[C320-list] Rebedding forward trapezoidal hatch

[Dave Hupe]

Butyl tape is very good ... I have used it in multiple applications (first time for my center cabin bomar hatch). However, you must think your application through carefully. In particular, think hard about places where screws are involved. If the bedding surface of the item is not big/wide, the butyl might be pulled apart by the butyl sticking to the screw shank as you screw down and not seal well near the screw shank (and up the screw penetration of the item being fastened down). Items fastened with thru-bolts/machine screws are better since someone can hold the bolt/screw head above from turning while someone else tightens the nut below. In this case the butyl doesn’t  get pulled apart.
I have read multiple guidelines recommending countersinking holes in the gel coat to form a space where butyl can get squeezed into the hole and facilitate a better seal.
Where possible, apply extra butyl "donuts" around screw and bolt shanks below the item being fastened in addition to the butyl on the flat hatch frames and/or deck surfaces to facilitate good seals around screws and bolts. 
Also, where you have screws that must be tightened from above, try to apply a small butyl "donut" just beneath the head of the screw that hopefully will seal the head area to prevent water migration down the penetration hole. 
In very hot weather it can be difficult placing the butyl tape where you need it.  It can stick to your fingers rather than stick where you want it.  I had this problem when I rebedded a genoa track.  As a result I did not get a good seal (very little bedding surface beneath the track around the many bolt holes). I wound up needing to redo the job (successfully) at a later date during cooler weather. 
Butyl squeezed out from under the item you are bedding can be cleaned up pretty easily, especially in cooler weather with a razor knife. Just be careful not to cut your gel coat or pull the butyl out from under your item. 
Lastly, as Ferris mentioned, don’t ignore taking your hatch latches apart periodically,  cleaning all surfaces,  and replacing (and lubricateing) the rubber o-rings that are the seals that prevent water leakage.  If ignored, not only can leaks occur, but the acrylic lenses get scored by dirt grinding in the space.
Dave Hupe 
1994 C320 #32

Sent from Yahoo Mail on Android 
 
  On Mon, Jun 12, 2023 at 1:10 PM, Ferris Wills via C320-list<c320-list at lists.catalina320.com> wrote:   Hi,

I did this job recently on both my roof hatches - to get the hatch frame off, unscrew the perimeter screws (best to leave the hinges/hatch attached to the frame). I used wooden wedges and a mallet to unseat the frame from the deck. Remove all the old sealant - mine was a mess from previous owner hacked up attempts.

I rebedded with butyl tape and it’s now as good as new 😊. You might want to replace the washers in the hatch handles at this time too.

Ferris
Argo, #505

Typos by iPhone

> On Jun 12, 2023, at 9:54 AM, Mike Mellon via C320-list <c320-list at lists.catalina320.com> wrote:
> 
> I have a small drip-like leak in the forward trapezoidal hatch, apparently near the port side aft corner, between the deck and the hatch frame.  As far as I can tell, the acrylic lens is not leaking.
> 
> I plan to remove the hatch frame from the deck and rebed.  Any comments or suggestions on doing this and the curent best sealant to use to rebed?
> 
> Thanks.
> 
> Mike Mellon
> LaVida, 1996, #324
> 
> Santa Cruz, CA
>