backing plates

sel1 wrote:
 > 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
 >
 >
 >

  To do it properly takes a little time but doesn't cost a single cent
more as in;

(i) Aluminium is OK say;
  (a) 1/4"
  (b) Size/shape of the backing is up to you, usually the available space
will dictate the shape size etc, the rule is; if it looks right it
probably is:-)
  (b) it's not under water as such so dissimilar metals shouldn't be an
issue (even with stainless you'd still need to ensure the same stainless
as the bolts say 316 vs 3xx or it corrodes anyway:-)
  (c) aluminium is much easier to work & you can even drill it in situ
from the outside if you have a tricky nook or cranny.

(ii) Chamfer just the outer perimeter of the plates away from where
they'll pull against the hull, if you leave a sharp edge it can cut into
the outer glass under load & leave a crack in the flow or gelcoat for
water to get in.

(iii) You should try to seal inside all the through hull holes:
  (a) particularly if it's the cored transom
  (b) Coat the holes right through with any of the good epoxy fillers, then
  (c) push the bolts back in while it's wet, having given the bolt a good
coat of grease first (dipped in candle wax works too).
  (d) Once epoxy has gelled you should be able to get your bolts back out
with a spanner, leaving a good protection for the transom core (usually
plywood) & a good fit for the bolt.

(iv) When ready to put it all together again;
  (a) use plenty of any of the good sealants, sadly price is a good
indicator so any marine recommended 3M or marine sikaflex (German?? not
sure) is OK.
  (b) Clean the hull, parts, holes, bolts etc with solvent so the sealant
can adhere.
  (c) Put all the bolts in & tighten the nuts (don't turn the bolts if
you can avoid it, it messes up the sealant) just tight enough to get all
the parts mated & snug, don't over tighten at this stage,
  (d) get rid of excess squeezed out sealant with whatever solvent.
  (e) Let the whole thing set for a while at least a day but longer is
OK, so the sealant can fully cure.
  (f) Now you can tighten it all up, but again make sure someone holds
the bolts so they can't turn & you just tighten the nuts.

It'll be ticketyboo:-)


K
 >> Stay informed about: backing plates 

I just saw a nice chart of similar and dissimilar metals last week on the
Jamestown Distributors web site. It's here:
<a rel="nofollow" style='text-decoration: none;' href="http://www.jamestowndistributors.com/decoder_compmetals.asp" target="_blank">http://www.jamestowndistributors.com/decoder_compmetals.asp</a>

JD has a lot of hardware and information for boatbuilders and
do-it-yourselfers.

"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
 >
 >
 >
 >> Stay informed about: backing plates 

Thanks so much for the detail K, pretty straight forward. You say aluminum
is OK. As in not the best material?

Most of the work will be above the water line but my swim platform brackets
go below the water line and they are steel angle iron (probably home made).
Any ideas on what kind of support system I could use so that the it doesn't
have to go below water line? Either that or I switch to aluminum angle
pieces and stainless bolts. Aluminum should be OK below water line? Previous
owner didn't even use stainless bolts so they were really tough to get off.

 > To do it properly takes a little time but doesn't cost a single cent
 > more as in;
 >
 > (i) Aluminium is OK say;
 > (a) 1/4"
 > (b) Size/shape of the backing is up to you, usually the available space
 > will dictate the shape size etc, the rule is; if it looks right it
 > probably is:-)
 > (b) it's not under water as such so dissimilar metals shouldn't be an
 > issue (even with stainless you'd still need to ensure the same stainless
 > as the bolts say 316 vs 3xx or it corrodes anyway:-)
 > (c) aluminium is much easier to work & you can even drill it in situ
 > from the outside if you have a tricky nook or cranny.
 >
 > (ii) Chamfer just the outer perimeter of the plates away from where
 > they'll pull against the hull, if you leave a sharp edge it can cut into
 > the outer glass under load & leave a crack in the flow or gelcoat for
 > water to get in.
 >
 > (iii) You should try to seal inside all the through hull holes:
 > (a) particularly if it's the cored transom
 > (b) Coat the holes right through with any of the good epoxy fillers, then
 > (c) push the bolts back in while it's wet, having given the bolt a good
 > coat of grease first (dipped in candle wax works too).
 > (d) Once epoxy has gelled you should be able to get your bolts back out
 > with a spanner, leaving a good protection for the transom core (usually
 > plywood) & a good fit for the bolt.
 >
 > (iv) When ready to put it all together again;
 > (a) use plenty of any of the good sealants, sadly price is a good
 > indicator so any marine recommended 3M or marine sikaflex (German?? not
 > sure) is OK.
 > (b) Clean the hull, parts, holes, bolts etc with solvent so the sealant
 > can adhere.
 > (c) Put all the bolts in & tighten the nuts (don't turn the bolts if
 > you can avoid it, it messes up the sealant) just tight enough to get all
 > the parts mated & snug, don't over tighten at this stage,
 > (d) get rid of excess squeezed out sealant with whatever solvent.
 > (e) Let the whole thing set for a while at least a day but longer is
 > OK, so the sealant can fully cure.
 > (f) Now you can tighten it all up, but again make sure someone holds
 > the bolts so they can't turn & you just tighten the nuts.
 >
 > It'll be ticketyboo:-)
 >
 > K
 >> Stay informed about: backing plates 

sel1 wrote:
 > Thanks so much for the detail K, pretty straight forward. You say aluminum
 > is OK. As in not the best material?
 >
 > Most of the work will be above the water line but my swim platform brackets
 > go below the water line and they are steel angle iron (probably home made).
 > Any ideas on what kind of support system I could use so that the it doesn't
 > have to go below water line? Either that or I switch to aluminum angle
 > pieces and stainless bolts. Aluminum should be OK below water line? Previous
 > owner didn't even use stainless bolts so they were really tough to get off.

