New compreesion post required.

[Porthandbuoy]

I've removed the steel compression post from Ladybird as the bottom, which was once adjustable, is a rusty mess of dubious integrity. It needs replaced or repaired.
It occurs to me a nice timber post would look a lot better than a painted steel one (as well as being lighter!)

I'm thinking perhaps a hollow post, 6' 7 x 2 ¾" dia. It needs to be that diameter as that is the size of the hole in the middle of the table, and hollow to allow wiring up to the deckhead.

Is birdsmouth construction suitable? Any timber not suitable? I have loads of mahogany flooring lying around in the workshop.

 

[Laminar Flow]

The important question here is whether the new timber post is capable of withstanding the same compression load of the old steel one. Which, if it has the same outside dimensions might be questionable.

Your best bet might be to reverse engineer it from the old post using Euler's formula for columns under compression, most likely with a pin/pin constant.

I know this sounds terribly nerdy, but there are online engineering programs where you simply plonk in the numbers and you get your results.

No doubt you'll feel a lot easier thrashing to windward in a good blow, knowing it'll all hold up.

If you feel at all uncertain and prefer the look of wood you could clad a new steel or, if you wish to save weight, aluminium post (after checking the numbers) with the timber of choice.

 

[Poignard]

Would a s/s post break the bank?

If you fancy timber you could always clad it with strips of hardwood.

 

[PlankWalker]

It depends on the size of your boat, 2 3/4" seems a bit dinghy size, it has to take the compression of your mast, in a pounding sea.
For my heavy 36 footer I have a teak oval section 6" X 9" with 1 1/2" wall thickness.
Birds mouth construction in mahogany would be fine.

Plank

 

[guardian]

Bought myself 2m of 100 x 50mm mild steel channel, made some composite end plates that bolt the channel to the floor and coachroof respectively then bolted this into the back of the existing timber post in the saloon.

 

[Laminar Flow]

It depends on the size of your boat, 2 3/4" seems a bit dinghy size, it has to take the compression of your mast, in a pounding sea.
For my heavy 36 footer I have a teak oval section 6" X 9" with 1 1/2" wall thickness.
Birds mouth construction in mahogany would be fine.

Plank

The critical load for a 2 3/4" steel tube with a 3/16" wall (70mm x 70mm x 4mm) and 6' 7" (2m) long is near enough 38 tons - that is quite some dinghy!

 

[Motor_Sailor]

Ian Nicholson's 'Boat Data Book' has the design tables for wooden columns.

 

[Porthandbuoy]

Ian Nicholson's 'Boat Data Book' has the design tables for wooden columns.

Aha! I have a copy of that somewhere. Thanks.