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Old 24 July 2012, 12:17   #11
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prop

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A friend of mine lost a relatively expensive SS propeller (roundabout 1200 euros), from a outboard. Its a small prop about 15 inch diam. The search area is relatively narrow(within 200 x 200 meters), depth is less than 20 m. The water is not clear so having a diver searching it
without accurate position would be a huge job.

But, how about using a echo sounder to locate it first? What type of kit(leisure level...) would be needed to find such a small piece, or is it a totally mad idea?

I think the sea bed is solid rock with a unknown layer (guess pretty thick) of sediment on top
have you tried contacting your local dive club, most are obliging and it will give them something to do for a couple of hours? Be prepared for the bar bill!
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Old 24 July 2012, 14:40   #12
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Good comments, seams to be fifty fifty..... In the past my first ever outboard (johnson 2hp) dropped from the transom during towage. That one we tried to dive but in vain, difficult circumstances regarding visibility and sea bed.

Sounds like diving is more effective than sonar, was just thinking how these new downscan fish finders would be up to such task and to make a preliminary positioning before diving.

On leisure boats haven't used much sonar, previous one was a Shakespeare with the flashing led..., but will install something on the SR this summer.

Diving club sound like a good idea unless we can borrow a boat with top notch sonar.
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Old 24 July 2012, 15:22   #13
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Quote:
Originally Posted by wellhouse View Post
have you tried contacting your local dive club, most are obliging and it will give them something to do for a couple of hours? Be prepared for the bar bill!
I agree its the way to go, and your best bet, they'll see it as a good training exercise,and you could save a nice few Euro's...provideing ofcourse they're not all Rampant Alkies
As for spotting it on Sonar ect, unless it fell off thr QE2! forget it.
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Old 24 July 2012, 17:52   #14
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This "might" be a help?

Nauticalia Trade Sales : Sea Searcher Recovery Magnet
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Old 24 July 2012, 17:59   #15
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On stainless?
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Old 24 July 2012, 18:06   #16
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works in cheap s/s lol

s.
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Old 25 July 2012, 02:32   #17
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works in cheap s/s lol

s.
Some very expensive stainless is magnetic think expensive kitchen knives on magnetic racks. It's something to do with the crystaline stucture of the steel, I think, probably wrong
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Old 25 July 2012, 03:49   #18
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stainless

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On stainless?
Stainless steels are a very broad group of metals. The name was adopted as a generic term for steel alloys with a minimum of 10.5% chromium. The chromium gives the steel its 'stainless' properties - essentially corrosion resistance. On the surface of the metal, a very thin chromium-rich oxide layer is formed which is inert - i.e. it prevents the steel from rusting. The advantage of stainless steels over plated steels is that, if scratched or damaged, the steel will 'self-repair' as a new oxide layer is formed. In plated steels, scratches in the plate will often lead to corrosion of the steel underneath.

In general, the higher the proportion of chromium, the stronger the corrosion resistance of the steel. In addition to chromium, other metals are added to give the steel particular properties such as strength and malleability. Specifically nickel is used to strengthen the oxide layer.

As for whether they are magnetic, the answer is that it depends. There are several families of stainless steels with different physical properties. A basic stainless steel has a 'ferritic' structure and is magnetic. These are formed from the addition of chromium and can be hardened through the addition of carbon (making them 'martensitic') and are often used in cutlery. However, the most common stainless steels are 'austenitic' - these have a higher chromium content and nickel is also added. It is the nickel which modifies the physical structure of the steel and makes it non-magnetic.

So the answer is yes/maybe, the magnetic properties of stainless steel are very dependent on the elements added into the alloy, and specifically the addition of nickel can change the structure from magnetic to non-magnetic.

The following company website has a useful high-level definition of the broad stainless steel categories. parkrow.org

THE ANSWER IS MAYBE !!!?
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Old 25 July 2012, 03:59   #19
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Stainless steels are a very broad group of metals. The name was adopted as a generic term for steel alloys with a minimum of 10.5% chromium. The chromium gives the steel its 'stainless' properties - essentially corrosion resistance. On the surface of the metal, a very thin chromium-rich oxide layer is formed which is inert - i.e. it prevents the steel from rusting. The advantage of stainless steels over plated steels is that, if scratched or damaged, the steel will 'self-repair' as a new oxide layer is formed. In plated steels, scratches in the plate will often lead to corrosion of the steel underneath.

In general, the higher the proportion of chromium, the stronger the corrosion resistance of the steel. In addition to chromium, other metals are added to give the steel particular properties such as strength and malleability. Specifically nickel is used to strengthen the oxide layer.

As for whether they are magnetic, the answer is that it depends. There are several families of stainless steels with different physical properties. A basic stainless steel has a 'ferritic' structure and is magnetic. These are formed from the addition of chromium and can be hardened through the addition of carbon (making them 'martensitic') and are often used in cutlery. However, the most common stainless steels are 'austenitic' - these have a higher chromium content and nickel is also added. It is the nickel which modifies the physical structure of the steel and makes it non-magnetic.

So the answer is yes/maybe, the magnetic properties of stainless steel are very dependent on the elements added into the alloy, and specifically the addition of nickel can change the structure from magnetic to non-magnetic.

The following company website has a useful high-level definition of the broad stainless steel categories. parkrow.org

THE ANSWER IS MAYBE !!!?
Good! Now i know!
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Old 25 July 2012, 18:44   #20
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Downside with the sea searcher magnet is that its just about one directional and it won't draw itself to a nearby object unless it's just about dropped onto it , I used to keep one on the fishing boat if I needed to pick up the mooring chain ,
having said that if it gets a good flat surface to stick to it takes some getting off unless you start doing a load of twisting .
Only last week we were messing about with one and it supported my mates weight 14 stone from a steel beam .
Just tryed mine out using various stainless oddments from the dogs bowl right through to 30 mm bar and it wouldent stick to any of it .

funny thing is in the advert for it when they first came out it says ( recover lost outboard engines ) well to say most outboards legs are Aluminium and the only steel part would be the flywheel encased with a plastic cowl , that is unless it's an old Seagull and even then it would be the flywheel that it could stick to as everything else is stainless, Aluminium or Brass .
Oh and keep it away from computer monitors as I have just sucked all the display to one corner of the screen with it .
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