Sailboat design

[jedclampit]

BH...
Yes you are correct...I didn't spend much time...just playing on concept...
I would much perfer to have a center table fixed on the mast that would fold away...I've seen this a 100 times...and works well but then you lose the ability to have a double berth...

Anyway if I had the time I would work on a v 2.2...but I have my own projects...

Good luck and thanks...

[FAST FRED]

"just for cruising"

If cruising is your desire starting with a race boat hull is a disaster.

Seakindly and seaworthy are far more important than .0001K or a low "rating".

First take a look at all the numbers , after the boat has an extra ton of "Cruising needs" placed aboard , and see where she sits.

FAST FRED

[solrac]

hi guys,
when I started this crazy idea of homebuilding a 33ft sailboat, about 2003, started searching the net for a starting point, and found (as I told on my first posts) an interesting info from someone in Sweden, who was on the same idea.
Well, the Swedish guy (Henrik) has completed the job, and posted a page with all the stuff. surprisingly, found today his internet page with the original sailboat from where I took the idea. (mmm, honestly I took some more than the idea, drawn the hull lines as similar as possible to the original model)

http://web.telia.com/~u21114029/#

[bhnautika]

Solrac I now see the problem, I think you are losing the fairness of the hull in translation from one to the other. I was wondering if the model you posted in thread nine was done in Autocad. I put a surface over your lines, then put a Gaussian Curvature map over the surface (see JPG) as you can see the bow section has a lot of lumps and hollows in it (red=hollow, blue=curve). If you like I can clean this up for you and maybe supply some more 3D lines.

[solrac]

bhnautika: thanks for your offer, would appreciate it too much, but think I must try it by miself. otherwise (abusing from you and the rest) will be something like stealing someone´s design....
The original lines I took from the net, were aproximated from an JPG image, then translated to autocad, scaled & retouched to fit a couple of spline curves & finally surfaced in Autocad. I´m conscious the result is not as good as a result of the freeship design proggie, but on those times I´ve never heared of it. last week downloaded the freeship v2.4 program & still familiarizing with it. promise for the weekend to post a new hull result surface and arrange of the cad model.(in advance preliminary hull results, lack of some severe hammer retouch...)
thanks again.

[bhnautika]

No worries. Like to see the new hull when you’re ready

[MikeJohns]

Solrac

I don't want to call rain on your parade but ....

I was wondering what sort of cruising you intended to do?

Form should not be put ahead of function. Racing hulls make poor cruising hulls and the demands are diametrically opposed.

Also have you done any preliminary weights and moments calculations with full stores life raft dinghy outboard, Solar panels, Wind generator etc .

I would also be very mindful of your stability curve with this sort of design used as a crusing boat. The keel and rudder are both deep and vulnerable to severe damage from collisions and grounding. I beleive a cruising boat should survive a collision with a reef at hull speed.

The hull is far from balanced, hard work for an autohelm.
Will also be a bit light for comfort in a seaway. Were you cruising alone or with family ? Hard racing sailors are quite a different breed to family members, too many get off after the first passage because of the intense discomfort sailing in light boats. Have a google for "comfort factor".

Do you have enough sweep back on the spreaders? This should be at least 30 degrees to make it worthwhile.

just my humble opinion

All the best

[solrac]

Originally Posted by MikeJohns

Solrac

I don't want to call rain on your parade but ....

I was wondering what sort of cruising you intended to do?

Form should not be put ahead of function. Racing hulls make poor cruising hulls and the demands are diametrically opposed.

Also have you done any preliminary weights and moments calculations with full stores life raft dinghy outboard, Solar panels, Wind generator etc .

I would also be very mindful of your stability curve with this sort of design used as a crusing boat. The keel and rudder are both deep and vulnerable to severe damage from collisions and grounding. I beleive a cruising boat should survive a collision with a reef at hull speed.

The hull is far from balanced, hard work for an autohelm.
Will also be a bit light for comfort in a seaway. Were you cruising alone or with family ? Hard racing sailors are quite a different breed to family members, too many get off after the first passage because of the intense discomfort sailing in light boats. Have a google for "comfort factor".

