Stabilizers for Blue Angel, engineering question

[MapisM]

I'd bet the displacement is a result of the superstructure rather than unusual dense hull scantlings.

Yup, that's probably another factor.
The boat doesn't feel at all like a top heavy vessel, though - quite the opposite, in fact.
Maybe she's just heavier overall, by modern standards. I mean, also the cabins interiors are clearly built without worrying too much about weight, for instance.

 

[BartW]

Some drawings
Floorplan cabin level

Floorplan with the frames and stringers (only in relevant part), this is a scetch made in paint, not 100% accurate.(yet)
Green is frames
Blue is stringers
Grey is bulckhead
Red dot is proposed position for the stabs

Cross section in red dot position

Other direction

 

[Deleted User YDKXO]

Is the stab assembly going to be braced back to the frames and stringers with some stainless steel plate or similar?

 

[jfm]

Is the stab assembly going to be braced back to the frames and stringers with some stainless steel plate or similar?

I would think it doesn't need it. I reckon what BartW has drawn is pretty much perfect. In a new build you might try to span 3 frames (2 frame gaps) but it is not feasible here and anyway the bigger forces are lateral, and BartW has spanned 1120mm in the lateral direction which is nice

Necessary detials are:
1. 80mm thick "plate" made from GRP. Mix of alternate woven and CSM
2. Good preparation of old surfaces (disk abrasion etc)
3. Careful feathering/blending of new GRP into old, at the edges, and
4. Flattening of the inside ~500mm circle where the stab flange will fit, using Crestomer or similar

But any good shipyard will do these things and I'm telling them how to suck eggs.

Pretty much a perfect answer imho. Great drawings Bart

 

[MapisM]

Just one question B, how was the transversal placement decided, based on the height restrictions?
Or to place the fins shaft in the center or the reinforced area? Or maybe both...?
I'm asking because the drawings make me wonder if it wouldn't be possible to place the fins nearer to the chines, or in other words a bit more distant from the keel.
Other than that, I can't think of any possible suggestions.
Looks like a great installation indeed, for a retrofit!
All the very best for the project.

 

[BartW]

how was the transversal placement decided, based on the height restrictions?
Or to place the fins shaft in the center or the reinforced area? Or maybe both...?
I'm asking because the drawings make me wonder if it wouldn't be possible to place the fins nearer to the chines, or in other words a bit more distant from the keel.

just as you say, in the center of the reinforced area,
but I'm waiting for some dimensions of the fins, to do the exact placing,
we still have a bit of height available to move them more away from the center, as can be seen in the other sketch
and the limit is that the fins may not touch the chine as you know.
CMC fins only theoretically can turn 360°

its just a 15 minute sketch, had no draughtsmen available yesterday,
but it's good enough for now, for the engineers on here and elsewhere to continue the planning and design work

 

[MapisM]

I see. Yep, all understood.
But re. the need of not exceeding the chines width with the fins, consider that actually this is NOT driven by a functionality requirement of the stabs themselves.
Rather the opposite, in fact: just think of cruise ships, where the fin stabs are fully retractable, and while in operation they are moved all the way outside the ship beam, with their shafts placed horizontally, rather than pointing downward.
That would be the best placement also for smaller boats, but of course, since the stabs we are talking about are not retractable, it's necessary not to place them in a position where they could hit a dock wall when moored alongside.
Otoh, while mooring, the fins are always centered, therefore a placement in a position where they can go outside the chines while operating is not a problem, as long as they stay within the boat width when they are centered.
Besides, in BA, as I recall the hull sides from the chines upward are significantly angled outward.
This means that when mooring alongside, the chines will always be more distant from the dock wall, if compared to a boat whose hull sides are perfectly vertical (as is the case with my boat, frinstance).
Mind, I wouldn't exceed the waterline boat width anyway, but I'm just mentioning all aspects worth considering.

 

[jfm]

Yup, agreed. On my boat the fins stick out substantially past the chines at full angular stroke. It is important to turn them off when docking, but actually they automatically turn off at 3knots GPS anyway, so you don't actually have to remember to do it. (The 3kt value is user selectable, deep in the menus)

 

[BartW]

Here is a drawing of the 0.8m2 fins,
when allowing a range of +/- 45° (CMC wants +/- 40°)
we would need a distance from the chine of about 0.7m

the fins have a tall shape (length is bigger then width)
I think its no good idea to make any mod on the fins for allowing movement over the chines, as the tale is the most effective part of the fin ,
and the fin needs to be as close as possible to the hull,

the fluidodynamics of the fin is a speciality on its own (imo) so no further 'speculation' on that from my side.

