5200 - How strong on fiberglass
 

Does anyone have any direct experience with how well 5200 sticks to
old but cleaned up fiberglass?

I have to put a new backing block in for a through hull in a very
awkward location. Since it’s a Signet Knotlog, it has to be flush and
there isn’t much back up in the taper for a direct hit on some
floating object. I’d like the back up block to be actually backing it
up.

Building up with fiberglass and epoxy working through a hand sized
opening is going to be tough. I’m wondering if a larger than normal
sized plywood backing block done with 5200 might not be nearly as
strong.


--

Roger Long

5200 - How strong on fiberglass
 

Forgot, 3M also list shore hardness of 5200 as 68A, full cure. This is about
the hardness of your daughters Barbie doll head.
BF

"BF" wrote in message
...
3M lists tensile strength of 5200 as 638psi in salt water, Emerson &
Cuming
26 Eccobond GP Epoxy has an adhesive bond strength of 2100psi.
No personal experience but the numbers don't look appealing.
BF


"Roger Long" wrote in message
...
Does anyone have any direct experience with how well 5200 sticks to
old but cleaned up fiberglass?

I have to put a new backing block in for a through hull in a very
awkward location. Since it's a Signet Knotlog, it has to be flush and
there isn't much back up in the taper for a direct hit on some
floating object. I'd like the back up block to be actually backing it
up.

Building up with fiberglass and epoxy working through a hand sized
opening is going to be tough. I'm wondering if a larger than normal
sized plywood backing block done with 5200 might not be nearly as
strong.


--

Roger Long

5200 - How strong on fiberglass
 

6 x 6 backing block x 638 = 22,968 pounds. That would lift this
particular boat, almost two of them, in fact.

My real question was whether the stuff appears to grab with close to
its potential strength on old fiberglass.

I'd certainly lay up a nice epoxy and glass backing panel in this area
if I could reach it. If 5200 holds even 60% of its book number on the
ground fiberglass, it's probably plenty strong though.

--

Roger Long



"BF" wrote in message
...
3M lists tensile strength of 5200 as 638psi in salt water, Emerson &
Cuming
26 Eccobond GP Epoxy has an adhesive bond strength of 2100psi.
No personal experience but the numbers don't look appealing.
BF


"Roger Long" wrote in message
...
Does anyone have any direct experience with how well 5200 sticks to
old but cleaned up fiberglass?

I have to put a new backing block in for a through hull in a very
awkward location. Since it's a Signet Knotlog, it has to be flush
and
there isn't much back up in the taper for a direct hit on some
floating object. I'd like the back up block to be actually backing
it
up.

Building up with fiberglass and epoxy working through a hand sized
opening is going to be tough. I'm wondering if a larger than normal
sized plywood backing block done with 5200 might not be nearly as
strong.


--

Roger Long

5200 - How strong on fiberglass
 

As said, I have no personal experience. But my understanding is that 5200 is
a bedding / sealing compound, not an adhesive / bonding agent. Without
substantial testing or experience, I would be very leery.
My guess is that 3M will say the same. They will, however; be happy to talk
to you about your application. In my experience, they have been quite
cooperative in trying to help customers solve problems.
BF


"Roger Long" wrote in message
...
6 x 6 backing block x 638 = 22,968 pounds. That would lift this
particular boat, almost two of them, in fact.

My real question was whether the stuff appears to grab with close to
its potential strength on old fiberglass.

I'd certainly lay up a nice epoxy and glass backing panel in this area
if I could reach it. If 5200 holds even 60% of its book number on the
ground fiberglass, it's probably plenty strong though.

--

Roger Long



"BF" wrote in message
...
3M lists tensile strength of 5200 as 638psi in salt water, Emerson &
Cuming
26 Eccobond GP Epoxy has an adhesive bond strength of 2100psi.
No personal experience but the numbers don't look appealing.
BF


"Roger Long" wrote in message
...
Does anyone have any direct experience with how well 5200 sticks to
old but cleaned up fiberglass?

I have to put a new backing block in for a through hull in a very
awkward location. Since it's a Signet Knotlog, it has to be flush
and
there isn't much back up in the taper for a direct hit on some
floating object. I'd like the back up block to be actually backing
it
up.

