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Basic advice before I start drilling

 
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thechadmiller



Joined: 20 Jan 2018
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City/Region: Portland
State or Province: OR
C-Dory Year: 2017
C-Dory Model: 22 Cruiser
Vessel Name: Agostino
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PostPosted: Fri Mar 09, 2018 8:12 pm    Post subject: Basic advice before I start drilling Reply with quote

Hi there. I want to install a few folding pad eyes or maybe light load cleats for hanging fenders or whatever. They would all be well above the water line.

The dumb newbie that I am just thinks I'd just put a couple of screws in, and maybe some silicone or something to coat the screw holes and that would be fine, but I thought I'd ask the experts first.

Any basic advice for a rookie? Thanks.
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colbysmith



Joined: 02 Oct 2011
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PostPosted: Sat Mar 10, 2018 7:45 am    Post subject: Reply with quote

At least on the 22 you have a lot of wiring and control cables running under the starboard gunell!
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journey on



Joined: 03 Mar 2005
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PostPosted: Sat Mar 10, 2018 10:13 am    Post subject: Reply with quote

Well, the first rule of drilling through a panel is to make sure a) there's nothing IN the panel that you going to drill through and b) there's nothing BEHIND the panel that you'll hit when you break through. And I've done both by ignoring my own advice.

Next, I wouldn't use silicone. It doesn't stick well, can't paint over or use another sealer. I use 3-M 4000 which avoids those problems. You can save the tube by storin it in the freezer.

Good luck, I've screwed hangers/cleats/whatever all over Journey On

Boris
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DavidM



Joined: 24 Dec 2017
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City/Region: Punta Gorda
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PostPosted: Sat Mar 10, 2018 10:15 am    Post subject: Reply with quote

If you plan to through bolt the fittings this is what you have to do to deal with the balsa coring in the deck. CDs have balsa or maybe pvc foam coring, right?

Drill the screw holes through the fiberglass at least a 1/8" diameter larger than the screw, Use a bent nail in your drill chuck to route out another 1/4" of balsa inside the hole.

Put a piece of duct tape over the hole from the bottom. Then fill with thickened epoxy. West Systems makes an easy to use caulk tube of the stuff but JB Weld or any thick epoxy will work. Then let it harden and drill out to the screw diameter.

This procedure seals the balsa core from water intrusion.

If you are just using screws from the top which is only ok for light loads, then put a layer of 3M 4200 under the fitting and all around the screws before you tighten. Let harden a bit and cut the excess out with a sharp knife.

This website gives picture tutorials on this and lots of boat projects- https://marinehowto.com/. They like to use butyl tape but 4200 works as well.

David
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journey on



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PostPosted: Sat Mar 10, 2018 11:43 am    Post subject: Reply with quote

OK, lets have a little discussion on 3-M products, specifically 4200 vs 4000.

4200 is a one part polyurethane that chemically reacts with moisture. It has a tensile strength of 180 psi.

4000 one-part polyester adhesive sealant. It has a tensile strength of 175 psi (wood) to 425 psi (aluminum). Designed for marine applications above and below the waterline.

So far, to us they're equal.

But 4000 has "superior UV resistance" and doesn't turn brown with exposure to the sun. Since 4200 ages to a yellowish brown I chose 4000.

Of course there's 5200 if you never have to disassemble it.

Boris
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Da Nag



Joined: 23 Oct 2003
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PostPosted: Sat Mar 10, 2018 11:52 am    Post subject: Reply with quote

Silicone on a boat is your enemy. Never use it. It's inferior to other products for permanent installations (if there really is such a thing), and you'll cuss like a sailor when the day comes to remove it from a non-permanent installation.

David's advice is spot on:

DavidM wrote:
This website gives picture tutorials on this and lots of boat projects- https://marinehowto.com/. They like to use butyl tape but 4200 works as well.


Except, I'm solidly in the butyl tape fan club. For most anything above the waterline, it's the bomb. A dream to work with, clean going on and off, and as long as you closely follow the instructions at the above link - foolproof.

Beware of sourcing it, though. The author at the above site touches on it, but you don't want the cheap crap sold at RV stores. I buy it from the site above, not only because I trust it to be the best - but it's a great way to pitch in a few bucks to the owner of the site who has provided tons of free, great info.

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localboy



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PostPosted: Sat Mar 10, 2018 1:55 pm    Post subject: Reply with quote

journey on wrote:
OK, lets have a little discussion on 3-M products, specifically 4200 vs 4000.

4200 is a one part polyurethane that chemically reacts with moisture. It has a tensile strength of 180 psi.

