outrigger canoe design challenge

General Discussion
1

hey y’all

i have spent the last couple months on a boat design forum asking questions about design perimeters for a 6 man outrigger canoe. there is a very good reason for me presenting the same questions to this body of artists, engineers, and craftsmen. i am in southern california and i am working on a new class of outrigger that will be designed for our water conditions, not hawaiian, which is what all existing canoes are designed for. there are a few simple concepts that i am trying to achieve in this design. 1. that it be fast in “flat” condtions and 2. that it surf in rough conditions. the hawaiian canoes are great in the rough but dogs in the flat. the boat forum guys were kinda stumped. but an outrigger is very much like a super long surfboard in many ways. and when you catch an open ocean wave it can be just as thrilling as surfing on a board. one more thing to consider is that the tahitians have water conditions that are similar to mine. i have studied their canoes. we want to go faster than their canoes if possible and definitely surf better. i hope you don’t mind me asking about an outrigger on this forum. but i am really anxious to dialog with some of the brilliant minds i have seen on this forum. if anyone cares to reply i will give more detail about the design concepts i have so far. thanks.

2

Okay, you have me curious, though I’m neither brilliant ( nor even close) , from the West Coast nor a paddler ( though a rower) … what’s a typical race course look like, say, and what is the typical weight per paddler? What sort of construction methods/materials are you looking at? What do the rules require for dimensions, weight and so forth?

From a quick look around various websites, it’d appear that a typical outrigger canoe hull (http://www.aocra.com.au/gallery/13.jpg - the Australians are doing some interesting things) is a kinda long, narrow and deep hull. This isn’t bad from the point of view of paddling speed, especially when you consider the first ones were whittled out of a Real Big Tree, but adding some flatter elements to the bottom wouldn’t hurt, not unlike midsection of the traditional North American canoe form.

Especially towards the bow… http://www.aocra.com.au/gallery/16.jpg and http://www.aocra.com.au/gallery/2.jpg

As a lot of this is, I’d imagine, open water paddling, some model tow-testing would be a Real Good Idea, to see what it takes to pull a scale model at a given speed. The easier it is to pull, the easier it is to paddle the full sized version. These critters are what, very roughly 30’ long? So paddling speed is around 8 MPH tops and they would plane at around 12 MPH. Best if the outrigger was a planing hull too, as it’d be planing a lot sooner ( being shorter) - an outrigger that started skimming on top of the water easily and quick would save some nasty occurrences.

There have been some pretty successful paddleboards, rowing shells and such with flatter sections ; http://www.joebarkpaddleboards.com/boards/newboards.htm , http://www.eatonsurf.com/EatonPaddleboards.htm among others… I might start with those general hull lines and proportions and play with it some.

doc…

3

hey doc,

because we are creating a whole new class there are essentially no limitations at this point. i used to build joe barks molded boards and i still paddle my own designs so i am familiar with the paddle boards. the canoes you saw in the pics are hawaiian designs. they are about 42’ long and 17" wide. yes we paddle primarily in the open ocean. the problem i am having is trying to figure out how to establish the rocker (sound familiar??) and what kind of plan view to have that best displaces bow water but does not lead to broaching. the water on a waves surface moves in different directions and at different speeds. the water in the trough is slower than the water on the crest. if the bow plows the trough water will be pushing against the bow while the stern /crest water is accellerating the stern and causing the canoe to broach or “come around”. you’ve probably felt your rowing shell do it on a boat wake. i had the idea of taking a swell size/speed average and creating a wave profile and then creating the rocker that would “fit” on the “average” open ocean swell. (make sense??) an eight man rowing shell type hull would be fast in the flats but would not surf. a 45’ surf board would surf great but be slow in the flats the trick is to combine the two and create a craft that is a fine entry displacement hull like a rowing shell and a planing hull like a surfboard. any ideas how to accomplish that?

4

Hey, for some reason this reminds me of F-14 Tomcats… they have those wings that swing out when they are going slow and then sweep back for serious speed. Sorry but I am sort of far out here, but if there was some way that you could modify the amount of rocker in your canoe on the fly, you could have the best of both worlds. Rocker for “surfing” and flat for hauling ass when paddling. Some how to jack the nose rocker up when you needed it the most. I dunno, thought I’d throw that in there. -Carl

5

Some of the ocean kayak designs have sleek hulls and anti-pearling “wings” at the bow. I don’t know if anyone has tried those with an outrigger hull. Maybe get a faster rocker without as much risk of pearling?

