Rafiki Coppercoating

rafiki_

rafiki_

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Rafiki now sporting a nicely coppercoated hull. Many thanks to Lewis Mills for all his hard work and efforts. The work has taken far longer than planned, as we were badly impacted by the cold and wet winter. She is now ready for launch.

This is the hull following prep. Many years of antifoul removed.
https://postimg.cc/image/4p8x92jth/

There were many blisters along the chine. These were routed out and filled. Fortunately no osmosis, but this would have been the result if we had left her much longer. The analysis was that the hull was not prepared last time the a/f was removed. No sign of any manufacturing issues.
https://postimg.cc/image/sszoxc7f9/

Coppercoat completed
https://s26.postimg.cc/j8g2agpt5/Port_bow_view.jpg


Stern view
https://postimg.cc/image/chzl11ad1/...o this. Any suggestions gratefully received.
 
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Looks great Paul. I was talking to a colleague the other day that races dinghy's. He says that lots of the competition report performance improvements with CC so I'll be interested to see if you notice any difference.
 
Doh! You already posted this thread by the time I asked about the results in the other one earlier today, but I missed it... :o

Rafiki looks in great shape indeed, with CC almost matching the covers colour! :cool:
Though CC colour won't last like that for long, as you surely know.
Can't remember if Hurricane did the same with his boat, but is it normally recommended to apply CC also on all u/w gear with the exception of props and (as far as I can tell from your pic) shaft brackets?
Btw, I'm a bit intrigued also because while I've already seen attempts to use something different for props, I never came across the use of a different stuff between brackets and rudders...

Looking fwd also to hearing about performance differences, if any.
In this respect, I'll be able to contribute with a reasonably accurate comparison, because last summer I seatrialed the DP extensively with traditional a/f, and I'm now also going for CC.
So, this summer I'll surely have the opportunity to check if and by how much CC will affect WOT speed at comparable load. :encouragement:
 
MapisM said:
Doh! You already posted this thread by the time I asked about the results in the other one earlier today, but I missed it... :o

Rafiki looks in great shape indeed, with CC almost matching the covers colour! :cool:
Though CC colour won't last like that for long, as you surely know.
Can't remember if Hurricane did the same with his boat, but is it normally recommended to apply CC also on all u/w gear with the exception of props and (as far as I can tell from your pic) shaft brackets?
Btw, I'm a bit intrigued also because while I've already seen attempts to use something different for props, I never came across the use of a different stuff between brackets and rudders...

Looking fwd also to hearing about performance differences, if any.
In this respect, I'll be able to contribute with a reasonably accurate comparison, because last summer I seatrialed the DP extensively with traditional a/f, and I'm now also going for CC.
So, this summer I'll surely have the opportunity to check if and by how much CC will affect WOT speed at comparable load. :encouragement:
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Yep, I’ve got a pretty good view of fuel cons at cruising speeds. The biggest variable has been the ammount of sterngear fouling, and of course the cc won’t change this. No doubt the cc is a much smoother finish than the old a/f, and we will see if this has an impact.
 
+1 with the soon to be able to report performance difference. My boat come out of the paint shop at the end of the month.

The CC application process is not just about the actual paint, as the preparation is also key. Obviously in general maintenance terms there is something to be said for stripping off all the old antifoul, sorting out any cracks or gelcoat dings, the new protection of the epoxy etc etc...... the prep work on my boat has been extensive and expertly done, she is literally as clean and smooth as an infants posterior !
 
rafiki_ said:
Yep, I’ve got a pretty good view of fuel cons at cruising speeds.
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How come P, have you got some Floscan or Maretron sensors installed?
Afaik that's the only way to get some accurate fuel burn numbers with your engines - as well as with mine, since both the previous 3116 and the current MAN are 100% mechanical.
Otoh, I appreciate that based on your cruise logs/refills you can have gained a good knowledge on the average fuel burn, but it's hard to make a reliable comparisons on that basis, and it takes time, too...
I previously mentioned WOT speed because that's the easiest empirical method for comparing also the fuel cons, not for the speed increase as such, which is irrelevant of course.
If before/after, AOTBE, the boat gains half a knot or whatever top speed, it might be hard to do the math for converting such speed gain in fuel burn improvement, but at least you know for sure that some improvement is bound to exist - by definition, so to speak. :encouragement:
 
No electronic gizmos P, lots of mileage and fill data though, and that's where it really counts. Nmpg doesn't really change between 2000 and 2300 rpm. Stb engine uses about 15% more fuel than the port.
 
rafiki_ said:
No electronic gizmos P, lots of mileage and fill data though, and that's where it really counts. Nmpg doesn't really change between 2000 and 2300 rpm. Stb engine uses about 15% more fuel than the port.
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Boat is looking excellent P. That genre of Azimut is very good looking over a long period

I'm curious P. How do you know about the 15%? Do you have each engine drawing from and retuning to its own tank? And do the heater and genset not mess up your numbers? 15% over burn in one engine is a heck of a lot. Makes you wonder if that prop has been overpitched since new. Have you had the props MRI scanned, so to speak (3D scanned)?

