General comments

That is a good price. Let us know how you go with the purchase.

I thought you had an aversion to plastic?

Exchange rate AUD1 = USD0.84 is looking better as well.

Rick W

 

whoosh. - "dont know where the block should be"

what's a block?

 

i've decided on my hulls.
i'll go planing.


i realise full well every person who reads this would advise against this course of action.


i realise everyone of you here would say good displacement jobbies are the sensible thing to do.





but,

true planing SA/D 37 or above

45m2 sail and 1400kg
500ft^2/2800 pounds heavily loaded 1400kg
= 39.5


light load, 2 people, no water, little fuel 1250kg
500ft^2/2500
= 42.6


so fiona sinclairs generated hull shape optimised for min drag at 11 knots.


and you're all invited
(mooloolaba 12 months from now)

 

To Bob,

Building a catamaran is an expensive thing to do. May I ask most politely why you do not buy an existing design from a professional designer. I think the time saved in materials and build time would much more pay for the cost of the plans, not to mention resale price. Additionally as skilled as any individual may be, a professional that has designed many many catamarans will probably design a better craft.

 

hi Mr Australia.
nice to have anybody who contributes/helps drop in.



to quote from the Wikipedia entry for catamaran

"
There are a lot of folks doing long-distance offshore cruising in monohull yachts of 9m (30 ft) and less. No responsible designer or multihull sailor would recommend this for a multihull. 12m (40 ft) is the minum recommended LOA and 15m (50 ft) is preferred. This size allows adequate storage for necessary cruising equipment and still give you a good turn of speed in comfort and safety.
"



15m (50 ft) is preferred.






Camping.

if you want to visit a national park in australia, to go camping, then a camping vehicle is necessary. a camper van.


there are mosquitoes that carry dengue fever, which can KILL you.
so mosquito netting all around is vital

also,
without water you will DIE!
so water is needed.

a shower is nice, hot water to, tele of course

more people DIE! from food poisoning in australia than car crashes, so a freezer is a necessity.

a microwave makes sense if you have a freezer.

are you old? did you know heat stress kills many old people, so air con is essential (you can truly DIE! without it.

solar panels are vital because we are killing the planet by over consumption

a generator is also needed because you can't realistically run the fridge, microwave, or aircon on solar.



to take all this gear when you go camping to visit nature that hasn't died from climate change (ie the 30% of coral thats left), you'll need some power to SAFELY go uphills, say a 200KW engine? ultra high tech for fuel efficiency, to be extra friendly to the environment, so twin turbo.



So the list of SAFE camper vans is growing shorter

Winnebago!






so i think we've fairly well proved by scientific reasoning that my camper ($800, and built by yours truly) is nothing but a death trap (aaaaaaaaaaaaaaaaaaaargh! etc)




great resale!
Winnebago Wilderness 1998 - Caravans Onsite Australia - Buy sell ...
Price: $135000





Same story in pictorial form
(for the hard of hearing)(so deaf people can enjoy this thread as well)
(the more gifted of you can skip on ahead)


a man wants to go camping,



and quite rightly,
arrives at the same conclusions i did. the (current) apex of human brain power.


TA DA!

the Winnebago.










The End.








"
Additionally as skilled as any individual may be, a professional that has designed many many catamarans will probably design a better craft.
"

i have no doubt they could design a better Winnebago than me. (see that bit on the side!









James Wharram, began designing Polynesian-type catamarans and built Tangaroa, a 23-footer for $420. He then proceeded to cross the Atlantic with it in 1957.

james! the load carrying capacity! leave the girls behind you fool! don't you know about load capacity?
you fool James! come back!!!! it's not 50ft long! aaaaaarrrgghhh!!!! (etc




i know richard hangs out here, and will definitely read this (hi richard!) and i have NO wish to rain on his parade, (thanks again richard for all your help!) but i've seen the astounding effort and hours that go into building one of his designs. have a look at this effort. read the entire thing, look at every photograph. i did.

http://www.navigare.com.ar/construccion_catamaran_27pies_english.html

astounding time and effort just to build a single wooden beam.




i've read other strip plank professional guys who say they can strip plank a hull in one day. n i'm going to do this. one day.

and i've planned the build process so it's almost finished when you turn it over.

2 days so far. )
truly, my planned build process should be astoundingly faster than average. people stick to what they know.





"
Building a catamaran is an expensive thing to do
"
no. building a winnebago is an expensive thing to do.

my cat is $2000 of wood.

?



was James Wharram a fool? his boat wasn't 50ft long, and he overloaded this cramped craft with german backpacker chicks as well. thats two major mistakes he made. he should have read Wikipedia first.
then
worked for another 20 years to get the Winnebago.






i presume from the gist of your mail you love your job (and would rather work than build a boat, and then pay to have somebody build it for you)

me?
i've retired (young) and LOVE having time, rather than responsibilities.
love having fun, rather than carrying weights every day.


to sum it all up,
sex - sure Duece Bigalow (Professional Gigolo) could do it better than me, but i think it's more fun if i do it myself, and i know i'll be much happier, much longer than if he did it for me.

