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bilge pump hose q's

Aug 17, 2013
484
Granpian G26 Ottawa/Gatineau
hey everyone, quick question, I'm redoing my old Grampian 26 and I'm getting ready to replace my bilge pump and the hose leads to nowhere, any idea on where I could/should install the output ?
 
Feb 10, 2004
3,276
Hunter 40.5 East Greenwich, RI
As direct as possible to a thru-hull on the side that is above a normal healing point. Use smooth bore hose, not the corrugated type.
 
  • Like
Likes: Justin_NSA
Feb 10, 2004
3,276
Hunter 40.5 East Greenwich, RI
The transom could work but unless the length of run is nearly the same, I would opt for a shorter run.
 
Aug 17, 2013
484
Granpian G26 Ottawa/Gatineau
or could I make it dump in the cockpit and let the scuppers handle it? I'm asking as that seems the way the PO did it.
 
Oct 22, 2014
12,566
CAL 35 Cruiser Portland OR, moored EVERETT WA
Fred. You do not want to be standing in bilge water in the cockpit.:yikes: Bilge water often contains the over flow of anything you can put in a boat.
That is why Rich’s suggestion is such a good one.
My bilge hose exits the transom. I’d encourage you to consider that as well.
 
  • Helpful
Likes: FastOlson
Aug 17, 2013
484
Granpian G26 Ottawa/Gatineau
ok, so transom it is, do I just need a tru hull, just drill a hole and install and double clamp the hose?
 
Oct 22, 2014
12,566
CAL 35 Cruiser Portland OR, moored EVERETT WA
Pretty much. Above the waterline. Note on some boats when motoring the transom can get lower in the water. Put your bilge above that level. You can get fancy and put a flapper in the outlet but that is just a pain when it gets stuck. Keep a peg around incase you have to plug the hole i.e. your messing about stern cabin of the boat and you kick the hose breaking the fitting. A wooden plug in the hole will stop any water till you get back to port. I know an unlikely condition to occur but still a smart idea. It is always the little things that can mess you up.
 
Jan 11, 2014
5,753
Sabre 362 113 Fair Haven, NY
No job on a boat is simple or without some controversy. ;)

The hose run should be as short as possible, the outlet above the water line, and there should be a loop that goes above outlet. This loop will help prevent any back flooding from the through hull, however it will reduce the output a little.

Groco sells a nice tool for installing a through hull, you can make a simple one with a piece fo ¼" steel bar stock. Just grind an end to fit the two ears in the through hull. Use an adjustable wrench to hold the bar while someone threads the nut in on the other side. Simple and cheap. If you need a photo let me know and I"ll take one.

Finally, don't buy a plastic through hull fitting. Yes it will be above the water line, however they degrade and are easily broken. The one in this picture cracked with a half turn on the backing nut. It was being replaced with a SS one.

IMG_2229.jpeg
 
Oct 22, 2014
12,566
CAL 35 Cruiser Portland OR, moored EVERETT WA
Need not be vented. Just needs to be 12 inches above the exit hole. Enough to stop water from siphoning in or forced in be wave. The forced in wave can be limited by a flapper. On my boat the pump is above the exit hole. The 2 feet from the transom and the foot rise stops the major ingress of water should I get hit on the stern be a wave.
 
Jan 11, 2014
5,753
Sabre 362 113 Fair Haven, NY
No need to vent because the outlet is not below the water line. The loop is there to help prevent any back wash from a wave or from heeling. Depending on where the outlet is located it could be submerged while sailing very fast and heeled. Once the boat tacks or the wave passes any siphon would naturally break. Locating the outlet closer to the centerline will also help.

Some of the new Rule pumps have a built in check valve, mostly to stop the pump from cycling. This will also stop any siphon as water can't flow back through the pump.
 
May 24, 2004
6,331
CC 30 South Florida
Above the water line and the shorter run possible, Do not like the transom idea because of following seas.
 
Aug 17, 2013
484
Granpian G26 Ottawa/Gatineau
The problem I have is that I haven’t taken the boat out yet so I don’t know where the water line is
 
Jan 11, 2014
5,753
Sabre 362 113 Fair Haven, NY
The problem I have is that I haven’t taken the boat out yet so I don’t know where the water line is
Geesh, you gotta bring up the waterline question.

Ok, so there is the designed waterline. That's the water line that the designers thought was the water line.

But, the design weight and the actual build weight are usually different so the waterline depends on the actual weight.

Then there is all the crap people put on boats, boats don't get lighter with age.

Not to mention the water and weight that is absorbed in the hull and every where else that adds weight.

And we haven't even gotten to the difference between fresh water and salt water. Water density makes a difference too.

If you put the outlet 6 to 8 inches above the edge of the antifouling paint you will be OK.
 
  • Helpful
Likes: jssailem
Apr 8, 2010
1,350
Ericson Yachts Olson 34 Portland OR
Agree with the advice to avoid (cast) plastic thru hulls, especially where they may face UV.
Use composite fittings (Marlon) or SS.
 

RoyS

.
Jun 3, 2012
746
Hunter 33 Steamboat Wharf, Hull, MA
Consider; If you are in a permanent slip, place the outlet on the opposite of dock side. Avoid having the outlet over your dinghy. Harbor launches generally come to your starboard side (here at least) so, all other things equal, place on port side. Dumping a quart of bilge water on the launch operator’s shoes mandates a sizable gratuity.