problems with fishfinder, need halp, thanks!

xpertski · 22 January 2006, 16:03

hello all, last year used the fishfinder for first time, its a hummingbird high res one, it seems fine when stationary, however when moving at anything over a few knots, the screen goes all grainy, and fuzzy, and yet the spec says it can handle high speeds up to 70mph, so should be fine..........what is the problem? could it be that turbulance from prop is interfrering? if so what should i do, if i move it much further away from prop, it would be very close to waterline, or should i mount in well at back of boat?

roycruse · 22 January 2006, 17:12

Transducers are very susceptible to turbulence in the water - some pictures of where you have mounted the transducer may help diagnose the problem.

In my opinion the transducers are always better off glued into the hull in the drain sump at the back of your boat (ie where the hull is thinnest or single skinned)

My Garmin transducer is glued into the sump at the back and will track the bottom at 25 knots in 65m deep water which i was most impressed with.

xpertski · 22 January 2006, 18:17

hmmmmmm, could try that, so your suggesting gluing it in the well inside the boat? then i guess just put some sealant in the drill holes on the transom where it used to be. id love to post some pictures, but unfortunately my rib is an hours drive away in a compound so not too easy. i just thought id start to think about how to rectify problems before the season really kicks off!!! haha! its so annoying when you have a good read out from fishfinder, then after a certain speed it goes crazy saying its 1000ft deep etc, and blurred screen. unless its just a massive shoal of fish always following me around under the boat! haha!

codprawn · 22 January 2006, 22:53

If you put it inside the boat you need a "through hull" type - different transducer to the type that fits to the transom.

"Through hull" are better at speed but not as accurate or deep reading as transom mount at lower speeds.

Repositioning will help a lot - bit of trial and error involved though.

roycruse · 22 January 2006, 23:38

Codprawn - I have always given you the benefit of the doubt when you've been in conflict with someone else - Ive even agreed with you on many occasions - but this time I'm afraid you are talking complete bollox !!!

And for the first time I can see why you infuriate so many people - you have posted in here what appears to be a very authoritative statement as if you know a lot about fish finders yet what you say is completely inaccurate.

1. "If you put it inside the boat you need a "through hull" type" - No you do not need a through hull transducer to mount it inside the boat - I have had 2 boats with a standard transom mount transducer epoxied into the inside of the hull.

2. ""Through hull" are better at speed but not as accurate or deep reading" - perhaps you missed the point where I said my sounder was tracking the bottom in a depth of 65m - how deep do you want to go?

3. "bit of trial and error involved though" - are you recommending drilling holes all over the transom until you find the optimal place for it.

roycruse · 22 January 2006, 23:45

heres an excert from a transducer manual - it expalins how you can test the transducer for use inside the boat without having to do anything permanent.

Quote:

To avoid drilling a hole to mount a thru-hull transducer, a transom mount transducer may be used with epoxy inside a boat (“shoot-thru-hull” installation). For a transducer to be mounted inside the hull (shoot-thru, not thru-hull), the boat must be fiberglass, no core (contact your boat manufacturer if you are unsure). Test by placing a small amount of water inside the hull, placing the transducer on top of the water, then verifying the accuracy of the locators versus the current water depth. If they are the same, use slow-curing epoxy (non-silicone based) to affix the transducer to the inside of the hull.

xpertski · 23 January 2006, 00:14

thanks for the advice guys, i was wondering how trial and error worked with drilling holes for transducer

i assume that by fixing the transducer with epoxy in well, if it were to be removed, the epoxy is also removable. the boat is a humber ocean pro 6.3m, its last years boat, i think they use a marine ply core for the transom, but not sure about the hull, i think its all grp....unless someone knows, ill check up on that!
so by placing in well would it give me reading from say inside well to floor to check accuracy?
thanks again for the advice!!!!!

Poly · 23 January 2006, 00:32

Quote:

Originally Posted by xpertski

i assume that by fixing the transducer with epoxy in well, if it were to be removed, the epoxy is also removable.

Epoxy is virtually impossible to remove other than mechanically - e.g. by sanding, drilling, grinding, cutting etc. So I wouldn't epoxy it in until you are sure you have the right spot for it.

roycruse · 23 January 2006, 07:14

The idea is that as long as you have nothing but glass fibre hull between the transducer and the water that hull will transmit the sonic pulses pretty much as well as the water does.

