sonar transducers

[jclays]

I have a Mainship 350/390 trawler. I have a keel that runs down the centerline about a foot deep. Can I mount the transducer on the exterior surface of the keel rather than on the exterior surface of the hull? I wouldnt have to use a fairing block if mounted to the keel since it is the lowest point on the boat. It is wide enough and it is hollow on the inside so I have full access on the inside of the hull.

 

[jgwinks]

I'd worry about running around and breaking the transducer. If it's plastic as many are, you'll sink. Even with a bronze one, gouging up the face will ruin it. I'd put it in a more protected location.

 

[jclays]

It's not plastic. If I was to run aground breaking the transducer is the least of my concerns. Easy replacement. Only one 1/2' hole. Would not sink me.

I am more concerned as to whether the water going over the transducer was smooth or turbulent.

 

[rendern]

A much better and easier solution would be to get something like the Airmar P79 Thru-hull transducer and mount it inside the hull. It will NEVER get knocked off in a grounding and doesn't add another hole in the boat. It worked great on my MS390. The Mainship is not a "cored" hull, so no worries. You can set the proper offset on your MFD or depth finder to account for the keel depth.

 

[Davil1]

Installed a thru hull inside my sailboat 4 years ago, works well and can check depths on my cell or tablets via bluetooth, very handy when moving around.
Left the old transducer in place, didnt want to remove and patch the hole.

 

[gerilla]

Epoxied a transom mount type transducer to the inside of hull under the lower helm ,for a 5" Dragonfly GPS/depth finder next to my factory mounted thru hull transducer in my MS 350. Works as well as thru hull. Both transducers read within 0.10 of a foot of each other. About 4" separate the 2 transducers.

 

[capran]

We just got the Transducer: Airmar “B744V Triducer” (Depth, temp, speed through water installed on our Helmsman 38. they mounted it where the old transducer was. the thru hull was smaller so they had to refill the old and later redrill the new. so far, out a week, and pretty impressed, although seeing it installed was pretty weir, as it mounts on a wing like appendage. But it has a speed through the water as well as the depth/sonar and water temp. it's about a foot away from the spine and we chose to offset -1 settings, so it reads total water depth rather than depth under the keel of distance from transducer to bottom.

 

[HeadedToTexas]

I'm also in the process of choosing a transducer. What are the real world benefits of the larger exposed surface of a transducer like the B744 compared to a flush model like the B75? That's a lot to be below the hull surface in places where floating sticks and such are the norm. I'm not much of a serious fisherman and have done just fine so far with simple depth finders.

 

[capran]

Here's a pic of our recent install of the B744V Triducer. I would have preferred a flat regular one, but wanted an in the water boat speed, as we have strong currents and wanted to know speed through the water. but have looked at the sonar a few times and seeing bottom characteristics is interesting. Only been out a bit over a week.

 

[HeadedToTexas]

Nice. Is it almost right below the pilothouse?

 

[capran]

Yes. Under the floor panel to the right of the bilge pump floor panel.