Fiberglass backing plates work well with fiberglass.
3/16"or 1/4" solid work well depending on aplication.
I make 4x6 ft. sheets w gelcoat and cut with a jig saw.
nice finish/no paint
Stainless and aluminum will corrode.

"sel1" wrote in message
...
Hi all,

I want to put on backing plates for all the stuff attached to the transom
(exhaust ports, swim platform, steering arms etc). Through continually
snugging them, the previous owner has burried a couple of nuts through the
glass! I am really new to all this but the first thing that comes to mind
is
reaction between two metals. If I use stainless bolts, could I use
aluminum
for backing plates or maybe I should use something else, or maybe I
shouldn't do this at all?

Still asking and not able to answer much yet.

Thanks, Steve

I've been a bit lazier with the same idea and used G-10 fiberglass-epoxy plate
from McMaster-Carr (catalog page 3345). It absolutely will not corrode and in
greater thicknesses, can be drilled & tapped to save the hassle of nuts in
inaccessible locations.


ddinc wrote:

Fiberglass backing plates work well with fiberglass.
3/16"or 1/4" solid work well depending on aplication.
I make 4x6 ft. sheets w gelcoat and cut with a jig saw.
nice finish/no paint
Stainless and aluminum will corrode.

"sel1" wrote in message
...
Hi all,

I want to put on backing plates for all the stuff attached to the transom
(exhaust ports, swim platform, steering arms etc). Through continually
snugging them, the previous owner has burried a couple of nuts through the
glass! I am really new to all this but the first thing that comes to mind
is
reaction between two metals. If I use stainless bolts, could I use
aluminum
for backing plates or maybe I should use something else, or maybe I
shouldn't do this at all?

Still asking and not able to answer much yet.

Thanks, Steve

Interesting thought ... but would 1/4" glass would give you anywhere near
the same strength as 1/4" aluminum? What sorts of applications have you done
and when would you not use them. I'm thinking glass backing plated would be
fine where there is no pressure being applied?

Steve



"ddinc" wrote in message
...
Fiberglass backing plates work well with fiberglass.
3/16"or 1/4" solid work well depending on aplication.
I make 4x6 ft. sheets w gelcoat and cut with a jig saw.
nice finish/no paint
Stainless and aluminum will corrode.

"sel1" wrote in message
...
Hi all,

I want to put on backing plates for all the stuff attached to the
transom
(exhaust ports, swim platform, steering arms etc). Through continually
snugging them, the previous owner has burried a couple of nuts through
the
glass! I am really new to all this but the first thing that comes to
mind
is
reaction between two metals. If I use stainless bolts, could I use
aluminum
for backing plates or maybe I should use something else, or maybe I
shouldn't do this at all?

Still asking and not able to answer much yet.

Thanks, Steve

"sel1" wrote in message
. ..
Interesting thought ... but would 1/4" glass would give you anywhere near
the same strength as 1/4" aluminum? What sorts of applications have you
done
and when would you not use them. I'm thinking glass backing plated would
be
fine where there is no pressure being applied?

You could use them in pretty much all places you would use aluminum backing
plates. You might make them a little thicker than comparable aluminum
thickness (say on the order of the bolt diameter x 0.4 as rule of thumb).
I would not use glass backing plates in areas where small dimensions are
important. Your last sentence doesn't make sense to me - why have a fitting
where no pressure could be applied?

Glass (especially G-10) backing plates are SOP on racing yachts.


--
Evan Gatehouse

you'll have to rewrite my email address to get to me
ceilydh AT 3web dot net
(fools the spammers)

Another plus to G-10 backers just occurred to me-
Metal (and g-10) backing plates are hard to taper at their edges, so they're
bound to have stress risers at their edges. With G-10, a little feather of bog
and another larger layer of glass will taper the stiffness out evenly into the
panel. Tidy, too.

Evan Gatehouse wrote:

"sel1" wrote in message
. ..
Interesting thought ... but would 1/4" glass would give you anywhere near
the same strength as 1/4" aluminum? What sorts of applications have you
done
and when would you not use them. I'm thinking glass backing plated would
be
fine where there is no pressure being applied?

You could use them in pretty much all places you would use aluminum backing
plates. You might make them a little thicker than comparable aluminum
thickness (say on the order of the bolt diameter x 0.4 as rule of thumb).
I would not use glass backing plates in areas where small dimensions are
important. Your last sentence doesn't make sense to me - why have a fitting
where no pressure could be applied?

Glass (especially G-10) backing plates are SOP on racing yachts.

--
Evan Gatehouse

you'll have to rewrite my email address to get to me
ceilydh AT 3web dot net
(fools the spammers)

Actually, you can have better strength. It has the same relative
stiffness as the fiberglass boat. They will tend to bend together
better, and not load the edges as much as a piece of aluminum.

