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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

Drilling through cabin top

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byh2os
1st Mate

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USA
32 Posts

Initially Posted - 10/25/2005 : 20:25:46

Well, I have decided to rig up for short handed sailing. My questions are how thick is the cabin top and what materials will I encounter? For example will I need to drill a bigger hole and fill with epoxy to prevent delamination. Sail# 4828 Thanks, Bill

Edited by - byh2os on 10/25/2005 20:59:09

crcalhoon
Captain

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USA
303 Posts

Response Posted - 10/25/2005 : 21:57:13

Hard to say thickness in different spots. I have removed my grabrails, and everything else topside for replacement. I measured cabin top thickness under the grabrails and on my 1979 it is 1 3/8". but don't know about other parts of the cabin top.

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ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 10/25/2005 : 22:03:04

The epoxy fill & drill method is certainly the Bristol way to do it... the alternative is to do a good job of bedding the deck hardware and not let the bedding deteriorate to the point where it allows water penetration.

Take your pick!

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Champipple
Master Marine Consultant

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USA
6855 Posts

Response Posted - 10/25/2005 : 22:51:12

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by ClamBeach
 The epoxy fill & drill method is certainly the Bristol way to do it... the alternative is to do a good job of bedding the deck hardware and not let the bedding deteriorate to the point where it allows water penetration.

Take your pick!
<hr height="1" noshade id="quote"></blockquote id="quote">

Or Both. Also, put a piece of tape down where you plan on drilling, and use a sharp bit. Also, this is kind of tough to do, but it will keep the interior from pealing away when you break through. That is to get some sucker to hold a peice of 1" ply snug against the inside cabin top.

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 10/25/2005 : 23:37:21

Another way to prevent damage to the fiberglass and gelcoat, particularly inside, is to drill a tiny (1/8") hole, and then use that to center the the correct size bit to drill halfway through from both sides. The bit usually makes a pretty clean cut on the side where it goes in, while it can do a lot of chipping where it comes out (if it goes through).

The cabintop is 3/4" plywood core with about a 1/4" layer of fiberglass on both sides, but the contour of the fiberglass can make the overall thickness vary somewhat. I drilled first, and then bought the bolts for the hardware after I figured out the thickness (including the hardware itself). Sorry--I can't remember what it turned out to be.

Edited by - on

StSimon
Captain

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USA
298 Posts

Response Posted - 10/26/2005 : 11:00:30

It also depends on what you are installing up there. For instance, the bolts for my deck organizers needed to be longer than the bolts for my rope clutches.

As was written before, drill first then go get the correct hardware. I kept several extras of each length of each 1/4" bolt I needed. I drill, put the hardware in place then put my washer and a 1/4 nut along with a cap nut in place to make sure I had the right length. Then a trip to the store to buy more. I would then replace the 1/4" nut with a nylon insert lock nut. Squeeze a little 4200 in there first to bed the hardware, snug it down, and badda bing... deck hardware is installed.

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Brian King
1st Mate

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USA
73 Posts

Response Posted - 10/26/2005 : 12:53:08

I installed a rope clutch this spring on my '89 WK. There is a gap between the liner and the cabin top itself. Bolting through and tightening - the proper installation - results in deforming the cabin roof liner. As a result I ended up using screws. The rope clutch has stayed rock solid all summer but I think at some point it will loosen up. Here is the question: Where can I get some plastic plugs (1"?) that are close to matching the interior off-white color? I can drill a larger hole in the liner enabling me to access the nuts that will go on the end of bolts coming through the cabin roof, then use the plugs to cover the holes on the interior.

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Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 10/26/2005 : 16:57:07

My impression is that when the C-25 deck assemblies were being put together at the factory, first plywood core (perhaps of more than one thickness) was bonded to the horizontal surfaces of the inverted deck using a mush of sawdust and polyester laminating resin. Then a whole lot more of that filler mush (buckets full) was poured where the headliner was expected (or desired) to contact the deck. Then the headliner (probably without any of the port openings cut out yet) was lowered into the inverted deck, and weighted down. Once that all cured, the deck was removed from its mold, turned right side up, and then the port openings were cut using a template. Next the deck hardware might have been installed before the deck was joined to the hull (which by then had its hull liner installed in a similar fashion).

In the interest of production line expediency, there might have been a generous clearance designed between the deck and headliner. This could result in no two boats having exactly the same deck 'thickness', and could also result in randomly located air voids between the deck and headliner. (I realize this is getting long winded -- I am getting to a point here.

)

All of that would seem to strongly recommend the 'drill oversize, fill, and redrill' technique for adding anything to the deck layout in order to avoid crushing the liner at voids, resulting in loose hardware and an opportunity for water to get into the plywood core (and ugly spider web cracks in your headliner).

-- Leon Sisson

- - - - - - - - - - - - - - - - - - - - -

Edited to add the following caveat and disclaimer: I wasn't there when these boats were built. I'm just speculating based on what I've seen while working on mine, and what little I know about boatbuilding. I'd appreciate it if Bill H, or anyone else who knows more than I do about what's between the deck and the headliner, would correct any misleading guesses above.

-- L.S.

Edited by - Leon Sisson on 10/26/2005 20:37:43

Gloss
Master Marine Consultant

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USA
1916 Posts

Response Posted - 10/26/2005 : 21:10:40

When I cut out a 4" hole for my Marinco vent in front of the mast, there was no plywood core, only solid fiberglass. When I drilled for rope clutches, no wood either, I wasn't aware of a gap there.
Maybe there is a difference in construction in different model years

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Champipple
Master Marine Consultant

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USA
6855 Posts

Response Posted - 10/26/2005 : 21:58:55

I didn't have a gap either but I did hit wood.

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Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Response Posted - 10/26/2005 : 22:34:27

my 89 coach roof is hollow

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StSimon
Captain

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USA
298 Posts

Response Posted - 10/27/2005 : 13:50:08

My 84 seemed solid when I drilled through. I secured the rope clutches with large washers and had no problem with the roof collapsing. To prove it is solid I even overtightened (by mistake of course)one of the bolts to the point it broke and there was still no deformation of the cabin liner.

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