Building up with fiberglass and epoxy working through a hand sized
opening is going to be tough. I'm wondering if a larger than normal
sized plywood backing block done with 5200 might not be nearly as
strong.


--

Roger Long

5200 - How strong on fiberglass
 

Well, I'm looking for some personal experience but thanks anyway.

The thing I have consistently heard about 5200 is that you shouldn't
use it on anything you hope to get apart again later.

--

Roger Long



"BF" wrote in message
...
As said, I have no personal experience. But my understanding is that
5200 is
a bedding / sealing compound, not an adhesive / bonding agent.
Without
substantial testing or experience, I would be very leery.
My guess is that 3M will say the same. They will, however; be happy
to talk
to you about your application. In my experience, they have been
quite
cooperative in trying to help customers solve problems.
BF


"Roger Long" wrote in message
...
6 x 6 backing block x 638 = 22,968 pounds. That would lift this
particular boat, almost two of them, in fact.

My real question was whether the stuff appears to grab with close
to
its potential strength on old fiberglass.

I'd certainly lay up a nice epoxy and glass backing panel in this
area
if I could reach it. If 5200 holds even 60% of its book number on
the
ground fiberglass, it's probably plenty strong though.

--

Roger Long



"BF" wrote in message
...
3M lists tensile strength of 5200 as 638psi in salt water,
Emerson &
Cuming
26 Eccobond GP Epoxy has an adhesive bond strength of 2100psi.
No personal experience but the numbers don't look appealing.
BF


"Roger Long" wrote in message
...
Does anyone have any direct experience with how well 5200 sticks
to
old but cleaned up fiberglass?

I have to put a new backing block in for a through hull in a
very
awkward location. Since it's a Signet Knotlog, it has to be
flush
and
there isn't much back up in the taper for a direct hit on some
floating object. I'd like the back up block to be actually
backing
it
up.

Building up with fiberglass and epoxy working through a hand
sized
opening is going to be tough. I'm wondering if a larger than
normal
sized plywood backing block done with 5200 might not be nearly
as
strong.


--

Roger Long

5200 - How strong on fiberglass
 

BF wrote:
As said, I have no personal experience. But my understanding is that 5200 is
a bedding / sealing compound, not an adhesive / bonding agent. Without
substantial testing or experience, I would be very leery.
My guess is that 3M will say the same. They will, however; be happy to talk
to you about your application. In my experience, they have been quite
cooperative in trying to help customers solve problems.
BF

You ever try to get that stuff off of anything. My cabin sole was glued
down with 5200. The bottom ply stayed glued to the floor. Had to use a
putty knife and hammer for about 10 hours to get it up. It is definitely
an adhesive/bonding agent. Use Lifecalk for bedding.
krj

5200 - How strong on fiberglass
 

Roger Long wrote:

6 x 6 backing block x 638 = 22,968 pounds. That would lift this
particular boat, almost two of them, in fact.

My real question was whether the stuff appears to grab with close to
its potential strength on old fiberglass.

I'd certainly lay up a nice epoxy and glass backing panel in this area
if I could reach it. If 5200 holds even 60% of its book number on the
ground fiberglass, it's probably plenty strong though.

Roger,
If you can sand the fiberglass surface then clean with mineral spirits,
5200 will stick. I have used it several places to bond things to the
hull during my boat refurbishing.
krj

5200 - How strong on fiberglass
 

On Mon, 27 Mar 2006 22:35:18 +0000, Roger Long wrote:

Well, I'm looking for some personal experience but thanks anyway.

The thing I have consistently heard about 5200 is that you shouldn't
use it on anything you hope to get apart again later.

Sound advice.

Keep in mind it's used to glue decks onto hulls.

Matt O.

5200 - How strong on fiberglass
 

On Mon, 27 Mar 2006 20:12:44 GMT, "Roger Long"
wrote:
Does anyone have any direct experience with how well 5200 sticks to
old but cleaned up fiberglass?

I have to put a new backing block in for a through hull in a very
awkward location. Since it’s a Signet Knotlog, it has to be flush and
there isn’t much back up in the taper for a direct hit on some
floating object. I’d like the back up block to be actually backing it
up.

Building up with fiberglass and epoxy working through a hand sized
opening is going to be tough. I’m wondering if a larger than normal
sized plywood backing block done with 5200 might not be nearly as
strong.

