Transducer location

[Lance Jones]

I'm adding a transducer for a new digital depth gauge. It is an inside the hull mount. What is y'all's opinion as to the best location for that?

[Stu Jackson]

Under the V berth forward of the keel.

[Ken Juul]

concur with Stu.  You want to know what your about to hit not what is past

[Lance Jones]

Thanks! Ok, is that area flat enough to shoot straight down through the keel? I need to mount it in a bed of epoxy to maintain physical continuity with the transducer and the hull. My current through hull mount is under the forward starboard settee.

[Stu Jackson]

Ok, is that area flat enough to shoot straight down through the keel?

Yes it is, but you should go look, too.  In other posts recently, people have shown doors and drawers in the fiberglass under the V berth insert.  If you don't have a hole there, you may want to consider adding something to give you better access.  You'll also need to find a way to protect what you install from damage from "stuff" in the storage area under the V berth from hitting the new transducer.

[Mert Gollaher]

I'm thinking through the same question now. I'll likely default to a location just forward of the current thru-hull mount under the forward starboard settee, not because I think it's better, but because, as Stu said, I want easier access and better control of the "stuff" in the same storage area.  I have a false bottom there already above the current thru-hull depth and speed transducers and only the original 1987 access to the area under the v-berth which ends up being a dumping ground for stuff that has no other place.  I guess I just don't believe (after my history with my old datamarine transducers) that I'll be able to set it and forget it for very long periods of time. The airmar transducer I bought has a pretty neat mounting system that can accomodate varying degrees of deadrise in the hull.   

[tonywright]

You don't have to put it in epoxy. You could expoxy some abs pipe to the hull, capped by a drain clean-out fitting. Put the transducer inside and fill the pipe with mineral oil.  This will maintain the continuity, and allow the transducer to come out for periodic inspection or replacement. A set up I had on a boat about 15 years ago...

Tony

[Lance Jones]

Tony,
I heard about that method when I was active with C-22s. Could you walk me through the process? I like the idea of having an amount of "portability" with the puck.

[Mike and Joanne Stimmler]

Has anyone replaced the through hull speed and depth transducers? I currently have a signet display that does both, but have upgraded to the raymarine st60+ and am waiting till the next time I need bottom paint to get the transducers done at the same time. I'm sure that the raymarine transducers are larger in diameter than the signet but how hard is it to get the old ones out and is the hull solid or does it need to be sealed between the layers like the deck. My through hulls are located under the v-berth and I'd like to reuse the same holes. I've already found out that the transducers are not compatable.

Thanks,
Mike

[Ron Hill]

Lance : On my 1988 C34 the transducers are in the hull just forward and srarboard of the mast - aft of the VBerth.  I like that location as it isn't too far fwd and is easier to get to than the Vberth. 
Also that compartment has a build up for the mast step and there's a drop down to the hull for the transducers (depth & knot log).  I put a piece of 1/4" plywood (contoured to fit) and it covers/protects  the top of the transducers as well as making a "flat" flooring for storage.  A thought   

[pablosgirl]

Hi Mike,

The hull is solid glass laminate through out.  It is approximately 9/16 to 5/8 inch thick in the area forward of the keel where the depth and speedo transducers are typically located, just forward of the rear bulkhead of the v-berth.  The hull thins to about 1/2 inch above the waterline except the the bow and transom edges where it is reinforced.  You will need to use a bedding compound around the transducer that is rated for bellow the water use (polyurethane or polysulfide sealant).  Getting the old transducers out depends on the sealant used to bed them to the hull.  If they used 5200, then you may have to get aggressive.  I would first try to back off the mounting nut from the inside of the hull and drive the depth transducer out using a scrap of 2x4 and a 5lb hammer.  For the speed transducer, remover the plug and use a long bolt and a washer large enough to sit on the through-hull with the retaining nut removed.  Pass the bolt through the through-hull and through a wooden block outside the hull.  Block the ends of the wood clear of the hull and tighten the nut on the bolt.  This should pull the transducer through-hull free of the hull.  If this does not work and the transducer flanges are plastic, the you can use a 16 grit sanding wheel and working from the out carefully sand the flange off till just before you expose the hull underneath the flange.  If the transducers are metal you will have to use a grinder.  This is very delicate work, because the grinding process will generate heat and you cannot let the hull get hot or you will DAMAGE the resign in the hull.  you will have to grind a little and wait.  Repeat this cycle until you get through the flange.  Then try and drive the transducer through its hole into the interior of the boat.  Once the old transducers are out of the hull, you can now drill the hole out to a larger diameter using a center pilot hole saw.  You will have to attach a temporary wood backer board to the inside of the hull  so that you can center the pilot drill bit of the hole saw in the existing hole.  I would attach the backer board with a few dabs of 5 minuet epoxy.  Use only enough to hold the board in place to drill the hole.  Use too much and you will have to work harder getting the backer board loose from the hull.

Paul


P.S.  Here is an interesting discussion on depth transducer compatibility http://www.sailnet.com/forums/gear-maintenance/8341-transducers-depth-sounder-high-teck.html  and http://forums.hunter.sailboatowners.com/showthread.php?t=77247

[Jim Hardesty]

Back to not having to epoxy in place.  My first sail boat was a 22 Columbia, had no depth sounder.  The salesman I bought my depth sounder from recommended "silly putty" between the hull and transducer.  It worked great for the 2 seasons I had the boat, even with a lot of bottom paint on the hull.
Jim

[Lance Jones]

Silly putty? Amazing! I guess one of the down sides of that is when you bounced up off a wave, you really bounced a long way due to the silly putty and then bounced even higher still on the rebound.  Man, I hate myself. Dear Lord, please forgive me and bless the pygmies in New Guinea.

I use to love silly putty when I was a kid. Great stuff.

[Ken Heyman]

not to steal others thunder but before you drill, keep in mind that transducers have no trouble functioning from the inside of Catalina hulls. When my OEM depthfinder stopped working, I simply put a transducer in the compartment just forward of the mast behind the starboard v birth bulk head. the key is to have no air between the transducer and hull. There are a number of easy way to do this. The attached link provides a discussion of the subject.

As some might say "your hole--your choice".

http://catalinadirect.com/forums/fr_topic.cfm?topic_id=1169

good luck,

Ken

[Ken Heyman]

whoops -I do see you are talking about an inside the hull mount. anyway the link provided is a good discussion.

Ken