ImpImp
Member
Good idea, just done the same. An utterly non value-adding poster.
New build Sanlorenzo SL96A 2024
- Thread starter jfm
- Start date
sarabande
Well-known member
I'm curious about the programming of the fins. It seems that seasickness is a combination of acceleration and period
(Sleipner's own website Why do people get seasick, and how can you avoid it?)
with acceleration being more significant (other citations available) .
Yet the graph seems to show the roll period is not reduced greatly, but the amplitude is. (hence reduction in in both g and duration of g for the roll axis)
Do the fins have a setting for 'under way' and 'at anchor' (where presumably the fins have to work harder and at more vertical angles to keep the boat flat,) please?
A chartist/quant would have real fun with that graph, especially for x, y and z !
It's all looking like a great deal of fun (and notebook work) for you soon.
(Sleipner's own website Why do people get seasick, and how can you avoid it?)
with acceleration being more significant (other citations available) .
Yet the graph seems to show the roll period is not reduced greatly, but the amplitude is. (hence reduction in in both g and duration of g for the roll axis)
Do the fins have a setting for 'under way' and 'at anchor' (where presumably the fins have to work harder and at more vertical angles to keep the boat flat,) please?
A chartist/quant would have real fun with that graph, especially for x, y and z !
It's all looking like a great deal of fun (and notebook work) for you soon.
Hooligan
Well-known member
Apologies in advance as I know you have probably shared this but we are now at 42 pages so if I might ask. What is the range at D speed assuming everything running ie generators etc? I know you love to whizz around at P speed 
but I was curious how long one could be on board without having to fill up if one wanted to make the fuel last. And is the relationship similar to let’s say the s78 ie you cruise at either 10 knots or 24 ish. Thanks.
but I was curious how long one could be on board without having to fill up if one wanted to make the fuel last. And is the relationship similar to let’s say the s78 ie you cruise at either 10 knots or 24 ish. Thanks.
DAW
Active member
The Sleipner Vector fins on my boat have two main modes, one for "Cruising" and one for "Anchor". For each mode, you have the opportunity to customise all of the parameters if you have the access codes for the software. As a basic user, you're allowed to modify settings like "gain" to make the movement of the fins more or less aggressive to prevent the paddling effect that you sometimes get at anchor. More advanced features allow you to customise settings like the amount of lean when cornering underway, etc.
How and when the fins work the hardest and what settings work best in different conditions is something that you learn as you get familiar with the system. The range of movement is larger when at anchor, but I've found that reducing the gain to slow down and reduce the amplitude of the movement of the fins can actually provide better stabilisation in rolling or choppy anchorages. It also helps to eliminate the paddle-walk effect. You still have to be careful as boats with stabilisers working hard can swing differently to those without and it's not uncommon to find yourself pointing in a different direction to everyone else.
sarabande
Well-known member
Excellent, just what I was looking for, DAW, thanks.
(We raggy types have to sit and suffer !
)
(We raggy types have to sit and suffer !
)
Bouba
Well-known member
if you are at an anchorage....and moving different to the other boats..don’t you run the risk of mowing down all the swimmers ?
Richard.C
Active member
On a slightly related point, for techy people, here is the antennae set up:
I appreciate the idea of redundancy but how many GPS antenna are really required?
Bouba
Well-known member
The boat is big enough to triangulate the satellites from
billskip
Well-known member
I suppose it depends whether you want to know where you are if you are on the pointy end or the blunt end
jfm
Well-known member
Yup it seems a lot. Various items have dedicated GPS antennae or mushrooms. The list is
a.Main GPS mushroom for nav
b.Back up GPS mushroom for nav (user selectable on screen whether to use main or back up)
c.Dedicated antenna for AIS transceiver
d.Dedicated antenna for VHF unit #1
e.Dedicated antenna for VHF unit #2
f.Dedicated GPS mushroom for MTU engines controllers
That's the six showing in the drawing. Additionally there will be a dedicated mushroom "g" for the Sleipner stabilisers, not showing on this drawing, and there is a satellite compass which is essentially a few GPS mushrooms mounted together in one unit, also not on this drawing.
To your question, everything is "required" except that b is only a nice-to-have and d+e could be dispensed with (and the VHFs could take position data from N2K) but for some reason Garmin prefer it this way. I cant see it's a big deal either way.
a/c/f/g are necessary rather than just nice to have. Satellite compass is also not necessary, but is the way the world is going these days
Although I say GPS, everything is Glonass/ EGNOS/WAAS too, these days.
jfm
Well-known member
I agree with what DAW says and would only add a little.
Roll period is not reduced by stabilisation, whether fins, gyros or anything else - that would be a fruitless task and near impossible. Stabilisation is all about reducing amplitude.
Underway and at anchor modes are VERY different. The thing switches between the two automatically at about 7 knots though you can choose that.
At anchor, the fins swim and you can have a lot of stabilisation torque for little time or less torque for a longer time, obviously. Just like a gyro. The software needs to make the decision.