I had a pair of Signet transducers on my old Cal-34 with no backing
blocks at all. I'd estimate the fiberglass thickness at about 3/8 in
or perhaps slightly greater, taper was about half the thickness as I
recall. Never had any strength issues.

That said, 5200 is tough stuff and would probably be fine.

5200 - How strong on fiberglass
 

Roger Long wrote:
Does anyone have any direct experience with how well 5200 sticks to
old but cleaned up fiberglass?

I have to put a new backing block in for a through hull in a very
awkward location. Since it’s a Signet Knotlog, it has to be flush and
there isn’t much back up in the taper for a direct hit on some
floating object. I’d like the back up block to be actually backing it
up.

Building up with fiberglass and epoxy working through a hand sized
opening is going to be tough. I’m wondering if a larger than normal
sized plywood backing block done with 5200 might not be nearly as
strong.



Talking about putting holes in your hull.
I'm trying to decide if I should buy a thru hull transducer.. or an
in-hull transducer for a depth sounder.
If I could feel sure that accuracy is similar, the in-hull might be
better for a trailerable sailboat...re all that loading & unloading over
rollers/bunks (& occasional beaching).

5200 - How strong on fiberglass
 

The in hull transducer on my boat works great. It's just slapped on
the inside of a fairly thick hull.

I can't imagine putting a hole in a hull if you don't need to.

--

Roger Long



"Don White" wrote in message
...
Roger Long wrote:
Does anyone have any direct experience with how well 5200 sticks to
old but cleaned up fiberglass?

I have to put a new backing block in for a through hull in a very
awkward location. Since it’s a Signet Knotlog, it has to be flush
and there isn’t much back up in the taper for a direct hit on some
floating object. I’d like the back up block to be actually backing
it up.

Building up with fiberglass and epoxy working through a hand sized
opening is going to be tough. I’m wondering if a larger than normal
sized plywood backing block done with 5200 might not be nearly as
strong.



Talking about putting holes in your hull.
I'm trying to decide if I should buy a thru hull transducer.. or an
in-hull transducer for a depth sounder.
If I could feel sure that accuracy is similar, the in-hull might be
better for a trailerable sailboat...re all that loading & unloading
over rollers/bunks (& occasional beaching).

5200 - How strong on fiberglass
 

Roger Long wrote:
The in hull transducer on my boat works great. It's just slapped on
the inside of a fairly thick hull.

I can't imagine putting a hole in a hull if you don't need to.

I experimented with shooting through the hull, and directly by
dangling the transducer over the side prior to permanent installation.
Shooting through the hull reduced the maximum range of the depthsounder
by about 25%. The solid FG hull thickness was about 5/8". A yard guy
said experiment with exact placement if you do shoot through the hull,
as a void or dry spot in the laminate directly below the transducer can
reduce the maximum range by a lot.

One good thing you can do with a shoot through the hull setup is orient
the transducer so it points straight down on a curved hull surface, by
using an adjustable mount (available from manufacturer) which immerses
the transducer in mineral oil. The gizmo is a tube with an angled
flange on the bottom which is glued (with 5200) to the hull, and a
sealing threaded top for the transducer.

My through hull mounted transducer is flush on a curved part of the
hull, about 20 degrees out of plumb, so I get greater range on the
tack which plumbs the transducer. When heeled 30 degrees on the "bad"
tack, the maximum range drops by over 50%. This is with a high
frequency 200khz trandsucer which has a fairly narrow emission cone;
the effect should be less with a 50khz transducer, as its emission cone
is wider.

Oh, and it's an inexpensive depthsounder with a rated maximum range of
200 feet.

5200 - How strong on fiberglass
 

Please remember 5200 is an adhesive, not a sealer. Unlike epoxy, its bond
strength is not comprimised by flex or thermal dimension changes.
Steve

"Roger Long" wrote in message
...
Does anyone have any direct experience with how well 5200 sticks to old
but cleaned up fiberglass?

I have to put a new backing block in for a through hull in a very awkward
location. Since it's a Signet Knotlog, it has to be flush and there isn't
much back up in the taper for a direct hit on some floating object. I'd
like the back up block to be actually backing it up.

