Jump to content

Recommended Posts

here's a video of a pacific proa sailing on it's lee pod for a couple minutes. not sure I agree with the comentary, but if you were wondering if lee pods work...

 

 

Link to post
Share on other sites
  • Replies 428
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Popular Posts

When I was 25 I bought a 10k mono overloaded it and shoved off with a few friends with far less sailing experience than me with a plan of going to Bocas Del Torros to start a new life as a surf bum. W

I wrote this eons ago (2011) and it's all dressed up over at pacificproa.com, but I prefer just the text. It seems like it might be valuable to some of you. I'd love to be involved in a proa forum, bu

The claim was that in specific, favourable circumstances, Sidecar was similar in straight-line speed to a Seacart 30. That's a far cry from the "faster around a racecourse" you're implying. I hav

Posted Images

It has always been interesting to me how there is so much 'traditional' confoundment at the idea of shunting in the sailing World, especially when it comes to mixing proas with 'proper' tacking/gybing boats. It is usually thought that confusion will abound and close quarter disasters inevitable...
Funny thing is that this exact scenario has been occurring virtually all over the world for a couple of decades in the kitesurfing world. Apart from hard core wave riding areas where surfboards reign, most of the (non race scene specialist) kite world exists in mixed fleets pretty evenly divided between directional boards (derived from windsurfing or surf style) and twin tips (wakeboard style). The latter are most definitely proas and shunt at every turn- at high speed and in close proximity to everyone else... Nothing seems to go wrong and all is quite universally understood. Fins on these bi-directional boards are usually small (or absent), so you can do some wild slide outs in course transitions. Even so, they can also surf Okay on wave faces- although sometimes sketchily- much to chargrin of surf-style purists. 
Full disclosure- I have been a kiter for many years and too lazy to learn the fancy footwork needed for directional boards- so in fact shunting is an easier, more basic system in this type of sailing (all those old windsurfer converts already had the skills, so can happily use directional boards...). The developments with foiling may finally tip me into getting into changing feet while piloting craft with distinct bow and stern, but only because current commercially available foils are unidirectional. ,☹️

  • Like 5
Link to post
Share on other sites

^  never thought of it in that way!  I suppose snow boarding is similar also when doing the falling leaf which to a surfer can be a weird feeling going from natural foot to goofy foot? 

Link to post
Share on other sites
2 hours ago, he b gb said:

^  never thought of it in that way!  I suppose snow boarding is similar...

Yes, all the board sports which seem to see themselves as progressive have totally adopted the shunting way and look back on their roots as primitive and awkward for still using the traditional bow/stern model: snowboarding vs skiing; wakeboarding vs water skis; skateboard vs roller skates...

  • Like 1
Link to post
Share on other sites
2 hours ago, mightyhartley said:

Yes, all the board sports which seem to see themselves as progressive have totally adopted the shunting way and look back on their roots as primitive and awkward for still using the traditional bow/stern model: snowboarding vs skiing; wakeboarding vs water skis; skateboard vs roller skates...

I grew up skateboarding.  I'm Goofy footed (port tack) but did flip tricks switch, I mean, starboard, so maybe this always made sense.  

Link to post
Share on other sites

As I mentioned before - kiting would suit a symmetric proa very well. Its hard to see a tack with a kite on a boat - maybe it could be done with ballast.

On a bord that weights next to nothing and where the sailor/kite totally dominate the energy its perfect.  

Downwind with a kite jibbing would be better - on a boat.... 

Link to post
Share on other sites

Don't use snowboarding as an example to support shunting - changing direction by shunting without jumping the board is very slow compared to carving the board.

Link to post
Share on other sites
1 hour ago, hump101 said:

Don't use snowboarding as an example to support shunting - changing direction by shunting without jumping the board is very slow compared to carving the board.

Actually, that makes it the perfect comparison.

 

Link to post
Share on other sites

I really don't get why folks are so confounded by shunting, for me it's great because it's laid back, at any point I can drop the sheets and the boat will drift to a stop ama to windward and the rig luffing off to the lee, when I'm ready to go I can pick up one sheet or the other and take off in either direction, handy when you overshoot your crab pot :) if I'm headed into trouble a one eighty is as easy as dropping one sheet and grabbing the other.

I sail to go freediving/fishing/crabbing/beachcombing/camping so an adverse current + headwind = the perfect opportunity/excuse to do more freediving/fishing/crabbing/beachcombing/camping rather than a challenge to bash my head against, but hey, different strokes for different folks.

