Log and sounder positioning

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Michael Green

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I have a 16ft oysterman long keel gaff cutter. Has anyone any advice as to where the best position will be for fitting the depth transducer and log paddle wheel. The hull is GRP, and I will be using a inside hull fitting for the transducer. Propulsion is by inboard diesel engine and 3blade prop. I know about using chewing gum to make a test.

All and any advice and help welcomed.

M J G
 
I think to avoid getting a spurious reflection from the keel you need a clear 45 degree angle each side of the face of the depth transducer. That means it mustn't be too close to the keel, but you have to consider that in relation to the depth of the keel at that point.
Ideal conditions are more likely to found forward rather than aft. Also of course you want the earliest possible warning of shallowing.

The cautions are that that also makes it more vulnerable to damage, especially as the fairing piece will probably be at a considerable angle to reflect the slope of the planks.
Also if too far forward it will lift more in waves.
 
Michael Green said:
I have a 16ft oysterman long keel gaff cutter. Has anyone any advice as to where the best position will be for fitting the depth transducer and log paddle wheel. The hull is GRP, and I will be using a inside hull fitting for the transducer. Propulsion is by inboard diesel engine and 3blade prop. I know about using chewing gum to make a test.

All and any advice and help welcomed.

M J G
Click to expand...

Depth sounder, I prefer the plastic bag and water to test for best location, must not be in a turbulent area so in front of the keel would be good.

Same goes for speed through the water, at the point the bottom starts to flatten up front.
 
Conversely, I definitely recall advice from Brookes and Gatehouse and from Seafarer (I am showing my age...) to the effect that the instrument heads should not be too far forward as they do not work well in aerated water.

Mine are about 2/3 aft and they have always been fine.
 
In danger of getting loads of conflicting information on this one so I'll just contribute with what I've done, which works for me
Depth transponder fitted forward of the bilge keel and as near centre as possible. Thick layer of stixall over the head then moved around until I found the best signal return point, so connected to the display and turned on then once you've found the point where you've got the best reading, wipe off the now old stixall and apply some fresh dollop, put it back where you had the best signal and hold in place while it starts to set, making sure you still have a good signal, then leave it to set.
May not be the method approved by some but it works perfectly for me

Stixall is here http://www.google.co.uk/url?sa=t&so...GOdhXb4yPGiFC_WKw&sig2=6Oufrg2FiOMh4vn1k3tSfw
 
Hi Mike
To be honest I haven't found out what it doesn't stick yet. A very good mate from this here forum sent some to me and I'm testing it in various locations. The transponder sits in my wet bilges, brackish water, and hasn't failed yet. So I decided to test it some more and used it to fit a patch in the cockpit and it stuck and sealed that. So next I stuck the depth display to it and that's still there, so I'm pretty impressed so far. It's not overly exposed to the elements in the cockpit but it is outside, and hasn't failed yet. But when I used it to fix the transponder I expected loads of problems and haven't had any
It certainly seems to do just what it says on the tin, and sticks all :cool:
Thought it might be something some hadn't heard of which is why I put the link, but obviously that isn't where I got it from
Thanks Simon, if you're reading this and lurking again :D
 
One consideration is the distance from the centreline. My Folkboat has the E/S transducer roughly amidships on the port side about 18" from the line of the keelbolts, so when well heeled to stbd it stops working. If starting again I would go further fwd in order to get nearer the centreline and reduce the heeling effect.
 
I acquired an old Seafarer sounder with the transducer mounted on the end of an aluminium tube through which the cable ran. The udea was to just poke the trtansducer in the water over the side or the bow of the boat. The beauty of this was (a) no hole in the boat, and (b) I could sound all around the boat and get an idea of any slope of the seabed.
Peter.
 
Minn said:
Conversely, I definitely recall advice from Brookes and Gatehouse and from Seafarer (I am showing my age...) to the effect that the instrument heads should not be too far forward as they do not work well in aerated water.

Mine are about 2/3 aft and they have always been fine.
Click to expand...

Good work !
Very cool, looking great so far. Keep going, I wanna see it finished! :o
 
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