly are Swanage to Poole and knowing where to expect pots helps.
I wouldn't do the trip to say Yarmouth from Poole at night because of the pots risk.

It's a very good original post and this reply is in line with what in practical terms we do. We have in the last year or so been arriving at places more often as its getting dark but never when it's been fully dark. Being very alert and ready for action is good but going further off shore minimises the risk

 

[MapisM]

I think one of these would be a very worthwhile investment if you regularly cruise at night.

Have you ever tried the thing in actual night cruising?
My funny feeling is that rather than on price reduction, they count more on folks who never actually tried it, but are attracted by the idea on paper.
In fact, based on my first hand experience, (btw, with a rather sophisticated FLIR version, 15k$ ballpark cost), I'm afraid that reducing the price will never be enough to make me even remotely consider the installation.

Wake me up if and when they will pay boaters to install one of those things.
Till then, I'd sooner install an ancam - should I say more...?

 

[MapisM]

It's a very good original post

Agreed, with one exception: the best thing to do whenever it's too late to miss the obstacle is NOT put the gear in neutral (and neither speed up as jfm suggested, imho: you never know how large and strong the line is).
The most effective way to stop the props PDQ is by shutting the engines off there and then, without even touching the throttles.
You might not find this recommendation in the boat user manual, but that's what I did in a couple of occasions, and it worked! :encouragement:

PS: just in case someone might think that just by coincidence/luck I simply missed the pot lines, in one of those two cases I didn't see the buoy popping up again at the stern, so before turning on the engines again and move on, I thought to have a look underneath. And one of the props had indeed grabbed the line, pulling the buoy till it got stuck between the prop and the rudder. But it didn't make any turn around the shaft (as it would surely have with the prop still spinning), so untangling the line and the buoy took less than a minute of snorkeling...

 

[CLB]

Have you ever tried the thing in actual night cruising?:

Yes I have and found it very good.

 

[MapisM]

Yes I have and found it very good.

Good for CRUISING, specifically?
I can think of situations where it can be useful, but during a passage (unless the helmsman can count also on a second mate, but that's not the usual situation on pleasure boats), imho TIs are more a distraction than anything else.
Actually borderline with being dangerous! :ambivalence:

 

[CLB]

Good for CRUISING, specifically?
I can think of situations where it can be useful, but during a passage (unless the helmsman can count also on a second mate, but that's not the usual situation on pleasure boats), imho TIs are more a distraction than anything else.
Actually borderline with being dangerous! :ambivalence:

Yes, cruising. No more of a distraction than the radar screen. Each to their own, but dangerous seems like a strange statement.

 

[MapisM]

Yep, each to their own indeed! :encouragement:

Just for the records, I believe I already posted in the past about a night passage where I was in the p/house together with a helmsman so focused on the TI screen that he completely missed an approaching vessel easily visible by Mk1 eyeball...
But I couldn't find that with a quick search, sorry. I can re-write that story if you're interested, but not tonight... :sleeping:

Anyway, I disagree that the radar is a distraction. I mean, of course it is, if you focus on it with no reason.
But in principle, the radar is NOT meant for the dark - eyes are fine also in darkness, to a fairly high degree.
It's meant for poor visibility, which is a completely different kettle of fish. You can have nights with excellent visibility, as well as days with zero visibility.
And with zero visibility, you have to rely on the radar simply because not only eyes, but also TIs are totally useless.

 

[Hambleite]

My experience is pretty limited to the Solent, although I have probably made close to 200 night passages over the past 18 years, all in open RIBs of various sizes.

One top tip that has worked for me is to stay in or very close to the main shipping lanes / channels at night. There are NO pots there as the Southampton harbour master takes a pretty dim view of such pots! I know the good seamanship guide says that you should stay out of the lanes / channel, however, let's be honest - in good visibility you can see any shipping movements from miles away.

So, for me, in the Solent it's a balance of risks.

I have never snagged any of my props, day or night....

 

[Piers]

When cruising at night, we have two in the pilot house. One at the helm, the other monitoring radar and the FLIR (on weapons!). Perfect - works a treat. No stress.