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OzDean · 27-07-2021, 02:03

Has anyone used one these "in hull" rather than "through hull" transducers? Saves making holes in the hull I guess! I have a 43' Jeanneau Sun Fast, current set Raymarine instruments (ST290 18 years old), I am not ready to buy a complete new set but need a depth sounder to go sailing. My plan would be to buy the Raymarine i40 with "in hull" transducer for about $450 AUD and mount the transducer about 1.5m forward of the current one or as far forward as I can. I will have to check hull thickness and angle. Then I would have a standalone depth sounder, can be a back up once I get a new system. Has anyone installed one of these in hull, do they work? The boat is on the hard at the moment so I could technically swap out the old transducer a new one, but launching tomorrow. Your thoughts? Thanks, Dean

OzDean · 27-07-2021, 02:21

I found some previous threads, all indications are the "in hull" work fine, I particularly like the advice from Reefmagnet "Use a wet zip lock bag filled with water to use as a medium for testing the position of the transducer. Even a solid hull may have a void which will upset the depth sounder."

AedanC · 27-07-2021, 06:10

We have an external sensor mounted in-hull in a 6m RIB. It’s in the sump so it’s always wet and it works perfectly to at least 60m depths.

mvweebles · 27-07-2021, 06:16

I used a cheap transom mount transducer epoxied on the inside of my hull for years. Worked fine. Some newer, higher end transducers have better inside mounting fixtures that are liquid filled. I'd say give it a try - not much to lose given your circumstances.

Only caution I can think of is if your hull is cored, which is unlikely.

FPNC · 27-07-2021, 06:19

Have installed quite a few shoot through the hull senders. Some very large senders about 7" diameter. Always had good luck with setting them in polyester casting resin. This worked even at extreme angles to the hull bottom in deep vee hulls. The fiberglass substrate must be free of voids and any core material. Avoid fiberglass overlap areas if possible as there is a better chance of air bubbles in the laminate at these points.

rwidman · 27-07-2021, 08:18

I have one and it works fine.

Tsuru · 27-07-2021, 08:40

I installed one of these on a past boat where the in hull transducer failed. The short story is that it worked seamlessly and I wouldn’t hesitate doing it again.

Lake-Effect · 27-07-2021, 08:44

We have a "fishfinder" for depth instrument. I cut the bottom from a PVC electrical octagon box, siliconed this box to a flat spot on the hull, filled it with non-toxic antifreeze, and plopped the transom transducer in there. And put the cover plate on, with a notch for wire exit. This has been working great for a few years now.

And yes we first used the water-filled baggie trick to test the location.

Stewie12 · 27-07-2021, 09:06

Used one for many years.No problems at all.

sail sfbay · 27-07-2021, 09:40

You might find this Airmar article on In-hull Chirp transducers helpful and another on mounting them.

https://www.airmar.com/uploads/broch...keel-chirp.pdf
https://www.boatingmag.com/story/how...cer-on-a-boat/

Ken Z · 27-07-2021, 10:07

I installed a “ hawkeye” transducer on the inside hull near the bow just forward of the keel, works great. One needs to make a temporary form duct tape and cardboard works to mount it level and you must use slow set epoxy.

**Hudson Force** · 27-07-2021, 11:18

I had the "old style" through hull transducer mounted in a mineral oil well and then followed this with the transducer mounted in epoxy after testing in on the water-filled plastic bag. Decades of sounding through the hull without a problem.

CarinaPDX · 27-07-2021, 11:23

As I have posted before, I used K-Y Jelly to test the transducer against the hull. In fact I left the puck on top of the mounting surface with K-Y for years and it worked, and had to be pried off with a chisel. I had made a flat surface with polyester resin and the tight fit wasn't letting go. I would be reluctant to use epoxy to put the puck down as it can then only be removed destructively. The arrangement performed very well for years.

Greg

marshmat · 27-07-2021, 11:28

In-hull transducers will not work properly through a cored hull. They have to be mounted on a solid section. As long as you have a patch of solid material for them to shoot through, they work fine. There is a slight loss of sensitivity and resolution, versus one that's in direct contact with the water, but unless you are performing bathymetric surveys and applying your own post-processing to the raw data, it's unlikely you'll notice the difference.