Bilge drain thru hulls

[spencer]

It's been awhile but my 31 is almost ready to get wet
Diesels installed , new exhaust thru the sides, new palm beach style throttles and steering
I'll take some new pics soon

I would like to not have the bilge drains exiting from port and starboard sides
I want a clean look without them , what is the best way to do this ?

I have seen pics of Bertram 31 like this, are the bilges exiting thru thru hulls with check valves on the transom ?
Or the bottom of the hull?

Thanks
Spencer

[Navatech]

It's been awhile but my 31 is almost ready to get wet
Diesels installed , new exhaust thru the sides, new palm beach style throttles and steering
I'll take some new pics soon

I would like to not have the bilge drains exiting from port and starboard sides
I want a clean look without them , what is the best way to do this ?

I have seen pics of Bertram 31 like this, are the bilges exiting thru thru hulls with check valves on the transom ?
Or the bottom of the hull?

I understand your wish for a "clean" look... You could achieve this by running all your bilge pump outputs to thru hulls on the transom... You could even run all of them to a sort of "sea chest" that connects to one sole thru hull in the transom... In fact, you could even run them through underwater thru hulls for the ultimate "clean" look...

Having said that, to achieve the best possible centrifugal bilge pump capacities you need to keep your discharge lines as short and as straight as possible...

Keep in mind that centrifugal bilge pump capacities are GROSSLY over stated by the manufacturers... Basically they're based on performance testing in a "bucket to bucket" scenario... Next to no hose length and no head... In the real world and depending on your specific installation you'll only get 1/3rd to 2/3rd of the stated capacity at the BEST of times...

So, if you are really dedicated to that "clean" look and you're willing to do the planning and go through the expense it is doable...

As for check valves, they're put as near as possible to the suction side of the pump as their purpose is to prevent water from flowing back into the bilge once the pump stops... I'm not a fan as they impede the flow and are a source for problems (they get clogged/stuck easily)...

As for underwater exhaust of bilge pumps, you could push the water out through an underwater thru hull... But, in modern boat building the current tendency is to incorporate AC, bilge pump and other discharges into the engine exhaust hull outlet...

[John Nardi]

Be careful what you ask for and desire Spencer...I once owned a beautiful 70s era custom boat that achieved that look many times over...She almost sunk when a check valve failed...I removed all of them and placed them appropriately...I have seen something similar to IR guy's rec where everything feeds into a central box (like grey water), and then feeds into the exhaust via a separate tube as they do with the gen set...Personally I'm a purest and will keep them where the engineers designed them to be...I saw your boat a number of months back when Cabrera was working on it....Looks great!!! Best of luck to you! John

[Tony Meola]

If you go with the check valve the only one the Capt. Recommended was a flapper design. I will have to do a search for the thread but it is somewhere on here.

[Tony Meola]

http://bertram31.com/newbb/viewtopic.ph ... lve#p74272

It was an easier search than I thought. Read through this thread.

[Rawleigh]

Unfortunately, the higher up the hull side the better for the thru hulls. My secondary pump, which is the largest Rule makes exits right up under the rub rail. I don't trust check valves for that although my stern thru hull exits just above the bootstripe.

[spencer]

Thank you all for the responses, gives me something to think about.
Seems pretty apparent that check valves are not good.

What kind and how many bilge pumps are you guys using?
Think I am going with two at the stern and one in between the engines

I have the bilge closed off in front of the engine/bulkhead

[Tony Meola]

Spencer

If you follow Capt. Pat's logic of #$@ happens then you will add one big pump up front in the cabin area also. Hate to hit something and have to worry about that area.

Also, even though you closed it off, you should install a Bekson port so you can open it and let the water flow should you need to.

[Yannis]

I dont know if the 31 is like my 28, but in mine, although I glassed the bottom part of the cabin/engine bulkhead, there are 2 other openings further up on each side. Everytime I wash the deck the water goes through those and reappears in the cabin bilge. Although I tried to seal these openings it is very difficult to completely block water coming in, hence the need for a cabin floor pump. You need an educated monkey to fit between each engine and bulkhead space and do a proper fair and glass job...let alone the dust on the engine, filters etc. As a friend says, these boats will NEVER be dry !

[Tony Meola]

Yannis

Actually on the 31, it is not too bad getting to those openings to close them off. Unless a shelf has been built covering it or you have a generator. Then it gets tough.

[Yannis]

Good for you Tony.
I wonder what other 28ers have done regarding this issue...

[Rawleigh]

I have two "regular" size ones (can't remember exactly the size, say 1200-1700gph) in the cabin and at the transom respectively. The transom pump has a light that comes on at both helm stations so I will know I have a problem while running.

I also have a Rule 3700 mounted higher in the cabin with an Ultra Pump switch as an emergency pump. 1.5" outlet for it comes out right below the rubrail on the port side.

In addition I have the Groco thru hulls for the engine intakes with the crash valves built into them. You can't have too much pumping capacity when something bad happens!