Hull Design - Rear Quartering Wind

[Guest]

Not done blabbing about decked canoes yet he said, grabbing a tape measure and wandering the racks.

My guess is that I'll modify my solo hull design by making it shorter, with more rocker, asymmetrical with a more full tail, and low decks. Once I paddle and play with it, I'll revisit adding a retractable skeg or rudder.
Ideally I'd have the time to make multiple hulls in order to experiment but that's just not going to happen anytime soon.

Yellowcanoe mentioned the rocker on the Monarch. Looking at the decked canoes on the racks, except for the Sockeye they all have at least a couple inches of rocker at each end, some sterns a bit less. But that rocker is gentle and near continuous, stretched back 3 feet or more at either stem.

Having said all that, whadda I know - the ancient Sockeye, which is nearly the antithesis of every design element mentioned; deep stern stem, rocker near the stems and not elongated, etc is one of my favorite decked canoes. It is in many regards a more standard canoe hull shape with a deck, 16 feet 6 inches x 30 max beam, 14 ½” center depth at the top of the cockpit, short stem rocker and deeper than usual decked canoe ends.

And the Sockeye cockpit is generous, 21 x 81inside the coming, which makes entry/exit comfortably canoe familiar. The coming sides along cockpit need to be wide enough to deflect waves and spray, but the actual cockpit width makes a big difference to this big guy. The Sockeye and Monarch both have wide-ish cockpit openings, 21 ½ inches on the Monarch. Much the same for the Vagabond and Kamerad, both 20 ½ inches.

The Optima, which is otherwise a truly wonderful decked canoe, is only 18 inches wide between the cockpit coming sides. It is not canoe-like for entry/exit, and kind of a PITA at awkward landings, very much like getting in or out of a kayak. There’s a reason I don’t kayak; getting into/out of a 30 inch wide canoe is a lot different than getting into an 18 inch wide cockpit.

For my wide and unlimber load I wouldn’t want a cockpit less than 21 inches wide. If you are skinny and gymnastic YYMV.

The deck and side coming design may be the most interesting/challenging aspect. The hull waterline performance can be deduced from experience and existing designs, but mid-ships wave deflection of partial decks is more of a what-works-in-harmony crapshoot.

I do not understand that beyond observational experience. The Monarch and Optima are both flared out along the sides up to the high cockpit seam and do the best job of handing and absorbing side waves without bobble or splash. The Vagabond and Kamerad are both more slab sided and get pushed around more and fling more spray.

What else in terms of cockpit design? The Vagabond, despite being originally designed as a Tandem, is only 11 inches deep at center, which is too shallow in waves even as a day tripper solo and must have been awfully wet as a tandem. 11 inch deep is not enough when the waves kick up, even at a 220-280 lb burden. All of the others are in the 13 to 14 inch deep center range, and those couple extra inches make a huge difference when things get sloppy.

Cockpit length-wise all of the decks extend 5 feet +/- from the stems. As a personal preference I like having enough open space behind my seat for some easily accessible gear storage, even on day trips. For decked canoe tripping purposes having room for a blue barrel laid down lengthwise is huge boon; that being the only place available for barrel storage (or large dry bag/pack).

Last word on decked canoes. For today anyway J

A decked, unbulkheaded canoe is a PITA when swamped. OK, worse than a PITA, it is a long and arduous chore to empty. For day paddling use the more float bag you can secure under the stems the better. That under deck area is a weird shape for most standard canoe floatation; sometimes narrower dual split bags better fully occlude that under deck volume.

Please post as you progress with the design, build and trials. I will be very interested to follow along and hope to learn something.

 

[Glenn MacGrady]

Think of it this way ...

Your boat has a centre of lateral resistance below the waterline; this is the point around which the hull would rotate when pushed from the side. In a perfectly symmetrical empty boat this would sit dead centre. This will move forward or aft as you move load forward or aft. This will also move forward or aft as you add skegs, or any other form of asymmetry.

Your boat also has a centre of lateral resistance above the waterline; let's call it the centre of effort. This is the point around which the hull above the water would rotate when pushed by a breeze. This will move forward or aft as you change fore/aft symmetry or move the paddler fore or aft.

