In-hull (Airmar P79) vs. through-hull transducer

[Nick14]

Greetings all,

I'm deciding between an in-hull and through-hull transducer for my upcoming boat.

Specifically, I'm weighing the Airmar P79 in-hull unit. Is anyone using one of these? What do you think of it?

My main interest is simply accurate depth readings. Some rudimentary sonar, to get some bottom information, would be very nice to have but not an absolute necessity. No 'fish sounder' capability needed (the only fish I encounter are on my plate when I eat them).

I understand a through-hull transducer will give much better sonar performance (if an in-hull unit can even do it at all). I'm balancing that against my preference to not put any unnecessary holes in the bottom of a new boat, and the ease of installation of an in-hull unit (the hull is solid glass so there shouldn't be any issues with depth readings through it).

Any and all experiences and observations would be greatly appreciated.

Thank you!

 

[porman]

I installed a P79 in our Camano and was very happy with it. We were using Raymarine electronics. When we sold the boat 9 years later it was still working great.

 

[Bacchus]

I had an Airmar P79 and replaced it with a thru hull unit and fairing block.
My reasoning was I wanted a picture of the bottom for anchoring decisions and I also wanted water temp as we do swim off the boat a fair amount.
My P79 only provided digital depth. Whether bottom is hard, soft and weedy was desirable. With digital only I sometimes read 1-2 ft when that was depth to weeds and not bottom. Now I can see conditions
Only you can decide whether either of those is important to you. I'm glad I changed and it wasn't all that difficult to do. It did take a helping hand for the install but it was pretty straight forward.

 

[Nick14]

I installed a P79 in our Camano and was very happy with it. We were using Raymarine electronics. When we sold the boat 9 years later it was still working great.

I had an Airmar P79 and replaced it with a thru hull unit and fairing block.
My reasoning was I wanted a picture of the bottom for anchoring decisions and I also wanted water temp as we do swim off the boat a fair amount.
My P79 only provided digital depth. Whether bottom is hard, soft and weedy was desirable. With digital only I sometimes read 1-2 ft when that was depth to weeds and not bottom. Now I can see conditions
Only you can decide whether either of those is important to you. I'm glad I changed and it wasn't all that difficult to do. It did take a helping hand for the install but it was pretty straight forward.

Thank you!

Does the Airmar P79 provide any sonar capabilities? A couple of electronics installers I've talked with have given me differing opinions on that.

 

[Bacchus]

Thank you!



Does the Airmar P79 provide any sonar capabilities? A couple of electronics installers I've talked with have given me differing opinions on that.

Mine did not but there may be some that do... not sure?
I found the model #s a short ways up the cable and checked it but was told digital only for mine.

 

[grahamdouglass]

I installed one for my Raymarine E80 and it has worked fine. I also had a Lowrance X52 that I had on my dinghy. I picked up a cheap shoot through the hull transducer ($10 at a used marine place) This sounder is independent of my networked Raymarine Electronics. This is in case my electronics go down. I will have a working sounder and I can use my charts.

 

[Woodstock]

Our boat had an original Airmar B60 through-hull transducer that was working fine but I wanted a backup so I installed an in-hull P79. These are both connected to Raymarine sonar. The P79 performance is not much different than the through-hull. Can hardly tell the difference so both are very good for our needs. I haven't used it beyond about 100' but I think it would be fine.

 

[High Wire]

We have the P79 for NMEA 0183. Our only issue was when we first bought the boat, the fluid that fills the base very slowly leaked out causing it to no longer read bottom. Had to pull it off and re-seal then refill. It’s digital depth only. Whatever you connect it to has to be able to add/subtract keel offset if you want true bottom depth.

 

[rslifkin]

If you want sonar you can generally adapt most transducers to mount inside and shoot through the bottom.

 

[DrissZougari]

You can do everything that you may need for a Trawler such as depth and fish sonar except the water temperature.

