Aft bilge pump lets water in?!

The Cabo's usually came with crash pumps - valved raw water intakes for the engines that could be switched in an emergency to move some real volume of water. Just for emergencies.

I don't care if you have multiple Rule 3800 gph's, they are NOT going to keep up with a catastrophic engine exhaust hose failure. I think Professional Boatbuilder had a good article on the losses/low efficiency of bilge pumps. Most boaters who do not have crash pumps or a watertight lazarette, a watertight engine room are probably operating under a false assumption that their Rule (or equivalent) bilge pump(s) are going to handle some type of large emergency/catastrophic water ingress.

Won't happen, they are less efficient than you think. I am impressed by the level of redundancy on this 31 though.

I do recall a large yacht built in the 90's that had to replace all their Wire Nuts (failed survey) - it was more related to the way the Wire Nuts cut the strands of the wires, rather than making a solid connection that did not physically alter the integrity of the wire strands itself. The vibration issue would also come into play with the "cut" wire strands, reducing the effectiveness of the connection over time. I believe the ones that were epoxy filled were kept, for the most part, mainly if they were less accessible.

I think bilge pumps are the weak link of boats. While on larger boats for coastal cruising they're better than on lakes, it's amazing how many boats sank each year on the lake we lived on. They all were shocked their bilge pumps didn't prevent it. I think it's wise to have more than you think you need, have quality pumps, plus be sure all are in good order. The ones used in runabouts and bass boats were so bad, the dealership we used always had a stack of warranty units they'd replaced. Most of the leaks or ingress or even the rains that boats sank from could have been avoided with better equipment. With that as background, I would never be comfortable with taking shortcuts, but would want to be sure they were in the best condition to function.

1/2 of the time it's not the bilge pump or float switch on those types of boats, even on yachts. Most of the times it's the poor wire connections people do. I've seen wire nuts, I've seen the two wires stranded together and just electrical tape or that liquid electrical tape holding them together, I've also seen automotive butt connectors, I've seen 2 wires put in 1 side of a too large butt connector and crimped, I've also seen none of the wires supported, the connections in the bilge water, you name it. But the vibration and movement on the small boats puts more stress on them.

For pumps and check-valves I typically use this source for its wealth of information for all things marine related:

http://www.depcopump.com/index.php

It would be helpful to see a picture of the bilge installation.

I prefer this done properly to many of the poor soldered connections I have seen on boats straight from the factory.
Not wanting to start an argument here, just find this a safer way if you do it properly.

I'm quite surprised no one has suggested what could be the obvious fix: quit slowing down so fast that water hits the transom hard. Has it been tried and then rejected?

I find heatshrink butt connectors to be the best method for connecting bilge pump wires.

. The best answer seems to be a "loop" and or a check valve

Based on the limited view of the photo (can not really see where the hose exits), the solution looks like an extended/new hose leading up to the underside of the sole with the proper hangers, then a check valve in an accessible location (maybe just off the pump?) Configuration and sophistication is up to you. What's the rating on that pump? Looks a bit small.

It looks to be a 2000gph Rule.

This topic made me think quite a bit, even though it started out as a pretty small localized issue. Would like to complete the picture with a shot of the discharge thru-hull above the rudder shelf inside the transom.

Taking time to summarize options:

• A vented loop is always the preferred option, but needs to be above the waterline and the vent needs to be serviceable as it will clog over time.
• A check valve - depends on a lot of things but MUST be installed above the waterline, so precludes it from being near the pump, then should be horizontal after the thru-hull but before some "loop" or up-hill hose run before the drop-off to the discharge side of the bilge pump. But needs to be serviceable, as even non-corroding types can foul due to sea crud. Another issue will be if the Rule pump can push hard enough to "swing" the check-valve open, a Rule 500 or 1000 maybe not, but a Rule 1500 or 2000 maybe so, you would have to test it to be sure.
• A manual ball valve like the OP originally suggested, would just entail switching the thru-hull to include a ball valve. But this is totally manual and up to the OP to keep track of. Am a little surprised at the corrosion levels of the thru-hull fittings, so hard to say how detail orientated the OP is, there appears to be some checking/cleaning of bronze fittings/hose clamps/steering line fittings needed. Back-up systems lend some security, but the potential for burning out the bilge pump with a closed discharge thru-hull exists.
• Another simple option - a non-corrosive (rubber/plastic) flap over the discharge opening on the outside of the transom?

But like all things that fail mechanically, you need to treat more than the symptoms and get down to what is the root cause?

• Negative transom pressure at pre-planning speeds causing the wake to "roil" (is that the right word?) attach itself to the transom and force its way back?
• As Bamboo suggested, chopping the throttles or de-accelerating hard when coming off of plane?
• Since the thru hull may be only 4" above the waterline, just basic wave pumping action from vertical hull movements while fishing or on anchor, enough to force seawater back in?

Having the underside of the cockpit deck so low to the waterline (maybe the OP can measure and give that dimension?) may limit the effectiveness of a vented loop, leaving the inline check valve as the viable solution, but one that needs to be monitored to ensure the flap does not stick closed. This makes it almost as equal to the manual ball valve. To get a better and more effective vented loop would require cutting the cockpit deck and mounting it well above the waterline, something you see on commercial vessels but not practical for a 31' Cabo? UNLESS, of course, you have room up into the transom coaming and can go higher than deck level, may require some re-routing away from the centerline transom bait tank/fish hold, going to one or the other side of it?

I might be inclined to get a flap on the outside of the discharge as a first step and see if it does the trick. This would be a simple and relatively maintenance free first try. But I would certainly call Stan Miller Yacht Sales in Long Beach, who have sold a ton of Cabo's or Basin Marine in Newport Beach, who have commissioned plenty of them and get their opinion as well.

check valve - depends on a lot of things but MUST be installed above the waterline,


Seeking to learn. Why above the water line, considering, it seems, he can't even get a loop above that level? Query: Why the heck is seawater even coming into that individual system in the first place? IMO, the thru hull is in the wrong spot.

The flap will not stop water intrusion at the dock, but, agree, it is a solution for stopping some back wash. When I'm backing down out East, I wish my scupper flaps were that efficient, 'cause if I ain't wearing boots I'm on my butt wrestling that 4 lb. founder that took my 5 lb. bait.

Joe, we all are just exploring the bad, the good and the best solutions. You are kind to put up with us

By keeping it above the waterline you get technical alignment with ABYC and also with Rule centrifugal pump requirements. It does get somewhat complicated depending on discharge hose routing and how much gets completely evacuated - if there is too much static head for the Rule pump it can become a "cycling" issue with the discharge water being pushed back and forth.

It is an interesting dilemma for such a basic issue but one that many SF have to deal with since there cockpits are so near the waterline (some lower than others).

Why not just spend a few bucks to install a diaphragm pump and be done with it?

I agree, after reviewing the many possibilities, seems like the easiest solution, something like a self-priming Jabsco diaphragm bilge pump (with a built-in check valve) and a strainer for the pick-up.

Diaprahm pumps don't have nearly the volume of a Rule 2000, plus the ends usually break off after a year or two. A checkvalve at the thru hull or just before it is above the water line with the boat at rest so it would meet ABYC standards and that is what I would do.