6

Carl, speaking of F-14 Tomcats…

I`ve built a few plywood paipos that had large wings on simple flat pivots. Fully extended to catch swells/waves earlier, then quickly swung around and tightly folded in over the deck just prior to dropping in.

Imagine a 24" wide x 3`-6" long paipo that could unfold 24" long x 12" wide “wings”… I answered some nagging questions, learned a few new things, it actually worked and was fun… and I also got pinched a lot when trying to quickly fold the wings in. But the basic idea was valid.

The custom surf mats which I build are designed to adapt and change their overall dimensions in response to both wave and rider. This is particularly noticeable when skimming fast at low air pressures in walled-up, smaller, choppy, flatter waves.

For example, a mat with maximum inflated 5" thick x 19" wide, can instantly become a 23" wide x 1" thick tapered blade when necessary… and then back to “normal” size again, in the blink of an eye.

Tuned, responsive flex is the eventual answer to resolving many of the design compromises which have always existed in solid/firm boards (and canoes)… bridging the dichotomy between higher levels of speed and control.

7

Found this site on the “SailRocket” they are looking to break 50-knot speed barrier. Interesting hull design.

http://www.whbs.demon.co.uk/sr2/gallery/side_view_hull.htm

http://www.whbs.demon.co.uk/sr2/content_fr.htm

8

an interesting Query …the canoes of Oceania,combined three volumes written in 1936-1937-1938 and reprinted by the Bishop Mueseum in 1975* is an overview of the tradituonal canoe styles …each Island group’s designs ,the equivilents of volkswagensedans through combis and then to uppeer end freight haulers,in each Island group the designs evolvedwithin the limits of materials and conditions,the first fiberglass canoes were molded from wooden canoes beloved by the clubs that own them and other clubs that covet them…the canoe racing community in hawaii is deeply concerned with the quest for the fastest canoe and are working all year long day in and day out on their personal solutions,talking to canoe guys they are very opinionated about the qualities of the canoes in the fleet, you think a Brewer "secret rocker " is guarded try and penetrate the canoe dynamic…the average swell slope and length is unique to your region Ill bet it’s different from community to comunity along the California and oregon coast as well as mexico…study Lorrin Harrison archival literature …measure the existing “legacy canoes” and talk to Velzy and ask his help identifying THE KUMU canoe builder…talking to a scattered group of surfboard builders is an interesting quest but…when its likely that You are looking at a heavy investment of time and materials not counting enormous amounts of man hours the necessity of a highly evolved design is imperitive .In 1977 a friend asked me to inquire about Steamboat’s new surfing canoe and then it was 5000.00 for the cast glass hull alone, Ill bet thats just materials now .The canoe clubs have fund raisers weekly to get their financial leg up on the rung just to buy a hull un finished…Buy the new bradley or whatever and finish it off modify it with a little q-cell that you can take off and on modifing til its tits and then cast that nd sell it to the next club you will make money enough to finish the cast hull…42 feet is a considerable cash front call the getty foundation.get a grant…and build in ensenada or san quentin baja california …you are on an enviable dream quest…get higher consel they are out there … ambrose…try Nick Beck…hes building a producton sailing canoe in california I lost the bookmark when my hard drive crashed last year.It looks cool and it sails bitchin.

*ISBN0-910240-19-1 Bishop Museum Press Honolulu Hawaii

Oh yeah dig on the Haida(sp) northwest indian canoe reproduction canoe and any Chumash info the likelihood of their thousands of years of design evolution will be enlightening and inspirational …I know I’m a Hack and the real canoe builders are the top of the pecking order…oh yea JOE QUIGG KNOWS who …you better believe that

9

Ah… a couple of thoughts. Maybe a few as my morning coffee starts to work…

The fine entry ( good boat term there) is great for a displacement hull under limited power ( six guys, 1/4 HP each max, and that’s in sprint mode ) and it’s low drag and all…but it’s gonna lead to broaching and, as you’re describing, slower water speed in the trough and higher on the wave face will give you some interesting things happening…and that interesting is used in the same way as the old Oriental curse may you live in interesting times. Your bow won’t plane, though it needs to, and your midsection and stern are trying to pass it with some ugly results.

But, that’s with a fine entry in a horizontal plane. That is, it gets very gradually wider from a very narrow bow. How about ( looking at the paddleboards again for ideas) a fine entry in a vertical plane; it starts out shallow and gradually becomes deeper and wider though mostly deeper forward so it won’t catch and broach you and instead it’ll lift, the hull would pivot around someplace back aft, towards the midpoint so it could be slewed around by the guy in the stern instead of tending to broach or pitchpole around the bow.

