CONTINUOUSWAVE

I am considering installing a through hull SONAR transducer in my 1986 OUTRAGE 18 in the fuel tank cavity area. I would do this after I removed the original fuel tank and installed a shorter one. I have read all the articles about installing a through-hull SONAR transducer in the aft bilge sump, but I’d like to locate the transducer close to the keel to protect when trailering and because there seems to be more room there. I’ve got fiberglass and sheet metal experience.

Give me comments on this idea.

Odonnell69 wrote:I have read all the articles about installing a through-hull SONAR transducer in the aft cockpit live well...

I hope you read the articles that mention that when Boston Whaler planned for a boat to have a through-hull SONAR transducer they created a dedicated area in the hull during the laminating and molding of the hull for just that purpose. These areas are called a "putty box" and are not filled with foam. Instead of foam a putty material was placed there so there would be more protection against the ingress of water into the foam interior of a Unibond hull.

If you did not read about putty boxes, you should read articles on that topic. This search result page will give you some links:

https://www.google.com/search?q=site%3A ... +putty+box

If you really want to install a through-hull SONAR transducer, consider getting one with a tilted element or angled beam offset to match the deadrise angle in the hull. AIRMAR makes a series of through-hull transducers. See more at

AIRMAR
P19 Traditional/CW Tilted Element™ Thru‑hull
https://www.airmar.com/productdescription.html?id=140

For an 18-foot boat, I think a through-hull SONAR transducer would be very unusual. Generally through-hull SONAR transducers are used on larger boats with very powerful SONAR transmitters that are run far offshore into deep water in search of pelagic ocean fish.

Odonnell69 wrote:I’d like to locate the transducer close to the keel to protect when trailering and because the seems to be more room there.

Your comment seems a bit unusual to me. Most Boston Whaler boats that live on trailers are on trailers with keel rollers. To avoid damage you would want to keep the transducer operating face away from the keel.

Also, with proper installation of a transom-mounted transducer, very excellent SONAR echoes can be obtained even at very high boat speeds. If you need more resolution in your SONAR for purposes of angling, then you should get a modern sweep-frequency-modulated continuous-wave SONAR (invariably called a "chirp" SONAR). These modern SONAR devices employ powerful digital electronics to significantly improve SONAR range and resolution.

Transom mounted transducer quality and relatively low cost cause me to wonder why you believe a through the hull transducer is worth the cost and effort to install. Transducers fail. The thought or replacing a through the hull transducer in your application when it inevitably fails seems daunting to me.

A dozen or so owners have considered the modifications you suggest [to install a through-hull SONAR transducer,] but have reconsidered once they have investigated the planning, fabrication, installation work, and cost. Through hull transducers are typically installed into a solid block of fiberglass made in the hull during construction at the factory.


Cutting into the hull for drains and transducers should be done with the utmost caution and skill and for very compelling reasons.

A professional fiberglass worker who is knowledgeable with Boston Whaler hull construction should be hired. Not just any Joe from a yard. Installed incorrectly, it can result in thousands of dollars in repairs. Several years ago I provided technical support to a new owner in Australia who bought a pre-owned Whaler with a damaged hull due to an improper after market installed thru-hull transducer. The repairs took a great deal of time and cost a significant amount.

Jim, Phil and Butch,

Thanks for the great feedback.

Regarding using a transom mounted SONAR transducer, there is good advice about transducer mounting in an article in the REFERENCE section.

The REFERENCE section is located at

https://continuouswave.com/whaler/reference/

The article on SONAR transducer mounting is located at

https://continuouswave.com/whaler/refer ... ducer.html

The article discusses SONAR transducer installation and operation with a special emphasis on installation and use with Boston Whaler boats.

Odonnell69 wrote:I am considering installing a through hull SONAR transducer in my 1986 OUTRAGE 18 in the fuel tank cavity area....Give me comments on this idea.

Years ago I had read an article in a boating magazine on how the writer had placed a transducer in a custom made well, and submerged it in an oil. The writer did not actually go cutting through the hull.

Doing a web query came across this link that was very interesting:

How to Install an In-Hull Transducer
https://www.youtube.com/watch?v=bMp_cmbdhYw

The shoot-through or in-bilge SONAR transducer that is shown being installed in the interesting video linked above won't work with a Unibond hull due to the presence of the embedded foam in the hull laminate structure.