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

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

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

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

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

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

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

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.

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.

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).