Cruisers Forum

Join CruisersForum Today

Thread Tools Rate Thread Display Modes
Old 12-06-2006, 03:30   #1
Registered User
Steve Kidson's Avatar

Join Date: Jul 2005
Location: Sydney, Australia
Boat: Hartley 32 RORC; Vixen
Posts: 193
Images: 10
Depth Sounder Installation

I am in the process of installing transducers for depth and speed/log instruments in my boat. I have bought Navman 3100 series instruments.

My question is that in the installation guide a maximum of 15 degrees offset is recommended for the depth transducer, but the only position forward of the keel that I can install transducer is greater than that.

Should I try to machine a wedge to bring into line with recommended offset, or can I compensate in other ways; ie with the setup menu manipulating waterline and keel depth data??

Any suggestions/advice will be appreciated.

Fair winds

Steve Kidson is offline   Reply With Quote
Old 12-06-2006, 04:25   #2
Moderator Emeritus
GordMay's Avatar

Cruisers Forum Supporter

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 29,364
Images: 240
Yes, machine a wedge (fairing block).

Locate the transducer amidships and away from keel at the point of minimum deadrise angle. The transducer must be fully immersed in water and not subjected to air bubbles*, or turbulent water flowing across the radiating face. A fairing is strongly recommended if your deadrise angle exceeds 10 degrees.

Nearly all vessels have some deadrise angle at the mounting location. If the transducer is mounted directly to your hull, the sound beam will be tilted sideways at the same angle as the deadrise. A fairing aims the sound of the beam straight down by mounting the transducer parallel to the water, and it minimizes aerated water flowing over the transducer's face by mounting it deeper in the water.

When cutting a fairing, carefully orient it on the saw so the wider end will be facing forward (toward the bow) after the fairing is installed. A wider leading edge creates less turbulence* as it moves through the water. The goal is to create a smooth surface, so the water will flow cleanly over the fairing and transducer. Boat drag will be minimized. And more importantly, water will be free of bubbles and turbulence for the best sounder performance. Also, If the transducer is recessed more than 1/64 inch (0.5mm) inside the fairing, shim the transducer or carefully file/sand the fairing until they are flush.

A backing block is mounted inside the hull to provide a level surface for tightening the threads that hold the transducer in place. It is fabricated with the interior deadrise angle. After cutting the fairing block the remaining section can be used as the backing block.

* Turbulent water contains air bubbles, and a transducer cannot transmit through air.

There’s a little more to it, if you have a “cored” hull.

Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"

GordMay is offline   Reply With Quote

depth sounder, installation

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
water depth Red44 Atlantic & the Caribbean 23 28-12-2011 20:20
Voluptuous lady gatecrasher xinxinxinaa Meets & Greets 33 08-07-2007 15:18
Depth Sounder Thru-Hull Alternative? markpj23 Marine Electronics 17 16-05-2006 22:34
Depth Sounder Troubleshooting exposure Construction, Maintenance & Refit 9 10-02-2004 14:47

Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities

Copyright 2002-2015 Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 11:07.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.