I did a small update on this sketch:

this is the part that still has to be designed by, and finalised with CMC

 

[MapisM]

when allowing a range of +/- 45° (CMC wants +/- 40°)
we would need a distance from the chine of about 0.7m

the fins have a tall shape (length is bigger then width)
I think its no good idea to make any mod on the fins for allowing movement over the chines, as the tale is the most effective part of the fin, and the fin needs to be as close as possible to the hull,
the fluidodynamics of the fin is a speciality on its own (imo) so no further 'speculation' on that from my side.

Bart, just to be sure to have understood what you mean:
0.7m is the distance required to avoid that the fins hit the chine border while flapping at 45 degrees, right?
If so, I would try to understand how much space between the fins and the hull bottom is required, to have the fins clear the chines while flapping, before deciding to just fit them so much inward.
As also jfm confirmed, in a normal installation on a planing V hull, the position is external enough to have the fins sticking out well past the chines, while working.
I suspect that by fitting the fins internally enough to not reach the chines, their effectiveness would be actually MORE reduced, than by leaving some more "air" between the upper side of the fins and the hull bottom.
Also, while I agree that the fins tails are the most effective parts of them, I wouldn't rule out an (hopefully small) cut on their top side, as a trade off for a wider placement.
All to be checked/confirmed with CMC, obviously. I don't think BA is the first boat they've seen with a lower chine border...

 

[BartW]

I agree with you that the further away from the center is better efficiency.
CMC was quite formal on the point that the fins need to be "as close" as possible to the hull.
perhaps making a "gap" in the chine (and filling from the inside with GRP) is a elegant solution ! ?

I forgot to mention, there are also some spray rails on the bottom, But I don't think we have to take care of these in our position planning,
one will be partially cut away in the fin area (already discussed with the yard, and no big deal...)


yes indeed here we need CMC's expertise / calculations

 

[BartW]

Is the stab assembly going to be braced back to the frames and stringers with some stainless steel plate or similar?

its never done like that Mike,
you can see pictures from installed drive systems on their site. (somewhere)
the assembly on its own is strong enough, when fitted on a solid 80mm base.

 

[MapisM]

perhaps making a "gap" in the chine (and filling from the inside with GRP) is a elegant solution ! ?

LOL, if someone would have suggested that for the hull of my old Fountain, I would have replied "over my dead body"!
But actually, considering the average speed of BA, and also the incidence of such gap vs. the total wet surface of her bottom, it isn't a bad idea at all.
Btw, chines on GRP hulls are normally extremely strong anyway, so maybe it's not even necessary to restore the missing thickness inside - to be evaluated, obviously...
...also because I should have learned not to make these assumptions, after my miserable guess on the hull thickness!

That aside, yep, I fully agree about not bothering with the spray rails.
IIRC, also on M1 build thread we discussed that, but even from Olesinski viewpoint it wasn't an issue.
Glad to stand corrected from jfm if my memory fails, of course.

 

[jfm]

LOL, if someone would have suggested that for the hull of my old Fountain, I would have replied "over my dead body"!
But actually, considering the average speed of BA, and also the incidence of such gap vs. the total wet surface of her bottom, it isn't a bad idea at all.
Btw, chines on GRP hulls are normally extremely strong anyway, so maybe it's not even necessary to restore the missing thickness inside - to be evaluated, obviously...
...also because I should have learned not to make these assumptions, after my miserable guess on the hull thickness!

That aside, yep, I fully agree about not bothering with the spray rails.
IIRC, also on M1 build thread we discussed that, but even from Olesinski viewpoint it wasn't an issue.
Glad to stand corrected from jfm if my memory fails, of course.

