A bluewater, ocean going water ballasted matorsailer. Why not?

Originally Posted by whoosh

Richard, that pic, looks like a painting, a very good one , but cant open or enlarge it
When I was on tugs North sea , it always felt good to have a ship below one
in the conditions depicted here, it would be rather scary, at sea in a cat, or a flimsy sailing boat

Be sure it is a photo Stu! And if you go one page back you will find more info.

And I do´nt think it was only one high scored member to wipe Xarax´s points, when you have followed the thread you could have seen there have been several completely disagreeing. Me included.

[xarax]

Originally Posted by apex1

The highest authority on earth...

I was refering to the highest authority on heavens,,,

Originally Posted by apex1

We are silly little creatures...

I agree !
The hull I see is a semi displacement, beamy, flat aft, quite fast type of hull, and the righting moment of the boat, when upside down, comes from the form instability in this position, instability that is due to the raised deck house.
Everybody prefers effective, passive, simple systems when is immersed in an unstable environment, such as the surface of the sea. But I think that in a sailing vessel, where we should not ignore windage, we can not achieve self righting by any other means * except a combination of a raised-as-low- as-possible deck house AND water ballast.
See the righting moment of the 47ft MLB at page 15 of:
http://www.dtic.mil/cgi-bin/GetTRDoc...c=GetTRDoc.pdf
* ( If we do not want to use even more complicated and unreliable systems, as automatically inflated air bags, for example.)
Now, if one gives me a self righting system that :
1. manages to flip the upside down hull in less than, say, 1-2 minutes even with the sails on and centreboard down
2. does not load the semi displacement hull as much as a lead keel does. and
3. does not use water ballast,
I will drink every drop of this dirty water ballast and forget all about it, I promise !

[ancient kayaker]

[quote=xarax;289614]Thank you ancient kayaker,

Could this tendency be contained to acceptable level through the use of compartments within the same tank?
QUOTE]

Sloshing of fluids in moving tanks is generally controlled by baffles which works for short term sideways acceleration while a vehicle rounds a corner for example. In a boat where the direction of gravity can be off-axis indefinitely while heeling you have a different situation.

The scheme used by fighter aircraft with fuel in externally-pressurized bags ensures fuel reaches the fuel pickup port but doesn't control sloshing too well.

Several tanks of different sizes could be used, say in 1:2:4 ratios, which would allow you to increment water ballast in steps from 1 to 7. Problem is, increasing ballast from say 3 to 4 involves water entering or leaving all 3 tanks at once.

Alternatively you could have 7 tanks of equal capacity and fill/empty them one at a time; involves a bit more plumbing. The same arrangement is needed on both sides. If the tanks' overall length is comparable with the boat's you might have a problem with fore-aft trim, which would involve adding yet more tanks or a return to tank-to-tank pumping.

These are only illustrations not necessarily what you might want to do, but they are unlikely to be a practical solution IMO.

Originally Posted by xarax

There is none!

The hull is by no means beamy! It is the opposite, a slender hull. And it is not a fast type of hull either, its just a semi nothing more. The instability capsized comes mainly from heavy engines, very heavy bottom structure and equipment, the superstructure is not raised too much. And is pretty heavy too! These boats are built to stand a capsize with the structure grounding!
The predecessors have proven that several times when they were cought by a grounding sea on the shallows of the North Sea.

Dunno what that is

here you again ask for the impossible

Live with it, nice thoughts no result! And that has nothing to do with being overly conservative or thinking oldfashioned.
(conservative we have to be, we are responsible for the lives at sea, adventureous games have no place in our business)

It is just a tested and proven fact, water ballast is nonsense in a bluewater boat.

And you will definetively not change that, no matter how many attempts, no matter which way round you try to solve a non existing problem. See it so:
Your Porsche is not the best performer, Whooshs Mondeo wins the trophy, when my refrigerator has to be transported.

[xarax]

Originally Posted by apex1

r does´nt mean we have a lack of knowledge in that speed range.

I was replying to a remark of Pierre R. about mathematical equations. I should have said that we do not have complete, mathematical knowledge, not yet, and this is the meaning of the words of Leo Lauzauskas. Knowledge is a very wide word, a truly planning word on the semantic sea! Most of our knowledge still comes from crude experiments, and past experience. This is not the kind of scientific knowledge Pierre R. suggests that is excluding wide semi displacement water ballasted hulls from been used on blue water boats. I am sure that even in the case of testing very sophisticated vessels, as these lifeboats, when they perform their final tests on them, the chief engineers are holding their breath and their fingers crossed! It needs only a frozen O-ring to kill all people aboard a complex vehicle......

[ancient kayaker]

Originally Posted by xarax

I was refering to the highest authority on heavens ...

... that would be the moderator in this context

Originally Posted by whoosh

happy to see the name calling and stuff has stopped and the thread is attracting some great posts
...

