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Old 09-10-2018, 08:44 PM   #41
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Thanks Kit, FF, Jeff, HighW, VitC.

The current engines are probably fine for a time - 3000 hours, but no maintenance records. While we are waiting the engine survey for pressure and oil analysis, the surveyor has pointed at the exhaust outlet - freshly painted antifoul: "see this, we just went across harbour at low speed to the liftout, and there's not even a hint of smoke in the air when we started or got going, or anything on the paint at all. You've got good motors".

I would guess that the fuel savings for common rail would eventually become a neutral changeover. We are intending the Atlantic and Pacific over the next years, so quite a few nautical miles to come.

We probably will just leave the existing motors, given everyone's help: there seems little fuel consumption benefit, and lots of complexity and cost. We will have to do without the mid-range and top speed increase we desire (which was cruising 9kn, not 6-7, and top speed 17+kn, not 13-14).
Or we could buy Domino
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Old 09-11-2018, 06:39 AM   #42
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Multi hull or lead sled long range cruise is always about the same efficient speed. SL.

SL is the sq rt of the LWL times .9 for fat heavy boats to times 1.15 for light skinny hulls.

6k or 7K is the common result for most cruisers, easy to plan for when route contemplating or at the A&P loading up.
120-140 miles a day is quiet and usually hassle free AP steering..


3000 hours is barely mid life , just well broken in.
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Old 09-12-2018, 03:39 PM   #43
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".
. We are intending the Atlantic and Pacific over the next years, so quite a few nautical miles to come.
I would love to know what 50ft design you have bought that can do that.
Not implying it can't be done, I'm sure it can, but shes obviously not your average boat.
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Old 09-12-2018, 07:58 PM   #44
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Hi Simi - give me a few more days and I'll post about her more...
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Old 09-17-2018, 08:00 AM   #45
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Wait..surveyor? You don’t own this boat yet? Let it go and buy something more ideal. I was going to suggest selling it but reading later in the thread it appears you don’t own it yet. This is an enormous undertaking that will never pay you back.
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Old 09-17-2018, 09:24 AM   #46
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Multi hull or lead sled long range cruise is always about the same efficient speed. SL.

SL is the sq rt of the LWL times .9 for fat heavy boats to times 1.15 for light skinny hulls.

6k or 7K is the common result for most cruisers, easy to plan for when route contemplating or at the A&P loading up.
120-140 miles a day is quiet and usually hassle free AP steering..


3000 hours is barely mid life , just well broken in.
What he said.
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Old 09-17-2018, 07:35 PM   #47
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Wait..surveyor? You don’t own this boat yet? Let it go and buy something more ideal. I was going to suggest selling it but reading later in the thread it appears you don’t own it yet. This is an enormous undertaking that will never pay you back.
Thanks - yes, I'm hearing what everyone is saying about cost.

Regarding the boat, there are many other reasons she is a good boat for us. The engines - which are probably just in run-in mode - are the only serious question (ie. can we get a faster "power mode" speed, not long distance cruise speed).
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Old 09-17-2018, 08:38 PM   #48
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I haven’t read all of this thread but what I have seen is someone looking to make a large increase in power and I haven’t seen anything about this particular hull and specificly whether or not it can benefit from more power. Anything close to a FD hull wouldn’t tollerate that and probably a hull anywhere close to FD but a SD hull probably wouldn’t tollerate that either.

But a hull closser to a planing hull would probably work well w more power. What kind of hull is this?

OK I see post #41 and it sounds like the OP has made good use of the posts on his thread. The hull is either a planing hull or a high speed SD hull. Another win for TF.
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Old 09-17-2018, 09:24 PM   #49
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Definitely a win for TF - thanks all.

The boat is a displacement power cat, 12.3:1 length-to-beam waterline. It could definitely benefit from more power - probably "limited" to about 22-25kn given size of engine room and fittings (based on other boats). But I'm learning that it would likely be at a serious expense and equipment pain. Go TF
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Old 09-18-2018, 01:48 AM   #50
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So now, to demonstrate my ignorance of diesels and show everyone I didn't grow up in a diesel's cylinder with oil on my hands ... is it feasible to convert, in-place, the existing Perkins M135 1006-6 models to 1006-6T or 1006-6TW? The first is a turbo version while the second is turbo + aftercooled. Visually, the 1006-6 looks different to the other two, so I assume it's not quite the same as adding an OEM or after market turbo-charger...?
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Old 09-18-2018, 02:09 AM   #51
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Worth exploring,the different engine price is just the start of an engine swap. I had the old Perkins 6354 and think it came in 3 versions. Mine was the full catastrophe, ie + turbo + aftercooler. Question is, were they beefed up anywhere to shoulder the extra output?
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Old 09-18-2018, 07:04 AM   #52
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"Question is, were they beefed up anywhere to shoulder the extra output? "

Most never are , the modern concept of a diesel operating life is lifetime fuel burn.

If you plug along at 2-5 GPH the engine will eat a lot of diesel before its overhaul or replacement time.

Roughly the same amount of fuel will be used if you consume it at a 15 or 20 GPH rate , before overhaul time.

This assumes the engine was neither under loaded or overloaded for long periods of time..
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Old 09-18-2018, 07:41 AM   #53
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Definitely a win for TF - thanks all.

