sleipner vector fins or seakeeper 16 for a 75 ft ?

was the boat you tested properly commissioned by Sleipner?
Maybe some teething problems with the installation needed a rerun of s/w and/or calibration?
No experience myself as of yet, but I'd be very surprised based on the videos I've seen.
I'd bet my money on something wrong with the installation and most likely at s/w level.
Push them to check and go for another test soon?

V.
 
Hi Benjenbav,

indeed I reed the comment from jfm and how happy he is with this fin system but I dont know what was wrong. were they not working properly for some reason I dont know... thx for your comment.
 
From what you write, there was clearly something wrong with the fins set up. 1m sq fins are undoubtedly correct for a 74 sunseeker. If you could not see the fins moving on the colour screen ( I think that is what you said-?) then obviously they were not activated or had a fault or something.

31kts + on 1550 mans and 74 foot boat proves there is no speed/drag problem with these fins, as said above.
 
Hi Jfm, to be honest I am not familiar with the system I only looked at the on or off on the display not on the movement of the fins. the size of the fins I am sure this is not the problem because on the pred 68 they install the sps 55 fins so for this boat the sps 66 are sure big enough. the drag as discussed in this forum is almost nothing because we had maximum speed of 35.1 knts not 31 knts so this is perfect.
 
jfm said:
31kts + on 1550 mans and 74 foot boat proves there is no speed/drag problem with these fins, as said above.
Click to expand...

They tend to launch and test , for weeps n seeps , finalise some customer spec instal , without any antifoul - yup as smooth and grag less as you can get .
Final commissioning it’s lifted , cleaned then it goes into the finishing shed for antifoul and even anchor warps cruising kit tender , etc .
If you read the SS brochure s there’s a small print cop out of the performance numbers .

Regardless of WOT or top speed ,@2300rpm , it’s the normal rpm or reasonable load % speed .
What we need to know or a prospective buyer is the 1850 to 1950 rpm speeds and a 1780 eco cruise for MANs .

Fuel burn over 2100 rpm is uneconomic.

However as allways its best to go for the largest engines over standard if offered .
1900hp should more than compensate for the parasitic drag of fins and antifoul + cruising kit + seasonal growth compared to a 1550 shiney polished gelcoated hull .
 
pascalsunseeker said:
dear all,

underway the boat was very stable with the fins but we tested at zero speed and this was a disappointment for me and my wife. the sea had a swell axpproximatly from 0.3-0.4 m and the boat was sometimes rolling sometimes not this was very strange. we pushed the fins on and off and even the sunseeker people couldn't say it the system was off or on when they not looked on the display.———Pascal
Click to expand...

You can,t have both sides
To keep drag down and top headline grabbing speed up =fin size is small - work well @ design cruise speeds —- high in this case as achieved (pre finished )35 knots .
But for stability at rest you need bigger fin area - hence it did not work at rest .



External zero-speed fins are considerably larger than standard underway fins as they must actively move large volumes of water to stabilise a vessel. These oversized external appendages result in significantly more drag and must be compensated by increasing engine horsepower or acceptance of a slower top speed. In addition, external fins negatively affect fuel efficiency due to the additional drag.

Small fins = speed
Big fins stability @ rest but reduced speed .

They are,t gonna send you out on a broken boat or like all salesman tell the exact truth .
 
Last edited:
Portofino said:
But for stability at rest you need bigger fin area - hence it did not work at rest
Click to expand...
No way, PF.
It did not work at rest because the system wasn't working as it should, it's as simple as that.
Just look at this short old video that I made during the commissioning of BA stabs - whose size btw is similar to the OP boat, and has smaller fins.
If with any decent star fin stabs you can't tell whether they are working or not, well, they aren't - period.

As an aside, if I should consider the purchase of a boat that makes 35kts (no matter how optimal the conditions), what I would consider is the installation of LESS powerful and lighter engines, if anything...

 
MapisM said:
No way, PF.
It did not work at rest because the system wasn't working as it should, it's as simple as that.
Just look at this short old video that I made during the commissioning of BA stabs - whose size btw is similar to the OP boat, and has smaller fins.
If with any decent star fin stabs you can't tell whether they are working or not, well, they aren't - period.

As an aside, if I should consider the purchase of a boat that makes 35kts (no matter how optimal the conditions), what I would consider is the installation of LESS powerful and lighter engines, if anything...

