A Boat ,Stainless Steel, Salt Water...in St. Louis

[jeffscarstrucks]

I know this might be a stretch for this board but I'm not sure I'd trust an answer from others. I am involved in a restoration of a 67 Chriscraft Roamer boat that has two 6v52 Detroit engines. Somewhere along the line over the past 3 years the heat exchanger exhaust tubes that carry sea water from the heat exchanger (water to water radiator)to the exhaust system have been lost, stolen, or abducted. The original items were 2 inch copper. I am going to use tubing that is of equall size but made of stainless using food grade fittings and TIG to assemble them. Lately there has been a lot of input by folks who are pretty well versed in boat stuff; and like the subject says...salt water in St. Louis? I would like to know if there are any problems with my planning as the water in the Mississippi is plenty muddy but not too salty! The boat is headed for the BVI when it's done so it really is important that I have my ducks (seagulls) in a row. Thanks, JEFF

[timw]

The Stainless should work provided you make sure you hook up ground connections to prevent electrolisis. If it is hooked up just using rubber hoses, add dirty water and you have a battery. You might need to add sacraficial annodes to it too. ( pipe fitting where they can be screwed in)

[HAWK]

jeffscarstrucks,

I'd pass on the stainless and look at a copper nickel alloy. I think your corrosion reisitance will be much better and have fewer problems. Copper nickel is a very popular material for heat exchangers. Aqua-Chem builds literally tons of them.

I bet if Engloid reads this post, he will have the correct answer for sure!

[jeffscarstrucks]

The project was already on for today with stainless. We discussed the copper-nickel but he had already purchased the stainless for the water manifolds. The copper-nickel was chosen as the best for the heat exchanger for the generator to replace a perfecly good fresh water unit. I am going to add ground studs on each isolated piece to aid in corrosion control. There are sacraficial annodes in the sea water system cooling upstream of the exchanger so I am still unsure if we need them on the outlet side. Thanks for the valuable input. JEFF

[timw]

I have been running Mercruiser Engines in saltwater for 25 years. They use castiron manifolds and accessories. I get a minimum of 8 years on a set some more than that, it's had to keep track of. The castiron is not very good quality based on how bad it is eaten up. I can come back from a day on the ocean and scrape the salt off the deck of the boat, it's that salty out there.
The stainless should work OK based on that. The only advantage to copper would be more heat conductive.