In search of the prefect Proa

[Inquisitor]

A perfect boat (for me). My desired...

1) Single hand
2) Fast
3) Gentleman racing
4) Live two
5) Sleep other couple and children (2 children and grand children)
6) Trailerable

For your consideration and/or entertainment, I offer the following Z40½ Roadster.

Specifications

• Atlantic Schooner Proa
• 40' (12.2 m) Windward Passenger Hull
• 60' (18.3 m) Leeward Performance Hull
• 5000 lb (2270 kg) Race weight
• 10,000 lb (4535 kg) Max weight
• 85:15 Race weight ratio
• 70:25 Cruise weight ratio
• 1 King bed on bridge deck w/ panoramic view
• 1 Queen bed in hull
• 2 bunks (1 double, 1 single) in hull
• Salon for 6
• 2 Heads
• 2 full 36"x36" showers
• Work shop / office
• Lee hull expected to contain kayaks and bikes.
• Three levels - Hull, Bridge Deck & "Crows Nest"
• Two helms - inside, in Crow's nest
• Bridge Deck can be sailed closed as depicted or open (It is a roadster!)
• Not shown - 10 foot dingy and tramps.
• On a perfect day... Mitchlet predicts 27 knots at eminent hull flying in race trim.
• And the insanity... It will fit within the USA interstate towing regulations of 40'x8.5'x13.5' and can be towed by mid size SUV's or full size 1/4 ton pick-up trucks. It is a true roadster

[ThomD]

I think that any time you are able in get it all in a multihull of reasonable size, there is something fishy happening. Proas can have difficulty get off the ground with modest goals like camper cruiser. Rig, stearing, and boards, can't be glossed over in these designs as they can to some degree with more conventional designs. m One needs to know where every screw is going for these parts as they are often pretty radical.

In this design the rig looks small, the main hull too large. Looks traumatic to trailer or launch though for enough money... Sure be fun to see it taken further and made to work. Right at the moment the Vision Harry looks like it would come closer to the mark.

[cavalier mk2]

It reminds me of some of Taylor's designs from a long time back. I'd put on a pod for safety. One problem with masts in the ends is the bow dive from the compression loads. In some conditions I'd expect the accommodation hull could trim bow down.

[Inquisitor]

Thank you for responding. I want make sure I don't overlook anything and if someone brings up an over site, sooner... is better.

[Inquisitor]

I was having all kinds of troubles trying to work out the issues of the Z40 Roadster catamaran with the same goals. Weights kept creeping up, expanding the hulls was going to be a night mare... on and on. Exploring the concept of Proa's just made most of those issues go away. The Z40 died on the vine... this has sprouted.

ThomD, There's no magic, no mirrors and nothing fishy. For the life of me... this go around, things are falling into place easier. Re-looking at the pictures, I can easily agree with your assessment of sizes. But here are some numbers that have persuaded me.

The first image shows the lee hull fully depressed at the point where the windward hull is just flying. This is calculated at the full (10,000 lb) gross weight on the lee hull. It is just before the start of the flare where the reserve buoyancy really goes up.

The scantlings for the hulls include the wood, cloth and epoxy. It does not include internal structure for the beams or bulkheads. For the 60' lee hull, the weight is 650 lbs. For the 40' windward hull, it comes to 2000 lbs. I'm probably going to miss my 5000 lb racing weight, but I have a full 7350 lbs left for internal structure, fit-out and necessities.

[Inquisitor]

As a matter of fact... Rob's HarryProa does fit the bill very well. I contacted Rob about his Visionary. It is SO close. I was about ready to purchase his plans. But, it isn't trailerable. Trailerable is a real pain in the ass specification... but its not optional for me. He has encourage me to post my design here.

I completely agree... trailering will be difficult. I'm not expecting 16' motor boat deployment. I'd be satisfied with a full day of rigging. I'm hoping for four hours. With this design, the heavy hull will be stationary and fully supported by the trailer.

The biggest issue is... can I step the mast(s). IF I have the masts on the windward hulls (as depicted) I can use the halyards and winches as a crane for most of the rest of the assembly.

[Inquisitor]

Originally Posted by cavalier mk2

It reminds me of some of Taylor's designs from a long time back. I'd put on a pod for safety. One problem with masts in the ends is the bow dive from the compression loads. In some conditions I'd expect the accommodation hull could trim bow down.

So far the design is such that I can place either one mast or two, either on the lee hull (HarryProa style) or on the windward hull (Atlantic style). I started up the thread HarryProa vs Atlantic to try to get a better handle on just that issue.

