Determining Bilge Pump Size

On my Bertram 54, I have:

2000 Lazarette
2000 Engine Room
500 Diaphram pump Engine Room
2000 Forward Bilge

Plus Engine Driven Pump

6500 total gph electric not including the engine driven pump.

Seems sufficient? Are newer quality yachts delivered with more capacity than this?

You don't have anywhere near 6500 gph capacity in real life. Due to most pumps flow rates being measured at zero lift and full voltage. I would add at least one 3500 gph+ pump in the engine room and a high water alarm. Or better yet, change out all your 2000 gph pumps to 3500s and add a second one in the engine room.

http://www.powerboat-reports.com/sample/bilge.html

http://www.powerboat-reports.com/newspics/pdfs/13-6-Lift.pdf

Personally, I like the Rule 2000's much better then the rule 3700now4000gph pumps. I've seen on many boats I've run, where the rule 3700's/4000's get airlocked and stay on for who knows how long yet aren't pumping water. The rule 2000's seem to never get airlocked.....

Then that's easy ... I just add 4 more Rule 2000 pumps!

So ... I would have

2 Rule 2000 in the Laz
3 Rule 2000 in the Engine Room
1 Jabsco 500 diaphram pump in the Engine Room
2 Rule 2000 in the Forward Bilge
Engine driven pumps.

4 additional through hulls.

Seems like overkill. What does Viking put on their new 63's? How about Spencer and some of the other customs? Are they really putting 8 bilge pumps on a 54 foot boat?

Capt. Bill ... is this the setup you have on your boat?

4 x 3700 gph pumps with 1.5" through hulls.
+ engine driven pump

Mike

In my personal 42' GB I had 2 - 3500s, 1 - 2000, 1 - 750 and crash pump valves and strainers on both engines.

On the boat I run for a living we have 6 - 3500s and a 4" portable gas powered trash pump.

ok ... I have reluctantly learned something today. I was thinking my bilge pump setup was completely sufficient.

One thing that would greatly help your boat IMO, would be a rule 4000 or even a rule 8000 (single discharge hose), mounted near the rear of the engine room with an automatic switch mounted about 2-3" above the bilge this would function as an emergency pump and the float switch should be high enough that it wouldn't airlock and you would only have to add a single discharge on the side of the hull.

One thing that would greatly help your boat IMO, would be a rule 4000 or even a rule 8000 (single discharge hose), mounted near the rear of the engine room with an automatic switch mounted about 2-3" above the bilge this would function as an emergency pump and the float switch should be high enough that it wouldn't airlock and you would only have to add a single discharge on the side of the hull.

are you saying the float switch would air lock or the pump ?

I was referring to the pump airlocking. With the float switch 2-3" above the bilge water, there should be enough water depth and waterflow to the pump through the bilge limber holes on the 54' Bertram that the poster has to allow a continuous flow of water to make it to the pump that it would not get any air inside of it. The 54' Bertram does not have a sealed bulkhead between the engine room and the cockpit area. A lot of times an issue is when the cockpit is flooded backing down on a fish, or I've seen an exhaust hose blow off as a result of too much backpressure from backing down on said fish. in addition to a possible Engine Room hose blowing or a breach in the hull usually if it happens would be in the engine room area as well due to the fact that at cruise, the front 1/3 of the boat is usually out of the water. (Unless you hit one of those magical Bertram Buoy's off of South Carolina, then no bilge pump will save the boat). Needless to say the normal 2000 gph pumps would take care of the normal everyday water intrusion (rain, dripping shafts, etc.) and the 4000/8000 would come on only in an emergency situation. If the cockpit is flooded for 5-10 minutes before it drains out the scuppers, your probably not going to be able to get the engine room door open, and with a big tuna or marlin on the end of your line (most likely cause of flooded cockpit) it's the last thing your going to be thinking about. He might have to put the pump at the front of the cockpit bilge. I cannot remember the exact layout of the center bilge in the 54' Bertram. I know it has 2 fuel tanks in the center bilge in the engine room and 1 further back in the cockpit (on some of them). It either has the open bilge space in the front section of the engine room or the rear section and that's where the factory installed 2000 gph pump resides.

However I have seen the ruleamatic plus enclosed float switches and the blue surebail enclosed float switches airlock when cleaning the bilges with soap and cause the pump to stay running as the rule only has a tiny hole at the top to let air out of it as water comes into the enclosed switch from the bottom. But I wouldn't recommend using either of those switches with a Rule 4000 or 8000gph pump. They are not rated for the amp draw of the pump, so one would typically use a Rule superswitch. Or an ultraswitch.

However, many manufacturers use Rule 3700's now Rule 4000's as the everyday pumps on a float switch which will still cycle with an auto switch. They use them because there are less discharge holes/thru-hulls in the hull side, and that size will also have hopefully enough capacity in an emergency situation. For example the Hatteras 75' I used to run had 4x3700gph and 1-2000 gph for normal bilge pumping = 16,800 gph at the pump and probably around 12,000 gph at the discharge thru-hull fittings.