Use a fin or several aft ( there’s a guy called Grahame King building wooden rowing shells with an interesting contour and multiple fins) and maybe a canoe stern type of arrangement. You’d probably be best off losing some length and gaining some width, as otherwise you have a hull that’s gonna be bridging the curve of a swell unless it’s awfully big, sinking the bow and stern while the midsection is unsupported.

Looking at the numbers, if 42’ x 18" or so works for displacement volume to support the crew and give the thing enough stability in the fore and aft ( pitchpoling) sense, then ( very rough numbers) 36’ x 24-30" will work too, maybe even a bit shorter. Not as deep in the water ( a plus) wetted area ( wetted area = skin drag) would go down, for planing the equivalent of wing loading ( lbs/square foot of horizontal planing area) would go down as well, so it’d plane easier. The trick would be to have as little rocker aft as you could get away with. For some reason the low volume kayaks they use on rapids came to mind… plenty kick in the nose, flat aft, you can slew them around too.

On a similar note… I once had a ‘surf ski’, of the long, narrow paddles-real-fast variety. It would ‘surf’ ripples. Paddled real easy too, but if you got it into a larger swell it’d either stick the bow in and pitchpole ( and that thing looked like a Polaris missle taking off when it pitchpoled) or else spin out/roll over if you had an angle on it.

Dunno, kinda random thoughts but maybe they’ll give you some ideas.

doc…

10

oh brothers forgive me for not coming to you sooner. you guys are a breath of fresh air. sweet thoughts. let me challenge a couple. not to debunk them but hopefully to grow them.first of all the idea of adjustment is awesome. what comes to mind is i hypolon (material used on the avon type boats) skin on the bottom of the canoe that would act as a air bladder. in the rough it would be deflated and flat for a nice planing surface. but in the flat it could be inflated to create a round hull shape. doc could you please explain what you were saying about the bow/entry? i’m sure it ‘s just me but i had a hard time following it. what i was thinking of doing was to create a wedge shape. so of you were to look at the canoe from plan view you would see the sharp nose. from the side view you would see the gunnels basically flat and following the horizon but the bow would have nose rocker. there would also be tail rocker. the entire bottom surface would be flat right up to the forefoot (where vertical line of bow meets horizontal line of hull). the “rails” would then be rounded. you may be right that a fine entry is doomed to cause broaching but if the bow had enough nose rocker then i may be able to avoid it. on the other hand it would greatly reduce my water line and therefore my flat water speed. as far as the rearrangement of the displacement volume i have a couple of constants i cannot avoid. the inside of the gunnel dimensions are about 16". this allows the paddler to lock his hips in. we are going to add foot blocks with straps to add greater support. also the paddling technique is such that we need to keep the boat as narrow as possible. this allows for a more powerful stroke. getting back to the f-14/adjustable stuff (brilliant) it may be possible to have an adjustable bow. if i could have a long water line/fine entry for flat conditions and then pull the nose up and possibly widen it for rough conditions i would be getting the best of both worlds. the question is can it be done in an cost effective way. existing canoes have a weight limit of 400 lbs. our class will probably be 225-250 lbs. we could go lighter but the cost of building a sea worthy vessel goes out the door when you have to use exotic materials. i, personally, have built 22’ one man outriggers at sub 20 lbs. and my 14’ paddle board was sub 14 lbs. (sorry i am bragging a little hoping you all will be impressed) anyways we are talking about a vartm type process infusing vinyl-ester resin into an e glass/pvc foam sandwich. you may be a bunch of scattered surfers but you are looking at the problems with an unbiased eye. existing canoes are in many ways hindered by the traditionalists and the governing bodies that over see them. this is great if you want to protect tradition, culture, and a heritage. as important as all that is we are not concerned with that. the key players in the outrigger world are mostly in hawaii. they will have an extremely difficult time in having an “unlimited” class because of the afore mentioned reasons. the hawaiians have lost so much of the culture that they are very leary (and rightfully so) of losing any more. therefore the builders/designers have their hands tied in the design arena. the swaylock’s crowd rocks!!!

11

how about bow planes to solve your potential pearling problem, then you could focus on maximizing flat water speed… or is that too non-traditional?

12

Nah, man, not your problem not understanding what I was driving at, more like mine for a lousy explanation. So, let me follow it up with a couple of lousy drawings;

May the shades of Colin Archer and Capt. Ben Pine forgive me for attempting to sketch boat lines with a laundry marker so they’ll show up on a scanner.