The aluminum back pads and the stainless bolts create a corrosion
problem as well.

I can't tell you how many corroding aluminum backing plates with the
paint peeling off I have seen. I have never seen a glass plate do this.

"sel1" wrote in message
. ..
Interesting thought ... but would 1/4" glass would give you anywhere near
the same strength as 1/4" aluminum? What sorts of applications have you
done
and when would you not use them. I'm thinking glass backing plated would
be
fine where there is no pressure being applied?

Steve



"ddinc" wrote in message
...
Fiberglass backing plates work well with fiberglass.
3/16"or 1/4" solid work well depending on aplication.
I make 4x6 ft. sheets w gelcoat and cut with a jig saw.
nice finish/no paint
Stainless and aluminum will corrode.

"sel1" wrote in message
...
Hi all,

I want to put on backing plates for all the stuff attached to the
transom
(exhaust ports, swim platform, steering arms etc). Through continually
snugging them, the previous owner has burried a couple of nuts through
the
glass! I am really new to all this but the first thing that comes to
mind
is
reaction between two metals. If I use stainless bolts, could I use
aluminum
for backing plates or maybe I should use something else, or maybe I
shouldn't do this at all?

Still asking and not able to answer much yet.

Thanks, Steve

G-10 pressure laminates (built correctly)are up to 40% stronger than 6061
tempered aluminum.

"Evan Gatehouse" wrote in message
...

"sel1" wrote in message
. ..
Interesting thought ... but would 1/4" glass would give you anywhere near
the same strength as 1/4" aluminum? What sorts of applications have you
done
and when would you not use them. I'm thinking glass backing plated would
be
fine where there is no pressure being applied?

You could use them in pretty much all places you would use aluminum
backing
plates. You might make them a little thicker than comparable aluminum
thickness (say on the order of the bolt diameter x 0.4 as rule of thumb).
I would not use glass backing plates in areas where small dimensions are
important. Your last sentence doesn't make sense to me - why have a
fitting
where no pressure could be applied?

Glass (especially G-10) backing plates are SOP on racing yachts.


--
Evan Gatehouse

you'll have to rewrite my email address to get to me
ceilydh AT 3web dot net
(fools the spammers)

I've been buying G-10 from McMaster-Carr, where 1/4" G-10 is about $23/ft^2.
Anybody got a lower-cost source?

ddinc wrote:

G-10 pressure laminates (built correctly)are up to 40% stronger than 6061
tempered aluminum.

"Evan Gatehouse" wrote in message
...

"sel1" wrote in message
. ..
Interesting thought ... but would 1/4" glass would give you anywhere near
the same strength as 1/4" aluminum? What sorts of applications have you
done
and when would you not use them. I'm thinking glass backing plated would
be
fine where there is no pressure being applied?

You could use them in pretty much all places you would use aluminum
backing
plates. You might make them a little thicker than comparable aluminum
thickness (say on the order of the bolt diameter x 0.4 as rule of thumb).
I would not use glass backing plates in areas where small dimensions are
important. Your last sentence doesn't make sense to me - why have a
fitting
where no pressure could be applied?

Glass (especially G-10) backing plates are SOP on racing yachts.


--
Evan Gatehouse

you'll have to rewrite my email address to get to me
ceilydh AT 3web dot net
(fools the spammers)

Make them yourself during laminating with scrap amounts of resin/cloth.
G-10 is nothing special, just consistent and convenient for a commercial
builder but a home builder can do well by just having precut pieces of cloth
to use on left over resin.


--
Evan Gatehouse

you'll have to rewrite my email address to get to me
ceilydh AT 3web dot net
(fools the spammers)


"Jim Conlin" wrote in message
...
I've been buying G-10 from McMaster-Carr, where 1/4" G-10 is about $23/ft^2.
Anybody got a lower-cost source?
ddinc wrote:
G-10 pressure laminates (built correctly)are up to 40% stronger than 6061
tempered aluminum.
"Evan Gatehouse" wrote in message
...

"sel1" wrote in message
. ..
Interesting thought ... but would 1/4" glass would give you anywhere near
the same strength as 1/4" aluminum? What sorts of applications have you
done
and when would you not use them. I'm thinking glass backing plated would
be
fine where there is no pressure being applied?

You could use them in pretty much all places you would use aluminum
backing
plates. You might make them a little thicker than comparable aluminum
thickness (say on the order of the bolt diameter x 0.4 as rule of thumb).
I would not use glass backing plates in areas where small dimensions are
important. Your last sentence doesn't make sense to me - why have a
fitting
where no pressure could be applied?

Glass (especially G-10) backing plates are SOP on racing yachts.


--
Evan Gatehouse

you'll have to rewrite my email address to get to me
ceilydh AT 3web dot net
(fools the spammers)