Click to expand...

Talking about the effect of fin area ( STAR and top speed )on the SAME boat .In this case a Pred 74 .

Not mixing up different boats / fin systems .
As I said way up in this thread “ try before buy “ and “ speak to captains “ .
Cos one system works fine in Sqaudie 78 does not mean it will work fine in ALL 70 odd ftrs .

When a sales team can,t answer a pointed question that Pascal asked “ can,t tell the difference between on / off “
Then they are covering up something .
Everyone in buying mode has a “smell a rodentometer “
 
I couldn't be more far from wishing to defend S/skr salesmen - or any boat salesman for that matter.
No, hang on, make it ANY seller of ANYTHING. :D

But, and it's a big but, I did try a few fin stabilized boats.
And there's simply no way that they were working as they should, if they made no perceivable difference.
That's totally beyond belief, regardless of the boat where they are installed.
 
MapisM said:
I couldn't be more far from wishing to defend S/skr salesmen - or any boat salesman for that matter.
No, hang on, make it ANY seller of ANYTHING. :D

But, and it's a big but, I did try a few fin stabilized boats.
And there's simply no way that they were working as they should, if they made no perceivable difference.
That's totally beyond belief, regardless of the boat where they are installed.
Click to expand...

They were working
I understand Sombody turned them on / off for them .
Without reference to the salesman who was with Pascal and his wife ,
Otherwise P would have reported ( he didn’t) that there was a technical problem with the stabs .

Are you saying under way they are connected to the engine rpm gauges ? I think not .They don,t know if the engines running or not , so when coming down off the plane or any speed for that matter to zero , they failed to adequately stabilise in only small waves .
Surley they will have control systems that display “ errors “ and alarms etc .

So assuming correctly they worked then the explanation is as I inferred to do with the balance of fin area / speed ( 35 knots ) for that particular boat .
Hence the rational to test .

So if the same fin system inc fin area works ( ok ish / acceptable) in one Squadie 78 and not so good STAR in another 74 - similiar but not identical.Then Why ?
It’s gotta be some difference in weight distribution , effecting the roll period or and the forces involved , differences of resistance to roll , different hull forms etc etc

That’s why you have to try each boat - they are different and will react differently even with the same kit fitted to similar L and displacement.
 
Portofino said:
They were working
I understand Sombody turned them on / off for them .
Without reference to the salesman who was with Pascal and his wife ,
Otherwise P would have reported ( he didn’t) that there was a technical problem with the stabs .

Are you saying under way they are connected to the engine rpm gauges ? I think not .They don,t know if the engines running or not , so when coming down off the plane or any speed for that matter to zero , they failed to adequately stabilise in only small waves .
Surley they will have control systems that display “ errors “ and alarms etc .

So assuming correctly they worked then the explanation is as I inferred to do with the balance of fin area / speed ( 35 knots ) for that particular boat .
Hence the rational to test .

So if the same fin system inc fin area works ( ok ish / acceptable) in one Squadie 78 and not so good STAR in another 74 - similiar but not identical.Then Why ?
It’s gotta be some difference in weight distribution , effecting the roll period or and the forces involved , differences of resistance to roll , different hull forms etc etc

That’s why you have to try each boat - they are different and will react differently even with the same kit fitted to similar L and displacement.
Click to expand...

I've been very polite on various things typed in here.
I understand that it's a open forum everyone writes what s/he feels like, it's a free world and forum.

BUT PLEASE!!!
we know you like Itamas (I like them as well, although I'd not buy an open boat, but that's just me)
we also know you consider speed as the only reason for having a boat (I don't, but that's me again!)
due to the second you ALWAYS argue that fins are the worse invention the boating world has seen.

so, you oversimplify, overgeneralise and using the bible of this guy that recons you need one gazillion horses to plane a deep or shallow vee hull conclude that fins don't work, fins cut 5+knots off a few boats and a few more things.

You easily find the reason why said SS is not loosing 5 or 10 knots (brand new, gelcoat only, no tender, no matresses, no fuel, no anchor, etc). REALLY???
So you conclude that fins are simply not working.

Could you not consider that there was an PROBLEM/ERROR on the system?