  • Like 1
Link to post
Share on other sites
On 2/24/2021 at 9:24 AM, TwoBirds said:

here's a video of a pacific proa sailing on it's lee pod for a couple minutes. not sure I agree with the comentary, but if you were wondering if lee pods work...

 

 

i could capsize and turtle that thing easy as shit....... but i have experience at these such maneuver's ...lol

  • Like 5
Link to post
Share on other sites

 

40 minutes ago, Kenny Dumas said:

Given that leeway resistance and balance are lacking in some modern proas, maybe the leeward side of the main hull should be straight, flat, and have a hard chine. 

I hadn't realized it was a problem, there have been asymmetrical proas built, not so much lately though, I suspect that any gain isn't worth the lost displacement,  better to put a big  lee/dagger board in the middle of the ama and then you have as much lateral resistance as you need when you need it without having to worry about tripping over it and capsizing.

 

  • Like 1
Link to post
Share on other sites
9 hours ago, Kenny Dumas said:

Given that leeway resistance and balance are lacking in some modern proas, maybe the leeward side of the main hull should be straight, flat, and have a hard chine. 

 

8 hours ago, TwoBirds said:

I hadn't realized it was a problem, there have been asymmetrical proas built, not so much lately though, I suspect that any gain isn't worth the lost displacement,  better to put a big  lee/dagger board in the middle of the ama and then you have as much lateral resistance as you need when you need it without having to worry about tripping over it and capsizing.

I generally agree with @TwoBirds about the limitations of the hull for leeway resistance vs. the effectiveness of foils (rudders and daggerboards).  I can't quantify the difference but disagree about "the lost displacement" of asymmetric hulls, as shown below.  This isn't necessarily how I would draw an asymmetric hull (21m, 69 feet) but it's a quick and simple demo that scales the width of each half hull (leeward and windward) such that waterline beam remains constant, along with position of the hull at the center of the boat.

Two things to notice:

  1. Displacement remains constant.
  2. COB moves to leeward (the flat side), up to six inches at the extreme, increasing righting moment (substantially at the extreme).

asymmetric_hull_2021Feb26a.thumb.gif.e518a07484da63704c58f93f801bea8a.gif

Link to post
Share on other sites

COB benefit is cool 

I guess some may not know that the original proas were made this way so I should have used the purple font. Anecdotal evidence is that the hard chine on some modern race boats works well for lateral resistance “it just settles in like it’s on rails”. I don’t know of a modern proa with a slab chined leeward side leeward hull   Anyone?

Link to post
Share on other sites
20 minutes ago, Kenny Dumas said:

I don’t know of a modern proa with a slab chined leeward side leeward hull

Not sure what you mean by "hard chine" and "slab chined leeward side"?  I believe Jzerro is slightly asymmetric.

jzerro5.thumb.jpg.3a2c8acf469dc13c7b7018f2fe8309e7.jpg

jzerro_haulout.jpg.17b9a6eb9ca8d0975b3d8b9b9035cbbb.jpg

Full size images here: http://pacificproa.com/brown/jzerro_haulout.html

By the way, anyone who thinks they could sail this boat to tip it over is kidding themselves.  Rogue waves are a different story.

Link to post
Share on other sites

ProaSailor is right re displacement. Any hull which has the same midsection area, the same LWL and prismatic coefficient will have the same displacement, regardless of where you bend the bows to and/or the shape of the mid section area.

I don’t think asymmetric shaped vakas help much unless you are designing for a specific, very limited speed range, like Venetian gondolas or outrigger canoes being paddled from only the “opposite” side. What is balanced at one speed, may cause problems at another.

Anything which produces lift, also produces extra drag, which is sufficiently small and may be acceptable at low speeds. But not at high speeds.

CoB shift is handy, but I wouldn’t design in asymmetry to get it. Above the water plane is an entirely different story. The more shift you can efficiently produce from a hull shape when the hull increasingly heels and immerses to leeward, the better.

Link to post
Share on other sites

Gary Dierking's T2 is asymmetric. Chris Grill built a larger version of it, sailed it all over Mexico, lived on it for over a year, and wrote up a long article on what he changed from the plans, what worked and what didn't:

https://grillabongquixotic.wordpress.com/2011/07/02/a-report-on-my-version-of-gary-dierking´s-t2-pacific-flying-proa/

Very nice guy, he dropped by my house on his way from NY to Mexico on one trip.

