"Thru Hull" or "In Hull" Transducer

MoonSailer · Nov 18, 2008

Holes in the hull. I am very reluctant to drill a hole in my hull!!!! I have /am using in-hull transducer with good results. Sound travels very easily through fiberglass that is solid so sensitivity is not impacted by going through the hull. I guess it might be affected a little but is the increase in sensitivity worth the expense and danger of having another hole in your hull???

Maine Sail · Nov 18, 2008

I use in-hull

I use in-hull but you need to find a good location first. You can use a ziplock full of water to rest it on or some wax from a Johnny Ring. You need to make sure it shoots through with reliability before mounting it permanently. Any air/voids in the fiberglass an cause erratic behavior..

I know of more than one boater who has left it stuck in the johnny Ring wax permanently. Also make sure you mash any air bubbles out of the wax before testing.. My in hull transducer is almost 24 years old, was originally used on a Datamarine depth, and is now used on a Raymarine ST-60 and it works reliably & flawlessly.

Tim R. · Nov 18, 2008

Joe Mullee said:
Looking for a new depth finder. Just curious about any experiance with the In Hull transducers. Do they work as well as the Thru Hull? I have a Hunter 34 and beleive the all fiberglass hull is roughly 3/4" to 1" thick directly in front of my keel. Any comments?

Thanks.

Do you have one now? If so, why does it need to be replaced?

kloudie1 · Nov 18, 2008

Joe, My old H-34 has an in-hull transducer from the original Signet instrument.. Still works fine.. It is mounted in the shower sump, under the floorboard, slightly to port. Like MainSail sez, you can check out the location beforehand for best performance.

Warren Milberg · Nov 18, 2008

I know some will disagree with this suggestion, but I have used (and would use again, if need be) silicone to mount an in-hull transducer in a previous boat. I like silicone better than any of the epoxy-based alternatives as it makes moving the puck a lot easier if you ever need to move or replace it. As MaineSail says about using a wax ring ( also an interesting idea), the key is making sure the mounting medium does not have any air bubbles in it.

Maine Sail · Nov 19, 2008

Joe Mullee said:
The reason I need a new DF is my SR Mariner is completely eratic. Probably 70% of the time it "seems" to be accurate and then off it goes, spinning thru numbers from zero to 100 for no apparent reason. This happens when under auxiliary or sail. Last month coming back from a five day trip I went aground when it was reading five feet under the keel. Currently it's located ahead of the keel in the shower sump. I've wondered if there was anything I could do to stop the erratic numbers and would appreciate any comments. I'm not looking to blow money but I got to get this straightened out. It's good to know the "in-hulls" work well.

Thanks again.

Joe,

Can you find out what the frequency of the SR Mariner transducer is. In my experience it is the display that usually fails not the transducer unless you got a big spike or lightning.

You may be able to connect another brands display to the SR mariner transducer seeing as most all of them were made by Airmar anyway and this would save you a step. As I mentioned above my Raymarine ST-60 is running off a 24 year old Datamarine transducer..

smitroe · Nov 19, 2008

What is a good brand to purchase for a thru hull transducer and gauge. I would like to replace mine. its an inexpensive model and seldom works. when it works its accurate. I mounted it forward of the keel underneath the forward storage area (flotation area ) on my 1979 vn23 and that should be a good place for it .pleae correct me if I am wrong. It always works well the first few times I use the boat and I keep the bottom clean under it . I would like to replace it , I am glad to hear so much good feedback about thru hull trnsducers. It sure pleases the insurance company as well as myself . I need to figure out what I am doing wrong or if it is just because I have a cheap one $150.00... they range up to the thousands so ?????????? Thanks all advice welcome..smitroe

sailaway78 · Nov 19, 2008

Thru Hulls

I know of no one who has mounted a transducer inside the hull that has not been happy with it, as long as they mounted it properly. The only critical steps are the location, and making sure the mounting method, silicone, epoxy, wax ring or whatever, has no air bubbles in it. Once again Mainesail is on the money. Check the frequency first, the existing ducer can work well with other units, if the frequency is the same. They are basically all the same, either 50 or 200 hertz.
Smitroe, I had a little digital Hawkeye on my last boat. It was very accurate, and reliable, for as long as I owned the boat. About five years.
The readout is somewhat small, so has to be mounted where you can see it, but they are very good and inexpensive. Unusual for boat stuff. Less then 100 bucks on ebay.

smitroe · Nov 19, 2008

Nice N Easy, Thank you..I will check out all my stats . and most likely unmount my transducer and re mount a new one. I am willing to bet that there is a bubble in there somewhere..its weird the way it always works just fine for the first sail or two of the season and then its hit or miss for the whole rest of the season...thanks.....smitroe

Maine Sail · Nov 20, 2008

Joe Mullee said:
Hey Maine Sail and Nice N Easy,

If you're still tracking this thread I got on SR Mariners site and they no longer make the unit. They do service them but I'm not interested in going there again. The website states that the frequency of the transducer is 160 KHz and the frequency of the Raymarine units is 200 KHz. Not understanding what KHz is, does that mean they are incompatable?

Thanks,
Joe Mullee

They won't be compatible.

Some older depth units used 210kHz, some 160kHz and most others 200kHz. The 50/200kHz transducers are usually for fish finders/depth units..

A good in-hull transducer is the Airmar/Raymarine P79 (part #E26001-PZ). It comes with the cable and the in-hull kit which can be mounted on a variety of angles to give you a vertical shoot through.

This transducer can be used with an ST-60 Depth head but is not the one that normally comes in the kit.

P79 Adjustable In-Hull Transducer (LINK)

sailingdog · Nov 20, 2008

This will also work with the TackTick display heads and hull transmitter.

Maine Sail said:
They won't be compatible. Some older depth units used 210kHz, some 160kHz and most others 200kHz. The 50/200kHz transducers are usually for fish finders/depth units..

A good in-hull transducer is the Airmar/Raymarine P79 (part #E26001-PZ). It comes with the cable and the in-hull kit which can be mounted on a variety of angles to give you a vertical shoot through.

This transducer can be used with an ST-60 Depth head but is not the one that normally comes in the kit.

P79 Adjustable In-Hull Transducer (LINK)