We have a few boats that are different, and owners seem v.happy, videos at rest and under way look too good to be true, so your only conclusion is that "nah, doesn't work, I told you so three treads ago, why bother?"

don't know, feels a bit too much, don't you think?

sorry for the rant, but considering you're a knowledgeable and really helpful contributor to the mobo forum, a bit more tact and a bit less generalisation would really help. Me thinks at least!

cheers

V.

PS. I know, now when I get MiToS back in the water, it wont even plane with the .35sqm fins and you'll come back saying I told you! :p
 
I can't for the life of me understand your point ref. rpm, Porto.
Afaik SPEED is one of the (many) inputs to the fin stabs controller, but engine(s) rpm is irrelevant, other than for spinning the pump which feeds the system.
In fact, STAR stabs can (and normally do) work with engines turned off, with the genset feeding the HP pump that keeps the stabs running.

Regardless, Pascal clearly specified that they tried them at zero speed, and that's when they couldn't understand when they were turned on/off.
Which is totally unrealistic, and NO, any difference between a Sq78 and the S/skr 74 can't even begin to justify that.
Of course the same equipment can work a bit better on one hull vs. another, but within reason (i.e. similar size), such differences are a matter of hair splitting. Any fin stabs that work perfectly on a Sq78 MUST be very effective also on a S/skr 74.
Fin stabs which don't make any perceivable difference, on any boat, are not working properly BY DEFINITION, so to speak.

Coming to think of it, hydraulic fin stabs, when working at zero speed, usually need a compensation tank feeded by a dedicated AC pump.
So, it is possible that if the seatrial was done without turning the genset and this pump on, when the poor fins tried to do their job at zero speed they didn't have the full pressure/flow they are designed to have - and this could justify a lack of effectiveness. But I'm now just guessing.

What is very obvious beyond any reasonable doubt is that they weren't working as they should at zero speed, if their action was irrelevant.
No way round physics: if they work as they should, they MUST do something, and their action MUST be clearly perceivable.
 
Last edited:
Vas - life’s not black and white otherwise it would be boring , it’s the grey areas that are interesting.

MapishM -ps explain ( reading post #19 from Pascal ) why Ross Donoghue ,the Sunseeker engineer is considering Pascals request to add a gyro , SUNY say SK9 , Pascal wants a SK 15 space permitting.

IF the fins were faulty at the demo ?

As said - again surley there’s displays / errors etc and the “ Sunseeker guys “ would have checked and told Pascal there’s a tech issue ? at Zero .
And Pascal would have said so ?

Let’s keep the speed out - if you read my post Vas - I,am referring to 1850 rpm or lower speeds and Pascal has allready said his cruise is low to mid 20 anyhow .
He,s reported they worked when running as well if you read his post .
Assume they were turned them on and off cruising and at or near WOT —. You know a test in the full sense !

Correctly fitted , MapishM, yup there are various ways to get hydraulic pressure .( that’s was the rpm comment btw )
Engine pump
Geny on - dedicated pump
All machinery off a D.C pump .
The whole system intergrated with displays and settings .

So no MapishM I don,t believe the “ Sunseeker guys “ would be dumb enough to attempt a STAR demo with knack all hydraulic pressure .

And Vas I think they are bright enough to spot “ PROBLEM / ERROR “ in the system too !

I,am completely open minded to either fins or gyros or both - both being the grey area .
As said the SUNY Pred 115 with these fins was disappointing in all respects - running and anchor compared to the same size Pershing 115 with gyros .
According to the captain ,crew owner and his wife !

So it’s not black n white -

Each boat and each system on its own merits

Those with fins on here
JFM a planing boat
BART - really a D speed
Silverdee a D speed
MapishM ( ex D speed )

Vas —— work in progress a new one fins in a14 M planing boat .- encouraged by the 3 above :)

So really only JFM and I,am pleased what he has done , Infact I understand he worked closely with sleipner and many other FL owners later copied :encouragement:

Buy one swallow does not make a summer :)

As said try before you buy
 
Last edited:
Portofino said:
MapishM -ps explain ( reading post #19 from Pascal ) why Ross Donoghue ,the Sunseeker engineer is considering Pascals request to add a gyro , SUNY say SK9 , Pascal wants a SK 15 space permitting.
Click to expand...
Porto, sometimes I wonder in which world you are living.
Let's say you are working for S/skr, and you just made a seatrial where a prospect client is happy enough to go ahead with a boat purchase in spite of the disappointing stabs performance at zero speed (regardless of why, and without stretching the reasoning to the point that you might have purposedly created such disappointment…).
The same client asks you to install an additional bit of kit on which you are making easily a 30%+ margin.
Would you NOT consider that? REALLY?