  • Like 1
Link to post
Share on other sites

I read somewhere that some of the original proas had a totally flat side to leeward. Like, take a modern vaka and slice it down the middle. Haven’t found any pics, but I’m guessing the early voyagers had some game.   
 

Grilla is amazing. 

Link to post
Share on other sites
1 hour ago, Kenny Dumas said:

I read somewhere that some of the original proas had a totally flat side to leeward. Like, take a modern vaka and slice it down the middle. Haven’t found any pics, but I’m guessing the early voyagers had some game.  

"Flying Proa" of the Marianas Islands
from Canoes of Oceania by A.C. Haddon and James Hornell
http://pacificproa.com/flyproa.html

Quote

The construction of this proa is a direct contradiction to the practice of all the rest of mankind. For as the rest of the world make the head of their vessels different from the stern, but the two sides alike; the proa, on the contrary, has her head and stern exactly alike, but her two sides very different; the side intended to be always the lee side is flat, and the windward side is made rounding in the manner of other vessels.

anson_proa.thumb.gif.f97a40dbda97bedbf8ee50a1df06bdf5.gif

Link to post
Share on other sites
3 hours ago, KONeill said:

Gary Dierking's T2 is asymmetric. Chris Grill built a larger version of it, sailed it all over Mexico, lived on it for over a year, and wrote up a long article on what he changed from the plans, what worked and what didn't:

https://grillabongquixotic.wordpress.com/2011/07/02/a-report-on-my-version-of-gary-dierking´s-t2-pacific-flying-proa/

Very nice guy, he dropped by my house on his way from NY to Mexico on one trip.

"A Wordy Report" indeed!  Amazing that he lived aboard" and sailed so far.  Some highlights, with a great deal more to read:

  • "I have been living aboard Desesperado [sic] for 14 months and have made it from Veracruz Mexico to Bocas del Toro Panama."
  • "Hull subdivided into three watertight sections with the tops of 5-gallon buckets set in for hatches. [These hatches have been a consistant pain in the arse, always leaking. The deck is frequently awash especially when beating to windward] "
  • "Take note of what Gary says “The T2 is a sport canoe for one or two people”. He means it, The T2 cannot carry more than this. Put weight on the hull, it will sink and plough under. Put weight out on a trampoline or platform, down goes the ama. If you want to carry people or cargo this boat will NOT work for you."
  • "However despite this plan I still put the deck too low, about a foot below the gunwhales, and found that it flooded hugely when struck by a wave, and until the scuppers drained it out I’d wallow along carrying a bathtub of water up front. If it was really bad out it would never drain (I could not bring myself to make really enormous holes in my lovely faired sides), just flood and flood again."
  • "The ama: Like everyone else I wish I had built this a little more buoyant. Two fatties on the platform will sink it completely, and it submerges a lot anyway. It is also a bit noisy; with its fully round cross-section constantly leaving the water and returning, it slaps a lot. I’d say that 90% of the noise aboard comes from the ama, but only 10% of the spray. I guess a v-shaped bottom might fix some of the noise. The ama is foam-filled. I can’t help thinking that the Hawaiians have it right with their amas swept upwards at the ends which must surely help prevent them from plunging under."
  • "I am not so sure about the Hawaiian curved ama idea. I think this is good if you have to run big surf, but as Gary Dierking says it would interfere with the wave-piercing quality of the ama. My ama pierces a lot of waves and it’s ability to do so means it has less resistance and the boat goes faster and probably with less stress on the iakos."
  • "Ama: length 4.54m [14.9 feet], cylindrical except at the ends, diameter 21cm [0.689 feet or 8.27 inches]."

Note: I calculated an estimated ama displacement of ~355 lbs. minus pointy ends.  For practical purposes, minus weight it carries at rest.

Link to post
Share on other sites
  • 3 weeks later...
On 2/19/2021 at 4:09 AM, SeaGul said:

The fact that nobody crushed what I stated - I think it rather close to the truth...   then to say its not a big deal that proas really have big trouble with basic boathandling is the real problem for them , not that they look different.  Most of the designs we see are coastal designs where tacking/jibbing/shunting is important. The problem could be solved wit a design that was atlantic on one tack and pacific on the other - and had a bow and stern. Could be a fun boat to sail - and cheaper than other solutions; simple rudder and dagger - much faster and easy and exiting to handle. 

