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Go Back   SailNet Community > General Interest > General Discussion (sailing related) > Do Whales like Concrete Boats!
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Thread: Do Whales like Concrete Boats! Reply to Thread
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Topic Review (Newest First)
10-10-2010 07:31 PM
SlowButSteady
Quote:
Originally Posted by poopdeckpappy View Post
Toothed whales use sound for location and communication, baleen whales use sound for communication only. If you get tagged by a Blue ,Hump,gray or another baleen whales it merely a case of wrong place, wrong time. Ya tagged by a toothed whale that's a different story, they know you are there, may not know what's there, but they know something is
Not exactly. It used to be thought that mysticetes (baleen whales) couldn't echolocate at all, mainly because they lack the specialized anatomical structures used by odontocetes (toothed whales) for such, and because they don't produce the high-frequency tones once thought to be necessary. However, while it is true that they can't track down small objects (prey, etc.), it appears that at least some mysticete species probably use lower frequency sounds for navigating, such as finding the bottom and ice surfaces. The effect is probably similar to the way human blind individuals often use their own foot-falls or cane taps to detect large objects (walls, phone poles, etc.). Although rather crude by "normal" echolocation standards, such a system would be quite useful for whales in turbid and/or deep waters, or at night. However, I don't know if they could detect a small boat.
10-10-2010 05:20 PM
tdw Interesting StAnna.....our antifouling is black and a year ot two back had an experience with a mother humpback and calf. Definitely a case of mama coming over to check us out and then getting junior to join the party when she figured we were 'mostly harmless'.
10-10-2010 01:25 AM
Stillraining Thanks for that bit of trivia pappy...I learned something..
10-10-2010 01:04 AM
poopdeckpappy Toothed whales use sound for location and communication, baleen whales use sound for communication only. If you get tagged by a Blue ,Hump,gray or another baleen whales it merely a case of wrong place, wrong time. Ya tagged by a toothed whale that's a different story, they know you are there, may not know what's there, but they know something is
10-08-2010 09:51 PM
Stillraining That's what I plan to do if the big boys get to close ..fire up the iron jenny and let them know your there.

Im all for nature and all that jazz ..but self preservation is #1 in my book.
10-08-2010 08:26 PM
SlowButSteady As I recall, sonar often doesn't work very well when the source/receiver is submerged and the target is close to the surface, and this problem gets worse as wave height increases. The problem being interference (scatter) from both the waves themselves and the bubbles they generate. Also, if you stop to think about it, a whale traveling just below the surface might well have a hard time "seeing", a small boat hull (with its sonar) that sticks maybe a meter and a half or two meters under the surface until the whale was pretty close to the target.

As for using their eyesight, remember that a whale eyes are on the sides of its head, and thus can't see anything forward, regardless of the acuity of the eyes themselves. You can see this effect yourself if a whale or dolphin ever comes along side your boat to "check you out", they almost always position themselves parallel to the boat and then roll over a bit to get an eye out of the water so they can see you. So, I doubt that hull color has anything to do with whales accidently ramming boats.

A couple of added thoughts:

Active sonar may well help, IF it is at a frequency the whales can use. There are "noise makers" used on passive fishing gear for just such a reason, to pretty good effect. Also, there is some evidence that Gray Whale migration patterns are altered by coastal boat traffic along the California coast, particularly on busy weekends near busy ports. The thought is that motor noise may be confusing/annoying the whales.
10-08-2010 07:01 PM
St Anna
Quote:
Originally Posted by killarney_sailor View Post
Last year we had a sperm whale that was a course to T-bone us alter course about 30 feet away and go behind us (thank you, big guy). I understand that whales do not see well, but this thread has me wondering. I assumed that he saw us on sonar and waited until he was close before deciding whether to alter course (we were on starboard!); perhaps he just could not echo-sense us at all and turned when he got close enough to see us.

Our hull has dark blue bottom paint and I had decided against black already. Going to paint next week, perhaps I should be using red to be on the safer side?

I must say that seeing a whale really close (in our case about 10') does focus the attention wonderfully. My wife who was the first one to see him/her could only make frantic noises - I chastised her for not using the classic, "There she blows" and she almost hit me. No sense of humour I guess.
In Qld, their numbers are rapidly increasing - there will be dramas one day soon. Maybe an active 'sonar' noise may discourage them.

I agree with you about certain closely related people you take with you onboard.....If it happens again to you guys, I'll nominate you for the FAMOUS LAST WORDS QUOTEBOOK.
10-08-2010 03:59 PM
killarney_sailor Last year we had a sperm whale that was a course to T-bone us alter course about 30 feet away and go behind us (thank you, big guy). I understand that whales do not see well, but this thread has me wondering. I assumed that he saw us on sonar and waited until he was close before deciding whether to alter course (we were on starboard!); perhaps he just could not echo-sense us at all and turned when he got close enough to see us.

Our hull has dark blue bottom paint and I had decided against black already. Going to paint next week, perhaps I should be using red to be on the safer side?

I must say that seeing a whale really close (in our case about 10') does focus the attention wonderfully. My wife who was the first one to see him/her could only make frantic noises - I chastised her for not using the classic, "There she blows" and she almost hit me. No sense of humour I guess.
10-08-2010 03:55 PM
QuickMick I can only imagine the reaction from your insurance adjuster as you explain you are making a claim for xx$ due to an unfortunate 'whale of a tale'
10-08-2010 02:37 PM
St Anna I have said this somewhere else , so apologies...

We alternate antifoul colours. Last year we went black. The previous time we were black we had whales around (& I mean we were almost part of the pods) on a daily basis for most of the whale season! We were travelling north from about May. - Imagine sitting in the cockpit, having a nice 6kn sail and over your left shoulder, a tail appears, 20' behind your quarter. It disappears, only for the whale to resurface 30' off your stb bow.

Last year, heading south around Cape Moreton, we saw probably 20 whales in about 4 or 5 groups in the afternoon. One breached towards us, about 100m away. I flicked off the auto and watched. It then did a full breach, one (1) boat length away, landing towards our bow. We could see the hairs on the barnacles on his chin. [As I was spinning the wheel to get away from him] Our eyes were out on stalks looking out for this guy. This year, we saw enough whales, not that close, but close enough for concern, up north. I feel there could be something with the black paint and they come over to us.

I will never repaint the hull in black again and never need to see another humpback!!!

The years we have a blue or red hull, we see whales, only in the distance.

As for those guys - they were lucky, very lucky to get time to put out a mayday and to be found. 'We got one back from the sea'
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