BartW
Well-Known Member
That's how it usually starts,
you know where daydreaming got me in to
@ rafiki and jfm
very interesting reading / update, thanks !
How is Match, after 4 months JFM?
- Thread starter rafiki_
- Start date
That's how it usually starts,
you know where daydreaming got me in to
@ rafiki and jfm
very interesting reading / update, thanks !
rafiki_
Well-Known Member
That's how it usually starts,
you know where daydreaming got me in to
@ rafiki and jfm
very interesting reading / update, thanks !
Bart, I always look forward to your posts and updates too.
Elessar
Well-Known Member
get the benefit - why can't the centre just be set dynamicly from SOW? Seems overly complicated to have to hack it to set it.
Good news about the pump - did the pipework get re routed or the lack of vibration mean in no longer matters?
Nautical
Well-Known Member
All looking brill J, have we here probably the best thought out and put together sub 24m flybridge planing yacht?, I think not much else can run Match close, having had a good rumage over her at LIBS can attest, one very well screwed together yacht.
Just a point though, ABT TRAC stabs have been using Bosch/Rexroth pumps for years now and you can (if you have the codes) also centre the stabs at various speeds, one of their features been around for a while.
Another poster on here was party to a recent sea trial with ABT, all very interesting stuff when they plug in their lap top. Tech engineer from ABT was able to simulate one stabiliser going down and allow the other to take all the work, report back was you could hardly tell the difference with just one stab doing all the work. Amazing bits of Kits these stabs, makes one wonder why everyone building over 20m isn't fitting them as standard they make life aboard so much more comfortable. I believe all the Brit builders are trialling stabs now, seems ABT are the choice at the moment but Sleipner albeit new to the market are catching up fast.
Happy sailing J, hope to catch you Antibies way en-route to Cannes show.
Just a point though, ABT TRAC stabs have been using Bosch/Rexroth pumps for years now and you can (if you have the codes) also centre the stabs at various speeds, one of their features been around for a while.
Another poster on here was party to a recent sea trial with ABT, all very interesting stuff when they plug in their lap top. Tech engineer from ABT was able to simulate one stabiliser going down and allow the other to take all the work, report back was you could hardly tell the difference with just one stab doing all the work. Amazing bits of Kits these stabs, makes one wonder why everyone building over 20m isn't fitting them as standard they make life aboard so much more comfortable. I believe all the Brit builders are trialling stabs now, seems ABT are the choice at the moment but Sleipner albeit new to the market are catching up fast.
Happy sailing J, hope to catch you Antibies way en-route to Cannes show.
tico
Well-Known Member
you could hardly tell the difference with just one stab doing all the work.
Interesting! So that begs the question, why not just have the one fin? .. Less drag hence more mpg.
Guess that the 'zero speed' effect would be less.
Interesting! So that begs the question, why not just have the one fin? .. Less drag hence more mpg.
Guess that the 'zero speed' effect would be less.
rafiki_
Well-Known Member
Would make the handling and steering a bit odd, with a lot of drag on one side.
Nautical
Well-Known Member
This was more at displacement speeds, vessel concerned was not a planing hull and max'd out round 14 knots, I would agree probably handling would be a bit skewed if travelling at 25 knots, still doable but probably not recommended. Nice to know though that in really rough stuff and at D speeds you could still have functioning Stabilisation if you lost one.
tico
Well-Known Member
Not if the fin was mounted vertically
rafiki_
Well-Known Member
Unless the single fin was on the centreline, then it would still cause a drag imbalance. However, I'm not sure where this is going, as I don't believe anyone is currently planning to fit 1 stabiliser are they?
tico
Well-Known Member
Thats what I meant... like a small 'active' fin keel.
The advantage being in less drag than 2 stabs, hence improved fuel consumption
rafiki_
Well-Known Member
Interesting. Does such a thing exist, or are you going on Dragon's Den?
Mr Googler
Well-Known Member
Surely an "active fin keel" is a rudder!!!