In any event, on the right you have my take of the half-breadths ( think of them as slices side to side) of a traditional outrigger canoe. Sharp-bottomed, not a helluva lot of deadrise ( rocker) or drag ( a straight line going downnward from bow-stern. Fast in flat water, yeah, not especially stable on its own, definitely. Push the bow down and it’ll go down very nicely. Most of the hull is in the water.

Now, on the left, you have the half breadths of a typical hull from a typical surfboat or whaleboat. Fairly fine entry, they rowed fast, but they were also meant to spend quite a lot of time either going way above hull speed or in surf. The bow ( and stern - most of 'em were double ended) had some flare so that if you pushed down the bow the floatation went up fast as the bow went down. The parts of the boat in the water most of the time were fairly flat, so they’d plane pretty well, but they’d also row well.

Some whaleboat photos here, http://www.whalingcityrowing.org/wc-show.htm and a fairly modern Australian surfboat at http://www.bilgolaslsc.org.au/gallery.html. You’ll see the similarity. I’d expect you could stretch the lines some, narrow it up a little, but keep that full bow above the waterline to keep her from pearling or broaching.

Width need not be such an issue, could go wider by tossing in some healthy foam blocks to make something like cockpits.

Now, the narrow wedge with no flare, just rocker…that might have some problems when running down a sea,

Dunno, I need to find some better drawings or do some, but maybe this will give you more of an idea of what I’m thinking about.

Also…for changing the rocker, let me toss in an older idea. Older? Yeah, back to Egypt and Nile boats, where they had a kind of strongback made of cable which could be tightened and pull the bow and stern up relative to the center. On a reasonably flexy boat, this would tend to push the sides out, which would also make it surf better…

this is kind of a fun concept to play with… also, may I suggest that the Surfboaties ( an australian surf boat racing forum) at http://groups.msn.com/surfboaties/southportbeach.msnw might be worth asking about this- they do something kinda similar.

doc…

doc…

13

Keith, in this situation(design phase) i don’t care about tradition. performance, performance, performance. the bow wings are a good idea in that they eliminate pearling but that doesn’t eliminate the broaching. i need to either create an adjustable rocker like Doc is talking about or have enough rocker so as to keep the nose/bow above water most/all of the time. it is a complicated problem. it would be easy to make a canoe that either surfed or was fast in calm waters. but, oh how to do both? Doc keep in mind that t he paddle stroke/technique takes place right next to the side of the boat unlike the austrailian surf wherrys that use the long oars. the geometry of the stroke is such that as you move away from the side of the boat you lose power.

has anyone seen the concave the aussies are putting on their paddle boards? why do they do that and what does it do? (jamie mitchel from australia will catch these open ocean swells on his paddle board and ride them for what seems like150-200+ yards. it/he is awesome? ) oh yea, Doc i almost forgot to respond to your sketches. did you show those to graeme king? ha ha just kidding. but seriously, the water line on the outrigger is even more extreme than the row/surf wherrys. you got it close excpt you need to accelerate the rocker much faster. the traditional modern canoe will have 4-6’ of bow and stern out of the water in the flat. i suppose i could run a cable down the gunnels and pull the rocker up. it is a good idea. i’ll have to think more on that one.

14

Yeah… Graeme King ( he do spell it unusual) would prolly have me shot for those. Never met the man, though I like his work.

While the anti-pearling wings would tend to allow broaching, maybe some strakes above the normal waterline but below gunwale height would kick the bow up and out when they were immersed. Also, flare in the bow would accomplish the same thing, kind of a wineglass section there if that terminology makes sense.

Width is gonna be real useful. You need a certain displacement to carry your paddlers, but your choices are a deep, narrow hull that won’t surf too well at all or a wider, shorter hull that will. So…who sez the paddlers themselves have to be on the centerline?

Put a bulkhead right down the middle, paddlers can wedge against that and the hull sides, seats attach to it and so on. While you get a decrease in waterline length and a consequent decrease in theoretical hull speed, the question is are you running up against that in actual use? Plus with 4-6’ at each end of a 40’ hull out of the water in use, wayull, you have an effective LWL of 28-32’. Better off with a shallower hull, wider, more paddleboard form, that’s immersed for all its length and using buoyancy and hull form to work better in short or steep seas rather than smacking into 'em. For instance, when a banana shaped hull hits bow or stern into chop, well, it’s kinda like hitting a bump or a curb - whack, you lose speed and momentum. A shorter hull tends to rise and keep momentum and speed much better… rocker is nice, but too much rocker or depending on lots of rocker and a round hull probably isn’t gonna help a lot.