 

[koliver]

You can do everything that you may need for a Trawler such as depth and fish sonar except the water temperature.

If you install the TDucer outside of the ER, you will get an accurate temp reading as well as accurate depth readings and all the sonar the TD and the display are set up to give you.
My hull has several old thru-hull TDs that are no longer in use. 2 of them gave boat speed. That is the only function the in-hull TDs fail to give you. My hull also has several in-hull TDs. None of the upgrades this hull has seen were due to TD failures. The newer TDs are only there to maintain compatibility with the upgrades to the display units that have required those changes. All the In-Hull TDs give depth, sonar and temp. I see depths down to the extent of the range of the display unit. IIRC that is in excess of 1000 ft.

 

[Nick14]

If you install the TDucer outside of the ER, you will get an accurate temp reading as well as accurate depth readings and all the sonar the TD and the display are set up to give you.
My hull has several old thru-hull TDs that are no longer in use. 2 of them gave boat speed. That is the only function the in-hull TDs fail to give you. My hull also has several in-hull TDs. None of the upgrades this hull has seen were due to TD failures. The newer TDs are only there to maintain compatibility with the upgrades to the display units that have required those changes. All the In-Hull TDs give depth, sonar and temp. I see depths down to the extent of the range of the display unit. IIRC that is in excess of 1000 ft.

Thank you everyone! Your comments are very helpful and useful!

@koliver what in-hull transducer are you using?

Thanks again!

 

[psneeld]

Pretty sure I used a P79 with my Raymarine MFD.

It says depth only but that means no speed or temp because it is a shoot through the hull type.

From the Raymarine website... "Note: Being an in-hull transducer, there is no water temperature sensor on the P79 transducer."

"The design of the P79 accommodates a wide range of deadrise angles from 2° to 22°. This transducer is intended for use on vessels with solid fiberglass hulls with a maximum thickness of 5/8". P79 can also be used on aluminum hulls less than 3.8mm (0.125") thick."

It is a 50/200 hz transducer and does full sonal with a matching fishfinder (or MFD with finder in it).

Doesn't do any of the fancy new sonar like down imaging or side scanning (I don't think) but is a great in hull for basic cruising wishing a basic fishfinder.

 

[jgwinks]

My in hull ducer has temp and appears to work fine. Could be a degree higher as it's glued to the inside of the hull but close enough. It's actually a thru hull type but I added it with the boat in the water so I mounted it as an in hull. Just about any ducer without a speed wheel will work just fine shooting through the hull as long as you find the right spot, no core etc.

 

[psneeld]

My in hull ducer has temp and appears to work fine. Could be a degree higher as it's glued to the inside of the hull but close enough. It's actually a thru hull type but I added it with the boat in the water so I mounted it as an in hull. Just about any ducer without a speed wheel will work just fine shooting through the hull as long as you find the right spot, no core etc.

Thru hulls designed to be thru hulls may have the temp sensor in them so they may actually read "something"...

Not so sure the company would waste money on installing a temp sensor in a transducer never made to come in contact with the outside water temp.

 

[Marco Flamingo]

I installed one earlier this summer. I'm pretty sure that the old one went out because the sounder was turned on while the boat was hauled. Cost to haul again and have the transducer replaced was about $2k and 6 days time (when the yard could fit me in). P79 was $130 and I installed in one afternoon. I tend to lose the bottom at >100 feet, but that might be the Garmin and not the transducer. Worked fine on a 10 week cruise, although there were a few times when I slowed almost to a stop to make sure it caught the bottom before entering a narrow/shallow channel.

 

[Nick14]

Thank you very much everyone!

I'm going to go with an in-hull Airmar P79, for the reasons others mentioned. All I really need is depth, it's all I've had in decades, it's easier and cheaper to install, it's easier to maintain, and it doesn't require another hole to be drilled through the bottom. Bottom-reading sonar would be nice to have, but I don't (yet?) see it as a 'need.' If it becomes a need I can always haul and drill, and put in a through hull.