Power multihull

[taniwha]

How seaworthy are power cats?
When will be the first circumnavigation by a serie production powercat? I am not talking of extreme design such as earthrace but just regular affordable powerctas under 45'.

[CORMERAN]

To taniwha :

I have designed and built, both: Power Cats and Power Trimarans.
That are all seaworthy vessels.

That is not the issue.

If you check out all the 'round the world, record holders over
the last few years - sail or power - you will find many similarities.

First: - they are pretty well, all over 45 ft.
( 80 to 100 ft is the general range.)
When you're in the Southern Ocean
......size DOES matter !

Second: - they are ALL, custom made boats.
( See above. You don't want a production boat,
built down to a price, when you are far from land.)

Third: - power boats are thirsty beasts.
( Even multi - hull power boats.)
It is hard to get big enough fuel tanks
into a 45' vessel - to cross an ocean - and still
have room for a crew.

Finaly; Earthrace looks Rad..........However, it follows some
very basic and essential rules:

As above:
- About 80 ft overall.
- Custom made. Very light; but STRONG
construction - out of carbon fiber.
- Very long and thin hulls that will give excellent
fuel efficiency.

Cheers !

[catmando2]

Hi guys,a couple of comments. we're doing a fifty foot powercat at moment that will have a 2000 + nm range. She will be light, around 4700kg dry and low powered,65hp each side, so not that thirsty, doing around 10kn. . We have no intention of doing southern ocean work in her but I will have no problems doing trips out to Vanuatu and New Caledonia in her.

Like Coremeran says, you won't get a boat like this of the shelf, we're building ourselves.

Have a look in photo gallery

Dave

[CORMERAN]

To catmando2:

Your vessel looks fine and your specs. are appropriate
to LONG range travel.
Also, you indicate a reasonable and seamanlike attitude,
to the realities of going offshore.

However, taniwa, used the ambitous word: " circumnavigation ".
So I was gently suggesting, that successfull circumnavigators
- historicaly - tend to lean towards longer craft.

It's true, a few brave souls have gone 'round the world,
in pretty tiny boats.
- And the reason their voyages are celebrated, is the proof
in it's self, as to how risky such an endevour can be.

Cheers !

[catmando2]

Indeed you are right coremeran, cicumnavigation is the word used, but does that mean it has to be a non stop trip or can we coastal hop until getting to jump off point. And yes. I reckon id love to have a forty foot acommidation cat on 80 ft hulls,but gee 50ft was as big as I could get in the back yard. + don't have the bottomless pit of money so 50ft sounds just fine and dandy.

Dave

[CORMERAN]

To catmando2:

We appreciate that you are working to the limits of
your situation.
Also, you are right - what are the terms of reference ?

The 80 footers I was referring to, are mostly, in respect
to people trying to break records. If you take away the
urgency of the a time element - this gives you a lot
more leeway.

Also: 50' doesn't sound much different than 45' to the
layperson.........but it is.
- Given that everything about boats seems to be
mulitiplied by either the square or cube root.......
...and a cat has 2 hulls....

- The load w.l. length can be seen as being increased,
in effect, up to 10 ft.
- and presuming a single hull beam of not more than 10 %
or 12%, of each hull's w.l. beam = maybe 4' ?
- with a draft of approx. 18" to 2' ?
That gives you potential increase in fuel tank cap.
over a 45' cat of:

- At least, 1.5' x 4' x 10' = 60 cubic feet.

So at your conservative projected cruise of 10 knots, that
gives you a lifesaving, increase in range
- over a 45' long vessel.

Good luck in your endevour.

[catmando2]

Did'nt think 80 footers applied to the real world

Dave

[taniwha]

When I say circumnavigation I actually mean longer distances. I have no problem in circumnavigating in 2 or 3 years. Or in 25 weeks such as a Nordhavn 40 Off-The-Shelf or such as the Buehler 50 footer aluminium dieselduck Idlewild with 50 hp !!! Look at trawler web.com or dieselducks.com and you will find plenty people circumnavigating under power. From the multihull builder I hear only that they boat CAN do it or will do it. I only wonder who is going to do it. I do not trust the brochures when the Nordhavn rally crossed the atlantic with 19 trawler they really made their point. If I see 19 power multihull crossing the Atlantic I might consider buying one.