If the centre of effort sits fore of the centre of lateral resistance the boat will have lee helm; it will want to turn downwind.
If the centre of efforts sits aft of the centre of lateral resistance the boat will have weather helm; it will want to turn into the wind.

A paddler can change this dynamic by moving his or her body aft (causing more weather helm), and by loading the boat to move the load forward (more weather helm).

A designer will aim for a neutral helm (or minor weather helm) as he/she wouldn't want to be guilty of designing a boat that only went upwind, or down!

What Trevor is calling the centre of effort is what I called the center of (aerodynamic) pressure (COP). It's the mathematical point where the wind impact on the hull is focused. We can think of it as the "finger of wind" pushing against the hull at one point.

The center of lateral resistance (CLR) can be thought of, somewhat technically incorrectly, as the pivot point of the hull.

Using this terminology, imagine wind coming at an angle from the rear quarter. If the wind finger touches the hull forward of the pivot point, the wind force will push the bow downwind (= "lee helm" = "lee cocking"). If, on the other hand, the wind finger touches the hull astern of the pivot point, the wind force will try to swing the stern around and push it downwind (= "weather helm" = "wind cocking"). If the wind finger touches the hull right at the pivot point, the wind force will want to blow the hull sideways downwind. Which of these results do you want, since you have to keep in mind that the wind will come at you not just from behind during a canoe trip, but from all different directions?

If we had an empty canoe hull with no paddler or gear in it, the way to design a lee cocking hull would be to have more hull sail area forward of the pivot point than astern of the pivot point. If you want a wind cocking hull, you would do the opposite. To have a wind neutral hull, the sail area of the hull should be equal fore and aft of the pivot point.

But it's really much more complicated than that. First of all, the pivot point moves forward as the canoe gains forward velocity. (Google "peripatetic pivot point".) Second, the wind finger (the center of effort or pressure) is affected not only by the hull shape, but by the shape of the paddler. Unlike a sailboat where the area of the sailor is trivial compared to the area of the sail, the area of a solo canoe paddler's body is very substantial compared to the area of a solo canoe profile, especially a small solo canoe. Hence, analysis of the position of the wind finger must take into consideration the size and position of the paddler in the canoe. Third, the position of the center of mass (the gear plus the paddler's body) can affect both the position of the wind finger (center of pressure) and the position of the pivot point (center of lateral resistance).

Let's look at the common advice to move your paddling position astern when your canoe is wind cocking (turning into the wind). We now know the theoretical reason to do this is to get the pivot point shifted further astern so it will be aft of the wind finger. Moving your body mass astern will indeed shift the pivot point astern. However, your body mass is a large part of the total wind profile of the canoe+you. So, if you move your body astern, you will move not only the pivot point astern, but you will also move the wind finger point (center of pressure) astern at the same time. Therefore, the strategy of moving your body astern to reduce wind cocking (= increase lee cocking) may not be very effective. Complicating the picture even more, the strategy of moving your body astern will push the stern further down into the water and raise the bow up out of the water a bit, thus increasing the hull's sail area in the bow. What the total result will be is . . . who the heck really knows!

In order not to shift the center of pressure aft as you shift the center of lateral resistance aft by moving the center of mass astern, a better strategy is to shift your gear mass aft while you stay in the same paddler position. Assuming your gear always stays below gunwale level, this strategy should shift the pivot point aft without changing the canoe+you wind profile or the wind finger point.

As to rocker, the absolutely worst I've ever been out of control in a stern wind was when I on a lake in a highly symmetrical rockered whitewater canoe. Even though that 5" rockered canoe can easily spin 360 degrees with a paddle flick, in that strong stern wind the canoe was pushed sideways downwind, and I couldn't straighten the canoe out with any amount of paddle manipulation or physical strength. Fortunately, the wind was blowing in the general direction I was going, so I had to let myself be blown along sideways with and over the whitecaps and limit my paddling to avoiding being flipped over.

