In hull transducer question
 

Hi folks, Just bought a Faria dash mounted depth sounder with a
'glue it inside the hull' transducer. Faria warns that it won't work
very good if my hull has core material in it. I am guessing it probably
has 3/4 inch plywood with the outer, and inner fiberglass body shell.

I only need to know when the water is perhaps less than 8 feet deep.
As long as it is deeper I have no worries.

What are the chances it will work o.k. out to perhaps 20 feet if I just
go ahead and glue it in anyway? I really don't want to remove the inner
fiberglass shell, and the wooden core, just to glue the transducer on
the inside of the outer skin.

Anyone currently running a half baked set up like I am going to try?
Do I have to just bite the bullet, and get out the Dremel?

Thanks all!

gudmundur wrote:
Hi folks, Just bought a Faria dash mounted depth sounder with a
'glue it inside the hull' transducer. Faria warns that it won't work
very good if my hull has core material in it.......

What are the chances it will work o.k. out to perhaps 20 feet if I just
go ahead and glue it in anyway?

Very slim. It won't "see" thru the core at all.

... I really don't want to remove the inner
fiberglass shell, and the wooden core, just to glue the transducer on
the inside of the outer skin.

You can try putting the transducer against a baggy of water, and hold it
by hand against a few different spots in the hull to see if you can find
a place it will read. Maybe you'll get lucky and find a spot it can read
thru.

You could also mount it on the transom.

It's not that big a deal to make a transducer bubble on the inside of
your hull, you already have a Dremel tool right ;)

Fair Skies
Doug King

On Tue, 10 May 2005 19:40:29 -0000, (gudmundur) wrote:

Hi folks, Just bought a Faria dash mounted depth sounder with a
'glue it inside the hull' transducer. Faria warns that it won't work
very good if my hull has core material in it. I am guessing it probably
has 3/4 inch plywood with the outer, and inner fiberglass body shell.

I only need to know when the water is perhaps less than 8 feet deep.
As long as it is deeper I have no worries.

What are the chances it will work o.k. out to perhaps 20 feet if I just
go ahead and glue it in anyway? I really don't want to remove the inner
fiberglass shell, and the wooden core, just to glue the transducer on
the inside of the outer skin.

Anyone currently running a half baked set up like I am going to try?
Do I have to just bite the bullet, and get out the Dremel?

Thanks all!

Can't you just place it in the bottom where you know the depth of water and see
if it works? Before you glue it?

--
John H

"All decisions are the result of binary thinking."

"John H" wrote in message
...
On Tue, 10 May 2005 19:40:29 -0000, (gudmundur) wrote:

Hi folks, Just bought a Faria dash mounted depth sounder with a
'glue it inside the hull' transducer. Faria warns that it won't work
very good if my hull has core material in it. I am guessing it probably
has 3/4 inch plywood with the outer, and inner fiberglass body shell.

I only need to know when the water is perhaps less than 8 feet deep.
As long as it is deeper I have no worries.

What are the chances it will work o.k. out to perhaps 20 feet if I just
go ahead and glue it in anyway? I really don't want to remove the inner
fiberglass shell, and the wooden core, just to glue the transducer on
the inside of the outer skin.

Anyone currently running a half baked set up like I am going to try?
Do I have to just bite the bullet, and get out the Dremel?

Thanks all!

Can't you just place it in the bottom where you know the depth of water
and see
if it works? Before you glue it?

--
John H

"All decisions are the result of binary thinking."

Good suggestion John.

gudmunder, if this does not work you will have to buy a through-hull or
transom mounted transducer.

Most boats have a spot in the hull that is nothing but glass. Some paint
this area black so you can find it. Others leave it clear and it will show
up as a clearer area.

To make sure it will work at this spot - fill the bilge with enough water to
cover the area by about 1/4". Lay the transducer on this spot and check.

The transducer will not work thru any air pockets so you have to put some
water in there to try.

To install - I use silicone. People will tell you not to but I have always
done this with no problem. Build up a large area of silicone about 1/2"
thick. Take the transducer and push it down all the way pushing out all the
excess. Don't twist. This will remove any air bubbles. Take and wipe up
the excess w/ papertowels being careful not to move the transducer.

Problem w/ epoxy is you need a lot to push down and make sure there are no
air bubbles.

--
Tony
my boats and cars at http://t.thomas.home.mchsi.com

-
"gudmundur" wrote in message
...
Hi folks, Just bought a Faria dash mounted depth sounder with a
'glue it inside the hull' transducer. Faria warns that it won't work
very good if my hull has core material in it. I am guessing it probably
has 3/4 inch plywood with the outer, and inner fiberglass body shell.

