1976 O'day 25 Bilge Pump Installation

May 14, 2012
68
Oday 25 Shoal draft Mystic
The boat never had a bilge pump installed. I found a purposely made passage between the bilge and the starboard berth bulkhead for a hose but it seems restricted as I could barely snake a tape measure through it. Has anyone done a fresh install, and what is the hose OD that I should be able to get through it?
Looking around the yard at other boats, it looks like most thru hulls are about a foot above the waterline on the transom. Does that seem correct for the 25?
Also, I replaced the thru hull for the head sink. It is at waterline and has no seacock. Is there any problem with backflow while heeling?
 

JRT

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Feb 14, 2017
2,037
Catalina 310 211 Lake Guntersville, AL
Most installs I've seen run the discharge out a stern thru hull fitting.

The head sink seems fine in the stock location to me, but I'm on a lake so don't spend a lot of time heeled over.
 

Ward H

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Nov 7, 2011
3,645
Catalina 30 Mk II Barnegat, NJ
On my 25, I could hear the gurgling coming from the head sink when healed over but never found water in the sink. Wondered about the lack of a seacock but not for too long. And the thru hull should be a few inches above the water line. If it is at the water line, I would put a seacock on it.

It sounds like you found a limber hole, a hole designed to let water pass through from one area to another, not a run for a hose.

On my 25, I thought about a bilge pump the first year. Then I weighed the risk/benefit. I didn't have shore power so a pump would quickly drain the battery. I considered how water would enter the boat. I kept the seacock for the galley sink drain closed. There were no other under water fittings so I thought risk was too low to worry about a bilge pump.
 
May 14, 2012
68
Oday 25 Shoal draft Mystic
It would be great to be able to flush the bilge with the pump. Looks like no other easy run to the transom. Have to wait on the seacock till next year.
 
Jan 27, 2008
3,045
ODay 35 Beaufort, NC
The sink drain should have a seacock. If the hose splits or a clamp breaks your boat will sink. The bilge hose needs to have a loop to get the hose above the water line or following seas could fill your boat and also sink it. This also creates a dilemma as you never get all the water out with a bilge pump since the water in the hose up to the top of the loop drains back into the bilge. The outlet for the bilge pump should be above the waterline. If your boat is taking on water and the bilge pump kicks on you want to hear the water flowing out while at the helm and give you a chance to investigate why. Underwater you wouldn't know about it until possibly too late.
 

JRT

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Feb 14, 2017
2,037
Catalina 310 211 Lake Guntersville, AL
The sink drain on the forward head is above the waterline in the original config and doesnt have a seacock. Having one would be a better idea fpr sure but I'm not sure it is always needed. For example I'm on a lake and really dont take on heavy sea states.
 
May 14, 2012
68
Oday 25 Shoal draft Mystic
Its in the middle of the bootstripe and I havent seen the boat in the water. It is in the original factory position. I brought an elbow to direct the hose upward and new hose. Brought a 3/4 " outlet bilge pump snd thru hull. Will put it a foot above the waterline.
 

Ward H

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Nov 7, 2011
3,645
Catalina 30 Mk II Barnegat, NJ
The sink drain should have a seacock. If the hose splits or a clamp breaks your boat will sink.
@jibes138
Only if you keep the boat heeled over hard to starboard.
Here's a pic showing the location of the thru hull in the boot stripe. Enough above the water line to not be an issue. Be sure to double clamp the hose.
IMG_0126.jpg

Now the galley sink drain definitely needs a seacock as that thru hull is below the waterline.
And, if it is a gate valve, replace it before putting the boat in the water. My 1980 25 had a gate valve. They saved it for me when I had the yard replace it with a quarter turn valve. The "gate" had completely disintegrated rendering it useless.
 
May 14, 2012
68
Oday 25 Shoal draft Mystic
My head sink drain is in the same place as yours. I put a bronze thru hull in it with a stainless ball valve with the elbow and new line, clamps, this weekend. Ball valves all around. Got the bilge hose in also, but spent alot of time pressure testing the seacocks and fixing leaks so the pump isnt in yet. Removed the Y valve and pump for the holding tank as the thru hull barb and pump bladder had leaks. Put a threaded nylon plug in the sea cock. Spilled a little 2 year old honey in the process. Used KO holding tank treatment to clean up and it worked great. Still some residual odor.
 
May 14, 2012
68
Oday 25 Shoal draft Mystic
I want to do a final low pressure test on the holding tank system, I can pressurize the pumpout spot on deck with a shop vac, but will the honey blow out of the head?