Seakeeper

[henryf]

What I would say is when very few boats of a given size are fitted with stabilisers yours sticks out and sells well. Stabilisers are considered the norm for something of JFM's 78 now for instance. At the time of Match 1 they hadn't been fitted before and I'm convinced his decision to break new ground and fit them was the reason it sold so well.

What will be interesting is to see how long it takes before stabilisers are fitted regularly on a 52, if it happens at all. If it does then boats without them will be penalised. I would halve the cost in my head and say you'll get that back when you sell the boat.

What I would say is when they become a factory fit it should bring the price down. More units sold = economy of scale and much easier to drop into a pre-designed hole than clearing the space, making the hole and running all the necessary plumbing.

Great idea about the extra batteries. Would it be possible to build a 24 volt unit and run the generator as and when required to charge them in the same way some electric cars have a petrol generator rather than engine to drive them when the batteries run down? That way the initial power up could be done either on shore power or with engines running when the batteries would be receiving charge.

Henry

 

[MapisM]

Kashurt, I think that you have summed it up quite neatly for all the reasons that you mention. I also ran the concept past my wife who was of the view why bother. If it is choppy move to a spot that is calm. It is a difficult one to argue against particularly as it is a 42k spend. I think I will wait.

P52, with all due respect for kashurst who is obviously entitled to have his view on stabs, the objections he raised are disputable to say the least.
I mean, aside from the point on the economic value of the thing - in that respect, as I already pointed out, monetizing something as qualitative as comfort is extremely subjective, so there's no such thing as a right or wrong answer.

But when kashurst said that at planing speed stabs are useless, and at anchor if it's lumpy you still need to move due to pitching, well, he's plain wrong - on both counts.

Firstly, with some beam swell you are bound to roll also with planing boats, no matter how big and how fast. And while I agree that the "slow rolling" typical of D speed can be more annoying than the P speed rolling, saying that at P speed the stabs do nothing is simply not true. You would never believe how small the waves can be to make the difference perceivable, by turning the stabs on and off, unless you actually try it.

Secondly, yes, of course if an anchorage is rough enough to make pitching uncomfy, you must move regardless of whether the boat is stabilized or not - but that's not the point. It takes a fair bit of sea to make a 50 footer uncomfortable because of the pitching, I'd say at least a couple of feet waves (depending of course also on their period). But it takes much less - and I mean MUCH less! - to make you willing to move elsewhere due to rolling.

Btw, I'm talking based on experience here, because also my boat is a 50 footer, and she has fin stabs, but not zero speed ones.
I did think of upgrading her, and eventually decided not to, because nowadays I spend enough time onboard to be choosy about when and where to go.
It's only in this sense that I didn't consider the zero speed upgrade "worth" the cost, also because it would actually be an almost complete replacement of the system, hence pretty expensive.
But it's undeniable that in many situations zero speed stabs allow you to stay in places where other boats with no stabs must go.

 

[MapisM]

Great idea about the extra batteries. Would it be possible to build a 24 volt unit...

I'm not sure if this is what you meant, but the big constraint is that only AC electric motors are reasonably efficient - hence the need to run electric stabs either straight from AC (be it shorepower or genset) or getting AC out of the batteries through inverter(s).
And btw, as Nick_H pointed out, I very much doubt that you could fire up gyro stabs from batteries+inverter alone, though it's probably feasible to keep them running once up to speed.
Afaik, BartW's BA with her electric fin stabs is the only boat on the planet that can, while anchored and with everything turned off, turn on zero speed stabs instantly and with no need to turn the genset on!

 

[Deleted User YDKXO]

Afaik, BartW's BA with her electric fin stabs is the only boat on the planet that can, while anchored and with everything turned off, turn on zero speed stabs instantly and with no need to turn the genset on!

Why is that? Surely there is a huge start up load when the stabs are switched on?

More of a general question. Is there a big difference in power consumption at rest between gyro, hydraulic fin and electric fin stabs? For me, a big advantage would be the ability to run the stabs off batteries/inverter for say a 2-3hr lunchtime stop rather than have to run the gennie continuously.

 

[Nick_H]

Why is that? Surely there is a huge start up load when the stabs are switched on?

More of a general question. Is there a big difference in power consumption at rest between gyro, hydraulic fin and electric fin stabs? For me, a big advantage would be the ability to run the stabs off batteries/inverter for say a 2-3hr lunchtime stop rather than have to run the gennie continuously.

In each case it will depend on how much work the stabilisers are doing, but in calm water when we have the gyro running just for passing boat wakes, it draws very little, less than a small toaster.

