Thru-hull fitting for new bilge pump

[NateD]

I am planning to add an electronic automatic bilge pump to complement the hand pump one that came with my CP23. My plan is to add a new thru-hull on the stern for the pump, but I'm having a hard time finding a plastic thru-hull with a 90 degree bend and a scupper valve on it. I'm going to be using 1 1/8" hose.

Here is what the current thru-hull/scuppers look like:


And here what the factory bilge thru-hull looks like from inside:


I did find this thru-hull at defender, which is 1 1/8" with a 90 degree bend, but it has a stainless ring on the outside of the hull and no flappy scupper valve:
http://www.defender.com/product.jsp?path=-1|51|106370|316448|315123|567957&id=1297045

Does anyone have a good source/part number for a thru-hull that looks like the factory ones on the exterior?

[MacGyver]

What you could do is tie into the hand bilge line with a Y fitting and also install 2 one way valves.

That way you wont happen to have drain back from the hand side when using the electric side.

Mac

[MacGyver]

Oh! Almost forgot!
No new hole too

Mac

[skip1930]

My electric bilge pump hooks into the same discharge line used by the hand bilge pump. The one way valve is in the hand pump.
An electric pump, a hose, a tee fitting, clamps and out the same scupper hole as the hand pump. No new holes in the boat.
The tee is down stream of the hand bilge pump.
Any sea water coming up the factory scupper hose toward the tee will not make it past the hand pump, just as the factory intended.
The tee is mounted right below the settee hatch. It's all down hill after hand pump outlet and the new tee.

If this is a Com Pac-19 or similar BE SURE TO CLEAN AWAY ALL BILDGE PAINT AND LOOSE MATERIALS. Nothing goes up the pump but water.

skip.

[NateD]

Yeah, I thought about a tee or wye into the existing line. ABYC standards recommend a separate line for each bilge pump, and if you use multiple pumps into a single thru-hull, then the hose/thru-hull downstream of T or Y should be sized properly to handle the max output from both pumps. So to follow the recommendation I would probably need to put in a larger thru-hull and hose back to the tee/wye. I don't mind putting another hole in the boat above the waterline on the transom, and the extra thru-hull and hose to reach it are pretty low cost items. It will be  a little extra work to put in the new thru-hull (and maybe a little extra cost), but I would prefer to do that instead of tying into the current bilge hose.

[skip1930]

"..T or Y should be sized properly to handle the max output from both pumps." I thought about the same thing years ago when I installed my electric pump.

Piping manuals used for standard pump formula indicate a max fpm of water at 33 fpm through a pipe. Size the pipe to the gallons.

The Gusher GH-400-H or GH-500-H hand pump having 12 foot suction, 12 foot delivery with Port sizes of 1 inch=10 gpm. [or] Port size 1-1/2 inch=15 gpm] far exceeds the electric pump capacity of 1-1/4 gpm [75 gph].

Figure the gallons, figure the inside of the pipe, which will be the same as the hand pump, and you will remain under 33 fpm.

skip.

[brackish]

Nate, I did the Skip plan (thank's Skip) and it works perfectly.  I tested it by using both pumps silmultaneaously and could not get any apparent back pressure, so hose and thru hull capacity is fine.  I looped the 12V outlet to the top of a tee so that if that pump was inoperative, I could still use the manual without pumping back thru that outlet.  The tee is a standard PVC from HD, can't remember the size but had to turn down the big ends just a little.  There is an old thread on mine do a search it will probably come up.

I thought long and hard and could not find any place I wanted to punch another hole in the ole boat

[rmotley]

I admit that I don't know why - but my (1985 23') auto-bilge pump dumps into the cockpit which flows out the existing scuppers.

Plumbed that way when I took ownership - thoughts?

[NateD]

All right, you guys have convinced me to tee into the existing hose. Thanks for all the ideas and real world testing.

[Bob23]

When I installed my Rule 750 gph electric pump in my 1985 23/2, I ran a separate line to a designated hull I installed on the starboard side of the stern, in back of the boarding ladder.

Yeah, it's high but it works quite well. I don't remember where I got the fitting. I'm glad I used a separate hose because the manual pump died a few years ago even after I rebuilt it once. I installed a check valve in the manual outlet but it allowed a lot of water to remain in the hose which caused some God-awful smells!
Bob23

[MacGyver]

Bob23,

I hope it doesnt turn on while coming up from a nice swim 

Catalina had that setup on their boats for a short run.  ........ they changed it later, LOL 

Mac

[Bob23]

Mac:
   I hope it doesn't turn on at all! The waterline should always be on the OUTSIDE of the boat!
Bob23

[MacGyver]

Lol Bob23
You are correct! How silly of me to think that........I still have that Catalina 38 on my mind I guess.....

Mac

[crazycarl]

after motoring in a storm with high, following, seas for hours, i reached my destination i went below to find water 6" deep on the cabin sole.  i figured the hull was damaged the night before while riding the storm out north of key west.

after snorkeling around the and not finding any marks on the hull, i climbed up the ladder looking at that bilge discharge. it was behind the ladder about half way up the transom. 

i figured the following seas had entered the discharge hose and overflowed the bilge. i spent the next 2 1/2 hours removing labels from canned goods and writing their contents on them with a marker cans. 

lesson learned?  install that float switch i already had for the pump and install a check valve in the discharge hose!

note:  some pump manufacturers do not recommend check valves on the lower output pumps.