Keeping Generator Running During Passage

Elessar said:
Hey J, why not have non STAR fins (small and low power requirement, balanced etc) that don't/can't work at anchor if you have a gyro?
(saves a special bow fender :))
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Could do M but both gyros and fins “run out” of stabilisation at rest if their stroke isn’t enough to eliminate the roll (eg a passing wake). So my preference would be to use both at anchor, with the gyros running first/most. But that’s personal choice- your suggestion is equally sensible.
 
Portofino said:
I think it’s best to try before you buy .
Stuff can get lost in translation when fitting leisure boat stabs or attempting to fix stability issues .
I don’t think it’s a case of picking something from the self and coercing a boat maker to fit it .
You can of course. . But I fear patchy results more luck than judgement.
I know some one who had a Predator 115 I think with stabs and his wife hated the ride , the captain told me it used to judder at anchor as well .
He was a serial S/Skr man until then ....
Got rid of it after one season and went to a Pershing 115 which was far better , it had gyros .
As it cruised at 37 knots there was a nice none rolling dynamic stability and at rest it was all silent .Such was the install in a 115 . Wife loved going out on it .

There’s an other thread about the interior vol and floating apartments trend of new boats being taller than ever .There in lies the problem the up top shift in weight making std stabs a must to sort of reverse out the poor dynamics / motion of the thing .....in a attempt to make a silk purse out of a pigs ear ride wise .

Something like this AB 100 ( under the 24 M rule ) is low and sleek with the weight ( triple MAN 1900 ,s ) doing there low COG assistances.
It’s just got a seakeeper and tops out at 54 knots , so ease back a bit to say 38 cruise and there’s enough to hull dynamics going on to give a nice ride .

https://m.youtube.com/watch?v=Z5fq-booOYY

lightshot

Obviously it’s not fighting physics it been designed WITH boat dynamics physics speaking .
Suppose over a 100 a whole new world opens up .
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@ Porto. So one guy in a sunseeker who didn’t set his stabilisers up correctly (judder) is what folks should take notice of, not the experience of those with a decade or so of successful (including never ever break down) use of fins. If that’s how you roll (scuse the pun), then great- go for it.

Dynamic stability is a big help but it doesn’t know where the horizon is. If you’re in a big beam/quartering sea with a wave the size of a ski slope coming from the side or quarter, dynamic stability will fix you to that wave face, so your champagne glass will fall over. Unlike fins it won’t keep you horizontal, because it doesn’t know what horizontal is. If that’s ok for you then yes definitely don’t buy stabilisers.

Likewise a gyro- it can hold you horizontal for half a second in the ski slope beam sea until it runs out of prescession stroke. Again if that’s ok, get gyros.

If you want zero roll in any beam sea even if the wave period is say 5 seconds, and zero roll in any twisty quartering sea, then get fins.

Remember that no leisure boat stabilisers will meaningfully help in a pure head sea.

It all just depends on what good effects you want to achieve and what ill effects you can tolerate. And whether you are happy to cruise based on not avoiding big seas, just avoiding head seas. There is no universal right/wrong or better/worse.
 
I think it’s not that simple and agree with the last sentence “ it all just depends.....”
completely agree ^^^

I look at it like this ....,
Take a scale keeping it simple 100 .
Boats that roll , no let’s call it move in all planes of direction at certain frequencies or periods ( not sure of the exact terminology?) can induce nausea or sea sickness or a sub level of just uncomfortable/ not a happy place to be for the occupants let’s call those “ bad feelings “

Say between for sake of demonstrating
17 to 23 , 37-44 and 79-100 .

Variables are the hull and of course the person(s) negativity effected .
Some folks might have zero “ bad feeling range “ in the scale or a very narrow say just between 56/58 or an average spread like the illustration.

A stab manufacturer claims x % reduction , it’s a validated no quibble research that nobody challenging .
The un stabilised boat is an the higher range but out side the higher 79-100
So no one ever feels bad as it rides or sits at anchor .
The prospective owner of the new build wooed by the stab manufacturer at a boat show opts for stabs ( does not matter which type ) .
Sure it reduces the roll etc by x % but drops it into a “ bad feel “ zone say from
75 to 18 .
A huge drop very efficient blah blah but folks now get “ bad feelings “ because it’s dropped / improved the motion into a bad zone that the OEM was not in there before .
Sure the plates or Champagne glasses don’t move .

