Installing Nasa Target Depth

[graham]

Will be fitting one in next week or so.The hull forward of the keel on our boat is quite a deep V shape so the transducer will be looking through the glass at a steep angle effectively making the hull grp very thick.

I am thinking of installing it aft of the keel on a flatter bit of hull.The instructions dont help much other than trial and error with chewing gum.

Anyone else any similar experiences?

Also can I bond it on with Silicon,one on last boat was in an oilbath which worked fine ,silicon seems quick and easy and could be scraped off if needed.

PS boat has an outboard so propellor wash wont be such an issue.

 

[simonfraser]

you can bond it with just about anything you like as long as it is solid, i.e. no air.
silicon will work fine.
try bluetack first to find the optimum position.

 

[jerryat]

>> I am thinking of installing it aft of the keel on a flatter bit of hull.The instructions dont help much other than trial and error with chewing gum. <<

I think you'll find that you'll get pretty odd readings in that position caused by the turbulence and bubbles from the water flow round the keel.

It might be better to site it up forward to one side of your 'V' but fixed vertically. I'm not sure an oil bath type of installation would work too well in this position though.

 

[Stemar]

Get a big dob of blutak and try all the likely places until you find one that works well. If it's somewhere that's unlikely to be affected by turbulance under way, go for it. If you're not sure try it out under way. Once you're happy, stick it down. Three years ago, I used the Gosport Pound Shop's version of No More Nails. It's still there.

 

[DaveS]

I mounted a fishfinder transducer inside the hull about 1 m behind the keel using epoxy resin. It reads deeper than either the normal depth sounder or the FLS, both of which are mounted in through hull fittings set just forward and to the side of the keel.

 

[graham]

Thanks for the suggestions people. I think I;ll try it forward first and trial and error before fixing permanently. Cheers

 

[theforeman]

for what its worth - the sounder would be more use if the transducer is mounted forward of the keel. you want to know the depth before the boat grounds, not after.
i have a target 1 which was stuck to the sole just under the companionway - never worked too well.
last year i poxied in a plastic drain pipe in the inside rear corner starboardside forrard locker. once i had cured the oil leaks ( most likely down to my poor epoxy technique ) it worked perfectly. the hull is probably 2 - 3 inches thick under the transducer. the pipe is filled with castor oil.

 

[graham]

If it worked through that thickness of grp I think mounting mine forward wont be a problem.It could also give me an extra couple of seconds to tack when the shallow alarm starts buzzing. /forums/images/graemlins/grin.gif

Having had a lifting keel for the last 9 years I tended to be laid back about touching the mud in the sheltered shallow entrance channel to the harbour.With a fixed long keel now i'll have to take more care or suffer the embarrasment /forums/images/graemlins/blush.gif

 

[theforeman]

up here its the rocks you worry about, not the mud /forums/images/graemlins/smile.gif

 

[milfordman]

Hi there theforman,

I was very interested by your coment that your hull is 2-3 inches thick. What matereal is that, and how big is your boat?

All the best

 

[clive1954]

hi i found a old fairy liquid bottle very handy you need to get the sensor as upright as possible it gives a better reading. cut the top and bottom off the bottle to give a sleeve, fit as tight to the hull as possible and bed it into putty to prevent the resin running out. Pposition the plastic tube in any approproate place and poor some resin in, position the sender and wait for the resin to set, make sure there are no bubbles in the resin and you should have a working depth gauge without cutting a hole in your boat If you want to try several different positions before fixing it you can use water or oil (bit messy) in the tube.

 

[roger]

I had a NASA Target fitted in an oil bath but was unsatisfied with its performance. It did not work in more than 30 metres of water or in shallow water over soft mud. I dont know if it was the instrument, the oil bath or the thick hull.
Incidentally do not cut the transducer cable. Salt water can wick from the cut end a very long way along the screen which then corrodes and the system fails. Make bigger holes for the coax plug to get through even if the are not so neat.