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-   -   Do Whales like Concrete Boats! (http://www.sailnet.com/forums/general-discussion-sailing-related/68897-do-whales-like-concrete-boats.html)

Ilenart 10-08-2010 08:47 AM

Do Whales like Concrete Boats!
 
Another boat was sunk this week off the West Australia coast by a whale & initial reports was that it was concrete (was actually wood, see link below).

I was having a discussion with a surveyor yesterday and he was telling me about the first Fremantle to Bali race back in the 70's where a whale came up between three yachts in company (two fibreglass and one concrete) and the whale starting rubbing himself under the hull of the concrete boat. Apparently the yacht lasted about three minutes before going down, the crew had just enough time to grab their wallets, camera and ditch bag. Apparently there is a very funny picture around which captured one of the crew marching off the yacht into the water with the whales' tail sticking up in the background.

The surveyor's theory is that the whale's sonar cannot detect the fibreglass yachts. However the concrete yacht looks like a rock so the whale came up for a scratch, unfortunately for the concrete yacht.

So what do you think? Any anti rock measures that concrete yacht owner's can take?

Ilenart


Men 'lucky to be alive' after whale sinks boat - ABC North West WA - Australian Broadcasting Corporation

Stillraining 10-08-2010 08:54 AM

Well the article says they hit the whale and the boat like you said was wood so What Does it have to do with your question....Just asking?

Wasn't it last years Ha HA race that one Glass boat sank due to hitting a whale as well?...it happens....I think it was a steel boat that was landed upon by a breaching whale this summer as well...I don't think their selective...with play toys or getting out of the way..;)

If my back itches I use whats available at hand....a few hundred miles out to see that's pretty limited for them...they take what they can get..maybe whales are smarter then we think and knew the concrete boat would last just long enough to get the job done..the glass ones not..:)

St Anna 10-08-2010 01:37 PM

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'

QuickMick 10-08-2010 02:55 PM

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'

killarney_sailor 10-08-2010 02:59 PM

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.

St Anna 10-08-2010 06:01 PM

Quote:

Originally Posted by killarney_sailor (Post 652544)
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.

SlowButSteady 10-08-2010 07:26 PM

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.

Stillraining 10-08-2010 08:51 PM

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.

poopdeckpappy 10-10-2010 12:04 AM

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

Stillraining 10-10-2010 12:25 AM

Thanks for that bit of trivia pappy...I learned something..:)


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