Reply
 
Thread Tools Search this Thread Display Modes
 
Old 02-13-2019, 02:09 PM   #1
Veteran Member
 
Jgutten's Avatar
 
City: Bonita Springs
Country: United States
Join Date: Jul 2017
Posts: 55
Transducer Depth

My Mainship 400 was recently on the hard and I decided to take an accurate measurement of the depth of the transducer from the bottom of the rudder, which is the lowest point on my boat.

The previous owner told me that the transducer was 18" from the bottom of the rudder. The transducer is mounted on the port side bottom just under the Racor in the single engine version of the Mainship 400.

I had set the depth finder gauge at 18" relying upon the former owners information. So after measuring the transducer, it's not 18" from the bottom on the rudder. It's 29" from the rudder bottom. I've had the boat for one year and had an actual depth of the boat that was 11" deeper than the depth gauge was set for. Never went aground but I guess I was lucky.

If your boat is out of the water, good time to check the measurements to be sure your depth gauge is set properly.
__________________
Advertisement

__________________
Jeffrey F. Guttenberger
2005 Mainship 400
R Time
Jgutten is offline   Reply With Quote
Old 02-13-2019, 03:45 PM   #2
Guru
 
kchace's Avatar
 
City: Brookline, NH
Country: USA
Vessel Name: Blue Heaven
Vessel Model: Albin 43 classic double cabin, twin 135 Lehmans
Join Date: Sep 2013
Posts: 1,530
Good point. Im planning on checking and adjusting mine. I've always assumed 2' but as you found, might not be correct. best to actually know.

Up here in the NE where the bottom is so variable, I always want several feet or more, but in some places, one can be within a few feet of the bottom for miles and that's normal.

Ken
__________________

kchace is offline   Reply With Quote
Old 02-13-2019, 05:28 PM   #3
Veteran Member
 
City: Grand Manan,N.B.
Country: Bay of Fundy-Canada
Vessel Name: Puffin II
Vessel Model: Mascot 28 PH Motorsailer
Join Date: Jun 2018
Posts: 49
Measure twice / Len


Click image for larger version

Name:	A little ding..jpg
Views:	122
Size:	130.8 KB
ID:	85301

Click image for larger version

Name:	A little ding.PNG
Views:	109
Size:	38.4 KB
ID:	85302
__________________
:) My personal experience &/or my personal opinion-feel free to ignore.
deblen is offline   Reply With Quote
Old 02-13-2019, 06:09 PM   #4
Guru
 
High Wire's Avatar
 
City: Cape May, NJ and Englewood, FL
Country: USA
Vessel Name: Irish Lady
Join Date: Dec 2007
Posts: 2,762
...and make sure you get the +/- sign right.
High Wire is offline   Reply With Quote
Old 02-14-2019, 03:12 PM   #5
TF Site Team
 
City: Westerly, RI
Country: USA
Vessel Name: N/A
Vessel Model: 1999 Mainship 350 Trawler
Join Date: Jan 2014
Posts: 1,722
If an 11" variance is the difference between floating and grounding, the water is too skinny for me to traverse.
Shrew is offline   Reply With Quote
Old 02-14-2019, 03:46 PM   #6
Senior Member
 
bgillroy's Avatar
 
City: Marathon, FL & On Loop
Country: usa
Vessel Name: Maka Honu
Vessel Model: Ta Yang, 42 Tayana PH Trawler 1976
Join Date: Mar 2014
Posts: 203
During refit last year, to align both depth instru, recorded measure from xdcr faces to deepest keel depth (running gear in pocket between keel & hull-protected). After launch adjusted instru so displays show water depth under keel,alarms set at 2ft. Installed forward sonar (2 dimensional picture) that sees 6 X current depth ahead; we only use when in skinny water.
bgillroy is offline   Reply With Quote
Old 02-18-2019, 09:22 PM   #7
Veteran Member
 
Djoub's Avatar
 
City: Parrish Fl
Country: USA
Vessel Name: Melody
Vessel Model: Mainship 350
Join Date: Apr 2018
Posts: 51
Just measured and adjusted the dedicated depth gauge while in water using the old fashioned way, with a weight and line. I have a 4’ draft to bottom of keel, I offset reading by 5’. This gives me 1’ buffer before depth gauge shows 0’. We’ve seen it go to 2’, a little too shallow for comfort.
Djoub is offline   Reply With Quote
Old 02-19-2019, 12:29 AM   #8
Senior Member
 
Brisyboy's Avatar
 
City: Brisbane
Country: Australia
Vessel Name: Malagari
Vessel Model: Island Gypsy 36 Europa
Join Date: Mar 2015
Posts: 261
To help with this, when the boat is on the hard, can the depth sounder be used to check this depth or will it damage it?
__________________
George
Brisbane
IG 36 Europa
Brisyboy is offline   Reply With Quote
Old 02-20-2019, 04:46 AM   #9
Veteran Member
 
Jgutten's Avatar
 
City: Bonita Springs
Country: United States
Join Date: Jul 2017
Posts: 55
I set my transducer to the actual depth of my boat, then set a 2' alarm for low water.