(
Deuce Bigalow: Male Gigolo with Ruth the tourette syndrome girl

http://www.youtube.com/watch?v=XBhlyXQeAL0
)


"think the time saved in materials and build time would much more pay for the cost of the plans,"

well, politely - this place your at, it's called the Boat Design net, not "gimme money dot com"
and it's where guys hangout who are designing their own boats.


if i charged me for my time at my rates, my plans would cost how much?

have a guess.





also,
most politely,
haven't you ever wanted to build your own meal, rather than eat MacDonalds?
why design your own home?
why cook your own meal?


you get exactly what you want.




annnnnd,
Cheers big ears!
mal )

 

Mal
The drag prediction seems way out. Not that it matters a lot. The hulls power quite easily.

Michlet gives a total drag of 904N at 12kts. The lowest drag hulls for this speed requires 834N. Both estimates for calm water of course which only relates to belting along in a sheltered harbour or close to a windward shore.

As far as the transom goes. With a boat this light it will not matter much. You simply move a bit of weight forward to lift the transom in light conditions. I did this in a 3 tonne boat with just crew weight.



Rick

 

Well each to their own I guess

I asked a polite question and got a kinda rambling answer that I tried to follow but found it hard.

From what I could work out, you want to build your cat on an extremely small budget which to me seems difficult to achieve. Well I guess good luck then. I will leave you to it.

call me Peter, you to do not have to call me Mr anything
N Peter Evans
tacking-outrigger.com

 

hi pete.

look at the time you got though!

and all that effort
(to come to the wrong conclusion)


the answer was FUN




it's time.

i've got buckets of time
some people garden with their time because they like doing it.

some people design boats and hang out here. for fun.



we, you and i, have such vastly differing perspectives from which we view the world, that it is astoundingly difficult for us to communicate. no doubt there.


you have to be extra careful what you type. people often take offense at attempts at humour.

yet if we were speaking together, you would not mistake me, because emotional tones, facial expression carry the real base of the conversation, and were we speaking face to face i would have said straight out,

"
don't you realise what a weird thing you've just asked?
like asking on cooking recipes dot com why don't you all go to a restaurant.
"

if this was cooking dot com, how would you reply to the person that asked that question?

lemme know


mal.

 

From what I can gather Bob here has turned this into a ranting of ridiculous concepts, contradictions and imposable to fully comprehend desires. Possibly his personal blog.

Frankly, if he was my client I'd have tossed him out of the office by now and kept the retainer as "frustration factor".

Is there something you need Bob? Will you still need it tomorrow? Just following your posts suggests you're either very foolish and/or very young or possibly needing medication.

You've shown sparks of comprehension, intermixed with gibberish and garbled efforts at humor, weirdness and just plain lack of communicative skill.

If you desire something from a discussion arena of mostly industry professionals, you'll find most success based in responding accordingly. Leave the melodrama at home and attempt your best diction, syntax and analytic philosophy, which can form a base from which to expand your understanding. Currently, I don't think anyone here has a clue what you want or even if you know what you want, which frankly is keeping most away. Clear, concise questions, get the same in reply generally. If not, this thread will die a useless death at least in regard to meaningful answers.

 

rick,

i knew fionas was out,

michlet kept giving me higher answers for a better hull shape (lower drag job)


but the overall gist of her hull shape does match generating lowest amplitude bow wave smeared over the longest wavelength, plus the lowering of drag at 10 knots.


the FreeShip hull file is not finished yet. the nose needs a lot of work, way too thin, then too fat suddenly. Cp.7333 at present. when get hull to .9 drag should drop some more










aversion to plastic?

only professional stuff

(ie cheap ****
polyester, vinylester, cheap, cheaper, cheapest. whatever the market will stand)

my plastic is not polyester fiberglass on foam




i can't think of anything better than epoxy/glass kiri sandwich.

and heavy carbon for the decks? brilliant.


chalk and cheese.
a world of difference.
specially after the first year. foam/polyester boats loose so much stiffness.
epoxy glass wood composite sandwich will have a hundredth? of the stiffness loss? (and i know you were egging me on, just to set me off. ) so there it is.









(
general interest to everybody;

my freeship generated michlet input file flashes up on the screen then disappears, the infamous invalid input file problem. can be quite painful to fix.

but just discovered Delftship 3.2 works perfectly.

generates a working in.mlt
)







can anybody recommend what to do next?

what would you change?

 

Designer?
Seriously.. cheap and light don't fit in the same concept..

 

You have Michlet running. It is not much more effort to run GODZILLA. You can use it to determine the lowest drag hulls for set constraints.

