masalai's model movie

Not far off what Rick Willoughby suggested, 10kw per hull I guess as the hull beam has to be at least 600mm to fit the engines JUST - Lombardini has some 2, & 3, cylinder engines and turbocharged options to waste your money on excess power. I am looking at the power-train as promoted at www.africancats.com - upload this - http://www.africancats.com/resources/documents/PRESS_GreenMotion_ENG1467.pdf

You can draw your own by downloading from here http://freeship-plus.pisem.su/indexEN.html and click on "support" then "downloads" this site is usually FULL of popups - ignore all of them, read all the content and ensure you download an English version, and find the pdf manuals in English too - - Have fun... There are several threads on FreeShip, a search of this net will find them...

Have fun... Screws are better as efficiency can be enhanced - read Rick Willoughby on propeller efficiency...

 

Here is an image of a simply developable version of the hull.

Despite what some think about water having difficulty negotiating an abrupt transition it does not make much difference with slender hulls. The boat shown will require same power as the fully faired hull to do 20kts and 10% more to do 10kts.

The other way to make it simply developable is to make it hard chined. A single chine would work OK.


Rick W.

 

Thanks Rick, The thoughts and ideas from everyone are appreciated. - My most recent version (post 82 and 87) are the hard chine version and about 11m, are about to be superseded - I have downloaded another cad package set up for hard chine design - I will see if that makes "developability" easier... for a hard chine version...

Charlie, I am still sorting out the concept and it relies on the stern being of "fixed" depth to work properly and variations in load less significant at the other end down to design waterline so as fuel is used, ballast (fresh water) is made and pumped into tanks mid and forard to maintain ideal displacement range... (I think)?

 

Hi Masalai,

I received your .fef file and imported it into FreeShip 2.6 ... and when the images came on-screen I saw a trimaran with three identical hulls!

I'm guessing that you may have had the "Show both sides of the model" button turned off when you made it. I couldn't get it to give me a proper set of numbers as imported so I moved things around and deleted the extra faces until I had converted it into a proper catamaran. Then I got interested in working on it some more, so I decided to simplify the model even further. It's a lot easier to work on now, and it is attached if you want to take a look at it in your newer version of FreeShip.

I figured you're going to want to install the rudders on the transoms, but the aft ends of the box keels were aligned with the transoms, and this leaves no room for the propeller in between them. So I moved the aft ends of the box keels forward about a foot, thinking that the propellers will be located here.

When I use "Mode > Developability check" there are places shown in red as you can see in the second image attachment. This usually means 'not developable" ... but this is deceiving in this case because these surfaces actually are developable. It's just that to make the software show them as developable would mean adding a bunch of new control points and lines, and this makes fairing a hassle. I prefer to let the software fair the surfaces itself, so I'm not concerned about the red areas ... and you can rest assured that the surfaces shown in red will not create any problems during construction. because they really are developable ...

One thing I did which possibly changes your hulls a little bit is to insure that there is a clear 'step' in the hulls between the lower and upper sections. I ran this step from the bowstems all the way to the transoms in virtually a straight line. My idea here is to create what is effectively a 'splash rail' which should help to keep the spray down. It also helps to reduce hobby-horse motion in rolling swells.

Since the entire boat is designed to be supported by its lower hulls, I see no reason why you cannot make the upper hulls much wider than they are. I widened the upper hulls an inch or so because this was the easiest way for me to simplify the model, but what I'm suggesting here is that you can probably make them 3-6 inches wider yet if you want to. This won't add much to the construction costs or total weight of the boat, but it will give you more hull interior.

The step in these hulls make them stronger, and that's a good thing when building long, slim hulls. They would be much weaker without this step, and this should help to reduce or eliminate the need for more structural components inside the hulls.

If you're concerned about the flat bottoms of the upper hull sections slapping when they come down onto the tops of waves, I suppose you could angle them a bit instead of leaving them flat. But given the fact that there's so little surface area here anyways, I don't think that angling them is worth the effort. Angling them will make the construction more difficult and time consuming too.

I think this is a very interesting idea. In this case those stepped hulls will come in very handy if you use them as purge-able water ballast chambers.

Note that the lower hulls can be built completely separate from the upper hulls. The upper hulls can have their own hull bottoms, and the lower sections can have their own tops. Then they can be fastened to each other at any time before you finish the boat. I created a perfectly straight flat surface in this model where these two hull sections would come together, so it would be a cinch to attach them to each other after they have been built ... and if you ever holed (or lost) the lower hull sections your boat would still float. What a great safely feature!

I ended up with about 500 pounds more displacement at 1.5' of draft than in your model. This is more or less the height of the bottom of the upper hull section at the transom. You can check the calculations in the attached image.

I have attached the .fbm file I used to generate these images. It was produced by FreeShip 2.6 but I think newer versions can open files created by order versions, so you should have no trouble opening it directly.

 

By the way, thanks for the link to Blender:

http://www.blender.org/

I use PCLinuxOS and it was right there in the Synaptic repository so I've already downloaded and installed it. Now all I have to do is find some time to play with it and see what it can do ...

 

Kenneth, I had given up on getting it sorted as I kept on getting "holes" and "kinks" and chines where I do not want which would not go away - AAArrrrrrrrrggggggh !!! so tried another direction and placed each point ONE by ONE then extending to gradually getting it almost there then several "invisible holes" appeared which the system said I had but no end of re-positioning the respective points could I overcome, - So I deleted all of the last 4 hours in effort......... argh again...

What you have done looks FANTASTIC,,, - I had opted to stick the Africancats retracting engine/screw but thanks as your effort will keep both options open...

