Screw length mounting bilge pump

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I need to replace the bilge pump in my new-to-me 1989 228 Seafarer. The pump looks ancient and I'm not likely to find a replacement that will snap into the old base. When I get a new one, I obviously don't want the mounting screws to penetrate through the hull but I can't figure out how thick the hull is. The question is how thick is the hull near the drain plug? What length mounting screws can be used safely.
 

seasick

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You have to remove the old screws don't you? If so, you know how much penetration works without breaching the hull. Adjust more or less to compensate for any differences in the old and new mounting base thickness.
Don't forget to fill the holes with caulk before you drive the screws in.
 

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The pump mounting area has a piece of plywood glassed in. It might be pretty wet by now.
1/2" screw is plenty.

The rest of the hull is solid glass. Don't screw into that.
 
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DennisG01

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Ditto and ditto to what was said above. Never screw directly into the hull.

You may want to cut out the old plywood that's glassed in and replace it. Or glass a piece of plywood in another spot.
 

Fishtales

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If you need to replace the wood block, suggest you make one out of plastic (starboard, search on Amazon for a block or even azek would work) glue down and screw mount so you don't penetrate the backside.
 

DennisG01

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If you need to replace the wood block, suggest you make one out of plastic (starboard, search on Amazon for a block or even azek would work) glue down and screw mount so you don't penetrate the backside.
Good idea. Azek is probably PVC? That would hold glue better than the HDPE.
 
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Thanks, all, for the feedback and comments. I don't remember seeing a feature on the hull that would be the plywood fiberglassed in at time of manufacturer. Regardless, because of the 228's full-transom design, the area is very hard to get to, so fiberglassing new plywood would be really challenging (for me). I should be able to make a bracket (AZEK or some plastic as Fishtales suggests), mount the bilge to that, lower the whole thing down to where the bilge is just off the hull, and then secure the top part of the bracket (the part I would be able to access relatively easily) to the transom or transom supports. I'll caulk all the screw holes I make in the transom to hold the bracket in place but none of these would be anywhere close to where they'd encounter water under "normal" conditions. I'll follow up with a photo of what I come up with...maybe someone else will find this approach useful for their bilge replacement.
 

DennisG01

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That sounds like a good plan. I'd probably put some good foam rubber weatherstripping in a few key areas of the bracket where it would rest against a surface - it may help to eliminate chattering/vibration of the bracket (and eventual loosening).

If your bilge floor is relatively level when the boat is at rest, there's nothing wrong with moving the pump a few feet forward, either - to a more accessible spot.
 

Hookup1

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Did you include a picture of your pump? Grady used pumps that are still around today. Unless the previous owner swapped it.

I always try to use the same pumps or floats originally installed so that I don't have a science project to adapt mounting and hoses when I replace one. Unless there is a compelling reason to switch - which I haven't found one yet.

Hull is not cored so I'm not sure why a carefully sized screw can't be used into the hull.
 
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Glacierbaze, your idea about using the partition for the livewell to mount the bracket is excellent...EXCELLENT! Your pics demonstrate the solution. DennisG's idea about the foam weathering stripping is spot on, and I happen to have some material on hand from pulling out the 34 year old (!) aluminum fuel tanks.
 
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Hookup, I think you are right. Pics show my current bilge pump (not my wiring) and what I think is the match on Amazon. Should I be concerned about the mounted bracket crumbling when I try to snap in a new one?
 

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Hookup1

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You can probably stretch (as I have to do) to reach the screw with a long Philips screwdriver. Bring wires up to you to do the work on and then put back in hole. A bruised rib but it will heal! If you can get on the screws swap the base out too. Should be same mounting holes.

Important tip: Tie up all your wires so they don't sit in the bilge water. The water will eventually intrude the wires and eat them up. Common cause of bilge pump failure.
 
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glacierbaze

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Your old pump is the new and improved model, introduced in 2010, so the base may be alright. That red button under the wiring connector is a test button. If you replace the base, just put the screws in place, and then a big glob of caulk on the threads underneath, to prevent them falling out. Drop it in, wiggle the screws into the old holes with a long screwdriver, and tighten down.
Like Hookup said, get those connections high, and use watertight connectors. Looks like your water level has been pretty high in the bilge.
 

Rlloyd

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I used the old school approach recently on my Gulfstream - screwing into the glassed in block, rather than using the metal yardstick. I used a 3/4” screw to mount the base of the bilge pump. A 1/2” was too short to get a good grab on the glass. Regardless of screw length, it was a major PIA due to the long reach down into the bilge. The bent yardstick is a much better way to go.
 

glacierbaze

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Lowes and HD sell the flat aluminum stock, so you don't have to ruin a good yard stick. Mine had already had a run in with a circular saw down one edge. I tried to make one sharp bend in a vice, but the Al cracked. I ended up scoring it in 2 or 3 places with a cold chisel, and making several smaller bends.
 

DennisG01

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Hull is not cored so I'm not sure why a carefully sized screw can't be used into the hull.
It's a "better safe than sorry" thing. In theory, it could be fine. But screwing into a 1" thick hull with a 1/2" or 3/4" screw just isn't the wisest thing to do. Screwing in creates, essentially, a small spot where the hull is now only a 1/4" thick and more susceptible to opening up (it's different than a seacock). The chances of it creating a problem are not big - but there is zero chance of a problem if you don't do it! :)

Besides... better be P-E-R-F-E-C-T with that pilot hole you drill! One little slip of the drill or drilling just one second too long by mistake and now you've gone all the way through and created a fountain inside your boat... which generally isn't a a good thing.......