hull #470 build

[mirjo]

hi everybody!

i have registered to the forums some time ago, but never posted, just studied the matter, and got pretty familiar with member's builds, along with the problems and solutions
i'm Croatian, one of a couple of builders, and can't wait to join the others in my country that have finished their builds
i attached the photo of the build so far (it's been 4 months since we started)



i must point out that this online community has been a great help to our build, the way you share your experience and the amount of info is fantastic!
we've solved some of the problems ourselves, but from now on i'll definitely seek some advice from you guys

for the beginning, since Chad turned out to be the most inventive builder ( and most patient one i guess), the first one goes to him
since i got a CNC machine on the hand at a VERY good price, i plan to make the bulb mould out of wood, and pour in one piece
do you have some kind of .DXF or other type of vector file for the assy bulb?
what do you all think about idea anyway?

all infos very much appreciated

cheers

Miro

[Chad]

Hi,
I've been asked this a few times. I draw houses for a living, and the CAD software I use isn't well optimized for the organic shapes of boats- I can get by with the i550 because of its sorta planar shapes, but the bulb is a real kludge. The 3d visual model I made isn't very geometrically pure, nor in a format that could be easily used by a CNC. The 2d shapes (thin plywood) for the bulb plug's "skeleton" could be easily cut with a CNC though. That would save several hours of hand cutting and shaping. Once the skeleton goes together, filling the voids with foam and shaping it is very quick, easy, and satisfying.

I'd be happy to send what I have and you can see how it might suit you. Let me know...

[admin]

I am not a chemist, but if I remember correctly, the flash point of most woods is well below the melting point of lead. I would make the plug for the mold out of wood, but not the mold itself. That sounds like a prescription for disaster...but definitely do not go on my opinion alone!

Thanks a million of the link to your photos, the boat looks great! I like the liberal use of carbon fiber in some areas and wish I had used some of your construction methods.

Best of luck the rest of the project, Miro! And Croatia may have to host the i550 Worlds some day!

[mirjo]

ha ha
i love the idea of i550 worlds here, we only need to organize national c'ship first!
which might actually happen this year

re wood mould, some older fisherman here have been pouring fishing lead successfully
and i think a layer or two of the aluminum thin foil should help
i understood that wood only needs to be very dry
anyway, i wanted to try something different, and it appears to me a little better solution than 2 halves option, so if it fails, there are quite a few methods that are well proven

Chad, do you think 2D files could be somehow imported in other CAD software, "assemble" the pieces as per given distances along the spine to create a 3D shape?
my friend the CNC guy said it might be possible to convert pdf drawings into something useful and tracing the points along each section, but would last forever

[mirjo]

was there an i550 worlds held so far anyway?

[Chad]

No, no "worlds" held anywhere, yet.

Some folk brush diluted gypsum (very thin drywall mud) on wood molds to reduce the charring, and that seems to work.

That's basically what I've done- assemble the profiles in a computer and use longitudinal splines to create an interpolated surface. Problem is, there are lots of mathematical "splines" out there, and the folks that built my software had different ideas about spline coding than the folks that design boat software. Horses for courses...

I can send you dxf files of what I have, and let you decide what's the easiest way to proceed. Shoot me a PM with your email address...

[mirjo]

PM sent
hopefully i'll get to something, at least i'll cut the sections for the male mould
the thing is, i have to downsize it to 70kg because of the heavy keel fin
good clue for the wall mud

thanks for your help

[mirjo]

Sooo,
as i mentioned , we were at the full stop for more than 8 months due to the season
Where i come from, tourism is the only industry, and it doesn't last all year so you gotta make enough money to make through the winter
We've continued the build some 3 weeks ago, and here are the results

BulbK18.jpg

WP_20131108_003.jpg

WP_20131114_005.jpg

WP_20131120_003.jpg

WP_20131120_003.jpg

WP_20131120_011.jpg

finishing the keel was a big milestone, as now we can laminate the sleeve
we have pretty much cut all the remaining pieces to measure, but we need the sleeve to install and finish the decks and cockpit
the build has stretched much more than we thought, but the good news is that exactly one year ago we have pulled first zipties

I see you're trying to work out things between NAca and Class rules, i think that's good thing
I was guided by Class rules and plans, but who knows what the boat will measure in the end

Cheers

[jray]

Thanks for the pictures and update. Looking good!

[micah202]

.

.....that keel-fin looks -SUPERB-!!!
..........is it hollow,,,glassed?.......good technology if it is.

....Can I suggest that people think twice about making a tight sleeve for the keel-box please----you probably won't have issues with the keel expanding like some wood-keels do,,,,but those tight trunks are a beyotch for raising,,lowering the keel if there's not a perfect column between the 2 there'll be some gription,,,,,and if you ever hit bottom,,,you could make some nasty damage.

.....I suggest a larger rectangle box,,with some type of breakaway feature,,,such as slots on the side of the trunk,,and tabs that fit the slots,,which are attached with bolts to the keel....if the keel hits bottom hard enough,,a bolt can sheer,,,keel move in trunk without damage to either!
....you can find some pics of what I'm describing at....... http://www.flickr.com/photos/59103003@N ... 076955693/ .......4th row down,,,there's more description if you click on the picture

...happy building,,,sailing!!!!

[ryderp]

After my binding keel issue, I agree strongly with adding some extra room in the keel sleeve. My keel box/sleeve setup is now so overbuilt, that I'm not worried about damaging the boat. I actually did glance off of a rock in Maine last summer which took a chunk out of the lead bulb and which dented the trailing edge of the foil. I'm thinking about re-fairing the back edge of the foil where it meets the bottom of the keel sleeve with a crushable material to soften any kind of future underwater collision.

Phil

[mirjo]

Thanks for the advice, but i really don't plan to go aground, we sail in a deep sea waters
i like the idea of the teflon (or delrin) wedges, though
Keel fin is laminated 20mm oak strips, CNC shaped and covered with a layer of 200gr carbon cloth (so we can tell somebody there's carbon built in
if we try to sell it one day )
keel box surrounding area khas been doubled already, so i have no fear of inadequate strength

the clearance between the keel and the sleeve was my question to my Croatian fellow builders just a few days ago
it looks like there's a consensus about 1-1.5 mm being enough to raise with no major problems

it's so cold here last 2 days, we need to take cqare of the heating

[micah202]

.

....you're going to install heaters???!!..........nice touch!!!