These are perhaps fine points but fwiw

1. on my boats the spray rails were cut away just to make a flat for the round flange of the stab unit, and not to allow the top of the fin to be ultra close to the hull surface
2. The top of my fins had/have a small triangle removed at the top of the aft edge to avoid hitting the reverse-chine when the fins are fully outboard. The thinking here was that you lose some fin effectiveness by losing this triangle becuase you allow a vortex at the top, but it's a good trade off becuase you more-than-make-up for it by having the fins further away from the keel

 

[jfm]

Agreed, this is not what all of us expect from this forum. In fact, this is not what I was suggesting, by all means.
And since we all expect "far more objectivity and cut through of marketing BS on this forum than from some commercial suppliers", let me try as objectively as I can to separate the facts from the marketing BS.

1) I asked you why an SL client should accept an undersized equipment, and you answered that they accept CMC stabs because that's the brand SL recommends, for commercial reasons alone and "with a complete absence of objectivity".
You also hinted that bribing can be another reason behind that.
Now, in my books, statements like these either can be supported by factual evidence, or they are just slandering.
Which, as we all know, is yet another form of marketing BS. A cheap and subtle one, but often rather effective.
But that aside, did you RTFQ, J? I didn't ask why SL clients accept CMC, I asked why undersized.
"Their" reason to accept CMC vs. your for choosing Sleipner was already covered by my foreword on the smartness difference.
But why undersized, ffs? CMC could well supply to SL (and to all their other clients, most of which - with all due respect for the Oundle folks - are not exactly in the same league as FL) much bigger fins.
All the way up to FOUR Sq.m, which means the DOUBLE of the bigger Sleipner fins.
I agree that CMC is the outlyer (btw, isn't it outlier?) vs. the hydraulic stabs builders, but if their marketing BS is aimed at selling smaller equipment, then they'd better rethink their marketing entirely, and double quick!
Not to mention that if they would be bribing purchasing managers (or whoever), just to invoice LESS rather than more as a result, now THAT would be indeed weird.

2) Talking of objectivity, let's consider our own positions in this debate.
Myself, I have ZERO interests with ANY stabs builders, and I can summarise my experiences with them in a few lines:
I got in touch with a couple of ABT engineers in the recent past, the first during a sea trial and the second in a few confcalls, to get some help in sorting out a commissioning problem.
I also worked together with a Naiad engineer many years ago for a maintenance check on my own boat, but I'm not even the one who specced those stabs when the boat was built, having bought her used.
Eventually, I spoke with Mr.CMC by phone in this occasion to discuss some basic technicalities of their stuff.
Oh, and I have no less than a dozen of years of first hand experience with stabs behaviour in all sorts of sea conditions, though not with zero speed.
Plus somewhere between 15 and 20 hours overall also with zero speed stabs, with boats other than mine, in more or less decent sea conditions.
And that's about it.
For yourself, obviously I'm not aware of all your connections and interests, if any - up to you to clarify them, if you wish.
Otoh, it's public knowledge that you are a Sleipner client, and afaik their one and only testimonial.
In fact, there's even a "user experiences" section in their online brochure which only reports a statement of yours.
Which btw makes one wonder why they used the plural, in the heading "user experiences"...
In turn, this implies that you have at least some vested interest in Sleipner image, if nothing else because their equipment is part of your boat value, also if and when you would want to sell her.
And let's face it, here we aren't just discussing a technology which clearly has major advantages when retrofitting stabs on a boat which wasn't designed and built for them, as in the case of BA.
We are talking of something which has various advantages vs. hydraulic systems also for any new builds.
And IF on top of that (note that it's a big IF) these things are really more effective, to the point of needing neither bigger fins nor longer actions to achieve a comparable result, that would be enough to make your stabs obsolete even before they'll hit the water.
After all, none of us like having big fins and shafts sticking out of our hulls - particularly on a planing boat.
It's just a means to an end, and in this sense, the smaller the better for any given final result, not the other way round!
Mind, with all the above, I'm not saying that your opinions so far on this matter were purposely disguised, far from that.
But surely, the way you approached my question, as per previous point 1, is one of the least objective I've ever read from yourself.

Oh, and just as an aside:
I'm sorry to hear that Lumishore didn't manage to make any business with Ferretti, because even without any first hand experience on their products, based on all I read around here I'm sure they are indeed good.
That said, I've heard for decades, during my previous job, commercial people arguing that they couldn't sell to this or that client because someone in their foodchain preferred to buy from their current supplier, to use your own polite but not unclear wording.
And you know what? They were always the worse salesmen (or even sales managers) who used that sort of arguments.
I never heard the best ones using such justification, even when they missed their target - which can obviously happen also to the best, occasionally.
No personal inference on whoever in Lumishore managed the negotiation with Ferretti, of course.
Just reporting a very solid first hand experience, simply to try - yet again - to separate facts from mktg BS.

