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Author Topic:   Transducer mounting?

here fishy posted 09-14-2000 02:35 PM ET (US)
The previous owner of my 13 whaler made several attempts at mounting a fishfinder to the transom. I've patched up the holes. I was hoping to avoid more drilling by mounting the transducer onto a plate and then gluing the plate into position with 3m 5200.
I saw Starboard in Cabelas and called the manufacturer, DIY Marine in Miami, to ask how to glue the Starboard onto the fiberglass transom. They said that Starboard can only be glued with "their" special glue. The guy gave me a ballpark figure to purchase the stuff and said when you're finished adding up the cost of the materials it comes out to about $130. The plate I need will be no more than 5" x 5".
I'm certainly not going to spend that for their glue. What other options do I have with the same approach as I envision. At one time I did see a similar plate in Cabelas but I don't know if it was made of wood or plastic. It seemed as if you had to screw it into the transom anyway.
I saw a vertical transducer mounting gadget that you clamp onto the top of the transom. It's adjustable and made of aluminum. Think I also saw it in Cabela's but not recently. Any experience with that apparatus?
Any suggestions? Great site!!!!
Bashaw posted 09-14-2000 04:38 PM ET (US)
Starboard is a version of ultra high molecular weight (UHMW) Polyethylene. All varions of polyethylene, including UHMW, are very difficult to use adhesives on. The transom bracket probably would work but I would be very concerned at using it at high speeds. If you do put a safety cable on it. That way if it or the transduder get hit it won't swing up on the cable and hit you.
triblet posted 09-14-2000 10:00 PM ET (US)
What was unsuccessful about the previous
owners efforts? I've got my transducer
screwed into the transom of my Montauk.
No problem, other than it doesn't work well
at over about 25 knots, but but the
starboard mounting wouldn't solve that.
Chuck Tribolet
lhg posted 09-15-2000 12:10 AM ET (US)
I have seen these "Starboard" transducer mounting plates in the boating catalogs, and although I have not yet tried one, they do seem to make sense. This is mainly because Whalers tend to last a long time, and depth finders tend to get obsolete real fast. I know on my 1986 Whaler that I am on my third sonar unit, and every one required different holes in the transom. So the theory is that instead, you only drill two holes in the transom, to mount the starboard piece, which is about 4" x 12",
then screw the tansducers, speed & temp wheel, etc. into this. Then if things change, you turn the starboard over, and start over with the new transducers, (or get another piece) and still only have the two original holes in the transom. It also gives you another chance to re-mount the transducer if you've goofed the first time, as I have done several times.
But DON't glue the starboard to the hull. Use only 2 wood screws long enough to penetrate into the plywood transom blocking.
A properly mounted "skimmer" trnaducer, such as Lowrance has designed, should give readings up to 60mph.
JB posted 09-15-2000 03:37 PM ET (US)
Bite the bullet and drill the two new holes...
here fishy posted 09-16-2000 01:31 AM ET (US)
The plywood in the transom is very midline and the transducer is supposed to be at least 18" from the midline so I don't think I can tap into that plywood. Probably will bite the bullet and go right in. Thanks gents.
gus
lhg posted 09-17-2000 03:37 PM ET (US)
I would not recommend mounting transducers where there is no plywood in the transom.
The screws could rip out or you could delaminate the hull. Putting screws into the glass skin where there is no backing is only for light-duty applications.
bschmitt posted 09-17-2000 08:24 PM ET (US)
So what's the general consensus on where to mount the transducer on a Montauk?
My first attempt led to flakey results, some definitely related to speed, some absolutely baffling. I have a certain area in Shinnecock Bay (my home waters) where my Garmin 185 shows a solid "---" no matter how fast I'm going, even if the engine is off, high or low tide.
Anyway, my new Garmin depth, speed & temp transducer is on its way to me. I'm ready to beach the boat, drill holes & patch the old (well, rather new) ones.
Where should I drill?
triblet posted 09-18-2000 10:22 PM ET (US)
How deep is that spot? Could it be too
deep for your depth finder? Anyway, since
you have problems when you are drifting,
it's NOT the mounting location, assuming the
transducer is mounted pointing more or less
down. Fix this problem before you start
moving the transducer around. You could even
test it when your new transducer comes by
just holding the transducer over the side
while drifting.
18" would be way to far. It won't be solidly
in the water at any planing speed. Maybe
on a jon boat ;-).
The transducer on my Montauk is mounted 8" to
port of the center line. The transducer for
the old unit was mounted 8" to starboard (My
old ladder made it risky to mount it near the
portside swimstep). Both seem to work up to
about 25 knots. Where'd I get the 8" number?