I only need to know when the water is perhaps less than 8 feet deep.
As long as it is deeper I have no worries.

What are the chances it will work o.k. out to perhaps 20 feet if I just
go ahead and glue it in anyway? I really don't want to remove the inner
fiberglass shell, and the wooden core, just to glue the transducer on
the inside of the outer skin.

Anyone currently running a half baked set up like I am going to try?
Do I have to just bite the bullet, and get out the Dremel?

Thanks all!

On Tue, 10 May 2005 19:40:29 -0000, (gudmundur)
wrote:

~~ snippage ~~

Anyone currently running a half baked set up like I am going to try?
Do I have to just bite the bullet, and get out the Dremel?

Yes, on two boats. Work fine for what I need. On the larger boat, I
have one mounted in the hull and one thru-hull - it's a personal
thing.

Tony pretty much detailed how the spot is located - it's usually a
different color. The various "wet" techniques are also great ideas.

The other problem is how your boat is set up. You need a special puck
to accommodate the deadrise - otherwise, you aren't shooting down but
at an angle.

Shooting through anything that has "air" is a problem. If your hull
is cored rather than plain fiberglass layers, then you are well and
truly screwed - you will need to use a thru-hull transducer.

I know guys are reluctant to do this, but mounting it on the transom
is always the best choice - direct contact with water under most
conditions. The problem with a thru-hull midships is that if the
signal isn't presented with a solid shot of water it's useless.
Sometimes on plane with a V hull boat, getting solid water on plane is
problematic. At least with a molded puck, you can place it back where
the hull is making contact with the water all the time and it will
work much better.

Personally, I would use epoxy rather than silicone. That's a matter
of personal preference.

Good luck.

Later,

Tom

"tony thomas" wrote in message
news:6yage.73235$c24.21202@attbi_s72...
Most boats have a spot in the hull that is nothing but glass. Some paint
this area black so you can find it. Others leave it clear and it will
show up as a clearer area.

I never knew that. Thanks Tony.

In article 6yage.73235$c24.21202@attbi_s72, says...

Most boats have a spot in the hull that is nothing but glass. Some paint
this area black so you can find it. Others leave it clear and it will show
up as a clearer area.

To make sure it will work at this spot - fill the bilge with enough water to
cover the area by about 1/4". Lay the transducer on this spot and check.

The transducer will not work thru any air pockets so you have to put some
water in there to try.

To install - I use silicone. People will tell you not to but I have always
done this with no problem. Build up a large area of silicone about 1/2"
thick. Take the transducer and push it down all the way pushing out all the
excess. Don't twist. This will remove any air bubbles. Take and wipe up
the excess w/ papertowels being careful not to move the transducer.

Problem w/ epoxy is you need a lot to push down and make sure there are no
air bubbles.


Thanks Tony, This is an old Four Winns (1985) Catalina open bow, and
the area I have been looking at just forward of the drain plug may indeed
be all glass the whole way through. I compared to the depth transducer
mounting on my brothers Stratos, and his is simply glued on exactly as
you have described. As for the silicone RTV glue, you are right on the money
there. I have glued ultrasonic doppler transducers to PVC pipes for many
years, and RTV is at least 90% as conductive to sound energy as any of the
lavishly expensive glues sold specifically for transducer mounting.
I went ahead and RTV glued the bugger in. I will launch tomorrow and
see what happens. I'll let you folks know the outcome, and hope it's
a positive one. As I said, if it even works down to 20 feet, I'll be happy.
I was guessing if there is core material, it is probably somewhat
water-logged anyway from 20 years of service, and that would actually be
an advantage in this case.

Bless all, Gummi.

On Wed, 11 May 2005 03:19:14 -0000, (gudmundur)
wrote:

~~ snippage ~~

As for the silicone RTV glue, you are right on the money
there. I have glued ultrasonic doppler transducers to PVC pipes for many
years, and RTV is at least 90% as conductive to sound energy as any of the
lavishly expensive glues sold specifically for transducer mounting.

I was given to understand that silicone wasn't that transparent to
50Hz transducers. Any truth to that?

Later,

Tom

On Tue, 10 May 2005 19:40:29 -0000, (gudmundur)
wrote:

Hi folks, Just bought a Faria dash mounted depth sounder with a
'glue it inside the hull' transducer.

I used to be on the board for Faria. Nice company.