[CORMERAN]

To taniwa:

I was born in South Africa. Therefore, I have,
I flatter myself, an understanding of the South African mindset.
So, I will not be so foolish as to stand in your way
- or try to discourage you - if you have set your sights
on an adventure.

As a designer, I concurr with your unwillingness to
accept at face value what people's brochures say.
Many lay people do not realize that there can be
enourmous differences between one multi - hull
and another.

- Are they:
- Hard chine, planing hulls ?
- Round chine, displacement hulls ?
- Fat beamed hulls that get filled up, with heavy " essentials " ?

However, if I am personaly involved, the vessel
designed by me - WILL be capable of off - shore voyages.

i.e.
I designed a SEAWORTHY multi - hull ferry, that was intended
to take people through very rough seas - to a former prison.
Formerly the residence of a famous S.A. president.
I'm sure you have heard of him.

Speaking of said, rough water:
I would strongly suggest that you put the brochures aside,
turn off the computer - and get some of the reps.
of the various vessels considered - to take you for some
demo rides off - shore, in those same waters.
Not far from your front door - is some of the worst conditons
a vessel will ever face.

I have never been reluctant to prove the capability
of MY boats to potential clients.

One memorable time, after jumping waves at twice the speed
of any other vessel brave enough to go out to sea - that
stormy day - my client became an instant beliver.
As soon as we tied up at the dock - and his knees stopped
shaking - he quickly wrote out a cheque to retain our services.

As our American cousins say:

Money talks - and B.S. walks !

Cheers and good luck !

[tgwhite]

A great read is the setsail website by Steve and Linda Dashew. Lots of good information showing the design parameters of the monohull WINDHORSE. I posed the question to Steve, "Why not a cat design hull?" His answer was about lilke this - "For circumnavigation the hull connections are in the big waves and receiving loads that require massive and heavy structures to keep the boat from breaking up."

Further he says, a circumnavigation designed power cat is not fuel efficient thus requiring big tankage as compared to a long thin monhull. Steve puts his money where his mouth is and has greatly advanced the business of hull design, sail vs power and safety at sea. I daresay he has more miles under his bottom than any other power cruser of the last few decades.

PS -I own no stock in his enterprises.

[taniwha]

well at least Steve Dashew went at sea with his own design now if he could make his design affordable it would be perfect. Again I wonder when the multihulls guys are going to go around. Cormeran shall we take uo the challenge?

[FAST FRED]

"now if he could make his design affordable it would be perfect. "

Smaller boats cost less , how big does it really need to be?

FAST FRED

[taniwha]

around 44ft, big enough to liveaboard, small enough to handle with two and kind of affordable.

[CORMERAN]

To tgwhite:

One thing Mr. Dashew and I agree on is:

- LONG and THIN !!

.....wether 'tis mono or multi.

I will admit I have a fondness for multi - hulls.

However, I also agree with Mr. Dashew - re:
the interconnections he is concerned about.
- They are also of great concern to me, as well.

I feel that the design I'm presently working on
- addresses these issues.

Given the proprietry nature of this work in
progress I'm not quite ready to show what I'm
doing..............just yet.
But I will soon.


To taniwa:

My intention IS - to produce the design I refer to
above - and take up the CHALLANGE.
Of some serious off - shore voyages.

Cheers.

[taniwha]

I am definitely looking forward to see your design. I would tend more toward monohull due to their experience but I am definitely an open minded person that why I would love people to demostrate me the offshore capability of a powercat. In 6 months time I will join a delivery of a powercat from Cape Town to the Caribbean which should make me change my mind on multipowercats .....or not.