Safe to mount screws in the bilge?

Aug 18, 2021
3
Catalina 27 Chicago
What exactly is directly under the bilge? Is just straight into the keel? I have a 1983 Catalina 27. I am needing to run an anti-siphon loop on my bilge pump and as such want increase from 500gph to 1500 gph. I checked the rule bilge manual and it appears the width of these pumps differs, so my current base which is already secured in the bilge will be too small. Can I just unscrew it, fill the current holes with epoxy, and then use the same length screws to drill down into the bottom of my bilge in order to fit the new base? I also bought this boat with a high water alarm installed, it’s wired and works but it’s not mounted to the bottom! It’s just in there and if water fills up, the whole contraption just floats and therefore the floating switch does not activate! Long story short, is it safe to drill a few short #8 drills into the bottom of the bilge?

Also, just an aside, but I am curious where some of you have looped the hose? I have some ideas which will work, just wondering if I’m missing an obvious placement.
 
Feb 21, 2013
4,638
Hunter 46 Point Richmond, CA
Welcome to the forum!!

I like your plan to fill the holes with epoxy. I am risk adverse since the previous owner or boatyard used screws to secure a bilge pump in my new used boat resuting in a leak in the hull, which I repaired with 2-part West System after taking possession of it.....what a PITA. So instead of securing the bilge pump to the hull with screws consider a couple of other options: 1) use 2-part West System epoxy or 4200 to glue the base to the botton of the bilge; clean and roughin up the area in the bilge you are going to glue the base to, and clean and roughin up the plastic base before applying the epoxy Installing a Bilge Pump : SanJuanSufficiency.com or 2) mount it to a piece of 90 degree angled stainless steel plate screwed into a stringer or bulkhead, in this way you never drill or screw into the hull.
 
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Aug 18, 2021
3
Catalina 27 Chicago
Welcome to the forum!!

I like your plan to fill the holes with epoxy. I am risk adverse since the previous owner or boatyard used screws to secure a bilge pump in my new used boat resuting in a leak in the hull, which I repaired with 2-part West System after taking possession of it.....what a PITA. So instead of securing the bilge pump to the hull with screws consider a couple of other options: 1) use 2-part West System epoxy or 4200 to glue the base to the botton of the bilge; clean and roughin up the area in the bilge you are going to glue the base to, and clean and roughin up the plastic base before applying the epoxy Installing a Bilge Pump : SanJuanSufficiency.com or 2) mount it to a piece of 90 degree angled stainless steel plate screwed into a stringer or bulkhead, in this way you never drill or screw into the hull.
Using 4200 is a fantastic solution! Thank you!
 
Oct 22, 2014
20,995
CAL 35 Cruiser #21 moored EVERETT WA
Welcome to the SBO Forum.
@sail sfbay set you on a good path to the solution.

The cardinal rule in boat work is to keep water on the outside of the boat. Drilling into and thru the hull is a pathway to violation of the cardinal rule.

much better to stick (glue) things to hull then screw into that attachment point.

An additional option is to attach fasteners to the hull to serve as attachment points.
Weld Mount makes a product that works.
1629382496339.jpeg
You epoxy the flat piece to your hull and you have a 3/8” bolt to use as a fastener.
Use care in where you attach the fixture. It will be a semi permanent rod sticking out to catch your skin and rip it to shreds.
 

PSR

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Sep 17, 2013
117
Catalina 27 4743 MB Yacht Harbor, Richmond CA
Also, just an aside, but I am curious where some of you have looped the hose? I have some ideas which will work, just wondering if I’m missing an obvious placement.
Hi FlyingSailor. You probably have finished the loop hanging, but if not, I mounted the antisiphon loop to starboard in the engine compartment, just aft of the engine access hatch in the quarterbirth. This has worked well.
P
 

AaronD

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Aug 10, 2014
723
Catalina 22 9874 Newberg, OR / Olympia, WA
An approach that has worked for me (Perhaps someone will chime in to tell me why it's a poor solution). I've epoxied little pads of G10 fiberglass, tapped for screw threads, as attachment points for various items. My process:
  • Cut G10 to size (e.g. a 1.5" x 3" pad) and bevel the edges a bit so they're not sharp
  • Drill and tap threads for mounting screws. G10 taps pretty smoothly, and @thinwater's engineering notes say that it will hold full screw strength at 1x screw diameter (e.g. threads in 1/4" G10 would hold the full strength of a 1/4" bolt)
  • Cover the bottom of the tapped holes with a tiny scrap of masking tape, so epoxy doesn't push up and fill the holes (that scrap of tape stays on the hull, and I can't see that it hurts anything)
  • Rough up hull and epoxy mounting pad(s) in place
  • Screw mounted item(s) in place.
  • If you ever need to remove an item, the G10 pad won't be as intrusive as the Weld-Mounts.

But maybe that's just my way of making it more complex than it should be :what:

There's a picture at Sailing and restoring #9874 (that one is double-thick, to take longer screws for a battery hold-down - for most equipment, 1/4" G10 is more than sufficient).
 
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Likes: Ward H
Sep 24, 2018
2,549
O'Day 25 Chicago
A forewarning:
My boat came with a pump screwed to the bilge. When we checked on the boat in March, after a very cold winter, we found some cracks in the keel. Upon further investigation we discovered that the sealant around that screw had failed
 
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Mar 6, 2008
1,078
Catalina 1999 C36 MKII #1787 Coyote Point Marina, CA.
Remove your existing screws and see if water is not coming in. If not, then cut a piece of 1/4" starboard and install in the bilge using the same screw holes. Then install the new pump on the starboard with screws not more than 3/8" long. You can also mount high water alarm pump on this starboard.