Here is SWFL, there is a lot of low water and you've really got to be aware of the tides, current, wind, etc. Keeps you on your toes!
__________________
Jeffrey F. Guttenberger
2005 Mainship 400
R Time
Jgutten is offline   Reply With Quote
Old 02-20-2019, 03:10 PM   #10
Guru
 
Dougcole's Avatar
 
City: Carrabelle, FL
Country: USA
Vessel Name: Morgan
Vessel Model: '05 Mainship 40T
Join Date: Jan 2008
Posts: 1,151
Hey Jeffery,


Interesting topic. I can't recall, do you have a single or twins?


Personally, I've never messed with an offset, though I know most people prefer to do it that way. I know my boat draws 3'8", a little more when fully loaded, so I just pay attention to the actual depth. If it's less than about 4'6" I don't go there.


A lot of places we sneak into in the Bahamas are super shallow, 11" under the keel is not comfortable, but doable. Eyeball navigation there is the most effective way to get around there anyway. A few years back our transducer went bad and we went on a month long cruise without it. I used a lead line to check anchoring depths, we had no issues.



Heck, my sounder just blinks in anything shallower than about 4' anyway.
Dougcole is offline   Reply With Quote
Old 02-20-2019, 04:46 PM   #11
Guru
 
High Wire's Avatar
 
City: Cape May, NJ and Englewood, FL
Country: USA
Vessel Name: Irish Lady
Join Date: Dec 2007
Posts: 2,762
Quote:
Originally Posted by Brisyboy View Post
To help with this, when the boat is on the hard, can the depth sounder be used to check this depth or will it damage it?
If you are on land, yes the DF can be turned on, but it will not read anything or nor damage it short term. The transducer ultrasonic pulses will not travel through air. If you put your ear up near the TD, you will hear a faint clicking sound when on. Sometimes you can feel the pulses with your hand.
__________________
Archie
1984 Monk 36 Hull #46
Currently in Cape May, NJ
High Wire is offline   Reply With Quote
Old 02-21-2019, 05:51 AM   #12
Veteran Member
 
Jgutten's Avatar
 
City: Bonita Springs
Country: United States
Join Date: Jul 2017
Posts: 55
Dougcole,
I have a SE MS 400. The problem with just going where you have 4'6" is how do you know without having a properly set depth reading?

The charts are unreliable. The tides affect depth, shoaling, etc.

Setting it to depth below the keel makes sense to me.
__________________
Jeffrey F. Guttenberger
2005 Mainship 400
R Time
Jgutten is offline   Reply With Quote
Old 02-21-2019, 07:44 AM   #13
Senior Member
 
Molly's Avatar
 
City: Punta Gorda
Country: USA
Vessel Name: La Bella Vita
Vessel Model: 2006 Mainship 34T
Join Date: May 2018
Posts: 127
I understand the thought process of having the depth set at "0" for the lowest point on the boat. I still prefer to set the gauge at the actual depth. I know I need 3'6" of water.
If I'm in water less than 4'6" I turn around. I just don't like using my math skills to figure the depth. Personal choice I guess?
Molly is offline   Reply With Quote
Old 02-21-2019, 10:11 AM   #14
Guru
 
Dougcole's Avatar
 
City: Carrabelle, FL
Country: USA
Vessel Name: Morgan
Vessel Model: '05 Mainship 40T
Join Date: Jan 2008
Posts: 1,151
Quote:
Originally Posted by Jgutten View Post
Dougcole,
I have a SE MS 400. The problem with just going where you have 4'6" is how do you know without having a properly set depth reading?

The charts are unreliable. The tides affect depth, shoaling, etc.

Setting it to depth below the keel makes sense to me.

Hey Jeffery,


Yes, this is for sure one of those personal preference things. Both ways work the same, it's just which one is easier for you.


I asked if your boat was a single as we have the same boat, so I was interested in your findings. Though my boat is a twin, the draft is a little different. Also, some of your mods that you were nice enough to share on here in the past have really helped me, specifically how you moved your holding tank vent. I appreciate your in depth understanding of your boat.


As to how do I know the depth before I get there? Well, that's the rub isn't it? To me, sounder really isn't much help in keeping me from going aground, unless it is as forward scanner. By the time I get a reading I am likely already in trouble.


What it does tell me though is what the water in a particular area of a particular depth "looks like." Personally, I trust my eyes more than my sounder, though this doesn't always work in dirty/dark conditions, so in those times I'm extra careful. I assimilate what the chart, the sounder and my eyes are telling me. I'm sure you do the same thing, even if you don't consciously think about it.


I'm a flats fisherman, I was a tarpon guide for 13 years. A big part of that sport involves looking for minor differences in depths of shallow water. It's a skill that I worked hard to acquire, but it's not rocket science. I look for water color, catspaws, current flows etc. I also pilot exclusively from the Fly Bridge in shallow water. That water reading skill has helped me a lot.



