bedding plexiglas for hatches and ports


Sailorman <kimberlite@...>
 

Years ago, I did a hull up restoration of a Tartan-37.

I replaced everything on the boat including every nut bolt and screw.

The only thing that I did not replace were the hatch frames.

They were made by Atkins Hoyle and they are made of heavy cast aluminum.
Stronger than anything I have seen on the market.



The point of this note is when I called Atkins Hoyle they said to coat the
surfaces of the Plexiglas and the frame with xylene before caulking. I
coated the surfaces and let the xylene dry. The surfaces were very sticky
and allowed the caulking to stick and they never leaked. I also called the
general electric silicone division and the recommended a non marine caulking
especially for this application. I never had a hatch leak a drop. In fact,
when I had to bed metal to the deck such as Genoa tracks, I painted the
xylene on them. It really makes silicone stick.

Fair Winds

Eric

Amel Super Maramu #376 Kimberlite











_____

From: amelyachtowners@...
[mailto:amelyachtowners@...] On Behalf Of Gene Carter
Sent: Monday, January 21, 2013 9:55 PM
To: amelyachtowners@...
Subject: Re: [Amel] Re: Port light / window eplacement on Amel Sharki





John

Much thanks on on your detail

Gene Carter Stargazer Sharki #135




Go Sailing

Gene C Carter
PO Box 895
Blaine WA 98231
Cell (360) 815-5388

________________________________
From: jjjk12s jjjk12s@... <mailto:jjjk12s%40yahoo.com> >
To: amelyachtowners@...
<mailto:amelyachtowners%40yahoogroups.com>
Sent: Sunday, January 20, 2013 10:09 PM
Subject: [Amel] Re: Port light / window eplacement on Amel Sharki



A couple of tips on window replacement...not a complete guide...

I have redone mine on my Maramu but think it is basically the same. I think
my windows were original but can't be positive.

Some of the fasteners are screws and some are through-bolts. It is
straightforward to carefully remove the timber trim strips that are nailed
on the inside of the windows to access the nuts. The screws may not all be
the same length so note where they go. Also the bolts are cut flush with the
nuts so they don't foul the timber trim. Likewise try to note where they go
otherwise some may end up too long and some too short when you put it all
back together.

Use the old windows as templates and easiest to get copies made at a
prespex/acrylic supplier rather than cut yourself. Hopefully the supplier
can also paint the blankened patches as on the original. It was easy to get
mine off without breaking them. It appeared two different sorts of sealant
had been used. It is hard to tell but a strong one seems to have been used
at the ends where the window buts against a portlight or other window, but
less strong sealant elswhere which seemed to be normal silicon sealant.
Whatever the reason some of the sealant was black and much harder to remove.
Acrylic can expand a lot in the sun so my guess is the stronger sealant was
used to stop movement at that location.

To cope with the expansion have the holes drilled oversize, (should match
the original) otherwise the perspex may crack at the holes. I drilled my own
holes but you have to use a blunt drill bit or use a grinder to flatten the
cutting edge of a new bit. If you use a new sharp bit it can "bite" and
crack the window when the holes are near the edge. Also use a washer between
the perspex and the hull on each fastening to ensure enough thickness of
sealant to allow for the shearing effect caused by thermal expansion and
contraction. Washers will be there on the original installation.

The thickness of my windows was slightly less than 10mm. I could only
replace with 10mm so had to renew some of the fastenings. It's easiest if
the new stuff is exactly the same thickness as old.

There is plenty of info on the internet about sealant. A few different
brands offer sealant specifically for acrylic. Best to take some advice from
your acrylic supplier. However, modern boat windows are often just glued on
without fasteners and the sealant is designed for this ie super strong. This
is the stuff that needs to be used when replacing the perspex in hatches.
With the Amel's stainless steel trim and fasteners the stength of the
sealant is not as important. The windows will not fall out! However, the
shear strength (modulus?)is very important as the length of the windows
means there can be a lot of movement caused by thermal expansion. Not sure
about Butyl tape. I have read about it but not seen it used and wouldn't be
confident it would not run with sun and tinted windows that get hot.

When installing get an extra pair of hands to help, use masking tape,
patience and Isopropyl alcohol as solvent (if you have difficulty finding
some try a cleaning supplies company). Abrade the edge of the perspex where
the sealant will grip and wipe with isopropyl alcohol to remove any dust and
properly clean and prepare the hull likewise. A google search will come up
with more advice about fitting the windows without getting sealant
everywhere....

Obviously check there are no leaks when it's finished.

John #91 Maramu Popeye

--- In amelyachtowners@...
<mailto:amelyachtowners%40yahoogroups.com> , "Gene" wrote:


Good day all,

Has any one attempted to replace the fixed port lights / windows on the
Amell Sharki

What issues did you have what type of sealant or gasket did you use.

Thanks in advance for any information.

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