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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

Transducer questions

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steephen
Navigator

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100 Posts

Initially Posted - 06/29/2003 : 18:58:09

I think I read somewhere in these pages that one could put a depth transducer in a plastic jar filled with mineral oil, and screw down the cap. The container is epoxied to the interior hull. This is the in-hull transducer, as I don't want to drill a hole in my boat this season. This jar method means one could change a broken transducer pretty easily. Questions: Has anyone experimented with this mineral oil job? Also, I'm thinking of the back end of the V-berth, where there is something of a flat spot on the floor under the cushions. My boat is a 1980 C-25. Does anyone know if the fiberglass is cored or solid in that area? I heard that if it's cored, the sending unit won't work.
"Little Wing"

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ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 06/29/2003 : 21:00:28

Usually an open-ended PVC "standpipe" is epoxied to the bottom
of the vessel, filled with mineral oil, and the transducer
is lowered into the pipe. A variety of methods can be used
to seal the top.. from saran wrap and rubber bands to regular pipe caps with a slot for the cable.

If you have a 'puck' style transducer, you can epoxy it right to the inside of the hull. You have to be careful not to trap any bubbles under it though.

AFAIK, the hull of C25 is solid fiberglass. (but not all the topsides)

Currently maintaining two holes in the water...'77 Venture 23 and new to the family,
'78 Catalina 25

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jsummerfield
1st Mate

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USA
96 Posts

Response Posted - 06/29/2003 : 23:14:11

I too am about to do an in-hull installation. Buy a cheap unit as the bells and whistles such as water temperature will not apply. If the sensor has temperature it will only sense the hull temp.

The Raytheon manual (many manuals are available as PDF files on the web) advises that an in-hull transducer may be limited to a fiberglass hull that is no more than one-inch thick. I lifted a lot of notes that are paraphrased or quoted below from other web sites.
There appears to be a lot of flexibility. Some use a Ziploc sandwich or freezer bag filled with water under the sensor to find a good spot. “Take your bag and puck and lay the bag on the inside of the hull and press the transducer onto the hull at the same angle (preferably perpendicular to the keel). When you find a spot that provides the best possible reading (of a known depth) mark it. Next, go for a cruise to some other known depth and a few unknown depths. When you are satisfied, that is where you want to place your transducer”.

Consider a location in a flat part of the hull, or no more than 10 degree rise if practical. Consider an angled in-hull transducer for greater angles. Do not compensate for the angle of the hull with an epoxy fill.

Some used a PVC plumbing fitting cut at the angle of the hull to be vertical. Consider just using silly RTV or putty to temporarily seal the pipe and play with the piping and transducer. Fill with water or with mineral oil for cold areas to prevent freezing. Some use Vaseline as a temporary adhesive for locating a good spot.

Some use the transom transducer supplied with the unit instead of buying the puck style. Consider a third-party transducer if bought separately. Many are furnished by the same sensor manufacturer.

For the permanent installation, use a hard epoxy. Soft or flexible adhesives such as silicone or RTV absorb the sound. After the location is well marked and ready for a permanent attachment, apply the epoxy then set the transducer down by the edge and roll it flat into the puddle of epoxy. Set the edge first to avoid air bubbles then slowly press it down flat and secure with a heavy object or tape for a day or so without movement.

Now having given all of the free advice based upon someone elses experience, please let me know what you did, how it worked, etc. so that I may gain from your actual experience.

John

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steephen
Navigator

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100 Posts

Response Posted - 06/30/2003 : 21:17:03

That's a lot of info. I will let you know how I make out. The boat is still on dry land, so there's no experimention with transducer location yet. I'm pretty sure I am going to go with the mineral oil in some type of container, because if the transducer doesn't work, or if it breaks, I don't want to be down there with a steak knife trying to free it up.
Will keep you posted.
Stephen Z

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77Gypsy
Captain

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USA
356 Posts

Response Posted - 06/30/2003 : 22:59:14

i have a shoot through the hukll transducer, i have also used mineral oil in the plastic housing, i put mine under the gally on the port side. works pretty well. occasionally i'll have the depth blinking on the display but most of ther time i get a solid reading.