4000 one-part polyester adhesive sealant. It has a tensile strength of 175 psi (wood) to 425 psi (aluminum). Designed for marine applications above and below the waterline.

So far, to us they're equal.

But 4000 has "superior UV resistance" and doesn't turn brown with exposure to the sun. Since 4200 ages to a yellowish brown I chose 4000.

Of course there's 5200 if you never have to disassemble it.

Boris


Butyl tape for bedding. Agreed. I've used it vs any of the above. So far, so good. I'm even going to pull my windlass this spring, do some under-cutting & sealing of the hawse pipe with West epoxy and re-bed with butyl.

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srbaum



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PostPosted: Sat Mar 10, 2018 6:17 pm    Post subject: Reply with quote

I too am a butyl tape fan (don't buy black, white or off white is what to buy for boats), for EVERYTHING above the waterline that does not have to have an adhesive bond.
One thing to remember, before cutting with a saw or drilling, is to put painters tape over the fiberglass before beginning, as this will aid in preventing splintering of the glass.
Another must do after drilling the hole is to chamfer the hole, from the surface of the gel coat down to the fiberglass. This will aid in preventing the gel coat from cracking down the road. Gel coat is much more brittle than the fiberglass below it. A lot of folks (and manufacturer') don't take this extra step, that only takes a moment. Walk around a boat yard and look at fitting on boats, such as bimini top fittings...spider cracked everywhere...there are so many places like this that get overlooked.

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thataway



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PostPosted: Sat Mar 10, 2018 9:41 pm    Post subject: Reply with quote

I like to run the drill bit in reverse before starting the hole, this will cut back the the gelcoat, Tape and cambering will help.

I am not such a great fan of Butyl tape. I have seen too many cases where water and dirt had gotten under it.

Agree with 4000 for most deck work. If it is any heavy load, then bolt, rather than screw. Most of the vertical surfaces are not cored. An exception is the aft cabin bulkhead on all of the C Dory's.

One comment on the Epoxy. It is best to coat the wood or foam core with "neat" (unthickened epoxy) to give a seal and bond to the core. Then use the thickened epoxy. I prefer a Dremel tool bit to a bent nail for the under cutting--a bit cleaner, and neater. Plus more controllable.

Here is a PDF document on 3 M products.

Also when using plastics, consider BoatLife LifeSeal--a hybrid silicone/urethane (and made for boats).

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localboy



Joined: 30 Sep 2006
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PostPosted: Sun Mar 11, 2018 12:26 am    Post subject: Reply with quote

Quote:
I prefer a Dremel tool bit to a bent nail for the under cutting...


What about a small Allen (head) tool? Laughing
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thataway



Joined: 02 Nov 2003
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PostPosted: Sun Mar 11, 2018 10:32 am    Post subject: Reply with quote

localboy wrote:
Quote:
I prefer a Dremel tool bit to a bent nail for the under cutting...


What about a small Allen (head) tool? :lol:


An Allen Wrench could be used, but I put it in the same category as the bent nail--you get more of a chewed up core, and control is better with a Dremel tool (for which there are many uses on the boat. The only electrical tool I carry regularly on the boat is a 110 V AC powered Dremel tool, with a small box with all of the accessories. This is powered with a 300 watt inverter. You can drill holes, cut metal and fiberglass, etc.)
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ghone



Joined: 13 Aug 2008
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PostPosted: Tue Mar 13, 2018 6:36 pm    Post subject: Reply with quote

Hi there. Good advice from all above
Question. You have a new boat, and you want to drill holes? For fenders? Easy does it. Most of us put a fender at the spring cleat. Another can hang on the cockpit handle, another on the aft cleat. Many 22ís use just 2 fenders . My rule is anywhere I think I want to screw or bolt something on, I figure a way to do it temporarily until Iím sure
More holes, more possible leaks
I feel it far more important to go put 200 hours on the boat before modifying much.
Have fun.
George
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ssobol



Joined: 27 Oct 2012
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PostPosted: Tue Mar 13, 2018 11:23 pm    Post subject: Reply with quote

The 22 has a rather bowed side. Usually you only need a fender at the spring cleat (by the nav lights) and at the back of the cabin (in line with the aft cabin bulkhead). I added a cockpit cleat on the inside of the gunwale right at the cabin bulkhead.

This cleat is drilled through and bolted from the back side.

P.S. I use butyl tape to seal bolts and screws. In a few places I use 3M 4200 or 4000 to hold screws in place (e.g. snap bases).
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