Reply
 
Thread Tools Display Modes
 
Old 01-05-2016, 05:02 PM   #1
Senior Member
 
GoldenDawn's Avatar
 
City: Brentwood Bay, BC
Country: Canada
Vessel Name: Golden Dawn
Vessel Model: Krogen 42
Join Date: May 2011
Posts: 116
Transom-mounted Transducer ?

I am planning to install a transom-mounted transducer on my Kadey Krogen 42 and would welcome comments on previous experiences with such a set-up, especially suggestions on where to mount and issues with weed, etc collecting on it.

The reason for this configuration is to add a Humminbird side-scan sonar transducer, which is not offered as a thru-hull. I already have the Humminbird side-scan system on my skiff and find it really useful. With a transom-mounted transducer on the KK, I can just move the deck unit back and forth.
__________________
Advertisement

__________________
John Harper
Golden Dawn, KK42-82
GoldenDawn is offline   Reply With Quote
Old 01-05-2016, 07:15 PM   #2
Guru
 
caltexflanc's Avatar
 
City: North Carolina for now
Country: USA
Vessel Name: Small Incentive
Vessel Model: Boston Whaler 130 Sport
Join Date: Aug 2011
Posts: 3,783
I'd consult the manufacturer for mounting requirements. The issue with transom mounts is the propellor is in front of them, thus harder to get "clean" water. They tend to be much more popular on outboard and sterndrive type boats. I'd guess Humminbird will want you to mount well off to one side, and not in the downstream path of any stabilizer fins or existing transducer protuberances.
__________________

__________________
George

"There's the Right Way, the Wrong Way, and what some guy says he's gotten away with"
caltexflanc is offline   Reply With Quote
Old 01-05-2016, 07:54 PM   #3
Guru
 
tpbrady's Avatar
 
City: Anchorage/Wrangell
Country: USA
Vessel Name: Silver Bay
Vessel Model: Nordic Tug 42-002
Join Date: Sep 2012
Posts: 505
John,

I mounted a Lowrance side scan on the transom of a 38 foot trawler and didn't see any issues due to the prop. I did mount it on port side as the prop wash would offset slightly to starboard although I don't think that would really matter that much. I didn't notice any problems on the screen looking port or starboard while underway. I flipped on the macerator pump (outside the 3 mile limit) and could even see the output on the display as it passed the transducer.

Tom
tpbrady is offline   Reply With Quote
Old 01-05-2016, 07:59 PM   #4
Senior Member
 
GoldenDawn's Avatar
 
City: Brentwood Bay, BC
Country: Canada
Vessel Name: Golden Dawn
Vessel Model: Krogen 42
Join Date: May 2011
Posts: 116
Tom

Exactly the type of advice I was looking for.

And to date you haven't had any hassles with weed collecting?
__________________
John Harper
Golden Dawn, KK42-82
GoldenDawn is offline   Reply With Quote
Old 01-05-2016, 08:08 PM   #5
Guru
 
tpbrady's Avatar
 
City: Anchorage/Wrangell
Country: USA
Vessel Name: Silver Bay
Vessel Model: Nordic Tug 42-002
Join Date: Sep 2012
Posts: 505
Never had an issue with weed collecting. There really wasn't any place for weeds to get hung up. I had it mounted far enough outboard that I could reach it from the swim step. That was useful for cleaning off the moss and other things that liked to grow on it when we weren't underway.

Tom
tpbrady is offline   Reply With Quote
Old 01-05-2016, 08:41 PM   #6
Senior Member
 
Jetstream's Avatar
 
City: Tasmania
Country: Australia
Vessel Model: Old Town Loon
Join Date: Jul 2015
Posts: 175
Tom I had a Lowrance Structure Scan transducer transom mounted on my last runabout. From memory Lowrance suggested mounting it on the starboard side on a single outboard boats transom to keep it out of the prop wash but it would depend on the direction of prop rotation. As others have said mount it where you get a clean undisturbed water flow for best results.
Also something to look at might be the Stern Saver type of device that glues onto your transom so you don't have to drill holes directly into it. I did pick up a little weed on the transducer sometimes but it normally fell off once we stopped or gave it a little reverse.