MapisM I think |I sort of owe you a reply to the above. I fast-read it on sunday and my eyes glazed over a bit. It's quite a rant! It's too much thread drift to answer at length but here are some quick answers:

1. I wasn't intending to hint bribery. Interesting that your mind ran straight to that! I meant anything from the big menu of reasons to be not 100% technically objective, like buying Italian, a cheap deal (ARG?), possibly family connections, trade going both ways, whatever.
2. On the objectivity thing in general, ok forget Lumishore or whatever but surely you can see that Ferretti's ARG is a good example of a technically inferior product being pushed hard by a builder? If not, I'm happy to agree to disagree
2. I have no material interest in any boat company including sleipner, except that my business (which I co-own with others) has some marine companies as clients. None of these impacts my personal income by even 1%. My connection with SLeipner is only as end customer
3. My marketing help to Sleipner is as a favour to the guys who work there who have helped me a lot and in the process become friends. They don't give me a penny - in fact during that cruise on Match1 where they shot the marketing video and Sleipner's CEO and family were on board, I paid for all the food, fuel and berthing, LOL! They bought some great wine though . The Sleipner team is a great group of people right through the company; they are helpful and keep their word, and they're engineers through and through not just marketeers. I like their stuff (and I've been up close to the engineering) and completely objectively I've bought their stabs twice. I recommend their gear to others based entirely on its merits. You can think otherwise, which is fine
4. I dont buy your suggestion of vested interest because Sleipner's image impacts the value of my boat - jeeze, 5 months ago I could have chosen any stabiliser for Match2 or none at all, but I chose Sleipner completely freely. If no-one on here can comment on stuff they own then that's pretty much the end of the forum. I'll have to write just about Princesses and Henryf can only write about Fairlines, and neither of us can mention Caterpillar
5. Let's agree to disagree on fin size. As to why folks buy small fins, I've already said it is likely SL's and CMC's recommendation, rather than possession of degrees in engineering from Imperial/Cambridge/MIT etc on the part of captains. My view is that if a 1m sq fin is right with hydraulic actuators then there is no way that swapping for electric actuator makes a 0.6 or a 0.8 sqm equally effective, AOTBE. The fact the electric fin moves faster MUST mean it moves for less time, so runs out of effect faster. I don't accept electric accelerates faster either, but I have no data.

That's probably enough - it's thread drifty

 

[MapisM]

J, it wasn't absolutely meant as a rant, though in hindsight I accept that it might have appeared like one.
Otoh, sin and first stone are the concepts which spring to mind...
Anyway, since for the next few days I will very rarely be online, I took some minutes to answer right away, even at risk of not caring too much about the form.
Then again, I hope it's clear that the aim is just to clarify and not to have a rant, even if I'm used to call a spade a spade.

MapisM I think |I sort of owe you a reply to the above. I fast-read it on sunday and my eyes glazed over a bit. It's quite a rant! It's too much thread drift to answer at length but here are some quick answers:

1. I wasn't intending to hint bribery. Interesting that your mind ran straight to that! I meant anything from the big menu of reasons to be not 100% technically objective, like buying Italian, a cheap deal (ARG?), possibly family connections, trade going both ways, whatever.

Yeah, now it's my mind fault, if it ran straight to that. And/or because that's the Italian way, right?
I'd be interested to hear from EN mother tongue forumites if anyone thought of a cheap deal or whatever, when you said "Perhaps someone in the foodchain prefers to buy from their current supplier, for some reason".
If I'm the only one to have thought that in plain English you actually meant bribing, not only I'll apologise and eat my humble pie, but I'll also seriously reconsider my understanding of EN subtleties.

2. On the objectivity thing in general, ok forget Lumishore or whatever but surely you can see that Ferretti's ARG is a good example of a technically inferior product being pushed hard by a builder? If not, I'm happy to agree to disagree

No disagreement on this point. Then again, what the heck did that have to see with my question?!? Or with the whole thread, for that matter...

