New Boat, Swedish Delta "Yacht" - anyone got any info? Jack?

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This boat looks identical to a boat that was berthed on the portside of Blue Angel when she returned to her home base at Toulon at the end of the FDC 2013... BartW are you reading this thread? Looks like the boat that was rocking like mad, while Blue Angel sat still as a pond with the stabs.

OK so i'm sure there was more than 1 hull made, but still... memories

 

[jfm]

It must have been a different boat Alt, because Designo's old boat ex-Moonshadow is these days painted blue. Moonen made several hulls in that series though, so there are plenty of sisterships round and about. I'd be amazed if they didn't all have fin stabs, but not STAR of course

 

[MapisM]

OK so i'm sure there was more than 1 hull made, but still... memories

LOL, not very good memories though, N.!
The boat you are reminding was an Admiral, built by Cantieri di Lavagna.
Not a shabby vessel by all means, but the Moonen 85 is a completely different kettle of fish.
Not only bigger (the Admiral was around BA size), but also canoe stern, double deck, full displacement, steel construction...

 

[MapisM]

Actually JFM I a badly dyslexic so I think that's a little unfair.

Just for the records, I was completely unaware of that.
Not that it really matters a lot, now that the issue is water under the bridge, but just to put my previous reply to your objection in perspective.

 

[wakeup]

I thought I had stumbled upon the Xmas Panto thread by mistake, with MM being one of the big ugly sisters

 

[BartW]

The boat you are reminding was an Admiral, built by Cantieri di Lavagna.
Not a shabby vessel by all means, but the Moonen 85 is a completely different kettle of fish.
Not only bigger (the Admiral was around BA size), but also canoe stern, double deck, full displacement, steel construction...

thats correct, the Admiral is still there,
there have been quite a few nice boats in Toulon as you know Mapism,
but never a Moonen as far as I remember,
sorry N ;-)
by the way, some Moonen ships are equipped with CMC el stabs, (STAR)

and to keep my post on Topic;
CMC Electric stabs could be a good option for this Delta Yacht, when you are considering all possible weight reductions

 

[MapisM]

and to keep my post on Topic;
CMC Electric stabs could be a good option for this Delta Yacht, when you are considering all possible weight reductions

Dunno, B. I'd rather have gyros, on an almost 40 kts vessel.
Though I'd like the D80 also in a slower configuration (say capable of up to 25 kts), in which case I'd fully agree with you.

Oh, btw, I'm still posting here, but my offer to Lars still stands.

 

[jfm]

That all reminds me, and I was going to ask Lars this.

The D80 has, I think, ONE seakeeper 8000. Many 80 footers have 2. That suggests an low roll stiffness (angular inertia) for this boat. That value is a function of the boat's mass, but also the square of the distance of each element of mass from the roll centre. To illustrate that another way, if you move a boat's tender from the swim platform (where it is close to the roll centre) to the flybridge (where it is say 2m above the roll centre) then you have not changed the total mass but angular inertia increases based on the square of that 2 metres. That means the boat is roll "stiffer" with the mass up on the flybridge, and the boat's natural roll period increases. In fact, IIRC, a lot of trawler manufacturers like you to put a heavy tender high up on the flybridge for this exact reason. (Sure that increase CoG, but that's another thing altogether, and there are always pros and cons!)

Anyway, what to make of this? Lars, are you finding that one s'keeper 8000 does the job? Are you tempted to fit 2 on future boats? Does the boat "feel" ok to you (subjectively I suppose) even though it has (I'm guessing) a shorter roll period than other heavier 80 footers?

 

[Designo]

That means the boat is roll "stiffer" with the mass up on the flybridge, and the boat's natural roll period increases.

I must have slept over that math lesson... About the Seakeeper, I have not tried it out on the D80 so I can not say if one is enough, but two are too heavy I think. Anyway, the gyro is only for zero or low speed. For high speed we have the Humphree interceptors.

 

[stillwaters]

CMC Electric stabs could be a good option for this Delta Yacht, when you are considering all possible weight reductions

Which leads me to suggest an even more off the wall idea - Electric powered Quantum rotor arms similar to Abramovich's. STAR ability and, whilst not sure if they have yet developed the high speed version at Ft.L, I do know that the Dutch are developing the smaller version which is capable of providing stabilisation at high planing speeds, and have already taken orders for it. Ok, now don't shoot me.

 

[Thundergod]

https://hamnenplay.solidtango.com/video/131007-delta-88-subtitles
Dont know if this video been posten already? About Delta 88 in swedish with english subtitles.

 

[MapisM]

I do know that the Dutch are developing the smaller version which is capable of providing stabilisation at high planing speeds, and have already taken orders for it.
Ok, now don't shoot me.

No worries there. You obviously don't know BartW, if you fear to be shot by him...
But are you aware of any installation of Magnus effect stabs on any planing vessel?
Just curious, 'cause I never heard/read of such installations. But I might well have missed something, of course.