HomePage | THE STERN SAVER

Cheers

Brett
Jetstream is offline   Reply With Quote
Old 01-05-2016, 09:23 PM   #7
Guru
 
tpbrady's Avatar
 
City: Anchorage/Wrangell
Country: USA
Vessel Name: Silver Bay
Vessel Model: Nordic Tug 42-002
Join Date: Sep 2012
Posts: 505
Brett,

On a slow boat like my trawler or a KK42, it probably doesn't matter. I didn't notice any degradation on the side scan transducer to the starboard while running at 4-5 knots. The side scan coverage was from the surface down to a 45 degree angle. The turbulence caused by the prop could only affect a small area of the side coverage to the starboard side as the prop was about 36 inches below the transom. The downscan transducer likewise only had a small area that could be affected. In practice I didn't see any indications that the prop wash affected the sonar operation. At higher speeds prop wash could be a factor due to the air bubbles created by a rapidly spinning prop. I haven't looked at prop wash from a trawler, but I suspect a large prop turning at 400 rpm doesn't create as many small bubbles as a smaller outboard prop turning at 2000 rpm.

Tom
tpbrady is offline   Reply With Quote
Old 01-06-2016, 08:02 AM   #8
Senior Member
 
Jetstream's Avatar
 
City: Tasmania
Country: Australia
Vessel Model: Old Town Loon
Join Date: Jul 2015
Posts: 175
I think your right Tom and the thru hub exhaust on most outboards could cause a problem that wouldn't exist with a shaft drive vessel. I'd like to install the new Simrad 3D Structure scan when we get our new boat but at this stage there is no through hull for it so I might be looking at the same problem,

Brett
Jetstream is offline   Reply With Quote
Old 01-06-2016, 10:02 AM   #9
TF Site Team
 
Larry M's Avatar
 
City: JAX, FL
Country: USA
Vessel Name: Hobo
Vessel Model: Krogen 42-120
Join Date: Nov 2008
Posts: 5,725
On the several transom mounted transducers we've mounted, I've found that there is a sweet spot that works under most conditions and at any speed. I'd temporarily mount the transducer on a piece of flat stock or a suction cup and play around with the positioning till you find it. Your swim platform may make that a little more difficult but you only have to drill holes once.
Larry M is offline   Reply With Quote
Old 01-06-2016, 11:13 AM   #10
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Country: USA
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 13,707
The only transducer we had on our Albin 25 was on the transom. I think it was a Lawrence and it worked fine. It was installed by a PO and I was always amazed how well it worked through the turbulence at the transom above the bottom line.
__________________
Eric

North Western Washington State USA
Nomad Willy is offline   Reply With Quote
Old 01-06-2016, 11:31 AM   #11
Guru
 
City: Doha
Country: Qatar
Join Date: Jun 2012
Posts: 663
Quote:
Originally Posted by Jetstream View Post
Wow Brett, I thought I was looking at a picture of my own 20' CC. Exact same unit and mounting location. Works perfectly. The transducer needs to extend below the hull about 1/2+ inch, but I have never had a problem with snagging weeds or debris. The only issue is that when I run up on the beach I need to be port side to the beach otherwise the transducer bounces up and down in the sand.

GoldenDawn, you bring up a great idea. I really hate the idea of drilling a hole in the bottom of my steel hull 5 feet down for a transducer. Would rather attach it to a small welded bracket under the stern and run the cable up to the waterline boot stripe where it can pass through a watertight seal.

This is much better than risking a leak in the hull. Damaging a $100 - $400 transducer is still cheaper than one dry dock to repair a leak in the hull.