2. I have no material interest in any boat company including sleipner, except that my business (which I co-own with others) has some marine companies as clients. None of these impacts my personal income by even 1%. My connection with SLeipner is only as end customer
3. My marketing help to Sleipner is as a favour to the guys who work there who have helped me a lot and in the process become friends. They don't give me a penny - in fact during that cruise on Match1 where they shot the marketing video and Sleipner's CEO and family were on board, I paid for all the food, fuel and berthing, LOL! They bought some great wine though . The Sleipner team is a great group of people right through the company; they are helpful and keep their word, and they're engineers through and through not just marketeers. I like their stuff (and I've been up close to the engineering) and completely objectively I've bought their stabs twice. I recommend their gear to others based entirely on its merits. You can think otherwise, which is fine
4. I dont buy your suggestion of vested interest because Sleipner's image impacts the value of my boat - jeeze, 5 months ago I could have chosen any stabiliser for Match2 or none at all, but I chose Sleipner completely freely. If no-one on here can comment on stuff they own then that's pretty much the end of the forum. I'll have to write just about Princesses and Henryf can only write about Fairlines, and neither of us can mention Caterpillar

Not a lot to say on 2 (the second 2, that is...), 3 and 4 above. I can only take your word for that.
But I still think that - regardless of whether and in which form there are economic benefits involved - none of us expect Clooney to highlight the defects of Nespresso coffee, if you see what I mean.
Besides, I have a funny feeling that when you said that at Sleipner "they're engineers through and through not just marketeers" you refrained to add "like at CMC" just because it wouldn't have been politically correct, but that's actually your thinking, for some reason.
...Otoh, the jury is now out on my understanding of what's between the lines of written English, so let's leave this guess of mine in the forum folklore category!

5. Let's agree to disagree on fin size. As to why folks buy small fins, I've already said it is likely SL's and CMC's recommendation, rather than possession of degrees in engineering from Imperial/Cambridge/MIT etc on the part of captains. My view is that if a 1m sq fin is right with hydraulic actuators then there is no way that swapping for electric actuator makes a 0.6 or a 0.8 sqm equally effective, AOTBE. The fact the electric fin moves faster MUST mean it moves for less time, so runs out of effect faster. I don't accept electric accelerates faster either, but I have no data.

Blimey jfm, not again!
I can't believe that you're still spinning in circles around my original question which started this megadrift, arguing that all the sheeps follow the builders suggestions.
It doesn't matter how stupid all the owners/captains are. TBH, I'm veeery skeptic that all superyacht captains, some of which have a navy background and zillions of miles under their belt, are worse than an MIT engineer at judging the effectiveness of ANY onboard equipment where it really matters, i.e. out there, rather than at the desk. But let's keep that aside.
CMC builds (and installed on 50+m boats!) stab systems with fins up to FOUR sqm size, and among others, they obviously build also one sqm fins.
Even assuming that the whole yards lot (Benetti, SL, ISA, etc.) choose CMC for weird foodchain reasons, as opposed to your personal scientific evaluations for cherry-picking Sleipner, why on earth shouldn't they fit bigger CMC fins?
Your reasoning implies that all these yards, whose reputation isn't exactly the worst in the industry, regularly install undersized fins throughout their range.
And this in spite of the fact that in most cases, the equipment components are exactly the same, and it would be just a matter of fitting bigger fins.
Now, that's a total nonsense, if I've ever seen one.
We can debate till Xmas about whether there is a valid academic reason or not behind the fact that CMC can be competitive with hydraulic stabs builders to the point of choosing deliberately (both CMC and the yards) to fit smaller fins.
But we can't change the FACT that this is exactly what's happening, whether you and CMC competitors like it or not.

 

[Deleted User YDKXO]

