Denia to N Sardinia & Corsica

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statgar

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I'm hoping to move my Fairline Phantom 46 from Denia, via N Sardinia and Corsica, to the Italian Almafi region where I hope to winter her ashore. The choices I have are to go north via the coast crossing to Corsica from Toulon or hopping the Balearics to Sardinia whereupon I could have a couple of family/friend cruises around the Massalena Islands and then the west Corsican coast eventually crossing to Italy via Elba leaving me with another delivery trip down the coast to Sorento.

My concern in going the Balearics route is the open sea distance of 200nm from Mahon to the nearest Sardinian coast. Allowing for a 20% reserve of fuel I have a range of 195nm at 24kts or 320nm at 9kts so I would plan for 100nm at displacement speed and the rest at the most economic planning speed. Does any one have an opinion on this plan? I prefer this route as it saves me having to back track Corsica in order to get to mainland Italy.

Any advice on my suggested cruises, and/or tips for berthing etc would be appreciated.
 
Are you sure you can't extend your range - just by "Pootling"
We've done that run the other way - Bonifacio Straits to Mahon.
Are you sure of your displacement range?
I would have thought that at (say) 9 knots you should be able to increase the range to well over 400 miles.
It would need to be tested but you could do that on the way to Mahon.
Mahon to Alghero is less than 190 miles - not used Alghero myself but I know someone who has and his range was similar to yours.

We were in Denia last October - had only been there by car before - quite liked the marina - we will probably go back.
 
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Thanks Hurricane, you are right about my displacement range I have only really checked it on a 30nm trip and the timing was from dock to dock so on the actual passage I was probably averaging more like 10.5kts when doing 9kts the flow is about 3.4 ltrs p/nm.

We loved Denia but wish to move on, eventually to Greece, the town has lots to offer and its very close to Ibiza (even at 9kts) although not a lot else. Check out El Portet Marina its closer to town and suffers less from swell.
 
Thanks Jimmy your forum knowledge is as commendable as my searching method is not! It is gratifying that my plan 50/50 D & P seems to be the favourite, just hope I can get the weather.
 
I'm not convinced about the fuel efficiency of cruising at 9 knots in a 46' boat. I think you'd be better off at 7 knots, then a bit more time planing. At 9 knots in my P57 i'm pushing quite a bow wave, but at 7, virtually nothing.
 
Nick_H said:
I'm not convinced about the fuel efficiency of cruising at 9 knots in a 46' boat. I think you'd be better off at 7 knots, then a bit more time planing. At 9 knots in my P57 i'm pushing quite a bow wave, but at 7, virtually nothing.
Click to expand...

Thinking about it, Nick, I agree.
The only thing I'd say is that, IMO, it is a good thing to "push" the bow wave a little to give the boat some stability.
It is a bit wasteful but makes for a more comfortable passage.
On our P67 I think we are doing just that at 10 knots.

statgar
Here are some stats from our P67
at 24.5 knots we burn 175 litres per hour per engine
We used to fast cruise at 22 knots but, due to engine configuration (turbos etc), we found that 25ish knots is about the same burn rate as 22 knots.
I like to think of that as 3 free knots!!!

at 10 knots it is around 22 litres per hour per engine
I tend to set the revs and theoretical fuel consumption (from the engine management system) but the wind does affect the speed a little - never goes below 9 knots though.

I believe the formula for max displacement speed is something like the square root of the water line lenght (in feet) times 1.43.
The figure of 1.43 is from memory and has always seemed to me to be a little too precise for this calc.
But the formula seems to work out though.
 
Nick_H said:
At 9 knots in my P57 i'm pushing quite a bow wave, but at 7, virtually nothing.
Click to expand...
LOL, did you try anything in between? Displacement cruising is a fine art, every half knot matters! :)
Btw, for those who have electronic engines/display, it's pretty easy to see when the boat begins "pushing" harder, just looking at the istantaneous engines load/consumption.
Incidentally, a true D speed, in a P boat, usually means a ridiculous load on her big, low rating engines.
Which is better to avoid, at least for a very long time.
 
Nick_H said:
I'm not convinced about the fuel efficiency of cruising at 9 knots in a 46' boat. I think you'd be better off at 7 knots, then a bit more time planing. At 9 knots in my P57 i'm pushing quite a bow wave, but at 7, virtually nothing.
Click to expand...