-me too!

Originally Posted by whoosh

...It is a pity that someone with over 800 pts chose to wipe all Xaraxs, points, simply becuse he disagreed ...

I strongly disagree with the entire concept of negative points.

[Pierre R]

Xarax the equations may not be exacting science but they do point you in the right direction. I can come pretty darn close on what to expect at semi displacement speeds out of a boat.

[xarax]

Originally Posted by apex1

The hull is by no means beamy! It is the opposite, a slender hull. And it is not a fast type of hull either, its just a semi nothing more.

Well, it looks quite beamy to me, compared with the hull of a traditional motorsailer, or of the slender hull of a motorboat like this :
http://www.rangeboat.com/index.php
designed by Nigel Irens. And when I say fast, I mean faster than the pure displacement speed. the 47 ft MLB travels at around 25 knots,
http://www.dtic.mil/cgi-bin/GetTRDoc...c=GetTRDoc.pdf ( see also its righting moment / heel on page 15 )
so does the 52 ft "trawler" like Beneteau, but the traditional Nordhavn 57 motorsailer, (that costs a fortune), drags its old lead foot at 9 knots !

[xarax]

Originally Posted by Stumble

1) Speed desired under sail and power
2) Range under power
3) Ability to handle what type of conditions (lake cruising or open ocean weather)
4) Self righting from a rollover, or just to some % of heel
5) Length
6) Draft maximum
7) Max beam
Living accommodations

As I have said earlier, if we want specific numbers we have to look at specific existing boats and figure out the market and engineering window.
The Beneteau Swifttrawler 52, the Nordhavn 56 MS and the 47 ft MLB of the US Coast Guard are completely different vessels, but of similar dimensions of what concerns us here. So :
1a) Speed under power : This is entirely unknown at this phase. We want a semi displacement, quite beamy hull (with large wetted area compared to a sailboat), to be propelled by a rig of low centre of effort, ( because our water ballast system would be less efficient than a lead keel ), so probably a schooner rig , or any other two mast configuration. Speed under sail and windward ability are of less importance than:
1b) speed under power. Now THIS is the fill or kill order of the whole idea. The above mentioned fast boats move their 50 ft and 20 tons at around 25 knots.
2) Range under power : As a motorsailer that can also use its sails, the range under power is of less importance than in the case of a passagemaker, a trawler or any other type of bluewater motorboat. 1000 miles at 9 knots, or 500 at 18 knots would be fine, I guess.
3) Trans Atlantic voyager, needs to handle conditions that can not be predicted by weather forecast and avoided by sailing away.
4) Self righting from a rollover in 1-1,5 minutes maximum.
5) Length : 50-60 ft LOA
6) Draft : 1.5 m
7) Beam : 5 m
Living accommodations for 2 couples,owner + guest, a captain and possibly 1 crew member.

[Stumble]

Xarax,

Buy a Bertram 510 and stick a 30' carbon fiber rig in the boat (Melgeus 24 rig should be about right). Since you don't care about sailing characteristics, then this is just another semi-planing hull power boat with a get home/stabalizing rig onboard. Then add a swing down dagger board and oversized rudder and be done with it.

[xarax]

Originally Posted by Stumble

Xarax,
Buy a Bertram 510 and stick a 30' carbon fiber rig on the boat...

Stumble,
Would you manage to hold it upright with the 'sail"'of your ( water ballasted AND self righting ) Unterseeboot ( and apex1 on helm ), or do I have to install a little nice water ballasted self righting system on board of my Bertam instead ?

[Guest62110524]

Originally Posted by apex1

Be sure it is a photo Stu! And if you go one page back you will find more info.

And I do´nt think it was only one high scored member to wipe Xarax´s points, when you have followed the thread you could have seen there have been several completely disagreeing. Me included.

yes was ONE, I posted Xarax,(who got under your skin) pos, he was 26, next second he was 2, I know from where that came, and he should be very ashamed
XARAX ranks as one of the most intelligent men I have ever met, he was testing you guys and he won hands down, he was never vulgar or rude as you yourself were
HE may not be the brilliant rocket sci , but he is far better than me or you
he offered me his beach home, for free, and I have known him a long time
i feel humbled in his presence, on the other hand many (high pts people) have yet to earn my respect
Tom Speers, Ric, ancient kyakkerr, Guillermo, Matt, Mike J, all have that respect

[john.G]

water ballast ... motor ... sails ... self righting ... easily modified to class 3A requirements ... and I like it!!!

http://www.dixdesign.com/cargo50.htm

Oh yeah, it can't be done right?!?!

[FAST FRED]

1000 miles at 9 knots, or 500 at 18 knots would be fine,


More likely to be 200 miles at 18K, IF that's acceptable , your task is easy.

FF

[Pierre R]

Xarax what kind of speed are you looking for under sail?