1. I wasn't intending to hint bribery. Interesting that your mind ran straight to that! I meant anything from the big menu of reasons to be not 100% technically objective, like buying Italian, a cheap deal (ARG?), possibly family connections, trade going both ways, whatever.
2. On the objectivity thing in general, ok forget Lumishore or whatever but surely you can see that Ferretti's ARG is a good example of a technically inferior product being pushed hard by a builder? If not, I'm happy to agree to disagree

jfm, as somebody who has a great deal of experience trying to sell to corporates, I can tell you that if it was as easy as proving your product is better via a technical comparison, I'd have retired on my superyacht long ago. It is very difficult to push out incumbent suppliers who have built up long term relationships with their customers. It's not just about having a superior product and/or a better price, it's about the relationships that the technical people have built up over many years, about the relationship that the service people have built up including spares holdings and, yes, even about how friendly the MDs of both companies are and whether they play golf together. There may be nothing underhand about any of this but in the end, business is about people. I don't want to teach a grandmother to suck eggs but if Lumishore think that the Ferretti Group is a nut worth cracking, they're probably going to have to keep knocking on the door regularly over a period of years before they get a break. Then there is the 'if it ain't broke don't fix it' inertia. If Ferretti are not getting complaints from their customers about their existing u/w lights then for sure somebody in Ferretti will be asking why bother changing. And the same goes for ARG stabilisers; if customers are not clamouring for Sleipner stabilisers, then why bother messing around with hull designs and manufacturing processes? After all neither u/w lights nor stabilisers are critical to the operation of a typical planing motorboat

 

[BartW]

It is very difficult to push out incumbent suppliers who have built up long term relationships with their customers. It's not just about having a superior product and/or a better price, it's about the relationships that the technical people have built up over many years, about the relationship that the service people have built up including spares holdings and, yes, even about how friendly the MDs of both companies are and whether they play golf together. There may be nothing underhand about any of this but in the end, business is about people.

exactly,
at Metz I had a long talk with the hiloplatform, H+B guy, about their business,
and despite the superior quality of their products, they can't get in to big yards ao Frerretti, and a few others he named,
where they have to compete with big native suppliers (Besesoni) who make package deals for the whole lot, passerelle, door hinges, etc...
but again that personal relationship is the most important imo, all from experience in my own business.
By the way, h+B have a exclusive deal with a superior Brit builder ;-) and confirms that they are doing very good business with them.

 

[jfm]

jfm, as somebody who has a great deal of experience trying to sell to corporates, I can tell you that if it was as easy as proving your product is better via a technical comparison, I'd have retired on my superyacht long ago. It is very difficult to push out incumbent suppliers who have built up long term relationships with their customers. It's not just about having a superior product and/or a better price, it's about the relationships that the technical people have built up over many years, about the relationship that the service people have built up including spares holdings and, yes, even about how friendly the MDs of both companies are and whether they play golf together. There may be nothing underhand about any of this but in the end, business is about people. I don't want to teach a grandmother to suck eggs but if Lumishore think that the Ferretti Group is a nut worth cracking, they're probably going to have to keep knocking on the door regularly over a period of years before they get a break. Then there is the 'if it ain't broke don't fix it' inertia. If Ferretti are not getting complaints from their customers about their existing u/w lights then for sure somebody in Ferretti will be asking why bother changing. And the same goes for ARG stabilisers; if customers are not clamouring for Sleipner stabilisers, then why bother messing around with hull designs and manufacturing processes? After all neither u/w lights nor stabilisers are critical to the operation of a typical planing motorboat

I completely agree Deleted User. People buy stuff not just based on objective technical reasons. In all industries, not just boatbuilding. Thus, the fact someone buys something doesn't count as evidence that it is the best product in a technical/objective/scientific sense. It could even be something as simple as higher margins or longer credit terms. That was in fact my whole point, and I cite the ok-but-somewhat-inferior ARG used by Ferretti as a good example.

MapisM, this is too much thread drift and we should imho drop this sidebar debate lest it spoils a good thread. There is so much in your post I disagree with it would be too dull to type it out, and anything I say risks being taken the wrong way (eg, bribery; and I was genuinely saying Sleipner is a bunch of engineers intended as a compliment to them, nothing else, and it was your imagination only that added the CMC=marketeers point). Just on that, i have much admiration for CMC hardware and have supported/encouraged BartW's project from the outset; my "negative" comments on CMC have only been to cut through the BS like heat being generated only in gearboxes and my reservations about their small fin sizes, the two points obviously being potentially linked. Anyway, no worries, tis only a forum, and let's just agree to disagree

 

[BartW]

Some pictures taken from in the bilge,
positions where the drives are supposed to be positioned:


Here on Port side,

looking forward

Looking to SB (center of the boat)

Looking to the rear (bulkhead)

Looking to the side (port)

On starboard side:

Looking forward

Looking to the side (SB)

To rear (bulkhead)

Or to the center