Underway you can have immense torque for unlimited time, so even if you have a beam wave the size of a ski slope the system keeps the boat horizontal (zero roll angle) indefinitely. If you need more torque, you can speed up. The fins are not swimming and instead they are acting like wings. This is where they differ from gyros, because gyros still have the "lots of stabilisation torque for little time or less torque for a longer time" character while the boat is underway, and indeed this is the reason I always choose fins not gyros.
The sensation driving a fin stabilised boat is quite profound when you first do it. Becomes a bit normal after a while and you never want to go back - I've lived with them for 13 seasons now. No fins or gyros will remove pitch or heave in a meaningful way, and all they do is eliminate roll, which means when cruising in windy conditions with fins you always hope that where you want to go is somewhere in the 180 degree arc where the waves are behind you or on your quarter or beam. Then it's bliss with fins (not with gyros, which only perform really well at anchor).
The walk forward at anchor with fins is no big deal - I've found it no problem in 13 years. Of course the world is moving to electric fins which will rotate 180 degrees and thereby eliminate walk forward.
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MapisM
Well-known member
What for? Will someone in Friedrichshafen be constantly monitoring your engines, wherever you will be?!?
vas
Well-known member
probably compare SOG to rpm and load and make no sense out of it as it wont know wind/tideWhat for? Will someone in Friedrichshafen be constantly monitoring your engines, wherever you will be?!?
MapisM
Well-known member
Funny you should mention it.
Can't be @rsed to search it, but I'm pretty sure we discussed here that possibility YEARS before anyone engineered that feature (Humphree being eventually the first, I believe).
I also recall to have mentioned it to Mr. AC (the CMC founder) when we met him in Antibes together with BartW for the tuning of his retrofitted stabs, but he didn't think it was worth considering the idea...!
What's next, will boatbuilders adopt BodgeFlow and AnCam as standard features?
jfm
Well-known member
Haha all very true. AnCam is a tick box option at Sanlorenzo.
. AnCam is a tick box option at Sanlorenzo.
jfm
Well-known member
I have absolutely no idea! Will ask. I wonder if the FNR control will not let you select R if moving forwards too fast? I rather doubt that, but am struggling to think of an answer.What for? Will someone in Friedrichshafen be constantly monitoring your engines, wherever you will be?!?
MapisM
Well-known member
My understanding is that there is indeed a safety check on FNR, when triggered by electronic levers, but based on rpm alone.
Essentially, allowing both engagement and disengagement only if the engine is spinning under 700rpm (or whatever).
Regardless, it's refreshing to hear that I'm not alone in struggling to understand all bits and pieces of modern gizmos!
Essentially, allowing both engagement and disengagement only if the engine is spinning under 700rpm (or whatever).
Regardless, it's refreshing to hear that I'm not alone in struggling to understand all bits and pieces of modern gizmos!
Richard.C
Active member
Thanks for the reply, I'm surprised it all needs dedicated antenna, I thought things would be more networked for position data with just a couple of back ups.Yup it seems a lot. Various items have dedicated GPS antennae or mushrooms. The list is
a.Main GPS mushroom for nav
b.Back up GPS mushroom for nav (user selectable on screen whether to use main or back up)
c.Dedicated antenna for AIS transceiver
d.Dedicated antenna for VHF unit #1
e.Dedicated antenna for VHF unit #2
f.Dedicated GPS mushroom for MTU engines controllers
That's the six showing in the drawing. Additionally there will be a dedicated mushroom "g" for the Sleipner stabilisers, not showing on this drawing, and there is a satellite compass which is essentially a few GPS mushrooms mounted together in one unit, also not on this drawing.
To your question, everything is "required" except that b is only a nice-to-have and d+e could be dispensed with (and the VHFs could take position data from N2K) but for some reason Garmin prefer it this way. I cant see it's a big deal either way.
a/c/f/g are necessary rather than just nice to have. Satellite compass is also not necessary, but is the way the world is going these days
Although I say GPS, everything is Glonass/ EGNOS/WAAS too, these days.
sarabande
Well-known member
Thanks for the extra info on fin-ology, jfm.
I can see that trying to diminish the moments of polar inertia for pitch or heave would be a mammoth task.
There are crew and passenger requirements for safe and comfortable movement on deck that had not occurred to me, even though I have bounced around on the sharp end of sailing boats attaching sails and spi poles. A different working and leisure environment.
I can see that trying to diminish the moments of polar inertia for pitch or heave would be a mammoth task.
There are crew and passenger requirements for safe and comfortable movement on deck that had not occurred to me, even though I have bounced around on the sharp end of sailing boats attaching sails and spi poles. A different working and leisure environment.
Hurricane
Well-known member
What for? Will someone in Friedrichshafen be constantly monitoring your engines, wherever you will be?!?
I don't know if they have changed procedures since ours were installed but they DEFINITELY record all events and report back base in Friedrichshafen when a laptop is connected.
Don't ask me how I know!!!