I have a manual billge pump that is not connected to a thru hull fitting. If I want to use iit, I must toss the outlet hose over the side and start to pump. There is an electric bilge pump with a thru hulll on the transom and I was going to attach the two together but was advised that I would need a check valve on the manual side and it would possibly fail at the worst possible time. I would llike to put a thru hull on the port side by the stern but I am not comfortable with drilling through the hull. Does anyone have any advise as to whether or not this is advisable or should I just rely upon tossing the discharge end of the pipe overboard when necessary?
thru hull for bilge
- Thread starter newboatowner
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Connecting two bilge pumps to the same discharge line is a bad idea. Even with check valves you run the risk of having one pumps flow just run back through the other pump into the bilge, getting you now where 
I went through the same logic a few months ago. I ended you just adding a second thru hole in my transom for a backup sump pump. Drilling the fiberglass was easy and there are enough sites on the web that offer good advise on drilling fiberglass.
I went through the same logic a few months ago. I ended you just adding a second thru hole in my transom for a backup sump pump. Drilling the fiberglass was easy and there are enough sites on the web that offer good advise on drilling fiberglass.
Here's where the manual bilge pump thru-hull is on my C22. It was there when I bought the boat, and I would have located a bit farther up the transom from the waterline, if I had installed it.
Don't be afraid to drill thru your fiberglass. They tell me the boat can't feel a thing. Drill from the outside to the inside using a hole saw sized for your thru-hull. Besure to mask off on the inside of the transom, the area around where the hole will be. I use Gorilla tape, because it sticks. Drill a pilot hole or centerpunch (lightly) for your holesaw's pilot. Start the hole in reverse to score the gel coat without breaking off big chunks. Once you're into the gel coat, proceed in forward till you think you're almost thru the transom. (A marker line on the body of the holesaw at about 3/4 of the thickness of your transom will help you know). Then get inside and finish the hole from the inside. Be sure you tape off around the hole on the outside first to prevent chips.
This tutorial by Maine Sail will show you how to bed the thru hull.
Take your time and measure 3X before cutting, and you'll be fine.
Don't be afraid to drill thru your fiberglass. They tell me the boat can't feel a thing.
Drill from the outside to the inside using a hole saw sized for your thru-hull. Besure to mask off on the inside of the transom, the area around where the hole will be. I use Gorilla tape, because it sticks. Drill a pilot hole or centerpunch (lightly) for your holesaw's pilot. Start the hole in reverse to score the gel coat without breaking off big chunks. Once you're into the gel coat, proceed in forward till you think you're almost thru the transom. (A marker line on the body of the holesaw at about 3/4 of the thickness of your transom will help you know). Then get inside and finish the hole from the inside. Be sure you tape off around the hole on the outside first to prevent chips.This tutorial by Maine Sail will show you how to bed the thru hull.
Take your time and measure 3X before cutting, and you'll be fine.
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