All in all, my preference for an all-purpose canoe to handle all sorts of water conditions and wind directions is a swede form waterline, with an asymmetrical rocker line (less rocker in the stern), and with fuller flare in the bow and a pinched volume in the stern. I might even use a recurved stern as in this Lotus Caper:

My Hemlock SRT is of this shape (not including the recurved stern), but it can be difficult in quartering stern winds. The Swift Osprey is also of this general design, but paddlers like Turtle report similar difficulties with quartering stern winds. However, the performance of these open canoes in most other circumstances makes up for this difficulty. Since they are open canoes, it would be a chore to install and use a retractable rudder, which is still the tool I would most recommend for a decked canoe.

Virtually all expedition paddlers use rudders with their decked canoes. They effectively work by shifting the center of lateral resistance (pivot point) without all the almost incalculable complexity of shifting the center of wind pressure or the center of mass.

 

[Alan Gage]

That was a great post, Glenn.

Alan

 

[Bothwell Voyageur]

Thanks for this discussion. It has been very interesting to read. I have had terrible problems sometimes with my Wildfire, stretches when it happily turns toward my paddle side when the wind is coming over my shoulder. One issue of have is that most canoe packs are too wide to slide them back into the hull. I am loathe to have a narrow pack just for the solo canoe but that may be the way to go.

 

[Canotrouge]

 

[memaquay]

Bart = Glenn
Ralph = Me

To be truthful, I usually just paddle harder and think about beer.

 

[Jim Dodd]

One last suggestion !
Square Stern.
Eliminate that fish tale that causes all the trouble !

Jim

 

[Guest]

I like the idea of the temporary test deck on my current hull too. I'll try that to see if my primary enemy is wind, or hull design. Good idea, thanks.

I like that temporary decks waterline hull test too. The experiment could be as rudimentary as taping some plastic sheeting or tarp to the hull on a windy day to see how the waterline shape works when decked. And who knows, DIY partial decks for your open canoe might be in your future.

Bow partial with paddle pocket and drainage baffle (from Cooke Custom Sewing):



Bow and stern partials with center storage cover snapped in place (also from CCS).




Partial covers can come dang close to decked hull effect, and offer definite on-off advantages, weight reduction over a hardshell deck, roof rack transport & storage ease, even using just the bow cover and leaving the stern open, which can be mighty nice when loading/unloading at awkward landings.

Load the bow and chuck the rest in the stern to reorganize at the next cobble bar.



Can’t do that with a hardshell deck.

Thanks for this discussion. It has been very interesting to read. I have had terrible problems sometimes with my Wildfire, stretches when it happily turns toward my paddle side when the wind is coming over my shoulder. One issue of have is that most canoe packs are too wide to slide them back into the hull. I am loathe to have a narrow pack just for the solo canoe but that may be the way to go.

We have partial fabric decks on a soloized Penobscot and Wilderness, and full covers on a tandem Cronje. I do not think it is just my imagination that those canoes all seem to perform better in the wind with the covers in place.

 

[Glenn MacGrady]

Thanks for this discussion. It has been very interesting to read. I have had terrible problems sometimes with my Wildfire, stretches when it happily turns toward my paddle side when the wind is coming over my shoulder. One issue of have is that most canoe packs are too wide to slide them back into the hull. I am loathe to have a narrow pack just for the solo canoe but that may be the way to go.

When paddling single blade in wind, it's important to be a proficient paddler on both sides of the canoe. Ambidextrous. That's very hard to achieve, but it's an important part of advanced paddling education. Practice, practice, practice on your weak side. For years and years and years.

Another dynamic that affects open canoes in wind is the "scooping" affect of the wind inside the hull, which is hard to predict. The canoe will react differently in quartering winds from the front or rear depending on whether you heel the canoe into or away from the wind. Radical hull heeling in wind is also an important skill to experiment with and learn -- just as radical hull heeling is a crucial skill in river and wind waves. Go out on a lake on a windy day just to practice paddling straight while heeling to your left rail and your right rail in different wind directions. And then do it while paddling lefty and righty.