 

[henryf]

I'm not sure if this is what you meant, but the big constraint is that only AC electric motors are reasonably efficient - hence the need to run electric stabs either straight from AC (be it shorepower or genset) or getting AC out of the batteries through inverter(s).
And btw, as Nick_H pointed out, I very much doubt that you could fire up gyro stabs from batteries+inverter alone, though it's probably feasible to keep them running once up to speed.

Yes I did mean running on 24 volts.

I suggested getting them up to speed either when on shore power / generator, or when the engines were running so that the batteries were being charged and could take a larger current draw without running them down too quickly.

At the end of the day start up only uses a lot of power as you reduce the time it takes to get up to speed so there is a balancing act.

I don't know if it's more efficient to use an AC motor through an inverter or a DC motor powered directly.

Henry

 

[Deleted User YDKXO]

In each case it will depend on how much work the stabilisers are doing, but in calm water when we have the gyro running just for passing boat wakes, it draws very little, less than a small toaster.

Nick, do you run your gennie continuously to power your Seakeeper, both at rest and under way?

 

[Nick_H]

Nick, do you run your gennie continuously to power your Seakeeper, both at rest and under way?

Yep, because I don't have an inverter. The Victron you mentioned above would be perfect, and I think i'll fit one, though we're just deciding whether to change boats so it may be the next boat i'll fit it to.

 

[jrudge]

The whole thing comes down to value for money. The snag is boats and value for money are not really decent bed fellows!

Will it make the boat nicer to be on. Absolutely yes.

Will you get more for it? Probably.

Have you got the money and do you mind the "asset " (if that is what it is) costing you more.?

If princess had offered a normal boat at £850, and a stabilised one for £885 then at the time of purchase is was just another 5%.

After the event more rational thought takes over - howe much diesel does this equal and so on.

There is no real answer. In my case the bill inc VAT was £87k. Did it make sense to me? At this moment in time no - but I would still like them!

We are lucky that in Mallorca the swell is not that bad. BUT we do have bumpy nights and I could well do without them. What price? Who knows!

Comes down to

Have you got the money and do you mind the "asset " (if that is what it is) costing you more.?

I suppose. I felt I had put enough into the pot for now. Time will change that view I am pretty sure.

 

[Deleted User YDKXO]

Yep, because I don't have an inverter. The Victron you mentioned above would be perfect, and I think i'll fit one, though we're just deciding whether to change boats so it may be the next boat i'll fit it to.

You'll have to ask the forum first before you're allowed to change boats

If you had an inverter, would it be correct to assume that under way at P speeds, the continuous charging of the batteries by the engine alternators would keep the batteries sufficiently charged to power the gyro continuously via the inverter? What about at D speeds when presumably (?) the alternators are not providing as much charge to the batteries?

I know it depends on sea conditions and how hard the gyro is working but would you think that with good batteries, you could typically power the gyro via the inverter for a 2-3hr lunch time stop at anchor?

 

[Nick_H]

You'll have to ask the forum first before you're allowed to change boats

If you had an inverter, would it be correct to assume that under way at P speeds, the continuous charging of the batteries by the engine alternators would keep the batteries sufficiently charged to power the gyro continuously via the inverter? What about at D speeds when presumably (?) the alternators are not providing as much charge to the batteries?

I know it depends on sea conditions and how hard the gyro is working but would you think that with good batteries, you could typically power the gyro via the inverter for a 2-3hr lunch time stop at anchor?

My alternators are 70 amp each, so max 140 amps at 24V. I've no idea what the efficiency of an inverter is, but if its 75%, then that would provide about 10 amps max at 240V or 2.4 kw. That's almost double what Seakeeper state as the running requirement for the gyro after spool up, so it seems it would work.

At anchor in relatively calm conditions, I'd guess the gyro only draws 0.5 KW average, or 2 amps, which would equate to about 30 amps at 24V and 75% efficiency. My battery bank is 420 AH at 24V, and if I can use half that (?), then that suggests the gyro could run 7 hours on batteries. Of course there's other 24v load for fridges etc., but it certainly seems the gyro could run a good few hours on batteries.

This all assumes my maths are broadly right, and I wouldn't bet on that!

 

[BartW]

Surely there is a huge start up load when the stabs are switched on?

More of a general question. Is there a big difference in power consumption at rest between gyro, hydraulic fin and electric fin stabs? For me, a big advantage would be the ability to run the stabs off batteries/inverter for say a 2-3hr lunchtime stop rather than have to run the gennie continuously.

There is no big startup current in our electric stab system, as the only parts that start working are controlling electronics. The biggest power peaks come when the stabs have to work hard: fast movement/ long stroke.
The cirquit breakers on the 2 x 230v supply are 20amp each, but i have a peak consumption figure in my mind of 6...8 amps. The two quatro,s can supply 20amp each, from the battery's .