Hi,

Where did the other 4800 Gals go?

A bloke with a bucket and a great desire not to go swimming?

Hi Fish,

Possible but I was thinking more it leaked out through a hole in the bottom.

Just as an aside, where do you mount the Head outlet on a Glassbottom Boat?

Loss of pumping capacity/efficiency due to the height of the thru-hulls and length of the hoses to them(HEAD). If you noticed it says probably has 12,000 gph AT THE DISCHARGE FITTINGS in the side of the hull.

Hi,

Yes, I did see that which is why I asked where the missing 4800 GPH went.

Pumps that I am familiar with have a rating based on whatheight they can pump a fluid of a certain SG to.

There will be a performance curve that shows what you should get at various heights till the advertised max.

I am yet to see one that will say it can suck in 16,800 GPH and only discharge 12,000 GPH. The correct way to describe that install would be to say you could pump 12,000 GPH out of the bilges if this is really the output your pumps can deliver at the outlet to overboard.

BTW: Do you happen to have any type of Oil Monitoring Equipment in that discharge?

This thread (and the Nordhavn 75 Sinks thread) has really opened our eyes and made us all take a good hard look at our bilge pump capacities. This is a very good thing because although it is one of the most important systems on our boat, many systems' capacity is not questioned until something like this happens or worse when it's too late.

My boat came from the factory with 5 Rule 3700's all hooked to UltraSwitches in each bilge and two Rule 2000's in the gen room (aft). When running, gen room bilge water is all the way aft and when at rest any water in the gen room bilge is fwd, so they used two 2,000's instead of one 3700 to be able to pump from either end of the gen room bilge. These provide for 22,500 gallons of regular, everyday capacity (at the pump). The boat has a 21' 8" beam and a 4' 6" draft, so the bilges are quite shallow which means the pumps only have about 2' of head to get over the stringers. There are two more Ultraswitches, one in the fwd bilge and the other in the aft bilge that trigger a high water alarm but there are no pumps hooked to the high water Ultraswitches (yet).

While I feel that the Rule pumps on Ultraswitches are adequate, the rest of the system is what I have been questioning as I read these through these threads. There is also a dewatering/firefighting pump that is rated at 26gpm (1560gph) with schedule 80 pvc plumbed into each bilge compartment connected to a clearly labeled valve system so that whoever operates the pump can select which bilge(s) to pump from. This same pump doubles as an emergency firefighting pump because it has a thru-hull with a strainer that with the turn of one valve pumps water to either the fire hose at the bow or the fire hose at the stern. There are also crash pump valves plumbed into the main engine raw water intakes so that if all else fails the engines can suck water out of the engine room, although I have no idea of how much pumping capacity the mains might produce.

I am thinking that the 26gpm dewatering/firefighting mump may be undersized for it's designated task because I read in the other thread that Steve Dashew uses a 160gpm (9600gph) emergency backup pump. I think that maybe I should consider adding a Rule 8000 to each of the two high water alarm Ultraswitches with two new dedicated 2" through hulls out the side. Hmmm, how much is enough?

I just ordered a strobe light from Aqua Signal that I am going to install on the mast near the all around light to wire into the alarm system. The strobe light and the loud bell that I plan to install under the flybridge dash *SHOULD* call attention directly to my boat if the unthinkable were to happen while I am away from the boat. This is all pretty scary stuff, but it is threads like these that help all of us to re-evaluate the systems on our boats. Better to evaluate and upgrade them now rather than wait until it's too late.

Rule's are rated at the pump (0' head), and their rating is printed on the pump in very large type. Rule 2000gph, 3700gph etc. I could not find a rating published on their website of the capacity at anything other then at the pump (such as 5' head). Basically everyone knows them as a Rule 2000 or whichever throughout the industry. So, if you go into West Marine and ask for a 24v Rule 2000, that is what they will hand you.

Theoretically If you really wanted to split hairs, a Rule 2000 could suck 2000gph for a very brief time until it starts pushing it up the hose to a higher height, then it would slow down the sucking to whatever head pumping capacity it is at, if the discharge hose only had air in it when it turned on. So technically all of the pumps combined could suck 16,800gph for a split second then slow down sucking speed and discharge at 12,000gph hehehehe.

CORRECTION
I found an info sheet on the Rule 2000gph model 12 (24volt bilge pump)
27.2 volts= 2000 gph (0' head), 1620 gph (3.35' head), 1300 gph (6.7' head)
24 volts= 1740 gph (0' head), 1450 (3.35' head), 1160 (6.7' head)


No oil monitoring system on the discharge of that particular boat, and I can't remember seeing more than 1 oil monitoring system on any boat under 100' I've been on. That boat has sealed engine beds that do not drain into the bilge (unless you lost 10 gallons in there and at that point you'd be looking at a rebuild.) as do most yachts under 100'.