Shunting a balanced rig (ballestron, mast raked forward, wing mast or wing), with 1:2 mainsheet and autoturning rudders is far less effort and faster than what was is being done with 30 year old ideas. There are plenty of other ideas yet to be tried to make it faster still.  The bigger the boat, the relatively easier modern proa handling gets.   

 

On 2/23/2021 at 7:13 PM, SeaGul said:

Ok foils can be two directional - but one is better, and two foils in the end - how is that working compare to a dagger in the optimal place?

Rick Willoughby posted an excellent analysis of why the 2 rudder harryproa set up works so well and some alternatives on https://groups.io/g/HarryProa/topics last week, based in part on his extensive number crunching and experience sailing on an 18m/60'ter.  

This site is also where the updates on the 24m/80' Cargo proa build are posted and discussed.  

On 2/23/2021 at 11:24 AM, Sidecar said:

The original rudders were windward side hung, and in terms of spacing, area and depth were proportionally almost identical to Bucket List. Without a centreboard, quite simply, the boat was barely controllable, wanting to round up the whole time, even with a jib, had bad VMG upwind and was slow, because the rudders were practically stalled out the whole time. You could feel the boat instantly accelerate every time you had a chance to straighten up the rudders.

I encourage people to copy and learn from what I have done, but there is a lot more to Harryproa and Bucket List rudders than simply copying the spacing, area and depth.  If you had discussed it with me before changing them, you would have saved yourself a heap of effort and money, and ended up with a better solution.  

 

Link to post
Share on other sites
4 minutes ago, harryproa said:

I encourage people to copy and learn from what I have done, but there is a lot more to Harryproa and Bucket List rudders than simply copying the spacing, area and depth.  If you had discussed it with me before changing them, you would have saved yourself a heap of effort and money, and ended up with a better solution.  

I didn’t say I copied Bucket List’s rudder set up. If you can recall, Sidecar was pretty much designed before Bucket List was in the public realm.

None of my rudders or their gantries have ever broken. How about yours?

I am happy with my rudder system now. No need to discuss anything further.

  • Like 1
Link to post
Share on other sites
On 3/14/2021 at 9:59 PM, Sidecar said:

I didn’t say I copied Bucket List’s rudder set up.

And I didn't day you did.  Just offered to save you a lot of work building 2nd and 3rd sets.  That you  say you didn't copy them, but saw fit to mention that they didn't work answers your question about "why proa designers can't just get along".

On 3/14/2021 at 9:59 PM, Sidecar said:

None of my rudders or their gantries have ever broken. How about yours?

I have broken more than I can remember on my development boats.  The result of designing near the limits and hard testing.  

On my designs built by other people: one gantry when they locked off the kick up system and sailed into a sandbank at speed, one where a stainless pintle developed crevice corrosion and snapped while sailing in the high teens and one set of non standard rudders when the boat dragged it's mooring in a gale and ended up on the beach (and TV).

On 3/14/2021 at 9:59 PM, Sidecar said:

I am happy with my rudder system now. No need to discuss anything further.

That implies that the things about your boat that you do discuss, you aren't happy with.  :-)     

I doubt I will ever be "happy" enough about any aspect of design or build that I don't want to discuss it.  Especially on a boat discussion forum and a topic as interesting as proa rudders, if you accept that they should work in both directions, be liftable and kick up in a collision.  And the latest ones which do this and have potential for foiling as well.  

Link to post
Share on other sites
Quote

Fulaga canoe

This is one of only two remaining sailing dugout canoes in the island of Faluga, southern Lau, Fiji. Its builder, Meli, uses it for fishing and collecting vegetables from one of the islands within the Fuluga lagoon.

 

Link to post
Share on other sites

Proa, that video shows the fastest (mast-foot swap) I've ever seen on "film", (not that I seek that out).  At first it seemed like it was as fast as a tack.  Then I realized that it didn't actually show a shunt with the whole; stop the boat, reverse the direction, build up speed in the other direction, routine.  It was also light wind/no-struggle conditions.  I compare that to the minutes long, winch grinding shunt I saw on the Red Boat thread.  I'm not a basher, proas seem like fine vessels in some/many applications.  I'd like a ride on one someday.  Beautiful photography. 

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Announcements


×
×
  • Create New...