About Project Darwin

Darwin is a 29' Sailboat that has adapted to a dry lakebed environment by developing giant mechanical legs to help it move around without water. Read more details about Darwin here ...

Monday, May 23, 2016

Big boned boat...

What is a polite way of telling someone their boat is fat?  I don't know... but Kari and I took our Ericson 29 to the Healdsburg Transfer Station to have her officially weighed and she's - uh - above spec.

Here's Kari handling a huge load.  Roxy kept a close eye as we towed her to the scales.
Then, whilst in the shop, I carefully measured the tongue weight - that's the weight held by the hitch on my truck:
The tongue weight is only 850 pounds.

The boat on the trailer weighed in at 9,390 pounds, a full 2,090 pounds heavier than she's supposed to weigh.   But what's a ton of extra weight between friends?  It's more boat to love (and less likely to get blown over in a dust storm).

And of course, sometimes you have to take a break from looking up the shear strength of polyester resin fiberglass, the yield strength of mild steel and your beam deflection calculators because... fruit.

The apricot tree said it was ready, and we couldn't resist the call of nature.  Yummy!

So much more has been going on behind the scenes - engineering (well, under-educated guessing to be honest).   The harness design is coming along nicely.   With the laser boat measurements, I was able to get a pretty good fix on the CG of the boat (196" from the bow if you must know) and verify that leg placement near the forward bulkhead is a reasonable idea.

Also - the 3d model let us know that the hull/deck line is probably co-planar, with a 36 foot radius arc!  Photos make it look like it curves in two planes- but that's probably a trick of the eye and perspective (I like to think Da Vinci would nod approvingly)!
So here's a rough sketch of the harness plan....
The main longitudinal beams will be C7x9.8, which means standard C-channel 7 inches tall, 9.8 lbs of steel per foot.   Van Bebber's in Petaluma is rolling it into a 36' radius arc, right now and with luck, we'll have help buttoning it onto the hull this weekend!

Finally, I have to give a big nod to Earl (aka Dodger), who has been really helping me double-check my design.  He spent his Sunday afternoon machining a part to get a big metal saw operational so we can use it for the project:
This saw used to be at the old Exploratorium, and probably helped make many of the older exhibits you all love - what a pedigree!   And a special thanks to Monkey Boy who's smaller saw really got me cutting up some serious steel before putting it back together different.  Sometimes you don't realize you'll like the big tool until you play with the smaller one.

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