Mike had generously offered, last winter, for me to go over to his, this past sumer, and sail and discuss this. I was unable to take him up on it. But the idea still seems great.... So, wanna design a boat?|

  The offer is still open for next summer.  We just bought a piece of property on which to store the future boat (all boats, actually), so our moving target is now out at least another few years. Yard fees up here would be about $5,100/year for a 44x22 multihull, plus the yard is 25 minutes from home, and it would be great to just drive down the road to store and work on boats.

  That said, I'm almost ready design-wise with the newest Ex40 as long as it folds like the first Ex40.  The more I look at those boats, the more they grow on me.

  Which probably makes me a less-than-deal dance partner -- there's just not much I'd change at this point.  The only major piece left to fall into place is the motor.

  Though it's possible I could be persuaded to use tub-in-tube inner/outer telescoping beams instead of the harry-scissors in the first Ex40.  That might make for easier trampoline lacing (just loosen a bit before collapsing, tighten after expanding), and could potentially allow a dingy to stay attached if the outer tubes are on the leeward hull.  Maybe.

Tube on tube for everything except looks.

  I wish I could like the tube-on-tube top/bottom design because it's so simple, but I can't get behind it aesthetically.  IMHO, it's just not pretty enough for such a good-looking  boat.

  The tube-in-tube also allows for greater overlap/bury than a top/bottom because the inner tubes get to extend that extra 3' in the leeward hull when collapsed.

But demountable is quicker, cheaper and lighter to build and gives more storage/trailer options.  Easy enough to have both.
Mike would be better with one piece demountable beams.

  Definitely simpler and less expensive.  But that said, all my strong friends have either died, lost limbs, or moved away, so in any given year I might only have my wife to help me haul the boat.  Plus we don't really have beaches in Maine, just lots of rocks for most of the coast, with trees beyond the rocks, so I'd have to haul and launch from an asphalt boat ramp with no flat or soft assembly area.

  In order to stick with a standard non-expanding trailer, I'd have to go with the scissors or telescopic beams so that I'd know two people could handle the job.

I may have had a brain pause on the tender-mounted outboard motor.  It's a brilliant design, but I'm not sure how it would work when the boat is collapsed/folded on the water.

If it is on the bottom beam of a sliding pair, it stays in place, but will not be usable when telescoped unless the controls are remote.

  The tender/motor is my favorite design by far, particularly if it could stay connected while the boat collapses and then be used to drive into a slip or onto a trailer while still connected.  That would be a dream.

  It takes care of everything -- weight is centralized, the motor doesn't ventilate because it's on a transom that moves with the water, yet it's still protected from being submerged when the odd bit of chop or wake comes by, there's a substantial tender right on the boat, gasoline and the motor are both outside so there's no problem with fumes, and there's a very nice boarding and loading/unloading system.

hang tender off aft beam when marina/trailering. Can motor with tender.

  That would certainly skip the problem of not having enough room under the boat.  Though if there's 14' between the beams on a 40' harry, the tender would extend a bit past the end of the leeward hull.  Unless one were to stretch that leeward hull to a 44' length.

  That works for everything but driving the whole system onto a single trailer when it's time to haul the boat.

  Which brings me back to a permanent motor on the big boat.

I would mount it on the beam or bridgedeck.  More room in the hulls, can be rotated for steering, lifted for drag and kick up for impact.

  You're convincing me.

  The well in the leeward hull, like the Presto 30, seems less desirable as time goes on. 

  I've seen the setup in person and it's beautiful.  But on the proa it seems needlessly complicated, it puts another hole in the hull, one that has to be beefed up structurally at that, it takes up storage or bunk room, and there's the issue of gasoline fumes in an enclosed area.  It's a nice idea that I don't think I'd want to live with.

Would a simple box on a pivot, one cat hull-ish?, be simpler and lighter to deploy/lift the motor?

  Which brings me to Eric's suggestion, along the lines of outboard mounts on wharrams that raise and lower:

    https://st3.ning.com/topology/rest/1.0/file/get/1930104886?profile=RESIZE_1024x1024
    https://st3.ning.com/topology/rest/1.0/file/get/1930104717?profile=RESIZE_1024x1024
    http://www.svluckyfish.com/wp-content/uploads/2016/10/20151114_192557.jpg (lowered

  One thought:  how about a 2' wide outboard sled, mounted in between the beams under the cockpit area on the windward hull, attached to a pivot mount that's level with the bottom of the foot well? 

  The mount could go under the "fore" cockpit seat in the Ex40 Mark II (or interior seat in the Ex40 mark I), and when the sled is up, it could be right under the "aft" cockpit seat. 