Agreed - that's definitely correct. For this trip I'd leave in the evening and do a night at 7 knots = 70nm say, then the rest at planing speed the next day. After studying the weather very carefully

It might also be worthwhile investing £1000 in a nmea 2000 bridge from Volvo so that real time fuel data is shown on the nav screens. This take a lot of guessing out of the process and creates peace of mind
 
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MapisM said:
Incidentally, a true D speed, in a P boat, usually means a ridiculous load on her big, low rating engines.
Which is better to avoid, at least for a very long time.
Click to expand...

It's another discussion so I wont drift this thread but if you're referring to the "bore glazing" thing I must say I've never really agreed with that theory in this context of running a P boat at proper D speed. Reason is that most of our engines are leisure rated, and when we run at D speed we are pulling from the engine 50-100% of the power the same engine develops in industrial rating, eg for a big genset. As the piston rings and cylinder materials are the same, then if the genset doesn't glaze neither will the boat, if you see what I mean
 
I do see what you mean, but by heart it doesn't sound right.
I would think that to keep your boat at strictly D speed, your C32 are spinning well below 1500 rpm, to start with. Or am I mistaken?
Besides, the same block used in a genset at 1500 rpm (at full or almost full load, which is typical of big gennies), surely has an output much higher than what is required to push the Sq78 at 8kts?
Mind, I'm just answering by heart, but I'll have a look at the specs when I have a minute.
You might have a point, not sure.
 
MapisM said:
I do see what you mean, but by heart it doesn't sound right.
I would think that to keep your boat at strictly D speed, your C32 are spinning well below 1500 rpm, to start with. Or am I mistaken?
Besides, the same block used in a genset at 1500 rpm (at full or almost full load, which is typical of big gennies), surely has an output much higher than what is required to push the Sq78 at 8kts?
Mind, I'm just answering by heart, but I'll have a look at the specs when I have a minute.
You might have a point, not sure.
Click to expand...

Yup I think we agree the potential concept MapisM, but the answer lies in the numbers/data, and I admit I'm guessing too. No worries.
 
Yeah, no big deal.
The point is interesting, though. I never looked at this matter under that viewpoint.
Worth checking some specs sheet, will revert asap...
 
I know this comment will be a bit controversial but I've often looked at these so called "Eco Boats"
Which have very low consumption at displacement speeds.

I always come back to a view of "What's the point"
OK we DO burn more fuel but it isn't a league different from these "Eco Friendly" boats.
And above all, we have the ability to run at higher speeds which has a safety implication (such as outrunning the weather) as well as the convenience of getting to places quicker.

As far as running for long periods at slow speeds on big engines, we always give them a bit of "exercise" every now and then.
Generally speaking, I will finish off a passage at high speed.
In fact when we went down to Denia last autumn, I opened he up to WOT which I hardly ever do.
Fully loaded and three quarters full of fuel - full water etc - she managed 31 knots - she was a 34 knot boat when loaded lightly during tests out of the factory.

Anyway, back to the OP's thread
I would run from Denia at low speed - there is a good 60 miles from Denia to Ibiza where you could do some tests
Fill up to the brim in Denia and then fill up to the brim in (say) San Antonio.
And work it out - If you keep the speed down to a boring 8 knots, I'm sure you will be very pleased with the result.

Then as JFM says - make your way to Mahon and wait for some good weather - there are some excellent restaurants in Mahon and if the weather is bad, it is a really nice and safe place to stay.
I also like doing what he says - I love night passages - so you get all the boring slow speed stuff done whilst half the crew are asleep.

When we joined JFM and the French lot down in the SOF, we crossed the Golf de Lions at night leaving Palamos at 23:00. It was so flat the we had a fried breakfast in the morning under way. The fuel burn on that trip was minimal - didn't need to fill up until just before we set off for Corsica - even then we only took half a load. I definitely recommend starting late in the evening - perhaps after a good evening out at a nice restaurant.
 
MapisM said:
Yeah, no big deal.
The point is interesting, though. I never looked at this matter under that viewpoint.
Worth checking some specs sheet, will revert asap...
Click to expand...
Using Cat32 just as an example:
The lowest c32 rating is 660hp. Mine are 1622hp, and you can get 1925hp version.
I would intuitively guess Cat are happy with you running the 660hp at 2/3rds load, forever, which is 440hp. That's roughly 25% load on my engines, so I'll see what is the load% reading on the electronics, when I'm doing say 9 knots of D speed, and report back. In about a month!