Thank you for the great idea!
makobuilders is offline   Reply With Quote
Old 01-06-2016, 11:42 AM   #12
Senior Member
 
GoldenDawn's Avatar
 
City: Brentwood Bay, BC
Country: Canada
Vessel Name: Golden Dawn
Vessel Model: Krogen 42
Join Date: May 2011
Posts: 116
I appreciate the comments/suggestions. As Larry suggested, I can play around with a temporary mount rigged from the swim grid, then install it permanently during my haul-out. I like the idea of adding a mounting block - I wonder if just bedding a block with 5200 would suffice?

John H
Golden Dawn KK 42-83
__________________
John Harper
Golden Dawn, KK42-82
GoldenDawn is offline   Reply With Quote
Old 01-06-2016, 01:01 PM   #13
Guru
 
City: Doha
Country: Qatar
Join Date: Jun 2012
Posts: 663
What type of waterproof grommet do you propose for sealing the wire as it passes into the hull? I would not want to just rely on bedding compound/silicon, especially down at the waterline.
makobuilders is offline   Reply With Quote
Old 01-06-2016, 01:15 PM   #14
Senior Member
 
GoldenDawn's Avatar
 
City: Brentwood Bay, BC
Country: Canada
Vessel Name: Golden Dawn
Vessel Model: Krogen 42
Join Date: May 2011
Posts: 116
I will run the transducer cable to above the waterline, just above the swim grid. Not 100% sure of the fitting I will use on this.
__________________
John Harper
Golden Dawn, KK42-82
GoldenDawn is offline   Reply With Quote
Old 01-06-2016, 02:18 PM   #15
TF Site Team
 
FlyWright's Avatar
 
City: California Delta and SF Bay
Country: Sacramento, CA, USA (boat in Vallejo)
Vessel Name: FlyWright
Vessel Model: Marshall Californian 34 LRC
Join Date: Apr 2008
Posts: 10,170
Good advice here. Using a transom board to mount the transducer saves drilling into the transom. 5200 should work fine to attach the board.

I had a similar setup on my SeaRay runabout. I bought a small clamshell cover to protect the cable hole. Filling the hole with something like Boatlife or SikaFlex would work well. I'd even consider butyl tape as a plug in the cable hose.

Before I passed any cables through the new hole, I'd seal the new edges with a coating of 5200 to keep the transom water tight.
__________________
Al

Custom Google Trawler Forum Search
FlyWright is offline   Reply With Quote
Old 01-06-2016, 05:59 PM   #16
Guru
 
koliver's Avatar
 
City: Saltspring Island
Country: BC, canada
Vessel Name: Retreat
Vessel Model: C&L 44
Join Date: Nov 2007
Posts: 2,165
Tom:

I did exactly what you are contemplating, but for a regular fishfinder, so had a sounder head that went back and forth between the Flybridge and the dinghy. It worked as long as I had that dinghy, but when I sold it with the sounder, I would have replaced everything with a better one, but couldn't easily get a long enough cable in the better brand unit, so I put the transom mount unit in the bilge, alongside my shoot thru transducer for the wheelhouse sounder. I epoxied a piece of 3" or 4" (can't go look just now) ABS cut to the angle of the hull, mounted the transom 'Ducer inside the pipe, added some light weight oil, and have had a top performing Flybridge sounder ever since. In the dinghy, I epoxied the transom mount Ducer directly to the inside of the hull, at the right angle, and again, top performing sounder in the second location. The dinghy was easier, as I could locate the transducer in the V at the bottom of the hull. Not possible in the engine room of the big boat, so I mounted it about 2' off centre. If you can get to the flat bottom of your hull just forward of the place on your transom where your outside mount would have been, you can mount it without fear of seeing the keel or of fouling, and without screw holes below the waterline.
__________________

koliver is offline   Reply With Quote
Reply

Thread Tools
Display Modes

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





All times are GMT -5. The time now is 03:42 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012