Through hull or transom mount transducer?

Murv

Murv

Well-Known Member
Joined
14 Nov 2012
Messages
2,127
Location
Kent
Visit site
I've ordered a Raymarine dragonfly, and am waiting on the through hull transducer to be launched in a Month or so.
However, the chandler has just called, they've just confirmed the price of the through hull over the transom mount is an extra £180.00!
It's a hell of a premium to pay, is it worth it?
The boat dries on it's mooring at low tide onto soft mud, which is why I wanted shot of the transom mount as it always seems to get disturbed whenever it settles on debris etc washed down river.
Any thoughts?
 
We have a transom mounted transducer and also on a drying mooring. Our boat does sit nicely up on her bilge keels though (its a Colvic motor boat btw) and the tranny is never in or near the sand/silt. Can you not mount the tranny any higher?......as long as its under water and out of too much turbulance it should be ok.
 
Thanks for that, I don't think it can really go any higher though, the boat has a very shallow draft.
I think I've got it wrong though, and mistaken an in-hull for a through-hull mounting. I certainly don't want to cut a hole for a through hole, so might have to make the transom mount work anyway! I'll phone the chandler tomorrow to confirm.
 
Murv said:
Thanks for that, I don't think it can really go any higher though, the boat has a very shallow draft.
I think I've got it wrong though, and mistaken an in-hull for a through-hull mounting. I certainly don't want to cut a hole for a through hole, so might have to make the transom mount work anyway! I'll phone the chandler tomorrow to confirm.
Click to expand...

Some years ago, I bought a Raymarine plotter, with fishfinder. It came with a transom mount transducer. I hacksawed the mounting bits off it, and installed it inside the hull on epoxy. Works perfectly.
 
Murv,

if your boats' hull has a vaguely flat run aft*, you could just epoxy ( or sealant works fine ) the transducer inside the hull, as NormanS mentions; no nasty holes !

I did this with a transom type fishfinder inside the hull of my sailing cruiser and it works a treat, I'd never dream of a hole thru hull installation.

A lot of people do this, it's simple, works well, and in this case apparently £180 cheaper !

* If your hull doesn't have a flat area you could either build up a tapered mount inside - air gaps must be avoided - or fit a small holder with the transducer in castor oil, nb it will need a secure top...
 
I too have had no problem mounting a transducer to fire through the hull. I experimented by building a coffer dam round the transducer with plasticene, filling the middle with water and pressing the transducer into the puddle. Worked so well, I cut the bottom out of a margarine tub, epoxied the skeleton to the bilge and put some cooking oil in followed by the transducer and it worked fine for 5 years til I sold the boat. That was on a Westerly where the hull was inches thick and the sounder didn't run out of puff until it was over 200 metres deep.
One problem I was trying to avoid was seeing how deep the bit was I'd just gone over - I prefer to have the transducer as far forward as possible.
 
I know this an old thread but I've just read it so I assume others might also. I too purchased a Dragonfly with a transom mount transducer in the hope that it would fire through the hull. Raymarine specifically state that it is not designed for in hull installation. I like others thought this was just sales pat to get you to buy the through hull transducer, however having tried, plumbers putty, mastic, and oil bath, I lose the bottom at about 10m, so whilst it clearly will fire through it is not effective once over around 10m. I better start saving for the extremely expensive through hull transducer.
 
Well that is not my experience. I have a Raymarine Downvision transom transducer, mounted in Sikaflex in my hull. It works perfectly. Indeed, it works better now than when I tried it on the transom, because it is in the middle of the hull so the effects of pitching are less.
 
Interesting because I have read some fishing forums where others have had the same issue with it not working properly where it's mounted in the hull. Can I ask what boat you have? There are some suggestions that hull thickness might also play a part. Obviously I would like to use the transom transducer in the hull to save having to cut a big hole in the bottom of the boat not to mention the cost. Has anyone else had success with mounting it in the hull?
 
I just mounted it in clear CT1 stuck down in the hull, worked fine down to the deepest water I've been in which was around 35 metres.
 
I might give it another go, I didn't use a clear silicon I didn't think it would make much difference as it was shooting through the hull but it's worth another go, I have coincidentally just bought some clear silicon so I'll try with that.
 
I've always used through hull transducers with no problems. Unless you have a very thick hull it will see through it easily. I had a NASA one which I mounted in a bit of plastic tube epoxied to the hull. The second was a Raymarine and I never investigated the method of fixing.
Both gave erratic readings in shallow water on sandy bottoms due to suspended particles. TBH, I'm not particularly interested once the depth is over 10m or so.
I wouldn't want a transom mounted unit I'd rather have it close to the bow.
 
I know this is resurrecting an old thread, but just wanted to say I just fitted a Raymarine Dragonfly 4 Pro transducer, facing forwards, to the inside of the hull on my Sadler 25 in one of the v berth lockers.

Simply smoothed out the fiberglass with a bit of sandpaper, made a little dimple for the temperature sender and bedded it on some clear silicon.

It works fine up to 50m, haven't been anywhere deeper yet.
 
Tricia said:
I know this is resurrecting an old thread, but just wanted to say I just fitted a Raymarine Dragonfly 4 Pro transducer, facing forwards, to the inside of the hull on my Sadler 25 in one of the v berth lockers.

Simply smoothed out the fiberglass with a bit of sandpaper, made a little dimple for the temperature sender and bedded it on some clear silicon.

It works fine up to 50m, haven't been anywhere deeper yet.
Click to expand...

My DragonFly Pro 4 will be here today, and am thinking of doing the same thing.. would prefer not to have any holes in the hull, and since this is in a 19 foot runabout, I'm never going to be in water deeper than 100 feet, usually less than 30..

I'm wondering how such a mount impacts the temperature reading.. Also, why did you choose to face it forward??
 
Would mounting internally this way, work if your hull is copper coated? Any one tried it? Fitting another through-hull has always put me off fitting a fish finder.
 
When I started this thread it referred to a different boat!
The current one is firing through a copper treated bottom with no problems though.
 
Using silicon, Sikaflex or similar will impair the efficiency of the transducer. Stuck in transducers should be attached with slow drying epoxy resin. Slow drying, so no air bubbles get left in it. Firing sonar through squidgy stuff isn't recommended by the manufacturers. The thicker the squidgy stuff the worse it is, which will most likely be why the results in this thread are a bit hit and miss.

1) Make a small dam where you want to fit the transducer.
2) Fill dam with epoxy resin, deep enough to flow level so the transducer points straight down.
3) When almost dry add a thin layer of epoxy and press transducer into it with a twisting motion.
 
As others have mentioned just epoxy to the inside of the hull. Just build a dam with plasticine and fill with epoxy and place transducer flat as possible. Mix epoxy slowly so no air bubbles show as this effects the ping.
 
You must log in or register to reply here.

Other threads that may be of interest

Y
The Seafarer 700 and NASA clipper sounders saga
Replies
10
Views
432
Dellquay13
Dellquay13

Share this page

Top