Do you have enough sweep back on the spreaders? This should be at least 30 degrees to make it worthwhile.

just my humble opinion

All the best

"Form follows function" said one of the biggest modern architects (Ludwig Mies Van der Rohe)
first, thanks for your advice, but my main interest is not a round alone, nor an America cup. just a design for cruising on weekends & holidays.
Maybe the cruising concept I have will sound weird to you, but here, (Uruguay, South America) the cruising distances we are acustomed to, are mostly summer sailing from Montevideo to Punta del Este (about 100kmts) and at least coastal sailing to Florianopolis - Brazil, about 1500kmts on about 10 to 15 days, and at least 2mts height waves, never as far as 10miles out from coast... (by the way, no coral reefs in this side of the world)
In my ears I´m still hearing someone of you shouting: "don´t waste our time, buy yourself an optimist!!!" hehehehe....
I admit, there is a kind of exageration in the tanking volume, but it´s just a preliminary sketch. probably on future drawings will adjust the weight & balance, but by now, think summing all stuff, we are around the 4.500 tons... (with a calculated displacement of 4.188 tons) maybe I´ll float a little deeper, a little slower, but still float...
About spreaders, seen other posts here recomending about 20 degrees, may I ask why 30? reduced tension?
and finally, thanks to all for your help.

[bhnautika]

Solrac 30 degrees would be the max angle. The reason for swept spreaders as you probably know is to remove the backstay and shifting the fore and aft staying to the lateral (side) shrouds. This then becomes a problem of vectors, the more you shift the push of the stay back to support fore and aft you reduce the support in the lateral direction. Also the more sweep the further back the chainplates can be placed, sometimes increasing the chainplate base, which allows for a lighter mast. There tends to be more tension in these rigs as they are not just holding up the mast but also tensioning the forestay.

[solrac]

Hi guys, as promised on last post, drawn some changes to the hull, with freeship, (now version 32.9 or 39.2, don´t remember...)
regards
Carlos

[jedclampit]

Solrac,

Hey, thanks for the link for the designer builders website...very nice job, don't you think? You hope that you understand that they built this boat to race with a crew of six. Thus the hi-tech materials (lightweight), wide deck, small cabin and open cockpit. You need 4 or 5 bodies hanging over the sides to reach top speed. This design works great for their requirements and I too also like their design, but this boat was not designed for comfort or ease of handling.

If this meets your requirements, then I’d say you found your dream boat…if you want speed you’ll have to have a crew…and watch your head… that’s just my two cents…not really worth that much in these times… good luck!

Nice job on the Acad file…

[MikeJohns]

Originally Posted by solrac

"Form follows function" said one of the biggest modern architects (Ludwig Mies Van der Rohe)

About spreaders, seen other posts here recomending about 20 degrees, may I ask why 30? reduced tension?
and finally, thanks to all for your help.

Regarding function , my comment was that you are designing a racing boat
for cruising.

As for spreader rake .. Sorry Solrac I am always in too much of a hurry I should state more information. From your early posts I glanced at it appeared that the rake was very small, small rake is not worth having and you are better going inline. 30 deg is the maximum but the final rake really depends on the design spiral too.

If it was just a question of rake 20 deg is alright too for most designs however 15 deg. is too little.

You may not need any depending on what sail combinations you fly and from where. I presume your rig is going to evolve further?

For some of the issues have a look at:

http://www.boatbuilding.com/article.php/rigdesignhints

[solrac]

ok kids, that´s the challenge.... a cruiser design with the elegant lines of a Vo70 racehorse, or a cruiser that resembles a petroleum bulker tanker shaped vessel like the Exxon Valdez? which would you prefer for holidays?
That´s the reason (I think) for spending time redesigning the original swedish racer for better interior spaces, the cabin height & the rest.
Maybe (surely) will end up with a sailboat really too fat/ heavy for racing and as spartan and uncomfortable as a naked racer, but I will not give up (at least not yet). in that case, the obvious solution, make a good fire with the sketches & buy a real industrial made sailboat...

PS. posting the new modified 3d model

[tamkvaitis]

sorry, but this boat is ugly, for me

[bhnautika]

Solrac don’t give up, Rome wasn’t built in a day (“two maybe, three tops”). The original hull shape based on a generic IMS hull form is more than adequate for the type of sailing/cruising you want to do. These types of boats enter and win the toughest ocean/ coastal yacht race in the world (Sydney to Hobart) so it does not take much to change them to a more coastal cruising type of boat.
You need to sail with less crew?
Change the displacement/ballast add more ballast make the boat stiffer. Set the boat up for shorthanded sailing, if one man can sail a 60 ft boat, 33 is no problem. It just a matter of systems.
The hardest boat to design well is a small boat; humans are just to damn big!
The hull is coming along. Remember longer waterlines are faster but watch out that your fore foot doesn’t get to deep as it tends to take over the steering on a run.
There seems to be a hollow running down the centreline this I think is a fairing problem in the computer model. May I suggest you work on just the hull first, then go back and add deck, cockpit etc.