Forwardscan cats and whales

[moreton99]

Hi,

Looking to upgrade my nav electronics and interested in the Forwardscan. Prob the B&G Vulcan 7. I am after some advice on what really works or possible.

So due the numbers of whales on the Qld coast(and I assume everywhere) I am very concerned about hitting one especially at night. I even had to deviate round one in Moreton Bay near Peel the other day. It just sat there broadside to my bows. I thought the forwardscan sonar might pick them up? I'm surprised to find no discussion about this.

Also how shallow is the forward scan effective in? Could you be sailing in 2 meters(known waters) and detect less than a meter? None of the videos online cover this that I could find.

Where do you mount the transducer if you have no mini keels?

Any experience with these units or other is appreciated.

Any other tactics for whale avoidance too. Other than staying at home.

Cheers,

Paul.

[moreton99]

Oh and just saw the Garmin Panoptix Forward. wow pricey but if it works be worth every cent.
https://explore.garmin.com/en-AU/panoptix/

[BigBeakie]

Hi Paul,

I just got one from Southern Seas Marine at Coomera ( super helpful guys by the way) and they don't set the expectation that you can see surface objects whether it is whales or logs etc. It is better for seeing reefs/rock approaching in murky waters where eye balling is not going to work.

The transducer is a 45* angled face that faces forwards and it is not recommended that you keep it in place all the time, but only when you need it, because it would be vulnerable to an impact with floating objects. There is a flush plug for the hole when not needing the transducer. So you can locate it in an exposed position as far forward as possible.

Re sailing with whales at night, one guy I talked to put a speaker against his hull and played Meatloaf into the water. They have acute hearing and that may give them a heads up that you are approaching. I know I would avoid Meatloaf music, so maybe it works with whales too.

[moreton99]

I was thinking that the forward sounder pulses might help let the whales know where we are?

Whilst not a hater of Meatloaf it might wear a bit thin over and over on an overnight passage.

[Paul L]

Forward scan is of no use for whales or partially submerged objects offshore. It is for slow speed poking around potential anchorage. For that it is very useful.

[ArmyDaveNY]

As others have said, it best used when moving slowly. Several units I've seen show an image out to 60 feet (18 meters) in the best of circumstances. Even at just 3 knots, that only gives one just under 12 seconds before one goes bump.

[S/V Alchemy]

I actually have this setup: a Navico forward-scanning depthfinder and a B&G Vulcan 7, which I installed last year. The forward-scanning function is related to depth and I have found the maximum I can "see" objects like shoals and seawalls ahead of me ranges from 4 to 7 or 8 times the depth, which is in line with Navico/B&G's claims. There's a learning curve, as with radar, in interpreting the visual representations, and the "data points" display is what I prefer.

Creeping up on a reef gap and finding coral heads or sunken debris is what this is for, because if you are in, say, 20 feet of depth, how fast can you be going before you reel off 100 feet or so foward? Doing seven knots on a fresh day in the ocean would give very little reaction time, so this is a "nice to have" technology, rather than an excuse not to keep a watch.

On the other hand, with a cat, you can go where others cannot, but if you put a 20 cm. offset on the "shallow" alarm, I can see the utility for anchoring in appropriate weather in some otherwise tight spots. But if you are blasting at 12-16 knots and a whale is snoozing ahead? Not so much!


I go into more depth, pun intended, in this blog post: https://alchemy2009.blogspot.com/201...teresting.html

[CatNewBee]

It is more of 60..75 degree than 45, so you look approx. 2-3 times the depth ahead. in very shallow water quite useless, but you can see steep underground ahead quite well. On a depth of 18m you may look forward up to 36m (3 boat length). Nothing for high speed. I turn it on when aproaching anchorages or marinas on my second display.

I think it gives some peace of mind, but it is not meant for whales or logs.

I have the B&G forward scan system with vulcan 7 display along with a 'free' C-Map of the eastern Med. I prefer the Navionics charts. Another disadvantage is that the vulkan displays have their sd card slot on the back. If you mount it in the navstation you must disassemble it to change the charts.

I use it therefore merely as a sailsteer and data display, and for the forward scan, and use my 12 inch Raymarine chartplotter with Navionics for navigation.

But it is a nice backup display so.

[moreton99]

Ok very informative thank you all. Really helps to get my brain around the practical use of this tech. Sounding like Radar is a far better bet when traveling at night.

[BigBeakie]

That's a thought. I wonder if radar on the "rain" setting will pick up the spout of a whale just in front of you at night?

Just kidding...

[CatNewBee]

Originally Posted by BigBeakie

That's a thought. I wonder if radar on the "rain" setting will pick up the spout of a whale just in front of you at night?

Just kidding...

it depends how high the whale flies [emoji108]

[BigBeakie]

True, but that's a breach, i.e. when they "jump" out of the water. I was meaning when they exhale, a big spray of water goes up. The new Quantum 2 radar is really sensitive picking up close objects, so I was just musing....

[SteveSadler]

I’ve hit whales 3x. Twice while sailing, once while motoring. Sonar has a short range but will give you a warning if you are watching it or if the alarm goes of. Still even with instant reactions the chance of stopping before contact is slim. Whales can hear well, therefore a noise generator (deaf leopard) is a wise choice. But no guarantees as I hit a humpback going 5 knots. I hope science can find a frequency that we can transmit for best results.

[CatNewBee]

Whales communicate at very low frequencies, they barely hear the sonar. Also they are quite big species and do not really fear other animals, so I doubt they will be scared off of Meatfoaf music at all, nor will they give way to a recreation boat. You can install a marine sonar like the ones in submarines to listen to the whales instead and try to avoid them.

But there are also other floating objects out there you may hit, that do not produce any sound, nor get scared by your music.

[clarkey]

Originally Posted by moreton99

I was thinking that the forward sounder pulses might help let the whales know where we are?

Whilst not a hater of Meatloaf it might wear a bit thin over and over on an overnight passage.

Hi I hit a whale off Currumbin, Gold Coast @ 0230 last year sailing south, I think it must have been dozing just below the surface, gave us a hell of a scare. Minor damage to the rubber but threaded 3 bolts on my sail drive still able to get to Ballina and cross the bar. See plenty of whales on my trips up and down the coast getting worse every year.
A cruiser told me to keep the depth sounder on around whale time the ping from the sounder gives them a warning, I can say it works as i've seen a pod ahead they disappear about 50m or so away and re surface behind me, which I think gives this theory some credence.