Thanks for all you have added to the forum.
Dougcole is offline   Reply With Quote
Old 02-22-2019, 06:12 AM   #15
Veteran Member
 
Jgutten's Avatar
 
City: Bonita Springs
Country: United States
Join Date: Jul 2017
Posts: 55
Dougcole,

My boat is a single engine. It turns out that it does draw the 3'8" that Mainship states. My transducer, which is mounted on the port side, by the forward bulkhead in the engine compartment below the fuel filter, is 29" above the bottom on the rudder.
__________________
Jeffrey F. Guttenberger
2005 Mainship 400
R Time
Jgutten is offline   Reply With Quote
Old 03-01-2019, 02:06 PM   #16
Guru
 
ben2go's Avatar
 
City: Upstate,SC
Country: USA
Vessel Name: Caroliner
Vessel Model: 28' Spira San Miguel
Join Date: May 2012
Posts: 2,367
Quote:
Originally Posted by deblen View Post



If'n ya can't dodge it, ram it.
__________________
What a pain in the transom.

ben2go is offline   Reply With Quote
Old 03-02-2019, 11:17 PM   #17
Guru
 
rgano's Avatar
 
City: Southport, Florida
Country: USA
Vessel Name: FROLIC
Vessel Model: Mainship 30 Pilot II since 2015. GB-42 1986-2015. Former Unlimited Tonnage Master
Join Date: Oct 2007
Posts: 702
Send a message via Skype™ to rgano
Quote:
Originally Posted by Molly View Post
I understand the thought process of having the depth set at "0" for the lowest point on the boat. I still prefer to set the gauge at the actual depth. I know I need 3'6" of water.
If I'm in water less than 4'6" I turn around. I just don't like using my math skills to figure the depth. Personal choice I guess?
So don't you have to perfom some mental math with the screen of your sounder reading zero at the face of the 'ducer? Or do I misunderstand the quoted portion of the post?
Personally, I have always set the sounders on my boats to read zero at the lowest part of the boat. If I see 2 on the sounder, I don't have any math to do to know that I have 2 feet to go before I am aground. Thus, an alarm setting of 6, common with me, means that when it goes off, I have six more feet to go before going aground.
However, I like exploring (slooooowly) in shallows when the tide is incoming and a reading of 1 or below is not uncommon with me.
__________________
Rich Gano
FROLIC (2005 MainShip 30 Pilot II)
Panama City area
rgano is offline   Reply With Quote
Old 03-03-2019, 03:22 AM   #18
Senior Member
 
City: Clearwater, FL
Country: United States
Vessel Name: Seas the Bay
Vessel Model: Hardin Europa
Join Date: Aug 2016
Posts: 491
Quote:
Originally Posted by Brisyboy View Post
To help with this, when the boat is on the hard, can the depth sounder be used to check this depth or will it damage it?
Ensure your transducer is /never/ powered up when out of the water. At best, it'll do no good -- air doesnt carry the signal well enough for it to work at all. At worst, it'll damage it beyond use or repair.

Transducers are water cooled. Water has a specific heat capacity about 1000x more than air and a thermal conductivity about 25x greater than air. Even warm water cools much better than cooler air.

Some people may report that theirs was powered up on land and it hurt nothing. That might be true. And, it might offer you some reassurance should you goof. But, it shouldn't encourage you to do intentionally.

Whether and how much damage is done depends on many factors, e.g. how long it was powered up, model, power setting, age, etc. And, unless the damage is immediate total failure, it might be hard to assess and correlate back to the out-of-water event later on, e.g. premature aging, reduced sensitivity, frequency drift, power loss, timing variability, noise, etc.
gkesden is offline   Reply With Quote
Old 03-03-2019, 07:51 AM   #19
Guru
 
ben2go's Avatar
 
City: Upstate,SC
Country: USA
Vessel Name: Caroliner
Vessel Model: 28' Spira San Miguel
Join Date: May 2012
Posts: 2,367
Quote:
Originally Posted by gkesden View Post
Ensure your transducer is /never/ powered up when out of the water. At best, it'll do no good -- air doesnt carry the signal well enough for it to work at all. At worst, it'll damage it beyond use or repair.

Transducers are water cooled. Water has a specific heat capacity about 1000x more than air and a thermal conductivity about 25x greater than air. Even warm water cools much better than cooler air.

Some people may report that theirs was powered up on land and it hurt nothing. That might be true. And, it might offer you some reassurance should you goof. But, it shouldn't encourage you to do intentionally.

Whether and how much damage is done depends on many factors, e.g. how long it was powered up, model, power setting, age, etc. And, unless the damage is immediate total failure, it might be hard to assess and correlate back to the out-of-water event later on, e.g. premature aging, reduced sensitivity, frequency drift, power loss, timing variability, noise, etc.
What cools transducers that are mounted internally, to the hull?
__________________
What a pain in the transom.

ben2go is offline   Reply With Quote
Old 03-03-2019, 09:42 AM   #20
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: 5,159
Quote:
Originally Posted by ben2go View Post
What cools transducers that are mounted internally, to the hull?
The hull itself, which in turn is cooled by the water it is in.
__________________

__________________
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
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 02:50 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012