You can use GODZILLA to see what shapes are best under given conditions.

With most cruising cats the minimum beam of the hulls is constrained by the need for accommodation space. If your hulls are only for storage than you can tolerate narrower hulls.

The actual lift you will achieve from your "planing" hulls will be quite small. It will not be useful until you get up over 15kts. Even at 20kts the lift from planing will be less than half the displacement.

The outright speed of a cat on a reach is achieved when it is on the verge of lifting a hull so it is really working as a monohull. The driving force is limited by the beam and the height of the centre of pressure on the sails. The boat is really a monohull with windward ballast. Doing drag analysis for an equally loaded pair of cat hulls for this condition is meaningless.

Going downwind the cat will power over the short seas you get inside the reef off Queensland. You need to consider what happens coming of a wave if you intend to drive hard downwind to make use of your "planing" hulls. Narrow bows with large flare tend to stop when they bury in a wave and the buoyant stern wants to keep riding the wave. The boat becomes a catapult.

Have a look at the amas on the big tris. These are the hulls that count on these big flyers when going hard.

You have eliminated one of the significant constraints cruising cats work within but I do not think you have made the best of this. Narrower hulls will power a little easier for most speeds of interest and points of sailing. It would be worthwhile determining what the lowest drag hulls look like and go from there.

I would be interested to know what foam sandwich boats you have found "soggy". Who built them? I have found that it is easy to get variability in the adhesion so am interested in construction methods and quality assurance procedures used.

Rick W

 

I have no comment on bobs concept other than to say I think its as built (ie. the model) as it ever will be. I recommend a course of Thomas Firth Jones re. minimum cruising requirements. Or a bit of Gilbert for a min Pacific cruiser concept;
http://www.duckworksmagazine.com/04/s/columns/gilbert/010/index.htm

The Wiki catamaran entry is full of misinformation and the quoted source for the 40'minimum 50' better multihull comment is laughable in terms of its commentary on multihulls. The lack of understanding demonstrated is mind boggling.

 

thanks rick

love to hear from you.


done Godzilla (just for the name alone of course!)
done michlets x lots


fall back hulls are/were fat tornado's, they do power easier of course, but as you know, it ain't by much, and i'm willing to wear the difference.


but,
understand plain vanilla and have agonised for a long time being the only person in the world to take this brave course of action. to boldly go etc

"
i realise full well every person who reads this would advise against this course of action.
i realise everyone of you here would say good displacement jobbies are the sensible thing to do.
"

but there are some positives;


fastest acceleration furthest out from a big wave,

best load carrying capacity of any hull shape (load X makes the least difference to the performance of these hulls)

best reserve buoyancy (lifts faster from a big wave than any other shape (except plain flat

some round for a bit of strength

great entry angle (you've seen the wave drag)

no rocker equals longer hulls in terms of passage making

no rocker gives best surfing

and wave drag goes flat real early as you know, and i'm more than happy to have the 3Kg/hull extra viscous drag at such high speeds





of course, normal rockered lowest drag jobbies also have their benefits.






these plans are going to be finished real soon

when they are, i'm going to release them here for the general public.

gunna call them Open Source Cat Plans Version 1.0

the average builder would like plain vanilla hulls a lot more though

you can do this faster than me. if you generate a michlet you're happy with, i'll do full build plans for them.

truly no idea why this web site doesn't already have a hundred plans in a repository from all the guys here.








"
The actual lift you will achieve from your "planing" hulls will be quite small.
"

true. but the hulls aren't finished, and there is no angle of attack on them yet.

i'll probably keep them straight/flat, and have water and fuel all the way aft, people too. this should do the trick. 3 to 400 Kg on the bum for average cruising, so i shouldn't need to put an angle from stem to stern like fionas hull has.




will digest your comments further,
and return after pondering.








"I would be interested to know what foam sandwich boats you have found "soggy". "

haven't you ever walked on any?

specially those that have been around the block a few times.

just go shopping for boats. there are plenty of old soggy polyester/foam jobs out there. at any marina there's always a brokerage with hundreds of boats to walk over in a day.

just walk on some foam and tell me what you think.


(my bias comes from 20 year old polyester fiberglass thats gone sloppy underfoot, so i am extremely biased i admit, and once this happens to you, there's no turning back either.

i've also had polyester/glass surfboards and i could cry when i think of what a true rip off they are. you get a brand new sexy shiny looking board with all the strength of a wet tissue. a leg rope will cause polyester to delaminate.





remember,
i haven't finished digesting yet.

am going away for a few days, will ponder more on narrowness etc (did work out planing lift for surfskis, water skis, wakeboards etc but the basic Pa/m2 story is 90cm wide at 10 knots or above)










jamez
thanks for dropping by.

all are welcome here who help. nice to have your contribution.




thank you all,
mal