Obviously the folks aboard have different perceptions of movement and my examples of “bad feeling range “ will differ from boat to boat .

That’s the point I was trying to make by trying the kit ( where possible) before buying .

With the Predator 115 , S/Sker where all over it like rash but it was the Mrs who whinged and even the captain was not impressed .Experienced boaters .
The hugely reduced movement with the fins on crated a “ bad feeling “ inducing boat .

Where as the AB 100 hull May only have one very narrow range of “ bad feeling “ inducing score for example 42/45 .
It’s primary score may be low to start with say 62 or something due to the low CoG etc etc so a couple or three gyros even with only one on misses the 42/45 bad zone .
All of them on and it’s in single figure say 5 or 7 such is the inherent smoothness of the ride . A significant amount of smoothness or “nice feeling “ could be contributed from the extra dynamic of the mid thirty ( could be mid forty btw ) speed .
So a 22/24 knot planing boats can’t add a great deal of extra dynamism it s has to major on its manufacturer stabs far greater so whilst it may be out of a bad zone , the lower 17 to 23 its ride can only go as low as say 12/15 .
The AB,s 5/6 is 1/2 that or twice as smooth .
They may both claim a similar drop in roll ( or what ever stab improvements are called ? ) from the manufacturers because the AB started lower down my notions scale to start with .

As regards pitching in a head sea and stabs yes , but that’s my point will the AB,s 37 knot pitch in 4 M seas create any “ bad feelings “ - if it doesn’t who cares .Nobodies fussed by the bow pitching in fact those on the rear sunpad are asleep with the “ nice “ rhythmic movement.

Or if the finned 22/24 knot cruise boat has met it match ( no pun intended) and folks are feeling bad on board at this heading to the waves .Worse with the kit turn off , so kinda self satisfying the decision to turn them on .
The 115 Pred capt told me it rides better with the fins off ..at speed ...not from a movement POV from a lower “ bad feelings “ which ultimately is what matters .

As I said stuff gets lost between theory ( that i am not challenging ) at the boat show stands , manufacturers literature and final execution.
 
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Portofino said:
I think it’s not that simple and agree with the last sentence “ it all just depends.....”
completely agree ^^^

I look at it like this ....,
Take a scale keeping it simple 100 .
Boats that roll , no let’s call it move in all planes of direction at certain frequencies or periods ( not sure of the exact terminology?) can induce nausea or sea sickness or a sub level of just uncomfortable/ not a happy place to be for the occupants let’s call those “ bad feelings “

Say between for sake of demonstrating
17 to 23 , 37-44 and 79-100 .

Variables are the hull and of course the person(s) negativity effected .
Some folks might have zero “ bad feeling range “ in the scale or a very narrow say just between 56/58 or an average spread like the illustration.

A stab manufacturer claims x % reduction , it’s a validated no quibble research that nobody challenging .
The un stabilised boat is an the higher range but out side the higher 79-100
So no one ever feels bad as it rides or sits at anchor .
The prospective owner of the new build wooed by the stab manufacturer at a boat show opts for stabs ( does not matter which type ) .
Sure it reduces the roll etc by x % but drops it into a “ bad feel “ zone say from
75 to 18 .
A huge drop very efficient blah blah but folks now get “ bad feelings “ because it’s dropped / improved the motion into a bad zone that the OEM was not in there before .
Sure the plates or Champagne glasses don’t move .

Obviously the folks aboard have different perceptions of movement and my examples of “bad feeling range “ will differ from boat to boat .

That’s the point I was trying to make by trying the kit ( where possible) before buying .

With the Predator 115 , S/Sker where all over it like rash but it was the Mrs who whinged and even the captain was not impressed .Experienced boaters .
The hugely reduced movement with the fins on crated a “ bad feeling “ inducing boat .