I cannot see that your data is going to prove whether coppercoat is more slippery. You're not going to have the same usage (mix of D and P speed, for example) of each fuel load, at least not to the fine 2-3% levels one needs to conclude on coppercoat's slippiness.
 
nice job P.

I was thinking along the lines of JFM above, could the difference be in tacho discrepancies? ie. one engine (stbrd in your case) doing more work all the time?
Assuming you dont use generator/heating, you could swap tacho cabling around (dunno, probably at the e/r) and see if the overburn moves to port?
Else, accurate gun rev counter on both engines?

cheers

V.
 
jfm said:
Boat is looking excellent P. That genre of Azimut is very good looking over a long period

I'm curious P. How do you know about the 15%? Do you have each engine drawing from and retuning to its own tank? And do the heater and genset not mess up your numbers? 15% over burn in one engine is a heck of a lot. Makes you wonder if that prop has been overpitched since new. Have you had the props MRI scanned, so to speak (3D scanned)?

I cannot see that your data is going to prove whether coppercoat is more slippery. You're not going to have the same usage (mix of D and P speed, for example) of each fuel load, at least not to the fine 2-3% levels one needs to conclude on coppercoat's slippiness.
Click to expand...
There is something about Azi styling that appeals to me,
There are 2 non-connected tanks. Heating not used from about this time of year. Main figures derived from the 3 fills on the 400 Nm trip from Brizzle to Southampton, no gennie use. There may well be a difference in tacho reading, but I haven’t swapped tacho’s, and of course there may be a prop pitch difference. Engines run same temp, so one not obviously working harder than the other.
 
jfm said:
I cannot see that your data is going to prove whether coppercoat is more slippery. You're not going to have the same usage (mix of D and P speed, for example) of each fuel load, at least not to the fine 2-3% levels one needs to conclude on coppercoat's slippiness.
Click to expand...

If the boat goes faster at WOT than it used to, isn’t that a good indication that CC is more slippery ? Proving the degree Of actual increase in slippery coefficient might be a more scientific calculation revolving around many variables but more or less slippery is fairly binary isn’t it ?

When My Superhawk finally comes out of the paint shed I am going to run her flat out across Southampton Water and assuming conditions are similar, then if she goes faster than 46.7 knots I am going to conclude that either CC itself, or a combination of CC and the smoothing and fairing process of applying it to her bottom has contributed to an increase in speed....... or slipperiness (depending on your preference). Am I missing something ?
 
I don't think you are. In fact, yours is exactly the point I was trying to make with my post #7... :)
 
rafiki_ said:
There are 2 non-connected tanks.
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Do you mean completely non-connected, or you've got valves on the connecting hoses which you decided to keep close?
If the first, it doesn't sound very convenient, because I guess that refilling is bound to be a two steps process on both sides, unless I'm missing something... :confused:

Fwiw, I concur with jfm that 15% sounds way too much to put it down to different tolerances between the two engines.
Particularly if they are both the originally installed ones btw, because Cat delivers them to builders in matched pairs.
Well, I suppose not just Cat actually, but I'm sure about Cat...
 
jfm said:
Engine power development won't show up as a jacket water temp difference- thermostat.
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Correct. If anything, EGT would probably be a bit higher in the more loaded engine, but that's normally unavailable in mech engines...
 
Boatbore said:
If the boat goes faster at WOT than it used to, isn’t that a good indication that CC is more slippery ? Proving the degree Of actual increase in slippery coefficient might be a more scientific calculation revolving around many variables but more or less slippery is fairly binary isn’t it ?

When My Superhawk finally comes out of the paint shed I am going to run her flat out across Southampton Water and assuming conditions are similar, then if she goes faster than 46.7 knots I am going to conclude that either CC itself, or a combination of CC and the smoothing and fairing process of applying it to her bottom has contributed to an increase in speed....... or slipperiness (depending on your preference). Am I missing something ?
Click to expand...
No, you're not missing anything. But we're looking for a few % difference here so you have to sure that AOTBE before coppercoat gets the cigar. Weight, air temps, tide effects, etc.
I'd expect something like 3% (which is a hunch number) from CC because it is smooth whereas normal a/f applied slapdashly is pretty rough. Down here in Med it costs a lot to have the a/f sprayed, but it can be done (MM/Trehard in Antibes did it to a racy dayboat boat belonging to a friend of mine but he is Royal Huismaned up and not very worried about yard costs!).
 
Paul, Re the odd fuel usage I had the exact same on my Azi, only it was the port tank that seemed to empty faster, this winter I fitted both tanks with OS capacitive level sensors and did a bit of investigation over the past few weeks, I found the breather line that runs from the tank to the vent had a low point, lower than both the tank outlet and outside vent, if you overfilled the tank at any time this caused an air lock (low point of breather line filled with fuel) just enough for it to be easier for both engines to pull from port tank, each engine returns to its own tank, so relieves the air lock a bit, so you pull a little from the locked tank. Have a look at the run of your breather hoses, is the a low point?
 
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