Other than a rudder, there is no device or gimmick that's going to make paddling in wind easier. (Maybe canoe covers do slightly, but I detest them as heavy, clumsy and outright dangerous in whitewater.) Practiced paddle skills, side switching skills, hull heeling skills, and weight shifting skills are your reliable weapons in any canoe hull.

But there comes a windy time when the proper skill to employ is to get off the water, tie up your canoe on shore, light up a Cuban, sip some Uncle Lee's decaffeinated green tea, and stare at a book, the sky or your belly button. That time comes fairly early for me. Wind blows.

As for the Wildfire, I don't consider it a good extended tripping canoe on the water. It's too short, too shallow and too lacking in space behind the paddler -- unless you are very short and light with very compact gear. My Duluth pack, which is my heaviest gear mass, cannot fit behind me in my carbon Wildfire, so it has to go in front. That shifts the pivot point significantly toward the bow, making the trim bow heavy, and as a consequence, makes the boat an unpleasantly strong wind cocker. If you're doing a lot of portaging, then the size of the Wildfire can be tolerated to take advantage of its light weight -- and there are paddlers who trip in even smaller canoes when portage weight becomes the primary consideration.

 

[Canotrouge]

One last suggestion !
Square Stern.
Eliminate that fish tale that causes all the trouble !

Jim

Like the one Mem is building... With a little motor and done no more trouble with he wind!!!

 

[Guest]

Other than a rudder, there is no device or gimmick that's going to make paddling in wind easier. (Maybe canoe covers do slightly, but I detest them as heavy, clumsy and outright dangerous in whitewater.)

Some paddlers like spray covers, some detest them. While I agree that a full cover would be outright dangerous in whitewater the OP’s question was dealing with winds on open water, an area in which I do believe covers aid efficiency.

Even there the potential entrapment issues and loss of ability to move about the boat with full covers are the principal reasons I prefer partial covers. Other reasons; easier to get in and out of the canoe, easier to access gear on the fly while paddling. Add to that when I first began considering covers I noticed that many photos of spray covered canoes, in actual use on the water, show the boat with the covers rolled back to form an open “cockpit” area.

While partial covers are of little help when waves begin crashing over the gunwales I, like Glenn, take that as a sign to get the heck off the water. But even partial covers are helpful in occluding open portions of the canoe from rain, spray, paddle drips and the occasional errant wave. And wind.

Heavy? The partial covers for the Wilderness are 400 denier urethane coated nylon packcloth. Including paddle pockets bow and stern and four paddle straps those covers weigh 1 lb 11 oz. For the benefits provided I’ll happily accept that minor weight. The larger Penobscot covers, including a center storage cover are still under 3 lbs. Either packs into a ditty bag the size of a small bread loaf.

Clumsy? Not in any definition of the word.
“Awkward in movement or in handling things”? They don’t move much and handle things just fine.
“Done without skill or elegance”? They are Cooke Custom Sewing covers, skillfully crafted and refined through years of experience and wilderness travel.
“Difficult to handle or use; unwieldy”? If the initial installation is done properly they are pretty simple to put on/take off. Some folks prefer the Northwater system of hooks and line/bungee, which is a bit more work in the initial install but even easier to use, especially with an over gunwales load.

Some paddlers like spray covers, some detest them. Guess where I stand.

 

[Glenn MacGrady]

Some paddlers like spray covers, some detest them.

I agree with that. Same thing's true with many aspects of canoe gear and technique.

I'd like to mention one technique that should completely defeat wind cocking and lee cocking. You simply accept what the wind is doing to your canoe and do a MacKenzie reversal, which is a 180 degree seat switch. In other words, you spin around on your seat and face the stern instead of the bow. Thus, if your bow was wind cocking in the stern quarter wind, your "new bow" will be lee cocking because your COM, COP and CLR have all stayed exactly where they were, except you are now facing the other end of the canoe.

The MacKenzie requires room to do it, and is easier in an open canoe than a decked canoe and from a kneeling position than a sitting position. And it will be facilitated by a bi-directional seat such as the Conk double contour seat (available from Hemlock Canoe Works).