The boat is a displacement power cat, 12.3:1 length-to-beam waterline. It could definitely benefit from more power - probably "limited" to about 22-25kn given size of engine room and fittings (based on other boats). But I'm learning that it would likely be at a serious expense and equipment pain. Go TF
22 knots with 36,000 pounds even in a Cat will be requiring some real HP.
And if it could reach 22 knots the actual realistic cruising speed would be much lower.
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Old 09-18-2018, 07:09 PM   #54
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"Question is, were they beefed up anywhere to shoulder the extra output? "

Most never are , the modern concept of a diesel operating life is lifetime fuel burn.
...
Thanks for that.

So you feel most/all of the elements of the actual motor itself would be the same between a naturally aspirated, turbo, and turbo+aftercooler versions?

Certainly some of the externals are different - looking at the pictures, there's different placement of some filters, oil filler, etc.

I'm seeking a feeling on whether the differences are purely cosmetic (e.g. had to change the position of the filter because of adding part X), or indicate an internal difference. The bore and stroke sizes are identical, which still could mean they changed the materials from unobtanium1 to unobtanium2 to cater for the higher pressure and power...
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Old 09-19-2018, 12:54 AM   #55
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22 knots with 36,000 pounds even in a Cat will be requiring some real HP.
And if it could reach 22 knots the actual realistic cruising speed would be much lower.
Definitely. We aren't interested in that speed but I gave it as an example that some power cats aren't quite as speed limited. For example, similar displacement & length boats such as this Queensland 55 can (apparently!) do 24kn with twin 670hp's, or 20kn with twin 435hp's. Personally, I can think of better things to do with my money and highly compressed dinosaurs than spend 240L/hr going 24kn . (that figure is about the same as business class or even first class airfares across oceans! While I realise that doesn't include hauling your "home" and possibly 6-8 other people at the same time, it's still a rather-large-load of cash!)

Or Domino, cruising 20kn at 23gph (87L/hr) with twin 300 hp's (proven over many nautical miles).

Or the Aquilla 44 maxing 21kn at 30gph (114L/hr) with twin 300 hp's.
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Old 09-19-2018, 05:11 AM   #56
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"So you feel most/all of the elements of the actual motor itself would be the same between a naturally aspirated, turbo, and turbo+aftercooler versions?"

This seems to be most common , although sometimes the really big power engines will use different pistons , to lower the compression ratio at high RPM .

These can be a bit harder to start in below freezing weather.

The most reliable diesel engines seem to be the "Naturals" no turbo , no before or after coolers. Hard to wear out what is not installed.

Gas engines ARE different , the "real truck" (not pickup) versions may have salt cooled valves in a heavier duty (different metal) block and heavier crank and con rods..
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Old 09-19-2018, 09:26 AM   #57
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Definitely. We aren't interested in that speed but I gave it as an example that some power cats aren't quite as speed limited. For example, similar displacement & length boats such as this Queensland 55 can (apparently!) do 24kn with twin 670hp's, or 20kn with twin 435hp's. Personally, I can think of better things to do with my money and highly compressed dinosaurs than spend 240L/hr going 24kn . (that figure is about the same as business class or even first class airfares across oceans! While I realise that doesn't include hauling your "home" and possibly 6-8 other people at the same time, it's still a rather-large-load of cash!)

Or Domino, cruising 20kn at 23gph (87L/hr) with twin 300 hp's (proven over many nautical miles).

Or the Aquilla 44 maxing 21kn at 30gph (114L/hr) with twin 300 hp's.
" similar displacement & length boats....24kn with twin 670hp's,"
Yes of course - there is your 24 knots with 1,340 hp and about 3 gals/mi or about 11.4 L/mi.
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Old 09-19-2018, 09:29 AM   #58
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Current boat:
1300rpm, 6kn, 1.2L/nm
1800rpm, 7.5kn, near 2L/nm
2100rpm, 11kn, about 2.5L/nm
2400rpm (as close to WOT as we get), 13kn, near 3L/nm

Is that per engine or total burn?
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Old 09-19-2018, 10:56 AM   #59
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Thanks for that.

So you feel most/all of the elements of the actual motor itself would be the same between a naturally aspirated, turbo, and turbo+aftercooler versions?

Certainly some of the externals are different - looking at the pictures, there's different placement of some filters, oil filler, etc.

I'm seeking a feeling on whether the differences are purely cosmetic (e.g. had to change the position of the filter because of adding part X), or indicate an internal difference. The bore and stroke sizes are identical, which still could mean they changed the materials from unobtanium1 to unobtanium2 to cater for the higher pressure and power...
Don't forget fuel delivery. The injection pump is likely a limiting factor. Also cooling capacity, exhaust sizing, and power delivery - you'd need to change props and/or gear ratio, maybe beef up shaft size, etc. These components are (or should be) integrated into a complete system. Trying to get more max power is not as simple as it might appear.
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Old 09-19-2018, 07:54 PM   #60
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Current boat:
1300rpm, 6kn, 1.2L/nm
1800rpm, 7.5kn, near 2L/nm
2100rpm, 11kn, about 2.5L/nm
2400rpm (as close to WOT as we get), 13kn, near 3L/nm

Is that per engine or total burn?
Consumption is total, adding the two.
Speeds are when both are running. I believe it's possible with the gearbox to freewheel with a shutdown engine, so the lower two speeds could possibly be done with one engine (at different consumptions; the hulls are hard chine and deep so there would possibly be little rudder needed to keep a single engine on track).
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