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3D Models and assorted stats

Posted by MikeInBoise 
3D Models and assorted stats
November 28, 2015 12:59AM
Below are the first six driftboats modeled. They were built into Free!Ship version 2.6 and had all the parameters standardized. These are the simplest line models possible defined by 3 lines each: the "keel", the chine, and the sheer. Each of the 3 lines are defined by 12-14 points described in 3 dimensions. The layers are set to plywood with a density of 31 pounds per cubic foot. Transom and bottom layer is 1/2" and the panels are 1/4". All models are set to draft 5.5". Water density is set to 42.6# per cubic foot (freshwater) and the displacement is reported in Long Tons (2240 pounds) so you can look at the Woody's Original Double Ender that equates to about 530 pounds inside to draft 5.5" of water. The Rogue 952 pounds, Briggs is 896 pounds, and the Honkey is 864 pounds to draft 5.5". This is but just one possible comparison. I will place all the draft/tonnage displacement relationships on one graph when I am done. I highlighted the wetted area with my cursor. That is another relationship I will later graph. Then is will time to play around with designs.... If you want to read the dialog box with all the info, click the image! I will send Sandy the model files. Edit them stretch them, play with, design a better dory!

Re: 3D Models and assorted stats
November 28, 2015 06:46AM
OK now that I got the standard drift boats modeled I started playing with my punch list for ww dory:

symmetrical bottom
dished chine
variable rocker fore to aft
around 17-ish feet, maybe 18.
exceeding 60" in width
Not exceeding 88" at the oarlocks (this is where I can model the crap out of that problem)
have just the right amount of flare
100% Plascore for sides, bottom, decks, and lids
somewhere around 66-71 oz of "glass" on the bottom

So this is a 18'x63" with 88" of beam at the oarlocks. The bottom is close to symmetrical though I still need to mess this is some. But for a quick visual and to see the weight it would take to draft 5.5" of water I punched this out:

So interestingly this hull holds 1,259 pounds to draft 5.5" when compared to the Briggs at 869 pounds to draft the same amount of water. With that much weight there is still a load rise in the back to keep the transom dry. The bottom is fairly symmetrical but I'll mess with that. I think I'd like some more flare without increasing beam at the oarlocks or decreasing beam on the bottom from 63". Maybe I'll add a little rocker in front. It has 25" of freeboard at the oarlocks. Put a deck on that and I think it will make a fin gear hauler. The rocker flattens out in the middle but there is not flat spot.

Re: 3D Models and assorted stats
November 28, 2015 01:04PM

I've got so much going on I can't do it all at once. I'm trying to get a new business off the ground doing product photography............specializing in "focus stacking." It's taking up all my spare cycles right now. But I do need to spend some time with FreeShip. I've got boat hull out there in the shop that's languishing. It barely looks right at all in its present condition. Software is clearly the right first step. Now that's affordable. And usable.

You've done really good work Mike. Thank you.

Re: 3D Models and assorted stats
November 28, 2015 02:41PM
So. On the drawing above if you drop a vertical line straight down from the oarlock position to the (virtual) shop floor that line forms a right triangle with the floor. The smallest angle in that triangle would be right below the oar lock position, thereby defining the side flare in the middle of the boat.

What is that angle, on the diagram above? 27' degrees or so?

More side flare in a boat like this makes the boat less likely to lurch awkwardly if and when you get spun sideways and suddenly find yourself sideways to a strong current. On a straight line chine boat more side flare means more rocker, which quickly becomes a problem as you increase side flare over 27 degrees or so.

That's why many builders, starting with the old Rogue River Boats, dish out the chine. It's the most effective way to reduce rocker.

Too much side flare might also cause problems with the oarlocks being too far apart. Depending on the length of the oars the handles might get annoyingly high. Requiring a high rower's seat.

I don't have a good handle on that problem. I'm thinking about it. As mentioned in earlier posts I have rowed a Cyrus Happy boat belonging to AJ DeRosa--that is surprisingly wide. Too wide was not a problem in that boat.

Re: 3D Models and assorted stats
November 28, 2015 04:51PM
I'll measure that angle. I have got a lot learn to make this software sing.....
On another note in a small rebellion against sleep I scaled your Honky up in all 3 axis by a factor 1.097. That keeps a continuous rocker and takes the LOA to 17'. Height at oarlocks is between 23.5" and 25.5" depending on how you position them. But the floor width scales to only 59.95". The max beam at the oarlocks is 86". Regarding the rocker it makes for 13" under the stem and 12.07" under the transom. On my 18'x63" above the chine is dished and it leaves 12" under the stem and 13.4" under the transom. I intentionally raised the transom after reading up some threads here. On my 18x63 the weight drafting 5.5" of water is roughly 1,260 and on the up-scaled Honkey it is 1,004 pounds.

Your advice on chine dishing bears out in the numbers above and your thoughts on a symmetrical bottom yields more capacity through increased wetted surface area at 53 ft^2 for the "Big Honkey" with its pear shaped bottom vs. 63 ft^2 for the 18x63. The length on both these dorys are similar in that their length to the bottom of the stem from a "point 0,0,0" (which would be a plumb line under the transom) is 16.2' for the Big Honkey and 16.88' for the 18x63. The 18x63 really has a more acute angle on the stem and it is therefore longer thus "gaining" LOA without really adding much mass or bulk to the equation. The profile of your original Honkey is eye catching to me because the stem is nearer to vertical than other dory designs. I went for an angle between the Honkey and Briggs for aesthetics on my working model.

Lastly if you look back up above at the 18x63 you'll see the floor isn't quite symmetrical and while I am going to edit some, I am not sure its all that bad now and is accounted for by less side flare behind the oarsman.

Re: 3D Models and assorted stats
November 28, 2015 04:53PM
Mike, is there any way to 'stack' the views from the top to compare the Honky Dory with the Woody Transom McKenzie? It appears that the Honky might be more narrow in the stern. Is it a question of different lengths of the actual boats? The Honky Dory does have a much great width in the forefoot of the boat. This is an interesting comparison of these boats. Thanks for your work. I might have to play with this software too. I haven't played with Linux in a while but it was pretty straightforward.

Rick N
Re: 3D Models and assorted stats
November 28, 2015 05:44PM
Rick. FreeShip is a Windows program. I run it on Linux with a windows emulator named "wine"

Macs have a windows emulator too. So in that sense this program runs everywhere. But it downloads as a native windows binary.

Re: 3D Models and assorted stats
November 28, 2015 06:48PM
I am going to work to pull them into another 3-D rendering program. If I can get them into Sketchup 7.0 then are all to scale so by looking at the different dory's side-by-side we will be able to learn a lot!
Re: 3D Models and assorted stats
November 28, 2015 08:15PM
RE> "they all have ... some bad"

Absolutely. Designing and building your own boat is the ultimate goal for all of us. That's how we transition from boat builder to boat designer. Most of us have to start with someone else's plans. I did. But I only built one that way. Software seems to be making it easier for everyone to do do it their way. I (now) never build the same boat twice. It's more fun to do something new each time around. I made the first Honky Dory in 1986.

Drift boats are close to a century old at this point. Not much changed for the first 50 or 60 years. I think we'll see some rapid shape shifting from here on out. Time will tell. But wider will be part of the coming change I think.

I'm guessing of course. What the hell do I know. But I expect to see open boats gradually disappear too. Decked is better. Even for day trip fishing boats. I seen it in my crystal ball.

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