  The aft cockpit seat would then have a removable top/hatch to access the motor for servicing.  The sled might need a hinge at the bottom to allow for two trim angles:  a standard angle, and then one that allows the motor to be vertical when the sled is up.  Perhaps set with some beefy pins.

  Perhaps it could have a floating section forward of the motor and its mount/transom, so that it moves with the ocean surface the way the tender would.  Though that might require more volume for a 160 lb motor than could easily be hidden under the seats. 

  Then there's only one set of controls for motoring, plus the motor is still out of the weather in a longevity sense, and out of sight in an aesthetic sense.

  There would have to be enough vertical clearance under that seat to allow the motor to be either tilted or down, partially to allow for that servicing with a vertical motor, and partially so that nothing gets crushed the the motor is lifted.

  Then either carry a traditional tender, or if cruising long-term, switch over the to beam-mounted option.  Heck, at that point you could have dual engines, one in the ww hull on a sled, one in the tender, and then be able to turn pirouettes. 

  But it does get away from the whole-system elegance of the tender with a single beefier motor. 

Some high profile ocean racers are choosing Oceanvolt now.

  Electric is something I want to do for many reasons, but the weight and price math don't work out for me if I want to be able to motor at full 10 Kw throttle for two hours, perhaps if trying to get through an anchorage in a storm, or re-set a dragging anchor in a big blow.

  My favorite pre-packaged system for an Ex40 would be a Torqeedo 10 kW outboard on a sled or tender with 30 kWh of 48-volt batteries:

    https://www.torqeedo.com/us/en-us/products/outboards/cruise/cruise-10.0-r/M-1240-00.html
    https://www.torqeedo.com/us/en-us/products/batteries/power-48-5000-/2104-00.html
 
  Then everything works without pods, retractable motors, sail drives, or other such solutions.

  But...  It's still a $40,000 system once you factor in all that storage, with 600 pounds of batteries and motor. 

  I think a 14' catamaran dinghy/tender could handle the weight, but it's still a lot to carry when compared to a 110 lb Honda 20 hp outboard, and it costs ten times as much. 

  Plus I'm not sure I could handle leaving a $45,000 tender alone on a dock.  I'd feel much more comfortable with an ugly inflatable and an equally ugly 5 hp motor (both in good condition, but painted to look like they're about to bite the dust).

  It looks like I'm talking myself into a permanent outboard motor on the main boat on a sled under the cockpit.  That's a very attractive tender to leave unattended, even if it "only" has a $4,000 Honda on it. 

It seems the anchor box needs strength. What if the ww cabin seat was the anchor box/toy box?

  Anchor/toy box in the left cockpit seat, to top/fore end of the motor sled mounted underneath, with the motor underneath the right cockpit seat.

  Now everything is nicely self-contained.  Though I'm not sure it collapses to 12 feet any longer.  Sounds more like 14 feet, which is actually okay for most marinas that handle 40'+ monhulls, but a bit of a nuisance when trailering.

2 piece masts are simple to build, handle, assemble and take apart.

  Good point.  I was thinking about how to get the tallest air draft out of a mast that fits in a 40' or 48' shipping container, but the two-parter might be a more elegant solution than stub masts. 

  When the booms were at a right angle to the masts, my plan was to have fixed masts and rotating booms, with laced-on sails just following the boom.  That would eliminate the bearings in the hull, with the stubs just pinned into sockets, so there would never be a need to access or repair the bearings should they decide not to work.

  But rotating booms might be tough with wishbone booms, plus the two-part mast could just as easily be a fixed mast as a one-part mast with a stub (which is also a two-part mast by definition, but the joint is in a location with greater bending moment).

  Given that I'd only handle the masts twice a year, the extra step for assembly of a two-part mast probably means an extra ten minutes when launching and hauling.

        - Mike

 

| Tube on tube for everything except looks.

So call it sold on tube on tube. Or box on box. With straps and ratchets.

| > We get ~22' with two beams? Is that enough for a ~44' HP?

| yes

| > Why fight for a 3rd?

| I wouldn't.

>From the department of nothing is ever settled...
Noting this;
| The beams are at about 30 and 70% of the length,

What are the rudder % lengths?
What was the LOA of the EX40F folded?

I ask because the folding beams, to my mind limited the folded/trailerable length of the boat. For every bit of length you add, you add ~40%? to the length. It's kind of a hang over length, but still.

With tubes, you don't

Rob, how long could one practically make a 12' foldable? And what would it's trailering length be? Assuming our 3' hull width.

Side question on tube overlap. You mentioned 10%. Assuming our 3' hulls and 6' cabin, what is the length of our tubes in that scenario? Do we measure from where they exit the hulls to their tips, or its total length?

__._,_.___

---

Posted by: Mike Crawford <mcrawf@nuomo.com>

---

Visit Your Group