Which depth sounder? In hull or through hull? Cheap or dear?

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Sheerline

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You can clearly pay anything for a depth sounder.

There's a Humminbird one that seems to do everything I want for US$77 - or slightly more glamorous ones from Raymarine or Northstar for four times the price. Are they worth it?

And the in-hull arrangement where I epoxy the transducer to my grp hull is appealing (one less hole on the hull) but do they work well? Do the through hull ones work better?

I have a 30 year old GRP keelboat and I intend installing the transducer just ahead of the keel in the V berth.

Advice from the panel is always appreciated.
 
i have had two boats with through the hull transducers which work fine. Only issue is to make sure they are fully bonded to the hull with no air bubbles or in oil. The NASA target ones are inexpensive and work well. They are also available through chandlers for after sales service and that may be worth the extra as sopposed to an american one mail order.
 
I've just installed a NASA Target2 (to replace an earlier model). It is currently only £84.95 inc VAT from AllGadgets

In installed it he same way as the existing one had been installed. The actual through-hull hole is quite small, then there is a streamlined wooden housing glued/epoxied to the hull with a larger hole in it for the larger diameter part of the transducer.

It only requires a half-inch through hull hole with the opportunity for loads of sikaflex. The plastic nut pulls the transducer up tight against the hull.

transducer2.gif
 
I also have the NASA target 2, works very well; good light for night sailing; very clear number for day sailing. no need for anything else.
 
Q - And the in-hull arrangement where I epoxy the transducer to my grp hull is appealing (one less hole on the hull) but do they work well? Do the through hull ones work better?
________________________________________
This is a perfectly normal and effective means of installing a depth log. The secret is to have no bubles of air in the castor oil fillling the housing tube when secured to the hull. This way the signal from the underside of the transducer radiates directly through the hull to the sea.

Installing is therefore a simple job.

For regular cruising in coastal waters, there is no advantage is hacking a hole in the hull.



As to make, any reputable name should work.

PWG
 
I put in a NASA as well. Tested for position by putting it in a plastic bag of water and nestling this against the hull where I wanted it to go. Worked OK so stuck it in a blob of Sikaflex. I'd looked around for plastic pipe to fill with oil but couldn't find suitable diameter; there are kits with tube plus epoxy but impatience led me to use Sikaflex. Could always glass it over later I suppose.
 
The dearer ones eg Raymarine are usually designed to be able to integrate with other items in the model line ie via NMEA / Seatalk or the later NMEA 2000. If you don't need that capability then ignore and go for budget gear .. Echopilot, Nasa etc.

I've had NASA rotating LED and digital - very good and do the job. My present boat has Dual Depth / Speed in an Echopilot item - good but it's nightlight is not as good as the NASA.

With prices as they are now - it's as well to go for the budget Fishfinders such as Cuda etc. You get depth, temperature as well chance to catch some fish ! With many of these you will also have transducer option to fit to transom instead of through hull or inside. Easy mounting....
 
I have a clipper one glued on inside.It works well.Last year got a Hummingbird fishfinder, it shows depth plus the rest.It cost 80$ and it is placed on the hull with a dolip of vasline inbetween and works fine.
 
[ QUOTE ]
For regular cruising in coastal waters, there is no advantage is hacking a hole in the hull.

[/ QUOTE ] One should never hack a hole in the hull unless running aground at the time. A hole saw is much to be preferred.

However - I am curious as to why you specify coastal cruising in your comment - i.e. is there some advantage in a through-hull fitting for certain types of sailing, and if so what types of sailing?

- W
 
I had a NASA target for several years in an oil filled tube bonded to the rather thick hull. It always gave up at about 30 metres depth.
I replaced it with a SILVA model with a thru hull fitting (fibre glassed in. This gives up at about 180 metres - good.
However it also respond to motor boat wakes and sets the alarm off unnecessarily - bad.
My untested opinion is that the inboard mounting with a thick hull reduced the sensitivity of the NASA rather too much for comfort.
 
If you go for the NASA, the earlier transducers for the Seafarer work, so if you have already got a through hull installation, you dont have to change it
 
My Echopilot transducer is sitting in an oil filled tube inside hull. It's a Seafarer tranducer as Nasa / Echopilot / Seafarer and many others use the same Airmar transducer. I can get good response out in baltic to over 100m apart from when boat starts to move around in swells / waves - as then the bilge keels tend to get pockets of air go between them and the transducer then fails to get signal return ... in smooth water - deep water will read. The lack mof reading when hull; moving about only seems to be in deeper water, shallow water where display is vital seems reliable and no problem.
I accept that if transducer was actually through hull - I would likely get greater depth reading - but for what ? usually I am looking for crossing a sounding line a lot less than the 100m line - so I'm satisfied.
 
Suggest you get a Fishfinder rather than a basic sounder. It will do all that the sounder will plus a pictoral view of what's underneath you. Price will be little dearer if not the same.
We've had three of these on our last 3 boats and epoxied the transducers in the bilges. All have worked well, though I've not had much success on the fish catching!!
 
If you go with e.g .Garmin then there is a choice - they use Airmar transducers and there are both through hull and in-hull styles. I chose an in-hull adjustable deadrise transducer, which cost about the same as a through-hull , give or take 20%
Airmar recommend silicone sealant to bond the transducer housing to the hull, and then to use antifreeze instead of oil

A previous Garmin installation on Forethought used a lake of epoxy behind a silicone dam to float a stern transducer in (as provided with their fishfinders) . This worked to at least 60 metres depth.
 
That's what I was going to say /forums/images/graemlins/smile.gif Advantages of a fishfinder include a picture of the bottom (and indication of the substrate), stick the transducer to the inside of a grp hull so no holes to make, system voltage display, can be relatively cheap. Oh yes and it shows the depth. And fish /forums/images/graemlins/grin.gif

Advantages of an depth sounder....errr?
 
[ QUOTE ]
If you go with e.g .Garmin then there is a choice - they use Airmar transducers and there are both through hull and in-hull styles. I chose an in-hull adjustable deadrise transducer, which cost about the same as a through-hull , give or take 20%
Airmar recommend silicone sealant to bond the transducer housing to the hull, and then to use antifreeze instead of oil

A previous Garmin installation on Forethought used a lake of epoxy behind a silicone dam to float a stern transducer in (as provided with their fishfinders) . This worked to at least 60 metres depth.

[/ QUOTE ]

Why Garmin ? Why the inflated pricing - when same information can come from a much cheaper item using same Airmar technology. In fact Fish Finders now available at cheaper than most basic Echo-Sounders !
 
Fishfinder and bottom quality

I've been told (i.e. have a vague idea) that a fishfinder can give you an idea of bottom quality so you can gauge whether your anchor will hold. If true, this would make a fishfinder a sensible choice.
NB. Fishfinders usually seem to be surface mounted nt panel mounted which could cause problems.
 
Thanks all.

How ugly an appendage is that NASA?! Another good reason to epoxy inside.

I don't really want a fish finder - just a discrete read out to let me know as I approach a wharf or beach that it's getting too shallow for a small boat that draws 6 feet.

Thanks for the excellent responses.
 
[ QUOTE ]

And the in-hull arrangement where I epoxy the transducer to my grp hull is appealing (one less hole on the hull) but do they work well?

[/ QUOTE ]

Got a NASA one - in-hull.
Does everything it needs to do for less than £100.
If it's good enough for the East Coast, it's good enough for anywhere else.
 
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