Building up with fiberglass and epoxy working through a hand sized opening
is going to be tough. I'm wondering if a larger than normal sized plywood
backing block done with 5200 might not be nearly as strong.


--

Roger Long

5200 - How strong on fiberglass
 

Roger Long wrote:
Well, I'm looking for some personal experience but thanks anyway.

The thing I have consistently heard about 5200 is that you shouldn't
use it on anything you hope to get apart again later.

I used Sikaflex 241 (a close relative of 5200 with similar strength)
to bond some plywood to the hull. The plywood was a T joint into the
side of bare fiberglass hull. Just an edge glued fillet of the
Sikaflex on either side of the joint.

When I tried to later remove the stuff it just laughed at me. I had
to cut the plywood into 4" wide strips AND use a crowbar with feet
well braced to get the bond to break for each individual strip of
plywood.

5200 has a well deserved reputation for not letting go. Yes, it has a
low hardness but for your application it won't matter.

Evan Gatehouse

5200 - How strong on fiberglass
 

Excellent point on the range. I'd forgotten that might be important to
many people. I only worry about the last few feet, myself.

I checked mine with a sounding line for some bottom survey work I was
doing as Harbormaster and it was as accurate as I could determine when
upright.

--

Roger Long



"Mark" wrote in message
oups.com...
Roger Long wrote:
The in hull transducer on my boat works great. It's just slapped
on
the inside of a fairly thick hull.

I can't imagine putting a hole in a hull if you don't need to.

I experimented with shooting through the hull, and directly by
dangling the transducer over the side prior to permanent
installation.
Shooting through the hull reduced the maximum range of the
depthsounder
by about 25%. The solid FG hull thickness was about 5/8". A yard
guy
said experiment with exact placement if you do shoot through the
hull,
as a void or dry spot in the laminate directly below the transducer
can
reduce the maximum range by a lot.

One good thing you can do with a shoot through the hull setup is
orient
the transducer so it points straight down on a curved hull surface,
by
using an adjustable mount (available from manufacturer) which
immerses
the transducer in mineral oil. The gizmo is a tube with an angled
flange on the bottom which is glued (with 5200) to the hull, and a
sealing threaded top for the transducer.

My through hull mounted transducer is flush on a curved part of the
hull, about 20 degrees out of plumb, so I get greater range on the
tack which plumbs the transducer. When heeled 30 degrees on the
"bad"
tack, the maximum range drops by over 50%. This is with a high
frequency 200khz trandsucer which has a fairly narrow emission cone;
the effect should be less with a 50khz transducer, as its emission
cone
is wider.

Oh, and it's an inexpensive depthsounder with a rated maximum range
of
200 feet.

5200 - How strong on fiberglass
 

Mark wrote:
Roger Long wrote:

The in hull transducer on my boat works great. It's just slapped on
the inside of a fairly thick hull.

I can't imagine putting a hole in a hull if you don't need to.


I experimented with shooting through the hull, and directly by
dangling the transducer over the side prior to permanent installation.
Shooting through the hull reduced the maximum range of the depthsounder
by about 25%. The solid FG hull thickness was about 5/8". A yard guy
said experiment with exact placement if you do shoot through the hull,
as a void or dry spot in the laminate directly below the transducer can
reduce the maximum range by a lot.

One good thing you can do with a shoot through the hull setup is orient
the transducer so it points straight down on a curved hull surface, by
using an adjustable mount (available from manufacturer) which immerses
the transducer in mineral oil. The gizmo is a tube with an angled
flange on the bottom which is glued (with 5200) to the hull, and a
sealing threaded top for the transducer.

My through hull mounted transducer is flush on a curved part of the
hull, about 20 degrees out of plumb, so I get greater range on the
tack which plumbs the transducer. When heeled 30 degrees on the "bad"
tack, the maximum range drops by over 50%. This is with a high
frequency 200khz trandsucer which has a fairly narrow emission cone;
the effect should be less with a 50khz transducer, as its emission cone
is wider.

Oh, and it's an inexpensive depthsounder with a rated maximum range of
200 feet.


I'm thinking..for coastal cruising/daysailing I'm really only concerned
with accuracy between 0 and 100 feet max.