A buddy at work has a Montauk, and that's
where the dealer installed the transducer.
The 8" is not perfect, and if anyone has any
better ideas, I'll try them.
Don't bother filling just yet. Just put some
3M 101 and SS pan head screws the same size
in the holes. That way you can always move
it back.
Chuck Tribolet
bschmitt posted 09-19-2000 09:35 PM ET (US)
>How deep is that spot? Could it be too
deep for your depth finder?<
No, not deep at all. Maybe 16-20 ft. Always the same spot, I have it marked on the GPS. Maybe it's jinxed.
>You could even
test it when your new transducer comes by
just holding the transducer over the side
while drifting.<
Yeah, I'll do that.

>8" would be way to far. It won't be solidly
in the water at any planing speed. Maybe
on a jon boat ;-).<
That is my current problem. On WOT, this spot is in wet air.
>The transducer on my Montauk is mounted 8" to port of the center line.<
Makes much more sense.
>Don't bother filling just yet. Just put some
3M 101 and SS pan head screws the same size
in the holes. That way you can always move
it back.<
Yeah. And it's on the to-do-list for when the boat is out of the water.
I usually use 5200 for these jobs. Is 101 better?
triblet posted 09-20-2000 08:22 AM ET (US)
5200 is seriously permanent stuff. It's
great for things you KNOW you will never
take off. 4200 is less permanent but
still suffers from short pot life once you
take the cap off. 5200 and 4100 are
adhesives. 101 is just a caulk and stays
soft.
Chuck Tribolet
dgp posted 09-21-2000 09:32 AM ET (US)
Per the Boston Whaler Center Console Series Owner's Manual that came with my Montauk sez, "Most transducers will act as a small trim tab affecting hull trim. Transducers should be mounted on the port side, or on center to provide lift or have a neutral effect on the trim." It also goes on to say, "The area you select to mount the transducer on the transom may not contain wood inserts. The fiberglass skin is suitably strong for fastenings such as stainless steel sheet metal screws." Don
triblet posted 09-21-2000 09:57 AM ET (US)
Also, the prop lifts the water on the
port side, which, in theory, helps keep
the transducer in the water when on plane.
In practice, I didn't see much difference
between port and starboard, and at this
point at least, I got better results at
speed on the starboard side (different
transducer, but same manufacturer and
same general shape.
Chuck Tribolet
triblet@garlic.com

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Author	Topic: Transducer mounting?
here fishy	posted 09-14-2000 02:35 PM ET (US) The previous owner of my 13 whaler made several attempts at mounting a fishfinder to the transom. I've patched up the holes. I was hoping to avoid more drilling by mounting the transducer onto a plate and then gluing the plate into position with 3m 5200. I saw Starboard in Cabelas and called the manufacturer, DIY Marine in Miami, to ask how to glue the Starboard onto the fiberglass transom. They said that Starboard can only be glued with "their" special glue. The guy gave me a ballpark figure to purchase the stuff and said when you're finished adding up the cost of the materials it comes out to about $130. The plate I need will be no more than 5" x 5". I'm certainly not going to spend that for their glue. What other options do I have with the same approach as I envision. At one time I did see a similar plate in Cabelas but I don't know if it was made of wood or plastic. It seemed as if you had to screw it into the transom anyway. I saw a vertical transducer mounting gadget that you clamp onto the top of the transom. It's adjustable and made of aluminum. Think I also saw it in Cabela's but not recently. Any experience with that apparatus? Any suggestions? Great site!!!!
Bashaw	posted 09-14-2000 04:38 PM ET (US) Starboard is a version of ultra high molecular weight (UHMW) Polyethylene. All varions of polyethylene, including UHMW, are very difficult to use adhesives on. The transom bracket probably would work but I would be very concerned at using it at high speeds. If you do put a safety cable on it. That way if it or the transduder get hit it won't swing up on the cable and hit you.
triblet	posted 09-14-2000 10:00 PM ET (US) What was unsuccessful about the previous owners efforts? I've got my transducer screwed into the transom of my Montauk. No problem, other than it doesn't work well at over about 25 knots, but but the starboard mounting wouldn't solve that. Chuck Tribolet
lhg	posted 09-15-2000 12:10 AM ET (US) I have seen these "Starboard" transducer mounting plates in the boating catalogs, and although I have not yet tried one, they do seem to make sense. This is mainly because Whalers tend to last a long time, and depth finders tend to get obsolete real fast. I know on my 1986 Whaler that I am on my third sonar unit, and every one required different holes in the transom. So the theory is that instead, you only drill two holes in the transom, to mount the starboard piece, which is about 4" x 12", then screw the tansducers, speed & temp wheel, etc. into this. Then if things change, you turn the starboard over, and start over with the new transducers, (or get another piece) and still only have the two original holes in the transom. It also gives you another chance to re-mount the transducer if you've goofed the first time, as I have done several times. But DON't glue the starboard to the hull. Use only 2 wood screws long enough to penetrate into the plywood transom blocking. A properly mounted "skimmer" trnaducer, such as Lowrance has designed, should give readings up to 60mph.