Comparing consumption with other systems, I know that the cmc electric stabs are much more efficient than their hydraulic systems, but don't know compared to any other systems

 

[Deleted User YDKXO]

At anchor in relatively calm conditions, I'd guess the gyro only draws 0.5 KW average, or 2 amps, which would equate to about 30 amps at 24V and 75% efficiency. My battery bank is 420 AH at 24V, and if I can use half that (?), then that suggests the gyro could run 7 hours on batteries. Of course there's other 24v load for fridges etc., but it certainly seems the gyro could run a good few hours on batteries.

Thanks NickH thats interesting

 

[MAFWeiss]

My alternators are 70 amp each, so max 140 amps at 24V. I've no idea what the efficiency of an inverter is, but if its 75%, then that would provide about 10 amps max at 240V or 2.4 kw. That's almost double what Seakeeper state as the running requirement for the gyro after spool up, so it seems it would work.

At anchor in relatively calm conditions, I'd guess the gyro only draws 0.5 KW average, or 2 amps, which would equate to about 30 amps at 24V and 75% efficiency. My battery bank is 420 AH at 24V, and if I can use half that (?), then that suggests the gyro could run 7 hours on batteries. Of course there's other 24v load for fridges etc., but it certainly seems the gyro could run a good few hours on batteries.

This all assumes my maths are broadly right, and I wouldn't bet on that!

I have asked Seakeeper directly if I could run one of their stabilizers off an inverter and battery once it was up to full RPM. This was their reply:

Once it is at full speed it is not a case of keeping it ticking over. Fine if that is all you want to do but then why keep it running? If you want it to operate as a stabiliser you will need it to be able to consume 2.5KW from the inverter as depending on the sea conditions it will consume up to that amount. If you are at a calm bay for sure the consume will go down as the gyro is not doing a lot of precession movements. But as you can imagine we cannot give any guarantees because one wave or a boat going past can change the scenario. So we cannot commit any firm figures. The period of the waves, the roll period of the vessel, are all unknown figures.

 

[jrudge]

Or translated - it will work, but we have no idea how well of for how long - and if it get rough you are stuffed!

 

[BartW]

This was their reply:

That was more or less the same answer I got from CMC at the time, asking them if I could run the Stabs from invertors
but they were more firm saying something like "I don't see a reason why that shouldn't work if the invertor setup is powerfull enough"

From my own experience with inverter driven stabs (instead of gyro's, but similar idea)
I can add that the 24V DC system has to be in top shape, to cope with the peak currents,
meaning:
-high quality slightly oversized invertors; my orriginal 2 x 3Kw Victron invertors didn't cope with peak currents at anchor, the new 2x 5Kw Victron quatro's are OK
-battery's in top shape, when a few battery's from our bank lost their quality, the system got in error with current peaks, replacing the battery's cured the problem,
-due to bad cabling two battery's suffered much more than all the others, I learned here on the forum how to improve battery cabling which we applied,
-we have installed a battery monitor, that gives a audible alarm after a certain battery discharge,
and soon we'll add auto genny start, to reduce the risc that battery's will be discharged too deep. (to keep them longer healthy)
I'm considering to place solar panels on top of the helm station roof, for charging battery's while at anchor, and extend the autonomy at anchor

 

[CLOUD9]

This is really interesting for me. I have recently bought a boat which has been retrofitted with an M8000 Seafarer. I was surprised to see such a device on a 58' boat (Im a bit out of touch perhaps) and didn't let it influence my buying decisions. Reading more about it Im excited that it might be a worthwhile extra! Im not afloat yet but will report back when I am.

 

[Nick_H]

This is really interesting for me. I have recently bought a boat which has been retrofitted with an M8000 Seafarer. I was surprised to see such a device on a 58' boat (Im a bit out of touch perhaps) and didn't let it influence my buying decisions. Reading more about it Im excited that it might be a worthwhile extra! Im not afloat yet but will report back when I am.

My boat is the predecessor to yours but has the same hull, and I also have the model 8000 gyro, so you'll get the same great results as me. Congratulations on the purchase, I'm sure you'll find her to be a great boat.

 

[CLOUD9]

That's good to know, thanks Nick. I had been a little worried about the reduction in lazarette volume due to the seakeeper but sounds like it's worth it. I'll just have to try to keep the unnecessary paraphernalia to a minimum!

 

[Jonmendez]

Having travelled a fair way on stabilised planning boats at displacement speeds they add a great comfortable cruising aspect to the boat, distance cruises at planning speeds is expensive, slower equals loads of fuel savedand you get to enjoy the scenery, may help you win the cost argument with yourself? Totally depends on your cruising plans but for me I don't think it's expensive and adds a lot to your enjoyment of the boat.