Newbie EchoSounder Question

[Guest]

Forgive my ignorance, but is it possible to buy a depthsounder where the transducer is mounted inside the boat rather than having to make a hole in the hull?

My current sounder has gone AWOL and I really wanted to get a replacement in without getting the boat out of the water. The current transducer is firmly fibreglassed in place.

Mark

 

[vyv_cox]

Yes but you need a couplant to carry the signals from the transducer to the hull. This is often an oil inside a tube epoxied or similar to the hull interior, then the transducer sits inside that. I have used a transducer epoxied direct to the hull with rapid araldite. All these variations will work but have drawbacks - accuracy is rather less, stowing heavy items knocks the tube off, they always fail when you need them most, etc.

Through hull is best, just ahead of the keel (or in the centre of the hull for bilge keels) best of all. Turbulence needs to be minimised as much possible and the transducer needs to be immersed at all times.

 

[milltech]

AWOL suggests someone nicked it. If the transducer remains, and if it was a Nasa, Seafarer, early Navico etc. running 150 khz then a currently produced Nasa Clipper or Target 2 sounder will just plug on to the end of it without having the bothersome problem of locating and installing a new transducer.

If this is an interesting option for you then looking at http://www.allgadgets.co.uk may assist your decision making process, not least because you can download the instruction manuals free, and this may assist you in deciding if you can go forward without professional help.

John

 

[Andrew_Fanner]

And if you are still shy a transducer/in hull mounting I have one of each for a small consideration, not needed because my old sounder transducer works with the new NASA machine.

PM me for details.

Two beers please, my friend is paying.

 

[duncan]

not disagreeing with vyv, but....
quiet frankly sticking the transducer inside the hull - in the right place - will work well for nearly all applications. For a fiberglass yacht this may well have to be off the centre line in front or behind the keel or it's shadow to avoid extra thick lamination or reinforcing. Sikaflex or epoxy or fiberglass will do the job - put a good dollop on and bed the 'ducer in well. I think sikaflex best as it will not crack if the hull flexes leading to a possible air pocket between the hull and 'ducer. It is also easier to cut away and clean up!
As a yacht rarely sails upright you are always going to get a degraded signal anyway.
I have used this on my last 2 boats and they deliver excellent results - in both cases driving high quality output 'fishfinder' units with no problem at up to 40 knots (ok they are not yachts!)
Note there have been a number of past threads covering this subject in great detail.
Happy boating

 

[bedouin]

I think the usual advice is to use rigid mounting rather than flexible sealant (i.e. epoxy rather than silkaflex/silicone). The idea being that the flexible compound absorbs more of the signal on the way through (twice) and so has poorer performance.

 

[petery]

Raymarine produce an in-hull transducer option with the ability to align the transducer vertically in the hull without the need to cut the housing - but surprisingly they never seem to advertise it. You simply use Sikaflex around the edge of the housing.

They suggest you test the position to fix it by placing the transducer in a plastic bag filled with water and placing the bag in various positions in the hull to ensure you get a good signal.

 

[duncan]

agree again but in practice the degredation of signal if the hull is prepared to a reasonably smooth finish and the transducer is pushed firmly down to minimise the quantity of 'filler material' will be very small.
I have tested normal silicone v sikaflex v epoxy v external mounting and only the external has made any difference - but not so much that I mount it outside.
Yes - over about 150ft in saltwater I seem to loose a bit of clarity on bottom detail when I compare the images afterwards but unless I was a survey vessel or professional fishing vessel working deep water wrecks it really doesn't seem to matter.

 

[vyv_cox]

Don't disagree about the attachment method, although my own results and those of a few others posting here have been rather mixed when not using through-hull mounting. I do take issue with you over mounting aft of the keel, though. My first boat was equipped like this and we never got a sensible reading out of it, except at anchor. Moving it to the correct location fixed it fine. Every sounder I have bought stresses that the location should be free of turbulence.

 

[duncan]

absolutely agree about the turbulance!
Generally yachts have a lot of reinforcement around the centre line and I was suggesting that 'off centre' may be better - (a bit not 6ft!) Equally to one side of the keel as to be avoided because you will end up indicating your keel as the bottom when sailing over a particular angle of heel.
If it's accessible, and not reinforced with wood etc , a couple of feet in front of the keel on the centre line gives the best of all worlds on a yacht...sikaflex (squeezed out as far as possible) for thin laminate that is designed to flex a lot; epoxy or glass resin where flexing is not expected......all imho.

happy boating