Below the water line, the best materials are bronze or stainless. I
wouldn't use aluminum.
 >> Stay informed about: backing plates 

"sel1" wrote in message

 > Thanks so much for the detail K, pretty straight forward. You say aluminum
 > is OK. As in not the best material?
 >
I tried both 1/8" ss plate and 1/4" aluminum plate this summer. Unless you
have a drill press forget the ss. damn hard to cut or drill. On sume of
the aluminum backing plates, wehere the ss bolts and washes came in touch, I
used cutout plastic washers made of ice cream containers and liquid
electrical tape.
 >> Stay informed about: backing plates 

Don White wrote:


 >
  >>Thanks so much for the detail K, pretty straight forward. You say aluminum
  >>is OK. As in not the best material?
  >>
 >
 > I tried both 1/8" ss plate and 1/4" aluminum plate this summer. Unless you
 > have a drill press forget the ss. damn hard to cut or drill. On sume of
 > the aluminum backing plates, wehere the ss bolts and washes came in touch, I
 > used cutout plastic washers made of ice cream containers and liquid
 > electrical tape.
 >
 >


There are also plastic grommets around that separate the stainless
fasteners from the aluminum plates.

The last time I installed hardware with backing plates, I used stainless
scrap pieces I bought from a marine fabricator that built tee-tops. For
a couple bucks, they cut the plates to the size I wanted and using my
hardware as a template, drilled the holes for me, too.
 >> Stay informed about: backing plates 

I use those hard 1/2" thick cutting boards with ss fender washers and nylock
nuts. Also I put epoxy between the backing plate and fiberglass. The
cutting board material cuts and drills like wood. Obviously it will never
rot and will not react with the bolts. I put my wake tower on 4 years ago
using them and I sometimes pull 6 people on 2 super screamer tubes from the
tower with no problems.

"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
 >
 >
 >
 >> Stay informed about: backing plates 

I like this idea of using a white plastic cutting board for a backing plate.
I'm going to file that one away for myself.

Thanks

"JamesgangNC" wrote in message

 > I use those hard 1/2" thick cutting boards with ss fender washers and
nylock
 > nuts. Also I put epoxy between the backing plate and fiberglass. The
 > cutting board material cuts and drills like wood. Obviously it will never
 > rot and will not react with the bolts. I put my wake tower on 4 years ago
 > using them and I sometimes pull 6 people on 2 super screamer tubes from
the
 > tower with no problems.
 >> Stay informed about: backing plates 

I'm waiting to see if anyone suggests to look for the reason for the
loose bolts, like rotten plywood core. So far there is a lot of good
info on backing plates.

Out drive boats are usually built with a plywood core in the transom,
because of the loads the transom takes. I doubt you'll find foam.

If you have some rot, there's no choice on the fix. Backing plates
isn't it.
Jim
 >> Stay informed about: backing plates 

Use a cutting oil when drilling the SS.

"Don White" wrote in message

 >


  > > Thanks so much for the detail K, pretty straight forward. You say
aluminum
  > > is OK. As in not the best material?
  > >
 > I tried both 1/8" ss plate and 1/4" aluminum plate this summer. Unless
you
 > have a drill press forget the ss. damn hard to cut or drill. On sume
of
 > the aluminum backing plates, wehere the ss bolts and washes came in touch,
I
 > used cutout plastic washers made of ice cream containers and liquid
 > electrical tape.
 >
 >
 >> Stay informed about: backing plates 

On Sun, 12 Dec 2004 18:01:09 GMT, "JamesgangNC"
wrote:

 >I use those hard 1/2" thick cutting boards with ss fender washers and nylock
 >nuts. Also I put epoxy between the backing plate and fiberglass. The
 >cutting board material cuts and drills like wood.

It's called Starboard. There is also a variant out there, but I can't
remember the name.

 >Obviously it will never
 >rot and will not react with the bolts. I put my wake tower on 4 years ago
 >using them and I sometimes pull 6 people on 2 super screamer tubes from the
 >tower with no problems.

Pardon my ignorance, but what is a wake board?

Later,

Tom
 >> Stay informed about: backing plates 

Snafu wrote:
 > I like this idea of using a white plastic cutting board for a backing plate.
 > I'm going to file that one away for myself.
 >
 > Thanks
 >


Boston Whaler used (and may still use) plastic backing plates for
hardware on its older Montauk series. If you go with the cutting board
approach, make sure you use BIG round flat washers to spread out the load.
 >> Stay informed about: backing plates 

"Short Wave Sportfishing" wrote in message

 > On Sun, 12 Dec 2004 18:01:09 GMT, "JamesgangNC"

 >
  > >I use those hard 1/2" thick cutting boards with ss fender washers and
nylock
  > >nuts. Also I put epoxy between the backing plate and fiberglass. The
  > >cutting board material cuts and drills like wood.
 >
 > It's called Starboard. There is also a variant out there, but I can't
 > remember the name.
 >
  > >Obviously it will never
  > >rot and will not react with the bolts. I put my wake tower on 4 years
ago
  > >using them and I sometimes pull 6 people on 2 super screamer tubes from
the
  > >tower with no problems.
 >
 > Pardon my ignorance, but what is a wake board?
 >
 > Later,
 >
 > Tom

As a snowboard is to snow skis, a wakeboard is to water skis.

<a rel="nofollow" style='text-decoration: none;' href="http://www.sunrizedigitalmedia.com/Brian/pages/wakeboard%207-03%20%282%29%20076.htm" target="_blank">http://www.sunrizedigitalmedia.com/Brian/pages/wakeboard%207-03%20%282...%20076.</a>

:^)
 >> Stay informed about: backing plates