Stabs deflect water up or down against the roll forces and unless I've a missed something,
you could only deflect left or right with a vertical stab which brings me back to rudder
Stabs deflect water up or down against the roll forces and unless I've a missed something,
you could only deflect left or right with a vertical stab which brings me back to rudder
rafiki_
Well-Known Member
If you had a wing that worked in 3-dimensions under the centreline, then this might work, but there are some downsides, depth, forces through U/J's etc.
tico
Well-Known Member
Re Farsco
It'll only act as a rudder if the axis of rotation is displaced from the central axis of rotation as a yawing (?) moment is then produced.
if it's mounted on the axis of rotation, then the only effect is to roll the hull as the 2 yawing moments would cancel each other out.
How's this for Fred Drift?
It'll only act as a rudder if the axis of rotation is displaced from the central axis of rotation as a yawing (?) moment is then produced.
if it's mounted on the axis of rotation, then the only effect is to roll the hull as the 2 yawing moments would cancel each other out.
How's this for Fred Drift?
rafiki_
Well-Known Member
OK for yaw, but what about pitch? Would need a further degree of freedom, making a very difficult mechanical system. I don't think we have sold this one yet to JFM?
MapisM
Well-Known Member
Blimey folks, it's amazing what sort of thoughts can pop up around here, when it comes to boat innovations...! 
Otoh, in my experience, when a MoBo is fitted with stabs, they become the second most important equipment - obviously after the whole propulsion chain: engines/props/rudders.
But at the end of the day, what you really expect from stabs is that they work, period.
I'm rather skeptic when I hear of any sort of new technologies in this field.
My old Najads have no software "brain" at all, and no controls. Just a switch to select between OFF, ON, and CENTERED. And the fins are simply driven by a gyroscope which senses the rolling. Nothing else.
In spite of that, they are amazingly effective. And all the attention they got in 15 years was ONE oil and filter change, just for the sake of preventive maintenance. Not bad, for an hydraulic equipment working at 1200+ PSI!
If I were building a new boat today, I'd rather still fit those, than test any sort of brand new hi-tech gizmo...
Otoh, in my experience, when a MoBo is fitted with stabs, they become the second most important equipment - obviously after the whole propulsion chain: engines/props/rudders.
But at the end of the day, what you really expect from stabs is that they work, period.
I'm rather skeptic when I hear of any sort of new technologies in this field.
My old Najads have no software "brain" at all, and no controls. Just a switch to select between OFF, ON, and CENTERED. And the fins are simply driven by a gyroscope which senses the rolling. Nothing else.
In spite of that, they are amazingly effective. And all the attention they got in 15 years was ONE oil and filter change, just for the sake of preventive maintenance. Not bad, for an hydraulic equipment working at 1200+ PSI!
If I were building a new boat today, I'd rather still fit those, than test any sort of brand new hi-tech gizmo...
jfm
Well-Known Member
Yup, agreed
Each to their own, but I wouldn't agree. I do agree that simple stabs work very effectively (I have used them on my brother's boat) but you can get improvements by going "hi-tech" (not that it's THAT high!). Ultimately the performance of a stab is a function of the blade shape/size and how it moves, and modern computing must improve the latter. I have tried 4 different sets of algorithms in my boat and each one feels different, and it is nice to be able to choose the one that feels best
Also remember that recent stabs work at anchor, which yours don't. The control of the movement of stab fins at anchor requires more complex algoriths and necessitates some "hi-tech"
tico
Well-Known Member
Raf
Don't think pitch comes into it? or does it?
Mainly roll is the one i'd be concerned with.
Don't think pitch comes into it? or does it?
Mainly roll is the one i'd be concerned with.
rafiki_
Well-Known Member
Interested in JFM's experience here. Is pitch an issue? Do the stabs help?
MapisM
Well-Known Member
I see what you mean, but I'm not sure that a computerised control is actually necessary.
I mean, of course there are relevant difference for STAR stabs, like the shaft moved further forward (with all the implications n terms of stronger supports and equipment) and the winglets (if that's the right name, not sure) at the fins bottom.
But I don't see any logical reason why a gyroscope driven system shouldn't work also at zero speed: the faster/wider fins action is "built in" with the purely hydraulic gyroscope control, so to speak, because if the gyro senses a sudden/wide roll, it automatically moves the fins faster.
I'm not saying that more sophisticated algorythms can't help (in fact those who invented the zero speed stabs always used them, afaik), but I'm just curious to hear if you see reasons why without them they couldn't work at all.