On Friday, April 3, 2020, 6:51:41 PM EDT, Mike Crawford mcrawf@nuomo.com [harryproa] <harryproa@yahoogroups.com.au> wrote:

>>So a collapsible ex40, with a movable tender that stores under the cabin when collapsed would work for you, Mike, you just would not use/build the tender. And you would add the sled.

>Agreed.  As long as it has external telescoping beams on the windward hull.

wait, what? Why is that?
It seems, to me, the 'wider beams' should go on the longer hull. But what do i know.

>But that said, once all the other design aspects are set, the difference in plans between two different beam options can't be much of an issue..

meh. I assume whatever beam will be reasonable. I am not gonna fight for an certain beam ascetic. Would rather have a set of plans that more than one person is building. I think there is a lot to learn from actually building the boat.

>And who knows, maybe Rob and Steinar will draw up a new, beautiful, streamlined beam design that renders my objections moot.

I would guess, probably.

>Regardless, the physics are already solved, so it's just a question of how many near-optimal options we can find.

yes. I have a question about the boat.
If we assume 12' collapsed width. so we assume ~12' beams.
If Robs 10% bury is a good number
Then, the sailing width would be about 22.8', right?

>> Could be tied or mounted at the fore beam. so perhaps removable?

> Yes, definitely fastened to the fore beam.  I'd want some big, beefy pins, perhaps set into big, beefy UHMWPE bushings, so that strength and reliability would never be an issue.  Stainless would probably be fine, though I might even splurge for titanium given there are only two pins.

>  The sled could then be pretty narrow, mounted just to leeward of the steps going down into the windward hull, allowing it to be cranked up tight against the aft beam.  Probably with a solid neoprene cushion under the beams so that nothing rattles around.  Then the boat could bounce all over the place without the sled moving.

> The one thing I'm not sure about is flotation.  One of my favorite features of the tender/sled is that it rides up and down with the water surface, so there are no worries about ventilating the prop in troughs or drowning the motor in crests.  I have both those issues on our current catamaran.

I wonder if you made the sled flat, and glued it to the beam bottom, it could remove your boyancy need some? If it could do a portion of the lift, it might be good.

> Perhaps a thicker-and-wider floating section on the sled that spreads out aft of the cabin stairs, fiberglass filled with closed-cell foam, just forward of the motor mount, with a total volume around 4 cubic feet in order to support 200 pounds?  It would protrude down beneath the beams a bit, but that's okay.  I'll lose that clearance as long as it's close to to the hull.  And maybe the sled has an angled portion at the bottom that raises the motor a bit more when it's up (end of the section), and then sits in the water more when it's down (the angled section).

  Just brainstorming here -- any boat thoughts have been far from my mind for a while.

> So, is that solved then?

  Everyone gets what they want!

        - Mike
Yay!