I'll tell you what.
Wanna bet that after careful evaluations, eventually they will find a way to install also a SK16?
Just in order to satisfy the client with a tailor made setup, obviously - not because their margin would be even higher in absolute value... :rolleyes:

Remember, we are not talking of a situation where someone feels that the fins at zero speed are not good enough for his needs.
We are talking of a situation where the stabs made no difference at all. And trust me, that is beyond a joke.
 
As said the grey area in between is the most interesting imho

Both fins for running at moderate mid 20,s speeds and gyro @ anchor is the gold standard- ideal .

Gyros only for faster planers mid 30 ,s knots definitely over 40 knots .
 
Hi guys,

At this moment the people from the factory are looking for the possibibilyty of installing 2 seakeeper sk9 in the sportyacht 74. if they don't find the place to install this 2 seakeepers then I asked for installation of the fins and 1 sk 9 on top. they are thinking this systems cannot work together which is for my very strange because I thought I read more then once on this forum that this 2 systems can work perfect together without confusion each other. grtz
 
Pascal please can you confirm that on the recent test the Sunseeker guys did not report any technical problems that may have accounted for in your view the unsatisfactory motion of the boat at rest with the Sleipner fins ?

The 2x sk9 sounds a good idea .

I suspect if sleipner fins and 1sk9 there’s no need to run both together .
It’s one the fins when motoring along with dynamic stability that’s more than enough.

And the gyro at anchor as the fins we assume were not good enough in this particular application.
Problem is a sk 9 on its own big enough on its own , with not much if any assistance from the fins ?

A pair of sk9 ,s sounds the best idea in this boat ,based on the fins did not seem to do a lot at rest with this boat .
 
portofino, no they had no error or anything on their sleipner screens, so they think everything was working fine. I expect an answer on my question the coming days what the possibilitys are... maybe the fins are good because I read on the forum most people are happy with this system but I have only experience with the seakeeper system and I am very happy with this so I am a little bit scared to make the wrong choise that why I asked to install the seakeeper system. After all if I see on second yachts riva perseo, riva domino, pershings they all work with the seakeeper system....
 
pascalsunseeker said:
portofino, no they had no error or anything on their sleipner screens, so they think everything was working fine. I expect an answer on my question the coming days what the possibilitys are... maybe the fins are good because I read on the forum most people are happy with this system but I have only experience with the seakeeper system and I am very happy with this so I am a little bit scared to make the wrong choise that why I asked to install the seakeeper system. After all if I see on second yachts riva perseo, riva domino, pershings they all work with the seakeeper system....
Click to expand...
Pascal, this does not hang together.
If everything really was ok on the Sleipner colour screen, then they were likely working ok. But it takes more than a typical S/seeker salesman to understand the screens and understand hydraulics, so I suggest everything was not ok on the screen. The fact a s/seekr salesman tells me all was ok would not fill me with confidence.

If everything was ok you would have noticed them stabilising the boat. You report above that it made no difference whether you switched them on or off, which is just implausible for a pair of 1 msq fins on a 74 foot boat if they were working. All the indications on this thread are that they were not working ok.

For you to make an important choice like this based on non-working fins beggars belief, but it is your choice. Sure, lots of riva, pershings, etc have gyro, but they do not have effective stabilisation underway. You said you wanted that.

You can have both fins and gyro. It is sub optimal to have them not driven by the same computer, but they still work well. Ferretti has Sleipner fins and Seakeeper gyro together as an option on their 920 fly.

By the way here are sleipner fins on my previous boat 6 years ago, where I told the computer to make the boat roll, not stop it from rolling. This is a fraction of full power, because I did not want to hit my neighbour. You cannot not feel this much stabilisation effort and that is why both MapisM and I say that there must be something wrong, if you could not feel the difference between on and off https://www.youtube.com/watch?v=3-Rv1yrGE-E
 
Last edited:
You must log in or register to reply here.

Share this page

Top