Steve
78 C25 SR/FK - Gypsy
<img src="http://www.websdf.com/gypsy_sign.jpg" border=0>

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Steve Shetter
1st Mate

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USA
60 Posts

Response Posted - 07/01/2003 : 22:52:39

When I bought my 1981 C-25, the p.o. had installed a transducer on the port side of the keel just forward of the keel winch. It is made of either 3 or 4 inch PVC, epoxied to the hull with a threaded cap to keep the mineral oil from splashing out. He said that it worked perfectly, until his daughter broke the unit (which he had in the cockpit). As soon as I get another unit, I will follow his advise and use the "tank" that he installed.

Good Luck,

Steve Shetter
"At Last"
#2381

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jsummerfield
1st Mate

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USA
96 Posts

Response Posted - 07/04/2003 : 13:16:36

I recommended buying a cheap fishfinder. However, I found a wrinkle that I will share. I ordered the Garmin Fishfinder 100 Blue. This is a pretty cheap unit but not the cheapest by far. Among the features that I liked, the Fishfinder 100 Blue has a dual frequency transducer. At first I was not impressed by this and actually prefered the Fishfinder 100 (not Blue) because of the power consumption figures. I was also interested in the Garmin GPSMAP 168. Each of these units, and many others have a 20 degree coverage cone. The dual frequency has a wide 40 degree outer cone and a narrow, 8 degree inner cone. The inner cone is supposed to provide the good bottom definition. I want the outer cone for that small advanced notice to detect a shallow bottom. Most of my sailing will be on Galveston Bay that is mostly about 10-foot deep. There will also be lots of motoring a channel in the very shallow Clear Lake to get to the bay. This may not prove to be the correct selection. Only time and installation work will tell.

John

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NuNees
Navigator

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USA
125 Posts

Response Posted - 07/04/2003 : 17:32:54

I bought Moonbeams last September...finaally got the transducer installed in the Vee berth locker , just froward of the through-hull drain for the lavatory sink.
The boaat came with a Standard Horizon Depth Sounder DS45. PO had installed it in the prot side cabin bulkhead. He included a transome mounted transducer, bu uninstalled except for the hole in the transome. The skeg and the transome are an unsuitable location for the transducer, IMHO.
Several previous threads talked aboutt gluing the traansducer to the hull. Some suggested cofferdam made of a pvc plumbing pipe cleanout.
I tried the 'Bag of Water' test where you load aziplock bag with water, place it on th ehull location you want to test, put the transducer in it, secure it a nd go saila nd see if it works. It did.
I laid out a really big dollip of clear silicone sealant, place the transducer in t and let it firm up. It works. No hole in the hull. Now all I have to do is hide the cable...
oh yes, I need to put a switch in to circuit...
But first I must get that damned 9.9 Sailmaster to run so I can get Moonbeams out of the marina.
Good Luck with your installation...remember...NO BUBBLES.

Bill Jaworowski
Moonbeams
C25 SR/SK #4953 Lake Carlyle, IL.

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steephen
Navigator

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100 Posts

Response Posted - 07/04/2003 : 20:31:28

Well, I epoxied a tupperwear container to the flooring by the back wall of the V-berth. Will fill her up with mineral oil when I launch, hopefully next week. Just painted my bootstripes today, and started taking my tools home...
Stephen Z "Little Wing"

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eric.werkowitz
Captain

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USA
283 Posts

Response Posted - 07/04/2003 : 22:40:10

Stephen,

Are you sure that epoxy really sticks to the Tupperware plastic? I know some plastics won't for a lasting seal with epoxy.

Eric Werkowitz
C25 #4969

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timpky
1st Mate

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USA
41 Posts

Response Posted - 07/04/2003 : 23:30:43

The instructions that came with my transom mount transducer offered an alternative mounting by simply using slow cure epoxy to glue the transducer to the inside of the hull. You just need to make sure it is in a location where there is minimal air bubbles under the hull. I have a swing keel and mounted mine about two feet aft of the cable thru hull. It seems to work just fine. Only problem is if it breaks you are stuck (literally).

Tim Peoples
Sarasota, FL
78 Catalina 25 SK Hull #875

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steephen
Navigator

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100 Posts

Response Posted - 07/06/2003 : 19:08:16

Eric:
I don't know if it was actual Tupperwear brand. It seemed glued down pretty well, and if it doesn't stick, I already have another container handy. I suppose a medium tug on the container should be sufficient to demonstarte if it seated well. I'll keep you posted.
Stephen Z

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