So allow some water to collect in the well and simply place the transducer in the pool of water touching the hull and the sound waves will travel through the water and hull into the water below. If you get good readings then simply glue it to the hull with epoxy (try to get as few air bubbles in the glue as possible when mixing it - and avoid trapping air when you place the transducer onto the glue) - if you ever need to replace it as Polwart says it can only be removed mechanically - I usually find carefully chipping it away with an old wood chisel or screw driver and a small hammer works best

Pete7 · 23 January 2006, 10:09

Sorry codders, I am with Roy on this one, they will work perfectly well. The only other thing I would add is that we used a silicone sealant to glue the tranducer in. Yes I know it says not to in the manual but we did anyway as a temporary measure for one afternoons diving. That was in 1997 and its still in place and working in the club diving boat. It means we can easily get it out again if we need to or if the signal wasn't vry good it could be moved again.

You must get to the inside of the hull though, some ribs have a flat ply plate glassed into the transom with a space underneath, if so the transducer won't work if its glued on top of this.

Pete

Hugh Jardon · 23 January 2006, 10:19

i put a thru hull transducer in a pipe which i fixed to the inside of the hull, filled the pipe with some sort of cooking oil if i remember correctly and then had the transducer submerged in that, it can be quite a good way of fixing the transducer in there for a short period to see if you are happy with the results before going the whole hog. making sure there are no air bubbles either in the fixant or oil or in the fibreglass are critical for reasonable performance, you could silicone the tubing to the inside of the hull so it is easily removed. you need to find a good bit of fibreglass hull that will give you the performance you need that has no imperfections that will impact the signal etc

wavelength · 23 January 2006, 11:57

all of our beach launched fishing boats around here simply silicone the transducer onto the single layer of glass in the well at the transom. Then it doesnt get damaged by rocks and shingle on the beach and the silicone is easy to remove if you need to. It will work perfectly well without silicone and without any nasty oil in a tube if you just throw a bucketfull of water in the drain well and toss the transducer in there! Helps if you wedge it upright of course

We used to do this with one of our fishing boats and then take the whole rig out when we went to Ireland with my mates boat so that we didnt have to run thru all that expensive paper on the one he had fitted-worked fine just thrown in a well full of water (transducer-not the top bit ! ). And No you dont need a shoot thru the hull type transducer to make it work

As a passing thought we dumped our last hummingbird as it didnt want to know at speed-replaced it with a cheap (£70) eagle cuda-brilliant, works at all speeds, the shallow water alarm is a godsend round here, and transducer is simply siliconed in the well! Got two now and they are both fine after over a years hard work.

jwalker · 23 January 2006, 12:20

Yup silicon for me too. 200ft and 35knts no problem. I used to cast a block of resin in the well and set the transducer into that, it worked fine, but silicon seems to be just as effective.

Hugh Jardon · 23 January 2006, 12:34

i did it this way rather than throwing a bucket of water int here because i have a large space under the floor that is dry where the fuel tank is and no bilge pump exists, so fitting a pipe with silicone was a good/only option for me. It was in there for years working fine!

I would suggest using silicone as well as you can then remove it and fit it else where if needed, if you use a more permanent fixing they you are somewhat buggered if you need ot move it.

Quote:

Originally Posted by Hugh Jardon

i put a thru hull transducer in a pipe which i fixed to the inside of the hull, filled the pipe with some sort of cooking oil if i remember correctly and then had the transducer submerged in that, it can be quite a good way of fixing the transducer in there for a short period to see if you are happy with the results before going the whole hog. making sure there are no air bubbles either in the fixant or oil or in the fibreglass are critical for reasonable performance, you could silicone the tubing to the inside of the hull so it is easily removed. you need to find a good bit of fibreglass hull that will give you the performance you need that has no imperfections that will impact the signal etc

xpertski · 23 January 2006, 19:26

sounds like sound advice guys, using silicone to fix it in the engine well, then test to see how its reading go, and if it doesnt work well after many positions, get a different fishfinder like wavelength did! i have to admit the sound of using silicone is much more attractive, no need to drill permanent holes, and using tough epoxy which is a bugger to get off! thats one of the many pre season jobs with a possible solution, cheers

roycruse · 23 January 2006, 22:16

many people i have heard have had sucsess with silicone but my old man tried it and had terrible results. I would like to know the difference between what he did and what those that had good results did.

my advice would be to try with just placing it in a pool of water and if you are happy - then try silicone.

if you cant get good results with the silicone - at least you can peel it off and try epoxy last.

wavelength · 23 January 2006, 22:51

thin silicone and avoid air bubbles

jwalker · 24 January 2006, 00:11

Wavelength, you beat me to it.

No air. Skoosh the silicon smoothly and continuously. If the transducer is not in the centre, you may need to support it while the silicon cures because you do need it square to the sea or your depth reading will be inaccurate.