 

Wow, that's a lot of work!

Thanks, I'm glad you like what I did to it, but you're the one who did all the work, all I did was clean it up and simplify it a bit.

I'm not familiar with that drive system but it sounds expensive. This hull would prevent prop and rudder damage using a simple, cheap, common inboard engine installation.

 

This is the pdf illustrating the retracting electric drive

From the trials using my rough model, I had found that the "spray rail/step" was only necessary about a third way back, but it must be about 2 inches/50mm wide and Definately at the bow... midships inside was taken care of by the 45 degree chamfer which it joined. The aft "box section was to be trimmed down to make a "spoon" or step access and hang the rudders off the pointy end of the hull - The drawing was the start of a motorsailor version using a "hitchhiker rig" with NO mainsail only roller genoas off each bow. That one I posted had leaks and tweaks/pinches which would NOT dissappear. same problem as with other things as mentioned above - maybe I am doing things around the wrong way. - - somewhat of a slow learner...

 

I can understand this, so it is certainly not necessary to have a full length step there. Nevertheless I made it full length for three reasons -- first it was easier to do in the software, second it makes for easier construction, and three because it makes a stronger hull.

This means you'd have to use 'barn door rudders', right? There's nothing wrong with this type of rudder but they are not balanced so it takes more control pressure to move them.

I was thinking that you'd probably want to use balanced rudders extending down from the transom to a shoe (something like a piece of stainless steel flat bar) that connects the bottom aft end of the box keel with the bottom of the rudder post. Then again I didn't know about your plans for modification of the transom area.

If you go with a traditional inboard engine / shaft / propeller, and assuming you still want the transom like you described it here, it may make sense to move the aft end of the box keel and the propeller forward another foot or two, or extend the upper portion of the hull aft the same distance. Then you can use a spade rudder aft of the propeller with your rrdder behind it, and your transom step will still be behind the aft end of the rudder.

Or better yet, why not leave the rudder 'sticking out' past the end of the transom and cut a slot in it for an underwater step up to your transom steps. This would make it easier to board the boat, especially for folks who aren't quite as limber as they used to be in their younger days. It's always nice to know that there's a re-boarding ladder built into your rudder, because it will always be there when you need it ...

 

True Kenneth, many things to consider, Thanks for the feedback and ideas... Time is something I have plenty of - and I hope that advantage will persist and that new lightweight high capacity batteries will become available at reasonable $$$ - A lot of other things are happening - technology wise, environmentally and every other which way...

Given some time and inclination, I will put your information, ideas and integrate this into next iteration in a new computer coming Monday or Tuesday - This one is too slow for serious number crunching & I have got to like 2 screens - new will be twins, hopefully making life easier for this old fart...

 

Hi sean, I am not real good at this computer cad thing so just do parts, and never get to be satisfied with the part done so do not progress too far to show the whole picture. I have a fair idea what I want - in my mind. - - Its just a matter of getting it into this stupid cad application so it will present it as I visualise in my head.

I will get there in the end (before I need to present my desires for a "get-real" assessment by a friendly NA...)

Also, I am still sorting out my priorities and objectives - to meet my longing, and yet, not displease my lady love too much...

 

The Weather Is Nice Here

Hello...

Sorry - I am trying to monitor myself - I should just give it all up...

Stop trying to conform to the software or look for software that works as you see things - me - I like Rhino - still took a year and half to get half way...

The arguement is - there is no one way to communicate form or thought - DO WHAT YOU KNOW...

Get it out there - carve stone - wood - or plastimorphic goo - that is what the engineers do..

SH.

 

you cant get Far in freeship, once you finished lines
I offered other programmes
you can start in Maxsurf, because there you can pull around surfaces. once there you can do all your eng structure in Rhino You say you wont shift off linux, so how can you progress? understand I am only letting you borrow these things for a day) and you cant make copy,
I have ground away at this thing now for 2 years maybe
more, and it is tuff, but you have the time
i suggest, that you find someone to tutor you through a messenger, yahoo works the bestest, then msn, use sound and microphone

 

Tooter Smooter...

Hello...

I am OK - thanks...

Masi - I imagine that the original question that I deleted or attached **** (or LUCY PINDER in Navy shorts) to was as follows - what is this thing intended for - a cheap *** condo run away from the wife - or run to with the wife...

Either way - it is worth exploration - me - I am tired - bored - about to lose my day job - not scared of same - just doodling boats on my time and floating about in the flotsam...

What is the 'brief' for your crazy big *** cat...

As for contemporary installation of high output turbo diesels in those narrow hulls - a shaft log - a shaft bearing - a cutlass bearing - sea water feed for same (STRONG seals) - well - think of servicablility - changing the Racors - the oil filters - any hydro coolers - cleaning sea strainers - augh...

Let me just spit - random thoughts - sail drives are a pain - perhaps volvo IPS - or aft facing Mercs - random thoughts - it is Saturday night - a blue collar rite...

Electrics - hell of a lot of area for collector panels if you intend to go per your first model - all DC - very easy stuff..

Even a hydraulic hybrid...

Just random thoughts...

SH.

 

Danish And German...

Hello...

Really depressed all the time and really angry about it too...

I don't know if this is a Tennant boat or other - sitting in the yard just now ...

HOLY CRAP IS THIS OLD - see http://frankscorner.org/index.php?p=rhino3d ...

Email McNeel with your request for a linux or whatever based version of Rhino - many have...

http://www.youtube.com/watch?v=qgYvmSYtO20&feature=related

SH.