You can see a tandem MacKenzie reversal at 3:50 of this video with return switch at 4:10:

 

[Guest]

You can see the MacKenzie reversal at 3:50 of this video with return switch at 4:10:

They never seemed to actually get anywhere. . . . .

Cool move though.

 

[Glenn MacGrady]

They never seemed to actually get anywhere. . . . .

Cool move though.

As you well know, the tandem team was doing the MacKenzie reversal simply as an artistic demonstration in a small rectangular performance venue. The maneuver is named after Tom MacKenzie, the recently deceased wooden boat builder, freestyle pioneer and ITE, and canoe symposium organizer.

Bill Mason much earlier performed the same seat reversal in the middle of rapids. At about 1:18:35 of this video, Mason seat switches when his stern is swept downstream rather than battling to get the canoe turned around. Doing a seat reversal in wind currents is the same tactic as doing it in water currents. Mason's video shows one advantage of running solo in a big tandem canoe rather than in a constricted and tippy solo canoe.

 

[Guest]

Mason's video shows one advantage of running solo in a big tandem canoe rather than in a constricted and tippy solo canoe.

So I do have something in common with Bill Mason. I’m so proud.

 

[yellowcanoe]

And if not in rapids simply let the bow go into the wind and paddle backwards. Or if the bow wants to stay in the trough perpendicular to the wave direction of travel you can do quite good correction going forward but not hard enough to delay downwind drift. Bow into the wind is quite stable
The MacKenzie Reversal doesn't work in asym boats. At least real well. The more v gaped skedded bow can grab and purl
Roy and Peg in the video are paddling a Duet. The wood canvas version of the StarFire

 

[PortlandBCS]

Coming back to this discussion after a while. I love all of the fantastic responses and analysis. I've since used the original hull and cut it down to make my decked canoe - it is indeed nearly impervious to following winds.
As an addition, I now recall that, surprisingly, one of the best solo's I've paddled in following seas and winds was a Wenonah Prism. I was caught out in this boat when a sudden storm blew in on the Columbia river, and had to surf it back to the put in, about 5 miles. It was very easy to control, and even when I let it get pushed off a wave, was very easy to recover. I played with it a couple of other times in more moderate winds and never had an issue. Other dislikes forced me to pass on that boat to someone else, but it's wind characteristics were actually quite good. I'll have to think about what it is with that particular hull that gave it this wind friendliness. Any similar experiences or ideas?

 

[Guest]

I now own a Colden Nomad solo. I'm calling it my "wind magnet" because all 3 of my trips last year turned out windy. Fortunately, this boat is surly the best solo in the wind I have ever paddled even in rear quartering wind. I love this hull for lakes.

 

[gumpus]

Coming back to this discussion after a while. I love all of the fantastic responses and analysis. I've since used the original hull and cut it down to make my decked canoe - it is indeed nearly impervious to following winds.
As an addition, I now recall that, surprisingly, one of the best solo's I've paddled in following seas and winds was a Wenonah Prism. I was caught out in this boat when a sudden storm blew in on the Columbia river, and had to surf it back to the put in, about 5 miles. It was very easy to control, and even when I let it get pushed off a wave, was very easy to recover. I played with it a couple of other times in more moderate winds and never had an issue. Other dislikes forced me to pass on that boat to someone else, but it's wind characteristics were actually quite good. I'll have to think about what it is with that particular hull that gave it this wind friendliness. Any similar experiences or ideas?

Here's one link that may give hints around why your Prism handled well in the wind. Just FYI the Swift Osprey is well known for being a bit hard to control in quartering tailwinds so it may be a good boat to compare/contrast with the Prism.

https://www.scribd.com/document/292341641/Pivot-Point

The article says that 1) length to beam ratio 2) beam to draught ratio 3) block coefficient and prismatic coefficient 4) center of buoyancy all affect handling. I am not an expert in any of these factors. But the Prism center of buoyancy looks to be around dead center while the Osprey's is way back from center...Osprey has very little volume towards the bow. I imagine that the Prism also has a higher prismatic coefficient which is supposed to make it easier to turn. I think the Prism would also run shallower in the water than the Osprey which may help it turn into the wind. I'm just speculating.