Hi,

Thanks for the reply. I should have referenced the other thread I started giving the drawings for the boat. They are in the files section of this group under "Gardner's Layouts".

One primary consideration of this design is that I be able to put it into a container. So, it will collapse to 12' for a slip, and to 7.5' for a container, with no more disassembly that sliding the crossbeams out.

From the calculations I ahve done (included on the front drawing), a 2' waterline beam on each hull should give me a design displacement of 4800 pounds, so I think I am within the design characteristics for the displacement. As for the weight, I have to admit that I am going on some calculations from otehr designs and from the figures from the harryproa site. I am also amazed by how light it is supposed to be.

The telescoping masts sound interesting, but I don't think any have yet been built, so I am hesitant to make a decision going that way. What about a dual ballestron rig, instead of dual mainsail only? Each of the schooner rigs I have seen in the harryproa designs leave off the jib, and I am unclear why that is.

Can you be more specific on why you think I need to up the budget? I am not disagreeing, I just want to hear the reasoning. It strikes me that it could be because my estimate boat weight is too light, but those calc seem to work. It could also be that my hulls are too fat, but I am running at a 20:1 length to beam ratio on the lw hull. In terms of increasing the hull length, I am already 10' longer than the maine cat and end up with 2500 lbs less weight, so I am not sure about that.

For me, it seems to come down to the sail area and the righting moment determining the performance, but I really am looking to learn something from the rest of the people in the group, so please come ahead with comments.

To be honest, the cost is the truely exciting thing here for me. It means that I might actually be able to go from dreaming to sailing. If it really will take an extra 50% to up the performance, then I will just sail slower and cry a little.

Thanks so much for the feedback. It is always helpful.

- Gardner

On Tue, Dec 9, 2008 at 1:42 PM, Mike Crawford <jmichael@gwi.net> wrote:

  That's a pretty big challenge.  Carry the same load as a boat that's twice as heavy, at one quarter the price, and still go faster.  Complicating this further is that you probably want to keep the feature where you can collapse down to a 12' beam for a slip (the Maine Cat 30 now has an 18' beam), and also be trailerable.

  It shouldn't be to hard to beat the Maine Cat when you're daysailing.  Your proa will have a nice weight advantage, as well as the flexible masts that will let you handle a wider wind range without reefing.

  Part of the problem is that you're increasing the boat's displacement by 50%.  That's a pretty substantial increase for a multihull.  It's hard for a 2000 boat to carry the same 2000 load at the same speed as a 4000 pound boat.

  You can probably do it, but not without giving up something, either your 12' slip beam or your 25% cost.

  I'd look at four things:

  - Telescoping or two-part masts for more sail area.

  - Telescoping or scissoring beams to give you a wider beam on the water while still allowing slip width.

  - Going up another ten feet in length.  This is really important for carrying loads on a light boat.

  There was some talk a while back about designing ends for the leeward hull that could slide on and off, or flip up, for transport.  But no one has yet had a reason to actually try to build such a craft.

  In any case, I'd estimate another $25,000 to beat that Maine Cat while carrying a full 2000 pound cruising load, bringing you up to 40% of its cost, and giving you a wicked fast racing machine when you're not loading down.  With some extra length, beam, and sail area, you should be able to carry that load much more gracefully.
 

       - Mike

Gardner Pomper wrote:

Hi,

I want to do a sanity check on this containerizable boat I am "designing". The stats on it are fairly close to the latest iteration of Harry (Aroha?) I think, but enough different that they probably don't apply directly. To get a feel for this, I compare it to the Maine Cat 30 I lived and cruised on for a year:

                             Harryproa     Maine Cat

LW:                        39 feet            29 feet

WW:                       26 feet            29 feet

Weight:                   2000 lbs        4500 lbs

FULL displacement: 4000 lbs        6500 lbs

Total sail area:           480 sq ft      500 sq ft (725 w/screacher, 10-12 kt max winds)

Beam:                      16 ft              18 ft

Bunks:              1 dbl, 2 single      2 dbl, 1 single

Cost:                       $50K             $200K

When I look at these numbers, it seem to me that in less than 10-12 kts of wind, the boats will perform similarly. I would hit 8-9 knots under the screacher, and about the same without in 20 kts of wind, when I had to reef.

The times that I might do significantly better are the 15-20 knot wind range, provided that I have enough righting moment to hold off on reefing. I can figure the righting moment with weights from my design, but how do I calculate the heeling force from 2 schooner rigged unstayed masts of with sails 240 sq ft each?

I could match the screacher based sail area if I had telescoping masts, or if I had a double ballestron rig. Any feedback on those two choices?

It would also help if I could reduce the weight, but with 500 lbs of crew, and 300 lbs for a dinghy w/outboard, I already have 800 lbs without food, fuel or water, so I don't think I would get significantly below 1500 pounds, so I figured I would compare to the really bloated weight when we lived aboard.

Obviously, the last line of the comparison is where the ENORMOUS advanatage of the harryproa shows off. Even if I only get the same peformance, I have saved 75% of the cost!! But, still, I want to sail FASTER!

Thanks, as always, for your comments,

- Gardner Pomper

York, PA