SWATH resistance predictions using Michlet

They are fascinating from a wave resistance aspect, too.
Are there any in service now, apart from the Lockheed original?

One feature I thought interesting was the ability to add another strut+pod
between the aft pair. Has anyone tried this sort of modification on a full-size
SLICE?

 

There are 2 in Mexico, Tenez and Lider are their names.

You mean have 5 strut/pods?

 

Yes. I have a short report touting that as one advantage of SLICE.
To carry extra cargo, operators can "simply" drop in another strut and pod.

Personally, I imagine that it is not as easy as all that.
There will obviously be knock-on effects on resistance and motions, and the
cross-structure would have to be able to cope with the additional loads.

 

Correct.

Their myopic gain, in buoyancy, for increase payload capacity marrs the myriad of losses it would suffer from, by the adding of a hull/pod.

For starters, it would only effect heave and pitch and only marginally at best.

SWATHs are not really designed for high payload as %'age compared to other multi hulls. SWATHs do one thing and only one thing well...seakeeping! As soon as you add other things into the equation it slowly degrades and compromises the seakeeping. SLICE is a classic example. Probably best seakeeping vessel ever made, yet at what cost!....very very expensive, slow, (for its size) the gear boxes are unique to that hull and have a lead time of 12 months....so you'd better have a spare, which means $1-2million dead cash etc etc....see what I mean? Hence a decent SOR is required first. As "normal" SWATHs can do much better, all round that is.

 

Apart from that, the structure must be strong enough to cope with the
occasional addition of the 5th leg. That means carting around additional
structual weight most of the time.
It just doesn't smell right.

I'll be interested to see the powering required for a 50 knot SWATH and
how much it can carry.
Bill McF: Are you free to disclose rough estimates of full load displacement
and powering?

 

There is the obvious too...which is over looked.

Looking at the pictures of Lider/Tenez,...er...where can you fit another hull?

Ahh..extend the main deck...oh..a redesign!

I'd be interested in the displacement and powering too at 50knots, see how it compares to ours at 40knots.

 

To be fair, the modification I saw was for a working vessel with a moonpool in
the centre. I'll try to find, scan and post the article here.

 

Unfortunately, I'm not. NDAs in abundance and all that. I can tell you this much though, so you don't think you are missing out on the 'mother load' of any paradigm-shattering envelope-busting data :

The prototype is very small, less than 20m LOA...and attempts to achieve the higher design speeds have not even been made yet.

Stay tuned...and I do appreciate you posting those papers; every bit of information regarding a "high speed" SWATH design is usefull to us at this point in the effort. And goodness knows, getting anything out of John is worse than pulling teeth from a lion..

 

Here's another one from 2009 on resistance prediction of high-speed SWATH.

 

Thanks Leo.

Technically, this isn't a SWATH at all, just a rounded hull form with a shape that looks at first like a SWATH but is in reality just a catamaran with a lot of shape.

 

Leo, are the singularity strengths of one hull of a multihull vessel in Michlet altered by the presence of the the other hulls, or are the singularity strengths of one hull what they would if that hull was the hull of a monohull vessel?

 

The latter, David.

I have been thinking of what to do to improve the model, but it is not as
simple as just modifying source strengths. In finite depth, finite width
towing tanks, bores can form between hulls, and solitons can shoot out
ahead of the vessel. That's tough to model! I have all the mathematical
work needed to include Havelock vortices in some models, but I don't have
much incentive (or time) to implement it all.

There are also some viscous interference effects when demihulls are closely
spaced. I am trying to include that in Flotilla. (It would be messier in
Michlet which can have up to 5 demihulls in any arrangement.)

 

Attached is a short article about the SLICE.
It seems that the ability to increase passengers from 250 to 400 by simply
adding a 5th pod has yet to be realised.

 

A classic example of a press release. More spin than substance.

There are only 2 SWATHs in the world that have successfully achieved 30knots or more on a regular service time table, SLICE is not one of them.

The hull form is also not capable of 30-35knots, well unless you can find GTs that don't consume so much power it doesn't take up all the available space for fuel nor weigh the boat down that its over weight to begin with!!

 

Now why does that last sentence sound familiar?

lol

-Tom