Exhaust system replacement using mostly Trident?

[Pub911]

My 1972 NorthStar (Hughes) 38 has a Universal M4-30, 25hp diesel engine that's fitted with a raw-water-fed water-jacketed exhaust tube that's about 2 1/2 feet long - an inner pipe of exhaust gas surrounded by a sealed tube where raw water flows.

The flanged end of this unit is fastened to a dry, glass-matt-wrapped black-iron exhaust pipe/system that exits the boat about 15 feet away - a home-depot parts, custom pipe-fitted frankenstein of a set-up installed by the PO.

The raw water used in the jacket above rejoins the exhaust pipe about 2 feet from the end of the black-iron exhaust pipe and flushes out through a seacock.

The glass-wrapped black iron fails about every 10 years. Cost of a custom fab'd SS exhaust is staggering. Can I use Trident exhaust-rated hose on this application or is it too hot (even though exhaust is cooled via the 2-foot double-pipe back at the engine)?

Any other ideas on how to solve this perrenial failure item?

[tommays]

Its a BIT hard to understand what you have

On older boats like my A4 there is a hot section warped in insulation and then its pretty much like any other boat in that i don't know of any gas or diesel inboard that does not go to the correct rubber right after were the water is injected to cool the exhaust stream

[JimsCAL]

The installation on my old Universal 5411 was a black iron pipe loop to a plastic waterlift muffler then exhaust hose to the outlet. You can't use hose before the water injection at the back end of the loop. Too hot.

[Pub911]

So I guess it really comes down to: how hot does the existing black-iron get?

And I guess I can answer this by putting an infrared reader on it. So assuming I get a range comfortably within the Trident high-point (which is around 400F).

Can I trust that this reading is not going to be exceeded?

Will an overheating situation melt the tube?

Does anyone know how much fluxuation there is likely to be on the exhaust temperatures if the engine were to overheat?

My point in asking is that I wouldn't want to set myself up with a solution that was too sensitive to withstand typical running variation - which may on rare occaission, involve a temporary overheat if say, a bet broke and went unnoticed until the temp alarm went off.

Thank you.

[JimsCAL]

Engine exhaust temp will be 400F+ at load.