[Rhodes22-list] Deck joint repair.

The Rhodes 22 Email List rhodes22-list at rhodes22.org
Wed Dec 10 07:26:47 EST 2014


Graham,
The newer boats all use a plastic rub rail. Aluminum was scrapped years  
ago. NP1 sticks to anything it comes in contact with. It is used in roofing  
because it seals during expansion and contraction events. It also has a 15 
year  direct exposure guarantee from the manufacturer. You are correct in that 
you  don't want to apply more than you can install the pop rivets and 
tighten within  an hour or so. It takes several days to fully cure, but becomes 
water tight  after skinning over. It never fully "hardens". 
I did this procedure approximately fifteen years ago on Rumrunner and to  
this day it's still water tight.
 
Rummy
 
 
In a message dated 12/9/2014 11:00:25 A.M. Eastern Standard Time,  
rhodes22-list at rhodes22.org writes:

As  expected, Rummy's instructions are spot on excellent. I might add a  few
additional bits that he does not mention and Rummy can correct me if I  am
wrong.

On my boat (1976) not all of the rivets came all the way  through to the
aluminium rub rail. To remove all of the rivets I had to  remove the
aluminium rail and I was unable to do that without destroying it  as any
bends that you put into the rail cannot be straightened. So plan  on
replacing the rub rail with a new one.

The sealant you decide to  use might determine how much you should do at one
time. I am not familiar  with the sealant Rummy uses but as it is intended
for roofs, I suspect it  stays very soft. Perhaps Rummy will advise what
happens to the sealant he  uses as it cures. But if you use a sealant that
hardens up when it cures  such as any of the marine sealants you will want 
to
close the gap with  rivets or bolts before the sealant cures. If you seal 
all
the way around  the boat and then start adding the rivets the sealant will
cure before you  will be able to compress the join. 

You will no doubt find that  everyone has strong and differing opinions 
about
what sealant to use and in  the end you will need to go with your best
judgement. Obviously you want a  top quality sealant that will last
indefinitely. You will also probably  want one that has excellent expansion
capabilities. As the deck and hull  expands and shrinks and also flexes, it
is important that the sealant has  the ability to tolerate that change. Even
sealant that has excellent  elasticity will not work if it is applied too
thin. Boat windows made of  Plexiglas and attached to the exterior without
hardware use a combination  of special thick double-sided tape and high flex
sealant - usually  Dow-Corning 795. The tape is extremely adhesive but also
maintains about a  1/8" gap between the window and the cabin side that 
allows
the sealant to  be thick enough to work properly. The 795 sealant is
extremely flexible but  also extremely adhesive. 

The main issue in the case of the hull deck  join, in my opinion, is not so
much adhesion, as the rivets will hold the  boat together, but rather to
maintain a good permanent and flexible seal.  You might consider using butyl
for this (the form that comes in a tube) but  because it would add nothing 
to
the strength of the join I would double up  on the rivets/bolts. 

One argument that might favour bolts over rivets  is that you can tighten 
the
bolts as needed while rivets apply maximum  pressure. If you want to make
sure that the sealant is not all squeezed out  of the join, bolts would give
you that degree of control. With butyl, that  should be less of a concern.
There is a lot (too much) of information on  the net about the pros and cons
of various sealants. I would be interested  to know which sealant Stan would
recommend.

Widen the gap with  wooden wedges/shims ahead of where you are injecting the
sealant to ensure  that the sealant is injected well into the gap. Put the
shims in first as  needed and then remove each as you reach that point with
the sealant. That  will allow you to get more sealant into the join and the
removal of the  shim will squeeze the sealant immediately while it is still
uncured.  