Besides, I just re-read jfm comment "That means the boat is roll "stiffer" with the mass up on the flybridge", and a doubt popped to my mind.
It's possibly just a matter of semantic - and I'm sure jfm knows what he meant anyway - but normally the term "stiff" is associated to the rolling behaviour of hulls which "snap back" faster from each roll.
In this sense, by placing mass elements (tender) up on the f/b, the rolling becomes LESS stiff - or more gentle, in other words.
Again, I'm sure jfm knows this stuff, but maybe I wasn't alone in having understood the opposite...

 

[MapisM]

https://hamnenplay.solidtango.com/video/131007-delta-88-subtitles
Dont know if this video been posten already? About Delta 88 in swedish with english subtitles.

Interesting stuff, thanks for the link.
There's something to be said about the fuel burn comparisons, but I'll stay out of that.
Otoh, the planing attitude is indeed impressive.
I'm wondering how (little?) loaded the boat was, when the video was taken.
Anyway, the 45 tons mentioned in the video are also very impressive for the size.
Though that's with empty tanks, surely?
Maybe Lars can throw some light on that...

 

[Designo]

Interesting stuff, thanks for the link.
There's something to be said about the fuel burn comparisons, but I'll stay out of that.
Otoh, the planing attitude is indeed impressive.
I'm wondering how (little?) loaded the boat was, when the video was taken.
Anyway, the 45 tons mentioned in the video are also very impressive for the size.
Though that's with empty tanks, surely?
Maybe Lars can throw some light on that...

If my memory serves me right this time of the day, the unloaded boat is about 42 tons and the video was with 7 tons more onboard. The fuel figures I have given is with half of that load.

 

[MapisM]

The fuel figures I have given is with half of that load.

Actually I was talking of the comparisons with other boats as mentioned in the video, but never mind, no big deal.
It's self-evident that the boat must be somewhat more fuel efficient than a "traditional" planing 80 footer.

PS: re. the comparisons, other owners of similarly sized boats can comment better than myself on the video numbers, anyway.

 

[stillwaters]

No worries there. You obviously don't know BartW, if you fear to be shot by him...
But are you aware of any installation of Magnus effect stabs on any planing vessel?
Just curious, 'cause I never heard/read of such installations. But I might well have missed something, of course.

No, surely not BartW, however it did occur to me that jfm might already be sufficiently aware of the Quantum/DMS developments to have already discounted them - hence it might be better to dive for cover.
And no, I'm not aware of any Magnus effect stabilisers on any planing vessels .....yet. However, when I was talking to DMS in Holland a few months ago I was informed that they not only were confident they had worked out how their system would work at faster planning speeds but had already sold the first installation to be fitted on one of the larger Van der Valk aluminium IPS drive yachts and were also in discussion with the owner of a 45 knot Eastbay. You are obviously familiar with the Magnus effect system and I assume you also understand that the basic ones only work up to about 14 knots for the lighter weight versions but also only at displacement speeds for the heavier Quantum backed systems as supplied on Eclipse etc. where they also operate at zero speed by slowly sweeping backwards and forwards when at anchor. However, the ability to operate at much higher speeds is provided by the simple measure of enabling the rotating arms to function whilst being angled at 45 degrees backwards of the centre line. Hope this clarifies.

 

[MapisM]

Yes, thanks. Looking forward to seeing the first applications on those vessels.

 

[Designo]

It would be interesting to see how it works on a 45 knot Eastbay..? I think anything protruding like that on a fast planing hull would make it more like a hydrofoil... or slow it down..?

This is the Delta 80 IPS turning in about 36 knots;

 

[stillwaters]

It would be interesting to see how it works on a 45 knot Eastbay..? I think anything protruding like that on a fast planing hull would make it more like a hydrofoil... or slow it down..?

Not so sure about that. By virtue of the way the rotating arms operate by providing either upward or downward force depending on their direction of rotation it surely doesn't follow that they would necessarily act as lift-only foils. However, having been on a number of hydrofoils, I have noticed that they have always been fairly rapid as well as stable.

And so to bed! ( thanks to Zebedee from the Magic Roundabout).

 

[jfm]

NoBesides, I just re-read jfm comment "That means the boat is roll "stiffer" with the mass up on the flybridge", and a doubt popped to my mind.
It's possibly just a matter of semantic - and I'm sure jfm knows what he meant anyway - but normally the term "stiff" is associated to the rolling behaviour of hulls which "snap back" faster from each roll.
In this sense, by placing mass elements (tender) up on the f/b, the rolling becomes LESS stiff - or more gentle, in other words.
Again, I'm sure jfm knows this stuff, but maybe I wasn't alone in having understood the opposite...

Sorry if I caused confusion there! When I said "stiffer" I meant higher rotational inertia. Or higher angular momentum for a given roll speed in radians/second I meant the the boat with tender on fly is "stiffer" (as I was using the word, at least) than the boat with tender on swim platform, so that when it starts to roll with a wave, then AOTBE it needs a harder "kick" from the stabiliser to stop the roll - ie is stiffer, in that sense. Anyway, I'll try to stop causing confusion