5200 - How strong on fiberglass
 

Absolutely right, I won't use 5200 to bed anything. I wanted to remove 2 old
Fuller brush portlights that were bedded with 5200 and ended up having to
cut them out in pieces with a sawzall.
5200 is a really good adhesive for a product that's not supposed to be an
adhesive!
MMC

"Matt O'Toole" wrote in message
g...
On Mon, 27 Mar 2006 22:35:18 +0000, Roger Long wrote:

Well, I'm looking for some personal experience but thanks anyway.

The thing I have consistently heard about 5200 is that you shouldn't
use it on anything you hope to get apart again later.

Sound advice.

Keep in mind it's used to glue decks onto hulls.

Matt O.

5200 - How strong on fiberglass
 

http://www.simplicityboats.com/jointtest.html

Roger,
These are joint tests on plywood, not a backing plate on vinylester
glass so it's not apples and apples, but it is knowledge... My belief
is that the 5200 will work just fine for your knotlog backpalte given
the low psi load that will be put on it... I would not hesitate to use
the 5200 for what you are doing..

denny

5200 - How strong on fiberglass
 

On Tue, 28 Mar 2006 10:19:09 GMT, "Roger Long"
wrote:

Excellent point on the range. I'd forgotten that might be important to
many people. I only worry about the last few feet, myself.

The range effect comes into play in other ways. I used to sail in a
shallow bay where the bottom was mostly very soft mud, which doesn't
return a particularly strong signal. With an internal transducer, I
often lost the signal entirely until I got back over hard sand. To be
sure, it was a crummy installation: one of those plastic bubbles
filled with mineral oil and the transducer monted at the top. I think
the transducer mounted directly to the hull would have been better.
__________________________________________________ __________
Glen "Wiley" Wilson usenet1 SPAMNIX at world wide wiley dot com
To reply, lose the capitals and do the obvious.

Take a look at cpRepeater, my NMEA data integrator, repeater, and
logger at http://www.worldwidewiley.com/

5200 - How strong on fiberglass
 

Don White wrote:

I'm thinking..for coastal cruising/daysailing I'm really only concerned
with accuracy between 0 and 100 feet max.

I'll add my support for mounting inside the hull - I had no trouble
seeing down 100+ feet shooting through a sold hull. Being plumb helps
but is not essential (within limits).

And I can't let it pass without mentioning, a fishfinder is vastly
superior to a simple digital sounder, and often even cheaper. Even if
you never plan to fish, its really helpful to have a history of your
depth. Some of them will give a good reading of the nature of the
bottom for anchoring.

5200 - How strong on fiberglass
 

mineral spirits is OIL, use acetone to clean the ground polyester/glass

5200 - How strong on fiberglass
 

yeah, I agree. if an "in hull" transducer works, why put extra holes in
the hull? Also, what about 3M 4200? it is supposed to be bedding
rather than bonding, it's what I used to install my two through hulls.

5200 - How strong on fiberglass
 

does a fish finder use the same transducer as a simple depth sounder?
It would be handy to be able to use the same transducer, since changing
them out is a chore, and involves hauling out the boat.

5200 - How strong on fiberglass
 

Luc wrote:
does a fish finder use the same transducer as a simple depth sounder?
It would be handy to be able to use the same transducer, since changing
them out is a chore, and involves hauling out the boat.



The fish finders I see use a 'transom mounted' transducer.
I don't think this is a good spot on a sailboat like mine...with the
rudder hung on pintle & gudgeon, and the outboard mounted on it's bracket.
I'd want the in-hull type I could mount in my cabin just forward of the
keel box. (cut down on turbulence)

5200 - How strong on fiberglass
 

Mys Terry wrote:

I bought a cheap Humminbird and set that "transom mount" transducer in
a blob of clear silicone in the bottom of my boat just ahead of the
keel and it works just dandy, despite all the warnings about not doing
exactly that in the Humminbird instructions.

Just make sure the blob of silicone doesn't have any air bubbles.

The fish finder my wife bought for me came with a transom
mount transducer, _and_ instructions about how to mount it
inside the hull if you did not want to do the transom mount
thing.

IIRC the method was similar to what you did, although there
was a section about making a temporary mount that you could
slide around before you put the glue in place. That was to
make sure that you selected a good location without voids,
etc. for the transducer to shoot through.