I hadn't thought about that paticular issue (trim bow down). But it does make sense. If they were on the lee hull, that hull takes care of it more directly instead of having to taking it by twist of the cross beam/bridge deck structure... Trim of the passenger hull (when pressed hard) would be slightly better if the masts were leeward.

[bearflag]

I like it, I have been designing something similar, except different.

Looking at the 3d pictures, where exactly does the leeward bridgedeck fold to?

I see it in red, but my head scratches.

[Inquisitor]

Originally Posted by bearflag

I like it, I have been designing something similar, except different.

Looking at the 3d pictures, where exactly does the leeward bridgedeck fold to?

I see it in red, but my head scratches.

That's a bad sign. When it becomes a full headache... you're there.

The "green houses" of the bridge deck are surfaces of revolution. The portions over the bridge deck "spin" in for trailering or for putting it in "Roadster" mode while sailing. The pit group in the salon "happens" to fit around the roof when folded over. There is a small portion of the King size bed platform that has to be removed, the king mattress and the salon cushions have to be stowed below for trailering. Then the bridge deck can be folded over. If the words don't do you in... check out the attached video.

Since this forum doesn't go in much for floating condos, I know this isn't many people's idea of a boat. But, by all means, post some of your ideas. I'm curious.

[bearflag]

Your video just repeats the same frame for me. ):

Did you make all of this in Sketchup?

I am in the pupa stage of redesigning everything I have from ground one.

Originally I was wanting catamaran, and I still do. However, economics and some other design considerations made me possibly thing about a trimaran.

Trailer-ability is something I really like the idea of, but the Farrier 39 even really isn't big enough. In california, and in many states I "could" tow something even bigger. But really even if it had to be broken into pieces that would be less awesome, but doable.

So I looked into basically a longer F-39, but more like a 55. Having the amas fold under is convenient.

But then I saw a cat I liked, (Chris White's concept 63) and I got to thinking. So I went back to a cat.

Then I started learning more about pro-a's and I started to think... Hey i could actually afford to build the thing! Long, slender, seaworthy.

So then I was thinking, well what about an Equal L type proa? So I did some designing around that idea (after looking at some atlantic/harry/pacific, designs. I liked Cheers, and the Gaia's Dream boat is inspirational.

But, it just wasn't clicking.

Right now I am "sort-of" leaning on a Pro-A, Catamaran hybrid thing. Tacking Pro-A/Catamaran hybrid thing.

Equal length Hulls, one for accomodation, one for floating. Sails carried on the cross member ala l'Hydropter but if non-bi-plane then appx. 3/4 (ish) towards the ama instead of the main hull.

My hull's are based off a semi-displacement/wavepiercing beachcat design that I fell in love with. And then put my own spin. Should start to develop some dynamic lift at speed, without costing "too much" in easy breezes.

With a penetrating Bruce-type foil it might even "almost fly" but I am not building a race boat, I want stability.

Lastly, the designplan (as of right now) is to be totally awesome with unequal displacement hulls, but to be able to be built into bridgedeck/pod cat later if i want.

So I suppose I am sort of designing several boats at the same time, and whatever my funding situation is at build time will determine what gets built. Plan is to be circumnavigating, rather than later.

[Alex.A]

Any pics yet Bearflag - as my thinking is similar - but much smaller and simplistic. Cost is sadly an issue. And cost after build....

[bearflag]

I am having cad problems.

I changed some variables and it broke my model, and now I am getting random memory exception errors. Working on a fix.

[Alex.A]

I'm still drawing but will get software soon and start a long learning curve - not looking fwd to it......

[ThomD]

As a home builder I want something that is trailerable to some extent. It is so much more doable. But one has to be careful about the time and compromises required. My 24 foot trimaran designed to be trailered, sort of, is still difficult to set up, and ends up making it's way to the water in two trips. Farriers obviously have that licked but at considerable cost. Always looking.

[bearflag]

Originally Posted by ThomD

As a home builder I want something that is trailerable to some extent. It is so much more doable. But one has to be careful about the time and compromises required. My 24 foot trimaran designed to be trailered, sort of, is still difficult to set up, and ends up making it's way to the water in two trips. Farriers obviously have that licked but at considerable cost. Always looking.

Well, there is "trailerable" and there is "trailerable"

Mine plan is more the later. Really only meant to be taken out of the water under extraordinary conditions, repair, refit, moving east to west coast and no time to sail it, etc. Plus even though i live a half hour from the coast, that is still a half hour I would have to go to build it if I did that. So, more for practical reasons than something I could be there and dump in the water 5 minutes later.

Once It gets in the water I don't plan on spending much time in the marina, plan is to live and sail in it (hence the need for some size).