Big thanks to the MTU support team

[jfm]

Did JFM have the Cat callibrators on M's 1 and 2 on there handover voyages? Or have I gone mad again? I know that this would not have been a full cal, but some tweaks around the props, lift etc. IIRC M2 had to be lifted for prop re-pitching at Southampton after her trip down from the Orient.

Yup Cat's representatives came out and measured/checked, but they didn't alter the engines' running parameters ie they didn't "chip" the engines. I think that is normal for a sea trial on new boat these days, ie the engine's curves are not custom chipped for each model of boat, exactly as MapiM was saying

 

[Nick_H]

For my boat, the big difference in nmpg is between minimum in gear idle speed, which is 7kts, and our maximum displacement speed, which is 10kts. Over this range of speeds, the fuel consumption more than doubles. Between 10kts and 25kts, the consumption increases again by about 60%. We do sometimes cruise at 7kts but I agree, that feels painfully slow and if I was going to cruise at this speed all the time, I've got the wrong boat. For us a good compromise between speed and time is 9.5kts which, length for length, is equivalent to the 10kts at which your boat feels comfortable

As i'm sure you realise, you would get to your destination in the same amount of time having burnt less fuel if you did some of the trip at 7 kts, and some at 25.

Drifitng the thread a bit, we did 750-800 NM's on our recent trip, 90% of that was at 8 kts, the rest at planing speed. I think the trick is to plan the trip differently. If we had a longish trip then the first thing we did in the morning is lift the anchor and set off at 8 kts. We would then have showers, breakfast etc underway which meant we'd put in a couple of hours cruising before we would normally even think of leaving. We would sometimes stop out of sight of land for a swim, which takes some getting used to but is actually quite nice, then carry on, and have long lunches, sunbathe, read, watch films, play games with the kids etc. while the boat is chugging away slowly eating the miles. I set the phone on a 10 minute timer to remind me to look out for other boats occasionally

Of course the gyro helps with this strategy, because you can do all these things at sea even when it's not flat calm.

We enjoyed the slow cruising sufficiently that I would now consider a displacement boat, the problem is that once i've accepted 8 knots I then start questioning why I need to burn any diesel at all !

 

[jfm]

Haha you have got this pootling thing real bad Hurricane

When I crossed back to Antibes from N Corsica (105nm) in July I did the whole trip at 9 knots. Took all day of course, instead of 4.5 hours. Really enjoyed the relaxing pace and saved myself well over £1000 in fuel

 

[rafiki_]

We also mix it up on Rafiki, forced on us a bit by the level of crud on the props, but we chug around a bit at 7-10 kn with a blast on the plane when we feel like it. I really quite like the chugging, it is very relaxing, and easier on the pocket

 

[MapisM]

We enjoyed the slow cruising sufficiently that I would now consider a displacement boat

LOL, welcome to the club.
Beware: before you know it, you'll consider also becoming a Priest:
http://www.dudeism.com/ordination

 

[Deleted User YDKXO]

As i'm sure you realise, you would get to your destination in the same amount of time having burnt less fuel if you did some of the trip at 7 kts, and some at 25

.
As I said, I haven't yet got my head around cruising any great distance at 7kts! I'm sure there's a therapist out there who could help me with this. As it happens, what I tend to do is cruise the first half of any longish trip at 9.5kts and then I allow myself to blat the last half at 20-25kts with the excuse that the engines have to be 'worked' for their own good!

Of course the gyro helps with this strategy, because you can do all these things at sea even when it's not flat calm.

I think stabilisers are the key because on several occasions I've been happy to cruise at 9.5kts but the rolling proved uncomfortable so I've had to speed up just to stop the rolling

 

[Hurricane]

Hallelujah

Nick seems to have got it
JFM - you don't need to do it the WHOLE way!!

I always work on 100 miles taking 10 hours including docking and anchoring etc
And it always comes out a bit less

About 2 or 3 hours at 10 knots and then about 15 mins at 25 knots
I think that keeps the engines happy as well.

Nick - remember that yachties can only dream of 10 knots!!!!

Doing all this is a significant fuel saving exercise and a much more enjoyable passage.
Time for that "Pootling" video again!!!


I remember crossing the Gulf of Lions - in the middle, we had all just had a fried breakfast and I got my head down - I woke to screams so I leapt out of bed - on deck there was no sign of anyone - the were all watching the dolphins playing under our bows - fantastic.

Nick - swimming at sea - be VERY careful
I know of an incident (just off SC in fact) - flat sea - no wind - wall to wall sunshine - when a couple on a sailing boat decided to strip off all their clothes and go skinny dipping.
After a couple of minutes, they realised that there was a current an they couldn't swim fast enough to get back to the boat.
She was the stronger swimmer so she tried hard to reach the boat leaving him behind.
Neither of them could catch the boat and now they were separated from each other.
They were close enough to land (about 6 miles off I think) to see the main features.
He found a pot marker (see they do have their uses) which kept in in a fixed position.
She also found one but hers didn't hold position.
They were both in the water for 20 hours
She drifted back and forth along the coast a couple of times.
Eventually, a fisherman came out to tend to his pots
Found the guy and said "where's your boat"
He replied ?ugger the boat - where's my wife.
A helicopter was called in and eventually found her
Imagine being winched up with no clothes!!
The funny thing (if you can call it that) was that the boat made its own way home!!!

There is a big moral to this story - be VERY careful
If you must swim whilst not at anchor make sure there is someone competent on the boat at all times
Run out a swim line - a fender on a long rope works
This guy's story should be a lesson for all of us
It is easy to say it won't happen to us but we all get tempted into doing things like this.

 

[Nick_H]

I think you must have missed out a relevant fact there Mike, or i've misunderstood the story. The boat and swimmers would drift at the same rate in a current so it would be simple to get back to the boat, much easier than with the boat anchored in fact.

 

[Hurricane]

I think you must have missed out a relevant fact there Mike, or i've misunderstood the story. The boat and swimmers would drift at the same rate in a current so it would be simple to get back to the boat, much easier than with the boat anchored in fact.

Yep - thats what I would have thought
I wasn't there (of course) but I was told that it didn't happen that way.
The boat drifted away faster than they could swim.
This isn't a rumour - I know the guy - it DID happen.

 

[rafiki_]

Yep - thats what I would have thought
I wasn't there (of course) but I was told that it didn't happen that way.
The boat drifted away faster than they could swim.
This isn't a rumour - I know the guy - it DID happen.

Of course, any breeze will blow the boat along, but not the swimmers.