Bilge Pump screws

[mattnj]

Hi,
About to install a new Whalesupersub 650 in a shallow bilge (sailboat) so I drill/screw in the grp directly or is there a better method maybe Sikaflex it down? I was thinking 2 screw holes underwater forever isnt a great idea?
Thanks

 

[rbmatthews]

I would be inclined not to screw directly into the GRP in case you go through it.

We installed our Rule Mate 1100 bilge pump by shaping a piece of wood to the curvature of the hull, varnishing it, and epoxying it to the GRP, and then screwing the bilge pump into the wood. That was five years ago, and it has worked well since then.

Description at: https://shetlandf4.wordpress.com/bilge-pump/

 

[Cloven]

I fitted a Whale Supersub pump in a shallow bilge. If I remember correctly, the pump body can be screwed either to a horizontal or vertical surface. At the bottom of my shallow bilge there is a vertical panel and I screwed it to that. Also used the same panel to screw on a float switch. I never ever even considered the option of just screwing down directly to the hull.

 

[oldsaltoz]

Putting screws into the bilge is not common practice for obvious reasons.
Getting the area clean and dry so you can apply a sealant is best done with the aid of heat gun.

If you must drill into the hull below the water line, then clean the area, drill the holes at least 6 mm oversize and fill them with a mixture of Epoxy resin and Micro Fibres mixed to a toothpaste consistency. allow this cure before drilling a pilot hole for the stainless steel screws.

Good luck and fair winds.

 

[prv]

If you must drill into the hull below the water line, then clean the area, drill the holes at least 6 mm oversize and fill them with a mixture of Epoxy resin and Micro Fibres mixed to a toothpaste consistency. allow this cure before drilling a pilot hole for the stainless steel screws.

...and be very careful about length

(My bilge pump was screwed directly into the bottom of the boat by the previous owner, or more likely the charter company's yard hands. It works, and has caused no obvious problems in 16 years, but I wouldn't have done it that way myself.)

Pete

 

[ningcompoop]

I've just fitted the same pump under the cabin sole of my little boat - I was also very reluctant to make any unnecessary holes in the hull, and wanted the pump as close to the floor as possible, so I took a 30mm square piece of stainless angle plate, drilled several holes in the bottom, 2 holes in the side and epoxied it directly to the GRP (clean and abrade floor first, ensuring epoxy squeezed up through the holes for good adhesion).Once solid, the pump is secured to the plate with a couple of cable ties through the holes and around the neck of the pump - easy to do due to the design of the pump and easy to remove for inspection/maintenance. Not yet tried in anger, though.

John