Where as the AB 100 hull May only have one very narrow range of “ bad feeling “ inducing score for example 42/45 .
It’s primary score may be low to start with say 62 or something due to the low CoG etc etc so a couple or three gyros even with only one on misses the 42/45 bad zone .
All of them on and it’s in single figure say 5 or 7 such is the inherent smoothness of the ride . A significant amount of smoothness or “nice feeling “ could be contributed from the extra dynamic of the mid thirty ( could be mid forty btw ) speed .
So a 22/24 knot planing boats can’t add a great deal of extra dynamism it s has to major on its manufacturer stabs far greater so whilst it may be out of a bad zone , the lower 17 to 23 its ride can only go as low as say 12/15 .
The AB,s 5/6 is 1/2 that or twice as smooth .
They may both claim a similar drop in roll ( or what ever stab improvements are called ? ) from the manufacturers because the AB started lower down my notions scale to start with .

As regards pitching in a head sea and stabs yes , but that’s my point will the AB,s 37 knot pitch in 4 M seas create any “ bad feelings “ - if it doesn’t who cares .Nobodies fussed by the bow pitching in fact those on the rear sunpad are asleep with the “ nice “ rhythmic movement.

Or if the finned 22/24 knot cruise boat has met it match ( no pun intended) and folks are feeling bad on board at this heading to the waves .Worse with the kit turn off , so kinda self satisfying the decision to turn them on .
The 115 Pred capt told me it rides better with the fins off ..at speed ...not from a movement POV from a lower “ bad feelings “ which ultimately is what matters .

As I said stuff gets lost between theory ( that i am not challenging ) at the boat show stands , manufacturers literature and final execution.
Click to expand...

The interface it’s lost at is the fact that the stab bit can all be accurately calculated quantified which is I think where you are coming from but the variable out of anyone’s control is the human “ bad feeling “ part which the other direction I am coming from .
They meet somewhere and it’s either a success or not a success .
 
jfm said:
Dynamic stability is a big help but it doesn’t know where the horizon is.
...
If that’s ok for you then yes definitely don’t buy stabilisers.
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Very far from pretending that this should be true for everybody, but FWIW, after 2 full seasons with a non-stabilized P boat used anywhere between 20 and 25kts most of the time, my personal answer is positively yes, that's ok.
A conclusion I sort of hoped for already when I decided to downgrade to a P boat, and which has been by now confirmed - in spades.

Btw, the very long swell scenario that makes the boat list rather than roll, albeit theoretically correct, is something I never came across, even with my humble 56 footer at 20 something knots, so I can't imagine it affecting a 100'+ boat cruising at 37kts or whatever.
Of course, that's bound to happen much more regularly when cruising at D speed and possibly crossing an ocean - it's no coincidence that practically all modern trawlers come with fins as standard.

But for me, based on the last two seasons of P boating, stabilization fell at the very bottom of the nice to have list.
It could still have its place for anchoring alone (hence obviously a gyro), if it weren't that both myself and swmbo are more annoyed by the genset noise than by the boat motion.
And luckily, passing waves are a very rare occurrence in our cruising grounds.
A win-win situation, if I've ever seen one... :encouragement:
 
MapisM said:
And luckily, passing waves are a very rare occurrence in our cruising grounds.
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As you may remember I was toying with the idea of fitting a gyro in my F630 when I was based in Calaforte. I concluded that given the lack of passing wakes and the fact that San Pietro is an island and if you are bothered by incoming swell caused by weather, you can always move to another anchorage, it wasnt worth the cost and hassle. My mind was changed on literally the first day we arrived in SoF. We anchored in Villefranche and because the wind was from the east we were beam on to passing wakes and swell and it was very uncomfortable. After another couple of uncomfortable experiences in other anchorages, I decided we had to have a gyro! IMHO the need for stabs at rest is very much dictated by your cruising grounds!
 
Must admit I can sympathise with Mike and JFM as the Cote d Azur from St Trop to Menton is crowded and busy .
Sky as well as sea .Not sure which was the worst nuisance tbo :)From a comfort POV the area is a victim of its own success .
Having recently moved less than 100 miles east it’s bliss sea state wise .Boat density / movements has dropped by 90 %
Previously in the Lerins on a calm day little wind the waves are from every other boat .Terrible rounding the Cap d Antibes or crossing the bay of Cannes mainly due to the sheer traffic vol , both close in and far ( ish ) out of bigger stuff .
So the drivers for a stabbed boat start to evaporate imho depending where you cruise .
As MapisM infers running my particular boat theres not in any “ bad feeling “ zones arguably helped by a above ave chunk of dynamic help .

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