Since I was mounting it on a power boat with only the ski
locker and engine compartment accessible for interior
mounting, I put it back on the transom, and ran the cable
through a hole high above the water line. If I were to add
a similar unit to my sailboat, I would most certainly mount
the transducer inside and shoot through the hull. The only
drawback is reduced range, and the transom mounted unit
already sees down to over 200'.

Don W.

5200 - How strong on fiberglass
 

I had a fishfinder that I located slightly offset (flatter surface) behind
the keel. I puttied a PVC tube just larger than the transducer onto the
surface, filled it with mineral oil, then put the ducer in there to test it.
When I was satisfied it worked, I glassed in the PVC, put the ducer back in,
then refilled the tube with oil. I also put a cap on the top of the tube to
keep the oil from sloshing out. Worked fine, even with the slight angle. It
wasn't accurate for over about 50 foot depth, but who cares at that point.
No extra holes in the boat is my preference.

--
"j" ganz @@
www.sailnow.com

"Don White" wrote in message
...
Luc wrote:
does a fish finder use the same transducer as a simple depth sounder?
It would be handy to be able to use the same transducer, since changing
them out is a chore, and involves hauling out the boat.



The fish finders I see use a 'transom mounted' transducer.
I don't think this is a good spot on a sailboat like mine...with the
rudder hung on pintle & gudgeon, and the outboard mounted on it's bracket.
I'd want the in-hull type I could mount in my cabin just forward of the
keel box. (cut down on turbulence)

5200 - How strong on fiberglass
 

Mys Terry wrote:
On Wed, 29 Mar 2006 22:25:27 GMT, Don W
wrote:



Mys Terry wrote:


I bought a cheap Humminbird and set that "transom mount" transducer in
a blob of clear silicone in the bottom of my boat just ahead of the
keel and it works just dandy, despite all the warnings about not doing
exactly that in the Humminbird instructions.

Just make sure the blob of silicone doesn't have any air bubbles.

The fish finder my wife bought for me came with a transom
mount transducer, _and_ instructions about how to mount it
inside the hull if you did not want to do the transom mount
thing.

IIRC the method was similar to what you did, although there
was a section about making a temporary mount that you could
slide around before you put the glue in place. That was to
make sure that you selected a good location without voids,
etc. for the transducer to shoot through.

Since I was mounting it on a power boat with only the ski
locker and engine compartment accessible for interior
mounting, I put it back on the transom, and ran the cable
through a hole high above the water line. If I were to add
a similar unit to my sailboat, I would most certainly mount
the transducer inside and shoot through the hull. The only
drawback is reduced range, and the transom mounted unit
already sees down to over 200'.

Don W.


My boat does not have any coring in the hull, so I just picked a convenient spot
and it was fine. If it hadn't worked, it would not be a big deal to move it. I
put the blob of silicone next to an upright and screwed the hinged bracket of
the transducer to that to help hold it securly. To check around easily for a
good spot, just fill and seal a ziplock sandwich bag with water. Rest the
transducer on top of that from a few locations until you find a good spot.



Thanks for the tip on the ziplock bag. I'll try that.

5200 - How strong on fiberglass
 

Dave,
I know what 3M says. That advise I just gave you is free. That lesson cost
me $10,000. Your call.
Steve

"Dave" wrote in message
...
On Tue, 28 Mar 2006 07:19:14 +0200, "Steve Lusardi"

said:

Please remember 5200 is an adhesive, not a sealer.

Take a look at 3M's marketing materials. Then go to the corner and put on
the little pointed hat.

5200 - How strong on fiberglass
 

"Jere Lull" wrote

5200 is too strong for that. You'll have to cut it out when you want
to
replace the knotlog. I'd suggest 4200, which is plenty strong. Prep
of
the fiberglass is key. Nothing will stick to an oily or otherwise
slick
surface

Quite right. It is only the block itself that I'm putting in with the
5200. The through hull will be set in something else which is similar
to 4200 but I've forgotten the name. I do want to be able to get that
out someday!

You can see it he

Http://home.maine.rr.com/rlma/Strider0604.htm#Block

You might find the clamping arrangement interesting. I'm going to
leave it in place until the last possible moment so the 5200 if fully
cured. I scraped to bare glass and washed with acetone. If anyone
ever wants to change this installation, good luck.

--

Roger Long