dunno, that’s my take on it. be worth doing some model testing and mebbe some half-scale or similar trials…

doc…

15

thanks for the input Doc. unfortunately (fortunately) we paddle on both sides. that is to say we paddle 15 or so strokes on the starboard then switch over to port. sorry, i should have mentioned that. even though the wider boat with bulkhead isn’t doable you have me convinced that the wider the better for surfing. in reality i am working in a very small envelope. if i were to push the width out 1-1.5" that would be quite dynamic. i just wonder where the point of diminishing returns is at. in other words at what point does the width start to create so much wetted surface area that it is a detriment? you have also got me wondering about a shorter canoe. the tahitian canoes (fast in flat water) have a water line of about 40-41’. the hawaiians (the surfers) are like 36-37’.

so let me take it back to everyones forte’. flat and wide makes for better surfing. right?! but how badly does it suck to paddle a short- board? is that because they just don’t have the floatation? i shaped a 6’ 0" balsa board that was 3.5" thick and it paddled pretty well. i was hoping to have the boyancy of a long board with the performance of a short board. but in reality it didn’t paddle like a longboard. therefore would the same principle apply as you increase the size/length of the craft?? a paddle board is only as wide as it is because if it were super narrow it would be faster but you would flip it if you knee paddled it. we have experimented with some narrow round bottom paddle boards but they are to difficult/impossible to knee paddle. but the canoe has the outrigger. so is wider really better. if it is why aren’t surfboards wider?? just asking, hoping to be educated.

16

Well… got me thinking that maybe a change in paddling technique might be in order? Or is that changing sides bit to equalise strain on the paddler’s muscles on left and right sides?

Wetted area doesn’t have to go up with width. You need a volume of ( call it ) V to float a weight W…and a long, skinny cylindrical shape of volume V is going to have a large surface area compared to a hemisphere of volume V or, say, a cube of volume V. Wider ( and shallower ) might well give less wetted area and less skin drag. Given a wider hull, it’ll float that much higher. Given a wider profile all the way down, not a vee bottom, it’ll float higher too.

Now, surfboards are essentially flat bottom planing hulls. Vee, belly, concave…they’re relatively minor compared to a round or pretty much vee-form canoe hull, the surfboard bottom is basicly flat with some variations. They are optomised around surfing, paddling speed isn’t the main consideration.

In the same vein, a lot of rocker in a flat bottom hull ( while it’s being paddled ) presents a squared-off bow section ( like a pram ) to the water. Like a flat bottomed skiff with a lot of rocker in the bow ( some of the Alaskan dory types are good examples) they tend to rise up and when they plane, like all planing hulls, you only have enough area in the water as the weight of the hull and payload and such require to generate sufficient lift to pick the whole thing up to a certain degree, which requires a certain amount of power. Look at a planing hull when it’s planing, well, a lot of that hull is out of the water.

Now, within broad limits, a surfboard behaves the same way. A surfboard isn’t all in the water when in use, only part of it. Look at a pic of a board travelling along a wave, only so much of the bottom is actually in contact with water. Nobody has measured it, but I’d be willing to bet that that area stays pretty much constant no matter what the direction travelled relative to the wave, providing the speed is the same. That is, at ( very arbitrary figures) at 20 mph you have 3 square feet of board in contact with the water, no matter if you’re headed straight down the wave, across it or whatever. Not necessarily the same three square feet, of course, but the area is prolly quite constant.

and that’s about all the thinking I have for right now, it’s late here on the Eastern coast and I gotta get up tomorrow and do a little house carpentry…

doc…

17

I was actually thinking of below the water line, adjustable bow planes (like a submarine) not bow wings, which are fixed angle and above the water line… still not sure if that solves your problem but it would be interesting to try.

18

very interesting thoughts gentlemen. yes Doc, we switch sides to avoid fatiguing that muscle group. i see your point now ,keith, about the bow wings. it is an interesting thought. my first reaction is to dismiss it on the grounds that if i were going to have wings i might as well have a wide flat nose. but then i have to ask my self would that really be the same, and now you’ve got me thinking. and that is just what i need. hey Doc what part of the east coast are you. there might be an outrigger club in your area. not many on the east coast but a few. it is brother to the surfboard ya’know? makes for a well rounded waterman. sorry i think i was coming close to proselytizing!!!

19

Nothing wrong with a little recruiting. Hey, maybe you know a guy called Rick Ciaccio, bodysurfer, kneeboarder and outrigger paddler from the Wedge area.

Me, I’m up on Cape Cod and my latest boat is more along the lines of slow and easy and very flat bottomed. Sail with an auxiliary outboard, but I’m thinking I might have to make some 10-12’ sweeps to get her around when the wind isn’t happening.

doc…