This is crude analysis I appreciate, but not too far wide of the mark I hope :)
 
Hurricane said:
I always come back to a view of "What's the point"
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I agree, Hurric. Well, sort of.
Anyone who is attracted by D boats for fuel saving alone, but actually feel that 8 knots cruising is as you said "boring", should rather stay with P boats.
Slow cruising is like slow food. It's not a matter of savings, it's whether you actually like it better than the "fast" alternative or not, in both cases.
I love very fast boats, but because I love the driving feeling they can offer - and the smaller the better, in this respect.
For cruising, no P boat on earth can beat the stability, silence, range (it's not just a matter of fuel burn, but also of tankage), and overall comfort of a D boat, for any given size.
Even if stabilized, though that does make a big difference.
And these are facts. But how much you rate all that, vs. the possibility of going much faster at wish, that's a matter of personal opinion.
Neither views are right or wrong, just different.

Re. engine load, I think you are very much right in stretching them every now and then, during long passages at slow speed.
Just curious, is it something they recommended to you also in Friedrichshafen?

Anyway, back to the previous debate with jfm on this matter.
J, I don't think it makes sense to compare the power at max rpm, for the purpose of this discussion.
I just checked some Cat spec sheets.
Their 50 Hz genset based on the C32 has a continuous output of 728 ekW @ 1500 rpm.
With the higher power E rated C32 (1417 kW @ 2300 rpm), the prop pulls 393 kW out of it @ 1500 rpm (prop demand curve with 3.0 factor, vs. 1098 kW max at the same speed).
Besides, I actually think that 1100 rpm or so should be sufficient to push a Sq78 at 8+ knots (subject to your confirmation), and at that speed the C32 only makes 155 kW (burning 40 l/h).
That's a helluva load difference (even at 1500 rpm), and while these numbers don't tell us how much time it can take to build up internal glazing, they surely justify the fear of it, imho.... :)
 
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Hurricane said:
I know this comment will be a bit controversial but I've often looked at these so called "Eco Boats"
Which have very low consumption at displacement speeds.

I always come back to a view of "What's the point"
OK we DO burn more fuel but it isn't a league different from these "Eco Friendly" boats.
And above all, we have the ability to run at higher speeds which has a safety implication (such as outrunning the weather) as well as the convenience of getting to places quicker.
Click to expand...
Not controversial at all, just common sense. If you're referring to these new hybrid powered eco boats coming on to the market, IMHO they're a con aimed at angst ridden motorboaters who want to do a bit of green willy waving. Yes, they might be able to do a few miles at 5kts under electric power but after that the batteries and the electric motor/generator just become dead weight adding to fuel consumption. Generally speaking, weight is the enemy of fuel efficiency which is why lighter weight planing boats tend to be more efficient at D speeds than specific D boats. Of course then you get into arguments about seakeeping and comfort but thats a different story
Actually there is one area where hybrid boats might score. With all that battery power, topped up by solar panels, it should be possible to run the boat on invertor power for much longer periods. For example Greenline seem to claim that you could run aircon all night on battery power without using the gennie and that in itself may be a good reason for looking at a hybrid boat.
Going back to the OP's original question, my old Ferretti 46 cruised from Majorca to Sardinia and then round the toe of Italy and up to the north of the Adriatic for the sale process and range wasn't an issue so I don't doubt that the OP's 46 could make the crossing to Sardinia without problem. Similarly, the chap who bought my old AZ46 regularly cruised it to Sardinia from Majorca without a problem.
 
Yup, fair enough on the maths MapisM - yes I see the logic of your maths and I agree with you that 155kw is likely "bore glaze " territory after enough hours

I will record some readings off the electronic instruments, next time I get the chance, just for the hell of it :-)

I guess then that Hurricane's analysis applies: even those of us who pootle quite often in our P boats do it for say 50% of the open-water engine hours. The hard press of the piston rings on the cylinders during the other 50%, which is run at full P speed and say 70% load factor, surely cures any bore glaze issues

Good to discuss, and I think we can all agree that this is item #280 on our list of things to worry about :D
 
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