Underwater exhaust conversion...

[vas]

As said.....anyone else....this would be madness but Vas....you’re a genius!

nah, better leave the accolades for after I complete testing and report relative values. Plan is to do the testing on various conditions with one exhaust on the box and the other in the original spot, some silicone tubing for the backpressure measurement and I need to get yet another WIKA boost gauge for millibars now (got a 3bar, a 10bar and a 50bar) and then pyrometer testing before I declare it safe...

 

[Mr Googler]

nah, better leave the accolades for after I complete testing and report relative values. Plan is to do the testing on various conditions with one exhaust on the box and the other in the original spot, some silicone tubing for the backpressure measurement and I need to get yet another WIKA boost gauge for millibars now (got a 3bar, a 10bar and a 50bar) and then pyrometer testing before I declare it safe...

I have faith

 

[MapisM]

still missing the deflector in the front, done but not epoxied yet

Sorry V if I didn't think of this before - I guess it's a bit pointless now, if the deflector is already built.
But just in case you would still be interested, I came across several different solutions for that, depending on builders.
Below is a short selection of pics which I found with a quick search in my files, but I've seen also others.
I guess the most logical conclusion - assuming that all the deflectors below are doing their job - is that its shape isn't so critical...

 

[vas]

interesting list of pics P,

I can only assume that the builders had their moulds ready and were happy to simply plug and create the hole and later form the front deflector in an additive manner.
All these pics show a roundish hole for the exhaust coming out, protected by something in the front, but no trailing forming.
I've already created a, may I say, relatively substantial in size outlet inwards slope that should create a serious Bernoulli effect once boat starts moving. I feel that a 100mm wedge from 0 to 20mm should be enough to increase this effect without any collateral damage in water flow around there...
I wish I could create a glass lid for the box so that I can see how the water swirls in there in different speeds

cheers

V.

 

[MapisM]

Intriguing idea.
I suppose that a GoPro or similar might withstand the water flow, also if placed underneath, just along the chine.
Main problem is probably to find a solid enough way to attach it in place!

 

[Mr Googler]

Perspex melts at 160c.......it would be fascinating to see what happens.....even if it’s temporary

 

[MapisM]

Actually, I suggested a placement along the chine, i.e. on the side of the outlet.
Btw, by the time exhaust reaches that point, after the re-injection of raw water, it's bound to be at just a fraction of its original temperature.

 

[Portofino]

FYI .;You are very close :encouragement:





Works at all speeds noise suppression wise inc 870 rpm = 9.5 knots for me

 

[MrB]

As said.....anyone else....this would be madness but Vas....you’re a genius!

+1 Bonkers but brilliant. If anyone can do it it's Vas!! :encouragement:

 

[Mr Googler]

Any update Vas?.......and the generator linear actuator mod. You’ve got a lot of updating to do! :encouragement:

 

[vas]

sorry guys,

pushed with time, after 3weeks onboard I'm back home/office, working for a couple of deadlines and flying tomorrow to Porto for a week for a conf.
system worked for sure, there are two issues that need better addressing when the boat is back on the hard and they strangely weren't what I was worried about:
A. the 4mm SS lid leaks around the edges from the pressure of the exhaust gasses, giving back inside small bubbles of water - redid the stbrd one, have to do the port now again
B. the 45mm bypass which dips inside the box manages to only bring up gasses and almost no water on idle (cannot check and tbh don't care what it does at speed)

having clocked around 300nm, hoses are fine and coolish, nothing else falling apart and most important you hear bugger all at D speeds. Up on the f/b I can only hear the sound of the water on the bow, same as when sitting at the bow, very impressive indeed!
Sitting and having a conversation at 7kn on the aft deck is now possible and actually pleasant
I have to acoustically "seal" the e/r a bit more and I have to fit something to reduce the engine induction roar (and especially on the generator which is now v.v.quiet otherwise)

Overall, excellent results, but I'm afraid you have to wait for a couple of weeks at least before I have time to report on all that.

BTW, linak thing programmed, but I decided to design my own PCB for most of my needs (fe, the e/r black boxes using ESP32S controllers turned out a disaster, only gear selection and EGT worked, all the other bits of info slowly died and it wasn't my wiring or welding...) and have it built in China, still a few things to check and short before sending it off.
So for now generator governor set at 3K rpm but I'm taking it easy on starting and letting it cool with no load before stopping (must have used the generator a dozen times mostly for the watermaker).


So expect also a longish thread on automation/NMEA2000 boxes for various uses when the weather turns foul

cheers

V.

 

[kashurst]

great result, look forward to pics when you get time.

 

[Mr Googler]

Awesome! Still think the kids should be clear acrylic so you can see what’s going on