Another thing I would worry about is removing all of the rivets at  once. 
The
hull is very thin and very flexible at the top and I would worry  about the
whole thing changing shape one all of the rivets and sealant has  been
removed. Assuming that the boat is on its trailer when you do the job  and
knowing that the trailer applies uneven pressure to the hull, I would  not
want to find that the boat hull and deck became misaligned. That might  not
happen but at the same time you can avoid the risk by doing sections  of
about 8' at a time. Remove the rivets in one section only after the  
previous
section has been sealed and riveted/bolted. Alternatively, replace  some of
the rivets (say every 4') temporarily with bolts that can be easily  removed
as you work your way around the boat. 

I would definitely  add more rivets or bolts to those presently on the boat
especially around  the fore deck. I think that the waves on the bow work the
hull-deck join as  the hull is very flexible in comparison to the rigid deck
and that is where  the sealant can/will break. Certainly on my boat it was
only at the front  section that I had trouble with leaks. 

Finally, if you use rivets, I  would definitely use washers with them.

Good luck

Graham  


-----Original Message-----
From:  rhodes22-list-bounces at rhodes22.org
[mailto:rhodes22-list-bounces at rhodes22.org]  On Behalf Of The Rhodes 22 
Email
List
Sent: December-09-14 6:04  AM
To: rhodes22-list at rhodes22.org
Subject: Re: [Rhodes22-list] Deck  joint repair.

Chuy,
I'm a little short on time, but I will try to  detail the procedure the best
I can. 
Remove the rubber insert from the  rub rail. In most cases it has
deteriorated enough that you will want to  replace it with new. Having
removed  the insert you have found the pop  rivets which you will have to
drill out in order to remove them. Most of  the rivet will fall into the
interior of the boat and you will continue to  find them for several years.
After drilling all the rivets out you will  clean the deck joint (area
between the two surfaces) with something small  enough to remove the 
hardened
and worthless caulking. 
The  cleaner  the joint is, the better. I recommend and used on my boat a 
one
part   polyurethane sealant called NP1. It is manufactured by a  company
called  Sonolastic and is primarily used in roofing  applications so it has
great  adherence and weathering properties. It  will stick to anything and
can be easily  found through Google.
Now  comes the really important part, filling the voids in the seam. Using  
a
caulking gun, you will squeeze the trigger as you push the gun  forward,
driving  the caulk into the seam. This is reverse as to how  you normally
apply caulk, but  you want to fill all the voids. Once  the seam has been
sealed, replace the  rivets which you have purchased  from an industrial 
nuts
and bolts supply house  and attach the rub  rail. Count the holes before
going and add 10% just because.  Do not  try to find them at a hardware
store, they don't have them.  I  used  a hand operated pop rivet gun, but I
would recommend purchasing  a pneumatic or  electric gun to save wear and
tear on your hands and  arms.
Simply sealing the top and bottom edge of the rub rail doesn't do  squat for
stopping water infiltration and besides, it looks crappy.
Good  luck and if you have any further questions don't hesitate to   ask.

Rummy


In a message dated 12/8/2014 12:52:48 P.M.  Eastern Standard Time,
rhodes22-list at rhodes22.org  writes:

Rummy,
Searched list but did not find any material  on  your deck join repair.  I
would appreciate if you could   repost.

Chuy


---- The Rhodes 22 Email List   <rhodes22-list at rhodes22.org> wrote: 
> Chuy,
> If you  search  the list archives you will find a post from me 
>  detailing
the  
>  easy resealing of the deck joint. If you  can't find it, let me know 
> and
I  
> will  repost  to the list. It's a not to difficult repair, but if  not
done 
>  correctly,  you will find yourself doing it all over   again.
>  
> Rummy
>   __________________________________________________
> To   subscribe/unsubscribe go  to
http://www.rhodes22.org/mailman/listinfo/rhodes22-list
> 
>  For  the list Charter and help with using the mailing list and 
>  archives
go to  http://www.rhodes22.org/list
>   __________________________________________________

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For the  list Charter and help with using the mailing list and archives go  
to
http://www.rhodes22.org/list
__________________________________________________

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To  subscribe/unsubscribe go to  
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For the list  Charter and help with using the mailing list and archives go 
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