Query for Knowledge: Elm (Tree) Pumps?

[rlwhitt]

Hi All,

 

I've been wondering about Elm Pumps.   Usually sitting right next to the chain pumps (who's function IS clear to me), I'm not understanding what they are pumping.  Just another way to pump the bilge?  Or something else?   Why are they called Elm, and sometimes Elm Tree pumps, and which is correct?  Are they made from Elm trees? 

 

 

[Morgan]

Hi Rick,

 

Elm Tree Pumps, also known as the common or brake pump were multifunctional.  In a ship with chain pumps the Elm Tree Pump served to bring fresh seawater up for washing the decks and feeding the condenser on the stove.  They could provide water for fire fighting on deck but they were only a lift pump and not a pressurised pump so couldn’t be directed at a fire as there was no head of water (ships had separate fire engines / pumps that could generate pressure and be directed at sails etc.)

 

Initially the pump casing was open directly to the sea through the ships bottom, but in the late 18th Century they were brought inboard and a system of indirect pipe work via valves and stop cocks could let sea water in to the cistern around the mainmast and the foot of the pump was now inside the ship within the cistern to lift the water.

 

In smaller ships without chain pumps the elm tree pump was the primary means of clearing water from the hold.

 

They are called Elm Tree Pumps as it was the bored trunk of an elm tree that was used for the pump casing.

 

Gary

Edited September 19, 2023 by Morgan

[rlwhitt]

Thanks Gary, that makes sense, I hadn’t considered drawing up fresh water.

[allanyed]

11 hours ago, rlwhitt said:

I hadn’t considered drawing up fresh water.

Whatever water was in the bilge which could be fresh from rain water mixed in with the normal sea water that was found in the bilges. Certainly not fresh drinking water.

Allan

[rlwhitt]

2 hours ago, allanyed said:

Whatever water was in the bilge which could be fresh from rain water mixed in with the normal sea water that was found in the bilges. Certainly not fresh drinking water.

Allan

 

Right, I guess I could have clarified - non bilge water 

[allanyed]

Hi Rick

Goodwin describes these as being the main bilge pump on fourth rates and below.  On larger rates they were used for taking water from holes in the hull or from cisterns.  The Construction and Fitting of English Ships of War, page 142.  I have no idea how they were employed on American ships.

Allan

Edited September 20, 2023 by allanyed

[iMustBeCrazy]

Two examples,

On the left 1 tap at the hull to let water drain into the well to then be pumped out.

On the right 2 taps one at the hull and one at the base of the pump, this allows you to do the same as above or to pump from outboard without filling the well.

 

[allanyed]

Craig, what is the ZAZ number on the bottom left, I cannot make it out?

 

THANK YOU

 

Allan

[iMustBeCrazy]

6 minutes ago, allanyed said:

what is the ZAZ number on the bottom left

6844  https://www.rmg.co.uk/collections/objects/rmgc-object-86635

 

[allanyed]

10 hours ago, iMustBeCrazy said:

6844  https://www.rmg.co.uk/collections/objects/rmgc-object-86635

THANK YOU!!!

 

Allan

[iMustBeCrazy]

7 minutes ago, allanyed said:

THANK YOU!!!

No worries