transducers

codprawn · 27 September 2005, 15:34

What is the best sort of transducer to go for??? Ideally to measure speed/temp/depth. It is for a Raymarine c80 with a dsm300 fishfinder module.

I chose initially a transom mount but am worried that it won't be accurate at speed. I assume a through hull is better but they do so many different kinds - and nobody seems REALLY to know enough about them - the bloke at Raymarine was just reading info off the website!!!

bogib · 27 September 2005, 15:37

Have a look at www.airmar.com as they are the main transducer manufacturer.

Bogi

codprawn · 27 September 2005, 19:15

I see what you mean - most of them look the same as the Raymarine ones!!! trouble is on their site when you choose Raymarine they say "no matches found"!!!

Would a through hull produce too much drag - one of the flush fitting ones???

Would really like the in hull 2kw model but shudder to think how much!!!

lc0021 · 27 September 2005, 19:26

Can you get speed readings from a 'through hull' transducer ??

I'm pretty sure that to get a temp reading the transducer must be physically in the water

Alex Brown · 27 September 2005, 19:35

My transom mount speed thingy is pretty useless above 30knots - it pretty well matches the GPS upto that point, and then it drops to say 15knots.

If you do go transom mounting the transducers, make sure they're sturdy enough to take the pounding the rib throws at it. I'm on my 2nd airmar now after the 1st one snapped off on my way out to the smalls last year doing about 30knots (it wasn't that calm). The current transducer is better, but even with the screws as tight as they will go, it still manages to pop up every so often.

Thru hull we priced at around £400 for the tug at work - you could quite easily get a transom transducer and stick it in the bilge and it'll work fine. The only thing that won't work from that is the temperature

-Alex

DGR · 27 September 2005, 19:43

That is how mine is set up - bog standard transducer mounted inside the hull, about 1m in front of the transom. As Alex says - the only thing that doesn't work is the temperature.

D...

IanE · 27 September 2005, 21:49

airmar stuck inside hull filled with oil -works fine with raymarine 400 fishfinder,
don't need temp or speed !!

I couldnt use transom type, I suspect it wouldnt last long at speed plus I berth in marina an it would get clogged with green stuff. Ther's a good thread somewhere on here!!

Mark Halliday · 28 September 2005, 07:52

Quote:

Originally Posted by codprawn

I see what you mean - most of them look the same as the Raymarine ones!!!

Thats because they are the same. You even get the Airmar instructions with them.

Quote:

Originally Posted by codprawn

Would a through hull produce too much drag - one of the flush fitting ones???

No. The projection is only about 3-4 mm for a standard depth transducer.
It just takes a load of nerve to cut 51mm holes in the bottom of your boat.

I have a Raymarine ST40 Bi Data, with through hull transducers. I cut a hole for the log and mounted the depth transducer "in-hull" in a bit of plastic pipe.

Charles · 28 September 2005, 08:43

Quote:

Originally Posted by Mark Halliday

.
It just takes a load of nerve to cut 51mm holes in the bottom of your boat.

I have all the bits to mount a through-hull transducer but do NOT have the nerve to do what you did! Spoke to Derek at Scorpion and Graeme Jelley will never do this on any of their boats ...... just don't know what to do as the transom mount on a rib never ever lasts. Broke 3 already and gave up. Need a solution for my Raymarine Tri-data which is a brilliant bit of kit but useless at the mo!!

Mark Halliday · 28 September 2005, 12:58

Ct01

I cut a hole for the log impellor just inboard of the st'board stringer and just behind the bulkhead that supports the back of the fuel tank. I guessed that there would not be too much flexing around there. The hull is about 10mm thick here.
The depth transducer may well get its own hole this winter as it is not much use under 10 ft when mounted inside the hull. Normally I recon you can see the bottom when it glitches out.

Luckily there is a planing pad so the depth transducer will sit level.
I also put a 500gph auto pump in there just in case. So far there have been no problems with the 1 hole.

bandf · 30 September 2005, 20:13

G'Day Guys,

I fit about 10 transducers a week, both through hull and transom, and in terms of discrimination and usability, there isn't much difference. When we fit a bolt through hull unit, we cut the 2 inch hole, then use an epoxy adhesive like Epiglue as a sealant when the nut is done up. Haven't had one leak or fail in over 10 years. Shoot through hull transducers (wetbox or not) are OK, but as you've observed, the temp sensors are useless, and you lose between 5 and 20% of the xdcr's output power and discrimination getting through the hull, so we try not to shoot thru unless we have to - in addition to this, a lot of our RIBs here in Oz have aluminium hulls, so shoot thru isn't an option. Best bet we've found over the years is the transom mount - as long as care is taken in locating, we haven't had too many problems (except for one customer who insisted on driving his into rocks!). In addition, the transom mounts are usually beter featured and cheaper. The Airmar comment is right too - most of the major manufacturers use Airmar transducers, except the standard range of xdcrs from Lowrance and Navman - they are produced in house by the manufacturers. In short, I'd use a transom mount, unless you've got a specific reason not to (moored boat, beach launching, etc..)

Hugh Jardon · 30 September 2005, 20:22

i used a piece of pipe just slightly larger than the transducer thing and then filled it with oil and seems to work a treat, i was not brave enough to drill a hole and i did not get the sounder fitted when i bought the boat.

you do need to change the oil every now and then though!!!!!!!