JB	posted 09-15-2000 03:37 PM ET (US) Bite the bullet and drill the two new holes...
here fishy	posted 09-16-2000 01:31 AM ET (US) The plywood in the transom is very midline and the transducer is supposed to be at least 18" from the midline so I don't think I can tap into that plywood. Probably will bite the bullet and go right in. Thanks gents. gus
lhg	posted 09-17-2000 03:37 PM ET (US) I would not recommend mounting transducers where there is no plywood in the transom. The screws could rip out or you could delaminate the hull. Putting screws into the glass skin where there is no backing is only for light-duty applications.
bschmitt	posted 09-17-2000 08:24 PM ET (US) So what's the general consensus on where to mount the transducer on a Montauk? My first attempt led to flakey results, some definitely related to speed, some absolutely baffling. I have a certain area in Shinnecock Bay (my home waters) where my Garmin 185 shows a solid "---" no matter how fast I'm going, even if the engine is off, high or low tide. Anyway, my new Garmin depth, speed & temp transducer is on its way to me. I'm ready to beach the boat, drill holes & patch the old (well, rather new) ones. Where should I drill?
triblet	posted 09-18-2000 10:22 PM ET (US) How deep is that spot? Could it be too deep for your depth finder? Anyway, since you have problems when you are drifting, it's NOT the mounting location, assuming the transducer is mounted pointing more or less down. Fix this problem before you start moving the transducer around. You could even test it when your new transducer comes by just holding the transducer over the side while drifting. 18" would be way to far. It won't be solidly in the water at any planing speed. Maybe on a jon boat ;-). The transducer on my Montauk is mounted 8" to port of the center line. The transducer for the old unit was mounted 8" to starboard (My old ladder made it risky to mount it near the portside swimstep). Both seem to work up to about 25 knots. Where'd I get the 8" number? A buddy at work has a Montauk, and that's where the dealer installed the transducer. The 8" is not perfect, and if anyone has any better ideas, I'll try them. Don't bother filling just yet. Just put some 3M 101 and SS pan head screws the same size in the holes. That way you can always move it back. Chuck Tribolet
bschmitt	posted 09-19-2000 09:35 PM ET (US) >How deep is that spot? Could it be too deep for your depth finder?< No, not deep at all. Maybe 16-20 ft. Always the same spot, I have it marked on the GPS. Maybe it's jinxed. >You could even test it when your new transducer comes by just holding the transducer over the side while drifting.< Yeah, I'll do that. >8" would be way to far. It won't be solidly in the water at any planing speed. Maybe on a jon boat ;-).< That is my current problem. On WOT, this spot is in wet air. >The transducer on my Montauk is mounted 8" to port of the center line.< Makes much more sense. >Don't bother filling just yet. Just put some 3M 101 and SS pan head screws the same size in the holes. That way you can always move it back.< Yeah. And it's on the to-do-list for when the boat is out of the water. I usually use 5200 for these jobs. Is 101 better?
triblet	posted 09-20-2000 08:22 AM ET (US) 5200 is seriously permanent stuff. It's great for things you KNOW you will never take off. 4200 is less permanent but still suffers from short pot life once you take the cap off. 5200 and 4100 are adhesives. 101 is just a caulk and stays soft. Chuck Tribolet
dgp	posted 09-21-2000 09:32 AM ET (US) Per the Boston Whaler Center Console Series Owner's Manual that came with my Montauk sez, "Most transducers will act as a small trim tab affecting hull trim. Transducers should be mounted on the port side, or on center to provide lift or have a neutral effect on the trim." It also goes on to say, "The area you select to mount the transducer on the transom may not contain wood inserts. The fiberglass skin is suitably strong for fastenings such as stainless steel sheet metal screws." Don
triblet	posted 09-21-2000 09:57 AM ET (US) Also, the prop lifts the water on the port side, which, in theory, helps keep the transducer in the water when on plane. In practice, I didn't see much difference between port and starboard, and at this point at least, I got better results at speed on the starboard side (different transducer, but same manufacturer and same general shape. Chuck Tribolet triblet@garlic.com