Brass scupper tubes question

FLexpat · #1 03-04-2014, 04:09 PM

Thanks OC - PM sent. The 1-1/4" tubes have 156% of the flow area of the 1" tubes. I got 0.030" wall thickness from McMaster Carr since it was as thin as I could get - I don't think I can flare the 0.045" stuff; 0.030" will be challenging enough anyways. I think Moeller does not make the 1-1/4" brass tubes long enough for the scuppers. McMaster has 1-1/4 brass tube but I'm not sure if it is a marine alloy so I decided to add some 316 stainless to a recent buy and try it - maybe several times before I get it right. I'm not rushed for time since I haven't even finished the transom yet, much less started the decks.

riptide · #2 03-04-2014, 05:58 PM

Flexpat you are right they do not make the 1 1/4 brass tubes long enough. 3 7/8" is the longest I can find them which is an odd size. You can get 1" up to 8" long. I made my own flaring tool and did a test flare on .049 ss tubing it worked but took alot of muscle on the wrenches.You have to remove any burr inside and outside before you flare or the tubing can split.

Bushwacker · #3 03-04-2014, 09:48 PM

Quote:

Originally Posted by FLexpat

. . . McMaster has 1-1/4 brass tube but I'm not sure if it is a marine alloy so I decided to add some 316 stainless to a recent buy and try it - maybe several times before I get it right. . .

If you ever get any leaks and the wood block gets wet around a stainless tube, you'll have the perfect conditions for crevice corrosion, due to moisture + lack of oxygen. The stainless might not be much better than brass in that situation!

FLexpat · #4 03-04-2014, 10:32 PM

Quote:

Originally Posted by Bushwacker

If you ever get any leaks and the wood block gets wet around a stainless tube, you'll have the perfect conditions for crevice corrosion, due to moisture + lack of oxygen. The stainless might not be much better than brass in that situation!

I suspected so - thats why I was looking at passivating the stainless. After checking into it more, that is a PITA for this small of a job and nitric isn't cheap with hazmat shipping. Plan B is looking like using a fiberglass tube through the (soon to be replaced) block and a stainless tube inside of that. Redundancy works for me. Makes more work too - I don't want to finish too fast and have to start enjoying the boat.

Should be easier to do since the cap is off for the transom recore.